The Advanced Passenger Train Experimental

The Advanced Passenger Train – Experimental.

A condensed history.

By Kit Spackman

In the late 1960s, British Rail found itself in a quandry, both the Class 55 Deltic locos on the East Coast Main line (ECML) and the Class 86 25kV electric locos on the southern part of the West Coast Main Line (WCML) were able to travel at 100 mph and the increased speeds were pulling in large numbers of passengers on those two routes. However the internal airlines still formed strong competition on the routes to Scotland and the North and BR needed to increase the speed of its next generation of passenger trains to maintain its growth. This would not have just meant increasing the locomotive power as the then current wheel/rail technology was approaching its performance limits and any higher speeds would have increased the likelihood of wheel hunting, the lateral instability that occurs under such conditions, leading to high wheel/rail wear, an uncomfortable ride for the passengers, and in the worst case an increased numbers of derailments.

While higher speeds on the ECML would have been a matter of solving the instability problem and increasing the locomotive's power, the WCML north of Crewe exhibited a very different problem. In the hilly counties of the North West and Scotland the line was very heavily curved and steeply graded as a result of it being built very early in the history of railways. The line to Glasgow had been completed by 1849 but in those days it was only possible to follow the contours of the land, not only because of the lack of heavy earthmoving technology but the locomotives of the time were limited in power and were not able to climb very steep inclines. Changes in the routing to ease the curves and grades was not deemed possible in the 60s because of limited funding and the storm of public protest that would surely have arisen as a result of such proposals. That situation has changed little in the years to the present of course.

Oddly enough the potential solution to these problems came from an unexpected quarter of BR. In the late 50s and early 60s very little research was being carried out within BR but the higher ranks of the state run company saw a need for an increased level of research and some recruiting was carried out to improve the knowledge base within BR. One of the engineers recruited at this time was Professor Alan Wickens, who joined BR in 1962 and who came from the aviation industry. He brought with him a high level of experience of stability problems in control systems and within a short while started to investigate the fundamental problems associated with the hunting issue, but at this time the work was mainly directed at the problems exhibited by four wheeled freight wagons. Attempts to run the then current four wheeled stock at higher speeds had resulted in a considerably increased number of derailments and the Chief Mechanical & Electrical Engineer's Dept. (CM&EE) and the Chief Civil Engineer's Dept. (CCE) were blaming each other for the problem but not doing very much about solving it.

Professor Wickens' work involved a detailed study of the actual wheel/rail interaction, something that had never been done at this depth before and certainly not by using the techniques available to him from his previous work. The work involved both theoretical and analytical approaches and

1 eventually resulted in the building of a 4 wheeled test vehicle to evaluate the theories both on a roller rig and on the main line. This test vehicle, HSFV-1, fleet no. RDB511023, eventually ran stably at 100 mph on the main line and at 140 mph on the roller rig, proving the basis of the wheel profiles and suspension settings that had been developed. Incidentally HSFV-1 still exists and is currently located at the Electric Railway Museum at Coventry in the UK.

The work that had been carried out on the wheel/rail relationship was expanded into an idea for a research train which could run at much higher speeds on existing track due to the fact that it could run through curves at high speeds and remain stable. The corollary of this ability was the need to tilt the vehicle bodies in order to maintain passenger comfort, and other requirements for high speed travel were incorporated into the potential project, including light weight construction, high power/weight ratio, good aerodynamics and improved brake systems etc. Hopefully such an experimental programme could be developed into a high speed passenger train that would become BR's next generation of passenger stock. This idea was presented to the BR Board in the late 60s but was unable to be started immediately due to lack of funding within BR itself, but the Ministry of Transport eventually agreed, after much lobbying, to partly fund the project and it was given a go ahead in 1969. The Advanced Passenger Train, Experimental (APT-E) project was under way.

Part of the project included a complete new laboratory at the Railway Technical Centre (RTC) in Derby and a 14 mile test track converted from a closed main line running from Melton Mowbray to Nottingham, with a control centre at Old Dalby in north Leicestershire, in addition to offices at the RTC and staff recruitment to start the project. Initially much design work was carried out on the train itself and on test rigs to develop the various systems and components to be used on the train. The initial design concept was for a four vehicle articulated train powered by gas turbine engines driving alternators that in turn powered a bogie under each Power Car. Two Power Cars, one at each end of the train, sandwiched two Trailer Cars, one of which was to be an Instrumentation and Control Car and the other was to have a properly trimmed passenger compartment to enable evaluation to be carried out of passenger's reactions to high speeds in a 'real railway' environment.

The Power and Trailer Cars exhibited radically different methods of construction, the Power Cars being built from a welded steel tube space frame with an aerodynamic aluminium skin applied over the outside, the basic frames being built by Metro-Cammell in Birmingham. The Trailer Cars however were built on aircraft aluminium stressed skin principles by English Electric in Accrington, alongside the production line for the RAF's Lightning F6 fighters.

The four vehicle train was mounted on five bogies, two power bogies and three articulated trailing bogies, one under each joint between vehicles. The two power bogies, designated E1s, were of relatively conventional construction with welded steel box side frames with depressed centres and cross bolsters arranged in an H section. They had conventional coil spring primary suspension and vertical fluid dampers but their ratings and the wheel profiles were developed from Professor Wickens' work. The secondary suspension was by air springs, a new step for BR, but which proved successful and trouble free in service. The articulated bogies were anything but conventional, almost by definition as such bogies hadn't been used on BR metals for many years. They were designated as Swinging Arm bogies (SA) as one of their visual characteristics were the large triangular swinging

2 arms that located each individually self-steering wheelset. These wheelsets also used the high speed primary spring and damper specifications but the bogie used hydro-static fluid secondary springs which supported a long beam that connected the two vehicles, this being called the Steering Beam. The vehicles themselves were connected to the Steering Beam by means of a large diameter ball joint that transmitted the traction and steering forces along the train.

The initial power unit plans were for a derivative of a Rolls-Royce Dart turbo-prop to the used, one in each Power Car, but Roll Royce and BR couldn't come to an agreement on the technicalities of such an application and the choice eventually came down to the Leyland Truck gas turbine, initially using four of them in each Power car with a fifth turbine as an APU to produce the relatively large amount of 'house' electrical power that would be needed by the test instrumentation. The Leyland turbine produced approximately 300 bhp at that time, and used two large ceramic disc heat exchangers to improve the fuel consumption. The turbines each drove an alternator providing electrical power which supplied two traction motors on each E1 power bogie via relatively conventional rectifiers and control gear. These traction motors were similar to those fitted to BR Class 37 diesel locos, but higher geared to reach an anticipated 155 mph. The use of a relatively large number of turbines gave a certain amount of redundancy in the case of turbine or alternator faults, and this proved useful later in the programme. One advantage of using the Leyland turbine was that it was already designed to burn standard road diesel fuel and similar fuel was readily available throughout BR for its diesel locomotives.

The trailing bogies used a new concept in railway braking called the Hydro-Kinetic brake (HK brake) which worked like a car's automatic transmission in reverse in that a water/glycol mixture was pumped into the large diameter axles and in between two halves of a rotor/stator pair when braking was required and which was then pumped through coolers to be re-used. As the HK brake's performance diminished at slower speeds the bogies were also fitted with conventional friction tread brakes who's action was blended in with the HK brake as the speed bled off. The Power Cars had rheostatic brakes, driven by the traction motors and conventional tread brakes on the E1 power bogies and as the trailing end of the car was supported by the articulated bogie it also had HK and friction brakes at that end, giving four different braking systems on the same locomotive!

All four vehicles of the train had an active tilt system installed which could tilt the cars through 9 degrees in each direction under power and with 3 degrees more passive tilt available under dynamic conditions. Each vehicle used four vertically aligned tilt jacks, two per bogie, which were powered by an above floor mounted hydraulic power pack which turn was driven by an analogue control system each of which took lateral signals from body mounted accelerometers. The cross section shape of the body shells was determined by the need to tilt the vehicles and yet still remain inside the C1 loading gauge requirements, giving the characteristic oval shape of a tilting body train.

One decidedly different aspect of APT-E was the access arrangements for the train crew and test staff. The Power Cars had conventionally arranged outward opening doors for the driver but with a retractable set of stairs below the door arranged to fit flush into the inward tapered underside of the cab. The stairs could be lowered be means of a large handle mounted inside the cab or by pressing a recessed button in the outer casing of the stairs. This arrangement proved to be a source of some

3 problems as the train could not be allowed to proceed with the stars down and the tilt system active as the lowered stairs would foul the C1 gauge at any tilt angle above around 5 degrees. In addition there were two doors on either side of the auxiliary bay that gave access to the rear portion of the vehicle, but these were generally only used for maintenance purposes.

The Trailer Cars had no doors at all in the sides of the vehicle, access was only via doors in the vehicle ends. These doors led into the area between vehicles and immediately above the Steering Beam and that area was filled with a strangely shaped fairing entitled the Joint Module. The Joint Module was shaped to fit closely to the end structures of both types of vehicle on the train and incorporated a pair of outward opening doors on each side. The Joint Module rode on small tracks built into the ends of its connecting vehicles and was moved laterally during curving by a drive rod connecting it to the Steering Beam. In addition the floor of the module was constructed of a number of RHS sections that could take up a median position between the positions of its two connecting vehicles, and as they could vary in yaw and roll angles this floor could take up some very strange shapes. To improve the aerodynamics of the whole train the slots between the Joint Modules and their adjacent vehicles were sealed by a flexible rubber diaphragm that could theoretically accommodate both opposing full tilt and yaw angles at the same time, but this would prove not to work in reality and the diaphragms were removed early on in the programme. This resulted in a 150 mph air stream rushing past the open 6” gaps in each side of the Joint Modules during any high speed testing.

One of the first pieces of rail-borne hardware to appear was a two vehicle articulated test train entitled 'POP Train', standing for 'Power-0-Power'. Each vehicle of POP Train consisted of the space frame of an APT-E Power Car but without any skin and no power units, these being replicated by ballast weights, but each car had a small off-centre cabin which contained the auxiliary power packs and controls for the HK brake system, the tilt system, the friction brakes and the hydro-static secondary suspension located in the same positions on the POP vehicles as they would be in the proper Power Cars. The two car test train was supported on three SA bogies, the outer pair of which only had a vestigial Steering Beam as they were in the same position as the E1 bogies would be on the real Power Cars. These two vehicles were numbered PC3 and PC4 but carried no RDB series numbers at this time.

Metro-Cammell supplied just the bare POP Train structures to the Railway Technical Centre in late 1970 and all the systems installation was carried out by the relatively newly recruited Advanced Projects Division staff in the equally newly built Advanced Projects Laboratory building. The three SA bogies were build at BR's Derby Locomotive Works directly opposite the RTC across the main line to Nottingham, Leicester and London, a line that would become only too familiar to the test train staff over the following years. The various auxiliary systems for the POP Train had been developed in the APD Lab earlier in the project although they were far from refined and in some cases were found to be totally inadequate for their intended tasks. Nevertheless the various power packs and control units were installed in the two POP vehicles and commissioned as well as possible without actually running the train.

4 By late 1971 the POP vehicles were ready for track testing and to this end they were formed into a three vehicle train, with a laboratory coach leading the two POP cars. The laboratory coach, usually Lab Coach 3, RDB 975002, was fully instrumented to measure the various suspension and brake performance parameters and was able to supply a limited amount of house power from its on-board generator. In later months a fourth vehicle, usually a BSK or a BG, was added to the train with a much larger generator and this became the standard consist for the POP Train test runs. Initially POP Train was taken out to the Old Dalby test track at low speed and with only the hydro-static suspension systems powered up. Slow speed runs at the test track went without incident and both the braking and tilt systems powered up for further tests as the speeds were increased.

By this time computer and laboratory tests on the SA bogies indicated that all was not well with the design, due to weight growth and excess friction in the multitude of joints and pivots throughout the bogies amongst other issues. The initial POP Train tests were carried out using a Mercedes Unimog road/rail vehicle as a locomotive and as a result speeds did not exceed 20 mph but later BR's last remaining Class 17 locomotive was used and speeds were able to be increased markedly. However the SA bogie issues mentioned above were predicted to cause serious hunting at around 45 mph on the turned rails that were part of the test track's comprehensive collection of varying track types. The hunting occurred only too readily at the predicted speeds and the excess lateral accelerations on the POP vehicles caused both tilt systems to exceed their hydraulic capacity and fall over onto their bump stops. While no damage was caused the issues with the SA bogies were emphasised and work to cure the problems back at Derby was accelerated.

While the POP Train was undergoing its initial tests the APT-E itself was being assembled in the APD Lab, the Power Cars (PC1 & PC2) having their turbines, alternators and auxiliary equipment fitted and the Trailer Cars being instrumented in the case of Trailer Car 2 (TC2) and sound proofed and fitted out in the case of the half-length VIP compartment in Trailer Car 1 (TC1). At this time most of the auxiliary systems were at the same modification level as those fitted to POP Train, as were the SA bogies, but modified wheel profiles and suspension units were being built to ensure the POP Train's hunting problems not occur on APT-E (E-Train). None of the four E-Train vehicles ever carried fleet numbers in the RDB range and the Power Cars never carried a Class number either.

Externally the APT-E was finished off in a striking overall silver scheme with a broad Rail Blue stripe and was ready for its official launch in December 1971, but many miles of control wiring, pneumatic and hydraulic pipework and numerous supplementary systems remained to be installed and commissioned. This work continued throughout the winter of 1971-72 while POP Train continued its development runs on the test track, and the modified wheel profiles and spring and damper rates on the SA bogies proved successful and the train was able to run at considerably higher speeds. These speeds outstripped the abilities of the singleton Class 17 and haulage duties for the POP Train were changed to the 'Peak' Class 45s and 46s or Class 47s for most of the tests in the East Midlands.

By June 1972 E-Train was ready to run under its own power, albeit limited to movement within the RTC sidings and the first move eventually happened on the 29th June in mid-morning with only two of the turbines providing power. Six Derby No. 4 Shed drivers were allocated to the project and all were trained in the somewhat esoteric method of driving the APT on the short track length available in the

5 RTC yard. Numerous faults were overcome during this period and it seemed doubtful that the planned date of July 25th for the first run would be possible. However herculean efforts on the part of the APD team enabled some degree of reliability to be obtained throughout the train and enough systems had been checked out to enable the scheduled run to take place. The initial northbound run from the RTC to Duffield was run at only 25 mph in order to check on various bogie forces and on arrival at Duffield quite a time was spent trying to clear the numerous fault lights that had shown up during the short run, some of them real but many turning out to be spurious. There were so many of these that it was decided to cut the runs short and only the initial run was to take place that day.

While the general public tended to call the APT 'The Tilting Train' none of the tilt systems were operating on that initial run although both Trailer Cars had had their tilt systems commissioned and could have run with them active. The particular geometry of the APT-E's tilt system was unstable in that it needed hydraulic pressure maintained in the system for the vehicles to remain upright but it was not necessary for the system to be running to maintain them in that position as the tilt jacks could be locked-off by hand valves when in position and the system powered down. This was called the 'Tilt Passive' mode and it was in this fashion that the first run was made, the decision having been made at high level not to try too many new things at the same time. One fault which was never rectified was the failure of the Joint Module aerodynamic diaphragms, all of which ripped from end to end as the train traversed the first sharp curve as it ran into Derby Midland Station. They were removed on the train's return to the RTC and were never replaced.

Immediately after the first run total chaos ensued as ASLEF, the locomotive driver's union, blacked the train, and the prototype High Speed Train (HST) as well, as they had an ongoing dispute with BR management over enhanced pay rates for driving trains at over 100 mph and single manning for such high speed trains. Both the HST and APT had been designed with a single central driver's seat and were not intended to carry a secondman in the cab, but ASLEF saw this as an 'open door' to single manning throughout the network and took a hard line on the subject. In a short while it became clear that this problem wasn't going to be solved in very short order and this markedly impacted on the proposed test programme for APT. The situation wasn't so critical for the HST as it was possible to move the driver's seat sideways a short distance and install a secondman's seat alongside, but with E-Train that solution was impossible due to the narrow confines of the cab. The entire cab of E- Train had been designed as a crash cell in case of a frontal impact, and the first turbine bay was designed to collapse progressively to lessen any impact forces on the crew. Accordingly there was a large hydraulic piston mounted underneath the cab floor which protruded into the fibreglass nose cone to take the initial impact, and the cab had very large box girders on either side, both above and below the floor, to transmit any forces through to the Power Car structure. The upper box girders were mounted quite close to the driver to maintain the tilt clearance for the upper profile of the Power Car, thus preventing any re-alignment of the driver's seat.

After some time it became apparent that any testing work on E-Train was not likely to resume for a considerable time, and this was seen as a golden opportunity by the design side of the APD as it was obvious even before the first run that a comprehensive rebuild of various areas of the train was needed. This was not only due to the results of the POP Train testing but also because deeper knowledge of the behaviour of the train had become clear as it was built and because more

6 comprehensive studies of the various components and systems had been carried out with the aid of the powerful Elliot digital computer located within the RTC. In the short term the two E1 bogies under the Power Cars were removed and re-installed under the outer positions of the POP Train vehicles to enable some dynamic testing work on their characteristics to be carried out and TC1 was removed from the E-Train consist for a comprehensive study of the vibration characteristics of the Trailer Car, both at low and high frequencies.

POP Train itself had meanwhile been operating on the WCML itself, initially from Crewe to Carlisle and later from Carstairs to Lockerbie, both test sites incorporating steep banks at Shap and Beattock. The Crewe – Carlisle tests were undertaken using a Class 47 loco that had been cleared to run at 110 mph, and with an extended consist incorporating one of the CM&EE's Test Coaches as well, the CM&EE's Dept. having realised that such tests gave them a golden opportunity to gather some data at high speeds and which did not cost their department too much. Later test runs on the Carstairs – Lockerbie section of the WCML were run at even higher speeds as the 25 kV overhead wires had just been installed on that section and one of the three Class 86/1 electric locomotives was made available for these tests. The 86/1s had been fitted with the new APD designed wheel profiles, long stroke coil spring secondary suspension and uprated traction motors and gearing, and the original loco of the Class, 86101 had run at 129 mph with an aerodynamic nose fairing in late 1971. Unconfirmed reports exist suggesting that POP Train may have reached in excess of 130 mph during the Beattock tests, which should be considered in the light of the fact that it was still running in its open frame form with almost no aerodynamic qualities whatsoever!

Back in Derby the decision had been taken that the E-Trains' planned Rebuild 1 should be brought forward and would incorporate many upgrades that had been deemed necessary as a result of the deliberations having been taken after the first run. It was not deemed that this work should take place in the RTC though as there was not a long enough covered area to do the work even with the train in 3 car form. Arrangements were made for the work to be carried out in No. 7 Shop of Derby Loco Works across the main line from the RTC, but the train still had to be moved there and the ASLEF blacking made this rather difficult. Arrangements were made for a shunting loco to move the train across the main line in November 1971 and the move was carried out entirely by Inspectors who were familiar with the E-Train's idiosyncrasies. While the move was successful it did nothing to improve relations between the Inspectors and the local drivers in No. 4 Shed, although the six drivers allocated to the APT project took no part in the subsequent differences of opinion. The move itself incensed ASLEF so much that they called a 24 hour strike across the whole BR network the following day, and the financial losses incurred by BR on that occasion exceeded the entire R&D Dept. budget for the entire year! One can't help but wonder how much it cost their members in lost wages.

The biggest single upgrade that was made to APT-E during the rebuild was the total replacement of the SA bogies. Although modifications had been made to those used on POP Train to improve their performance at higher speeds these mods were not considered comprehensive enough to ensure stability at the even higher speeds that E-Train was expected to achieve. In addition the hydro-static secondary suspension suffered some considerable problems and although the system had been modified a number of times its ride was never found to be smooth enough. Ironically the air spring secondary suspension on the E1 bogies gave the loco crew a superb ride and this was confirmed by

7 data taken during the E1's tenure under the POP Train. The radical step was taken to design and build three new bogies, based on the E1 design with the air spring secondary suspension but with a lower frame height to accommodate the smaller trailer bogie wheels. The design was arranged to use the Steering Beams in their original position and purpose but left some parts of the beams redundant. These new bogies were designated as E1Ts and they proved very capable in service during the later test programme.

The turbine's ceramic heat exchangers were removed, releasing an extra 50 bhp per turbine, giving an overall power rating of some 2800 bhp, and the exhausts were uprated for the higher temperatures produced due to the removal of the heat exchangers. Body mounted blowers were fitted to the traction motors and the still experimental silica gun system was installed. The Trailer Cars were virtually stripped as the end structures needed to be strengthened as a result of computer analysis performed earlier on and the opportunity taken to replace the original Mk 1 tilt hydraulic packs, which had been designed and supplied by an outside contractor, with the new and considerably updated and and enlarged Mk 2 packs that were designed in-house by APD staff and built by a different sub-contractor. The Mk. 2 packs used some original manifolds and valve gear from the Mk. 1s but were otherwise totally new, but they took up a lot more space and were considerably noisier. This resulted in the two Trailer Car packs being fitted with large sound deadening covers which eased the noise problem but made maintenance and modifications quite troublesome at times.

The end structures of the Power Cars were also strengthened in line with the Trailer Car modifications and attempts made to use some of the auxiliary systems aboard the Power Cars as tuned mass dampers to reduce the low frequency structural vibrations particularly in the lateral plane. These modifications did not turn out too successful and were later updated in a further rebuild. TC2 had a small, 2 seat VIP compartment installed to enable the environment to be sampled by non-APD staff, typically BR Board members. This followed the installation of an even smaller VIP compartment aboard PC4 of POP Train while the E1 bogies were being evaluated and which received good reports from those who rode in it. In passing it was found that APD staff themselves made poor judges of the ride experienced aboard any of the test trains as they either tended to be hyper-critical or totally oblivious to any issues that might have been experienced. Non-APD staff were a lot more objective in their judgements and could often point out issues that had not been noticed by the test staff who were more closely involved. When TC1 was re-installed in the consist later on in the programme its 24 specially designed seats proved a big help in this sort of evaluation as a wider sample of opinions could be obtained.

ASLEF's pay issues were addressed and eventually solved but their extra staffing demands required that the two jump seats already installed in the Power Car cabs were enhanced by an extra folding seat that was bolted to the door giving access to the rest of the vehicle. This enabled the already cramped cab to carry four people, the driver, secondman, an Inspector and a member of the APT Support Section staff to act as a communications link with the test staff aboard the train. The rear cab was occupied by the train guard and a member of the Field Trials Section, this relatively large number of cab staff making communications somewhat convoluted and difficult at times.

8 In the meanwhile POP Train had been undergoing test work elsewhere, including some runs up the ECML to Tyne Yard from Peterborough. These runs were scheduled at line speed, but the light weight of the 4 car consist enabled some impressive acceleration times to be recorded and some very liberal interpretations of the line limits by the East Coast drivers and Inspectors produced some good test data. On one occasion a member of the public had to be ejected from the train at Peterborough as he seemed to think he could get to Newcastle faster aboard POP Train than by the following service train. This despite the outlandish appearance of PC3 and PC4 and the bright red and blue colour scheme of the Lab Coaches. At the start of 1973 POP Train was the first test train to run over the Old Dalby track after the Christmas and New Year break, and on the very first northbound run the build up of light rust on the unused rail head and the wet conditions of the day itself resulted in the brakes being almost totally ineffective and the train ran off the end of the test track, burying the Class 46 loco, Lab 3 and PC3 up to their axles in the gravel at the end. Ironically a large foam arrestor bed had been laid at each end of the test track just in case of such an incident but this had been tested before Christmas and the foam bed almost totally removed by the crash test vehicle. The POP Train locomotive went straight on between the empty arrestor bed retaining walls which otherwise may have helped it come to a halt without the subsequent heavy lifting that was required to re-rail it.

The heavily modified APT-E, now only in a 3 car configuration, was out-shopped from the Loco Works in June 1973 and the much delayed test programme resumed, but using the short Mickleover test track originally as it was much nearer the RTC than the Old Dalby track rack and the initial tests would only be at low speeds. Even so speeds in excess of 60 mph were obtained on the short, 4 mile long test track. While most of the rebuilt components and systems proved themselves quite readily the single largest problem was the continual failures of the TC2 air conditioning equipment and that summer of '73 was blisteringly hot. The end of each test run was characterised by a rapid exit of the entire TC 2 test crew to cool off outside as the interior of the uninsulated Trailer Car was like an oven.

Initial tests following the Mickleover runs were carried out in 3 car form and ran from Derby to Leicester and the train was authorised to travel at line speed, which was 90 mph over the majority of the line but at first the train only ran at 75 mph, but before very much longer the full line speed was achieved. This series of runs exposed the E-Train to public scrutiny for the first time as the train reversed in Leicester Station and the covered roof there made it only too obvious that something different was happening as the APT sounded more like a jet airliner than any train then running. With the removal of the turbine heat exchangers the already heavy fuel consumption became even higher and on the return runs the train ran into Beeston Freightliner Depot to refuel just in case a fault caused the train to come to a halt on the main line and then run out of fuel. In fact this never happened, but the low fuel capacity of the Power Car tanks, only some 600 gallons, was always a factor in the planning of any series of tests.

Various faults showed themselves in these early days, one of the most irritating being that of the failure of the horn valves jamming full open due to their exposed position in the roof mounted Power Car9 exhaust blisters. Normally this would not have been too much of a problem but the horn's compressed air supply also supplied the air springs and if they sank below a particular level it produced a 'Stop' alarm in the cab which demanded the driver bring the train to an immediate halt. The short term solution to this was to use a pair of Mole grips on the flexible hose that fed the horn

9 valves but eventually the valves were moved and weather-proofed. In addition a rash of tilt system failures resulted in the affected vehicle falling over onto its tilt bump stops on more than one occasion. The tilt system control channels in all vehicles were duplicated in that there were two sets of accelerometers, two sets of control electronics and two servo-valves and while both channels operated the whole time a change-over valve selected which channel actually tilted the vehicle. A monitor accelerometer mounted under the floor switched channels automatically if the lateral acceleration reached a pre-determined limit, originally 3 degrees, but it was possible to switch to a channel that had already failed and was not being monitored.

These tilt problem persisted for some while and was eventually traced to minute fibreglass particles blocking the orifices within the servo-valves and ironically the fibreglass particles came from the system's filters that were meant to be protecting against just such failures. The filters, of a new design and material, were continuously upgraded by the suppliers and proved to be very reliable eventually, but at the time were a source of constant irritation. A side effect of solving this problem was that inspection of hydraulic pipework, valves and oil cleanliness standards were improved markedly throughout BR and reduced the operational costs of track maintenance equipment once the new standards were adopted.

Very soon after the Derby – Leicester tests the Old Dalby test track became available for E-Train after some strengthening had taken place at the critical Upper Broughton curve. This curve, one of the sharpest on the line, was instrumented to enable the track forces exerted by test trains to be measured and the outer rail of the track could also be raised or lowered to change the apparent cant deficiency of the curve. Such changes took a considerable time, but proved useful in later testing and while evaluating the load measuring wheelsets. E-Train arrived at the Old Dalby Control Centre in September 1973 and almost immediately began to suffer a problem that was to plague the train during its entire life. A traction motor bearing overheated and examination showed that the somewhat vintage wick type lubrication had failed and the bearing itself had to be replaced. Later on in the test programme the wick type lubrication was replaced with a pump driven pressure lubrication system, but the problem never quite went away entirely. During the following series of tests on the test track, still in 3 car form, the train reached 100 mph for the first time and these speeds became quite normal in the following months. Up until now the train had not had the actual HK brake components installed, although the large diameter tubular axles were fitted to the E1T bogies, and the use of the HK brake was deemed essential for speeds higher than 100 mph. Accordingly the train was returned to the RTC for the HK brakes to be installed and commissioned and the train then returned to the test track to commission and test the new brakes, along with other test work that could be carried on concurrently.

The Instrumentation system in TC2 was capable of monitoring a large number of sensor channels but only a limited number could be fed to the on-board REDCOR mini-computer for analysis. The term 'mini-computer' here should perhaps be explained as in the 21st century it doesn't mean what the term implies. In the 1970s a mini-computer was one that did not take up an entire room and did not need a large team of punch card operators to feed its appetites for programmes and data. In the case of the REDCOR it took up an entire 6 ft tall, 19” wide rack, and still needed a large electro- mechanical Teletype to output its results and to issue its commands, while the data was stored on a

10 large reel-to-reel tape deck in the 19” rack. Even so its capabilities were a mere fraction of a modern PC, let alone a smart phone! For any particular series of tests the data from that system's sensors was usually fed from the instrumentation amplifiers to the REDCOR, while other system's signals being measured were recorded on tape for later analysis or displayed on oscilloscopes or onto large 12” UV recorders. During any series of tests some signals, such as the vertical and lateral bogie forces, were always monitored, as these were critical to the train's safety. Other parameters were monitored on an 'as required' basis, but on very few occasions were there spare instrumentation channels available, and the side corridor of TC2 was always packed solid with engineers watching over their own particular system.

After the HK brakes had been commissioned and tested the train was able to run at higher speeds and 125 mph was reached on the test track before the end of the year. In addition some main line runs on the Derby – Leicester route were required so that the increased braking capability could be monitored, ironically by the CM&EE Dept., to clear the train for high speeds on the main lines and then the train was returned to the RTC for the second planned re-build.

Other events worldwide during this period were to affect the whole project however. In October the Yom Kippur war erupted in the Middle East and after initial Egyptian, Syrian and Jordanian gains Israeli forces gained the upper hand and swept the invaders from their territory and occupied areas outside their original borders. When peace was restored after some three weeks a state of tension still remained but one lasting effect was that the oil producing states in the Middle East quadrupled the price of crude oil in a very short while and this had massive effects on the economy and normal life in the West. The increase in fuel prices made the already dubious economics of a gas turbine powered service train totally unacceptable and the same held true for the Leyland Truck turbine project. Leyland promptly cancelled its plans for the truck but pledged to continue support for the E- Train turbines until the train had finished its test programme, and further planning for what was to become known as the APT-P (P for Prototype) switched to a 25 kV overhead electrically powered version.

The second rebuild was intended to ready APT-E for its targets of 150 mph and very much increased speeds on normal curved main lines, and to this end more power was required. The APU turbines were moved forward onto the opposite side of the Power Cars to add their power to the existing four traction turbines. In addition the mounting of the fifth turbine was arranged to be a much more effective tuned mass damper than previous attempts. This had the the somewhat undesirable effect of placing a large hydraulic damper across the central walkway through the Power Car at shin height, which caught out those members of the test staff who had grown used the placement of the various steps and other obstacles inside PC1 and PC2. To replace the fifth turbine as an APU a six-cylinder Dale diesel alternator set was installed and improved vane type air compressors replaced the original noisy piston type compressors in the same bay as the APU. In addition TC1, now having been fully trimmed and finished off with its VIP compartment, was returned to its proper place in the train so that all further work was with the train in 4 car form.

Main line tests were carried out in excess of the normal line limit for the first time and these proved satisfactory and testing moved back onto the test track for a series of tilt failure tests. These were

11 needed in case a tilt system failed during the upcoming high performance tests and were intended to prove that even with a vehicle tilted over onto its tilt bump stops the loads on the bogies and track did not exceed defined limits, and to ensure the C1 gauge limits would not be exceeded during such a failure. Because of the built-in instability mentioned earlier the vehicle bodies could fall right over onto their bump stops, either due to the hydraulic pressure being lost which was called a 'soft failure', or due to a control system fault which could drive the vehicle onto the stops, and this was called a 'hard-over failure'. In the former case the vehicle would most probably fall inward on any particular curve, increasing any desired tilt angle, but in the latter case it could fail in either direction and an outward failure, in effect tilting the wrong way, was by far the worst situation. This would load the outboard rail of the curve and would tend to de-rail the vehicle in the worst case.

Earlier attempts to limit the effect of a hard-over failure using barrier accumulators worked but needed constant adjustment and before the tilt failure tests extra shut-off valves were fitted to physically shut off the oil supply to the tilt jacks when the vehicle reached a predetermined limit. All the tests were passed with flying colours, including an outward hard-over failure of TC1 while running through through Upper Broughton curve at a speed that required an 11 degree inward tilt demand! During these tests the train reached a speed of over 130 mph on the Widmerpool Straight.

Further test runs then moved to a new location, running from Luton to Bedford on the Midland Main Line, and these were aimed at the suspension and braking systems. These were carried out successfully with especial emphasis being laid on the wheel slip detection system that would be essential during the high performance tests to come. From now onwards the train moved from one test site to another, with occasional returns to the RTC for further modifications to be fitted and on March 17th 1975 APT-E arrived at the London terminus of the Midland Main Line, St. Pancras, for the first time. Amazingly this visit went almost without notice, despite the unearthly sound of the ten turbines howling away under the massive arch of the station roof.

By late spring of 1975 APT-E was ready to prove that its performance lived up to expectations and the maximum speed runs were scheduled to take place on Brunel's race track west of Reading. Arrangements were made for a complete occupation of the Western Region main line from Uffington Loop, some 12 miles east of Swindon, to Goring, a distance of approximately 25 miles of some of the flattest and openly curved railway line in the UK, for three successive Sundays in July and August. The HST Class 252 prototype was undergoing service trails on the Paddington to Bristol line which traversed the same track on which the APT's tests would take place, and as these trials were running at up to 125 mph the track had undergone some considerable work to prepare for the HST's running. The APT team would profit from this work and in addition some of the critical sections of pointwork would be subject to close scrutiny both before and after the train's passage to ensure none of it had been misaligned by the high speeds that were anticipated. The train left the RTC for the Western Region on the 21st July and for length of the tests it was based at Old Oak Common, alongside the HST set. Familiarisation runs were made from Old Oak Common as far west as Swindon on Thursdays and Fridays, running in between the service train's paths and at speeds up to 125 mph, which seemed almost slow to the test team running in such wide open spaces compared to the confines of the Old Dalby test track and the Midland Main Line with their much sharper curves.

12 The Sunday test runs left the depot at an unearthly hour, 1 am approx., in order to maximise the number of test runs possible before the occupation was passed back to the WR around noon. In addition the cool, dense air of the early mornings enabled the turbines to produce a higher power output and there was less chance of the public gaining knowledge of the tests before their conclusion, successful or otherwise. The UK public had a rather jaundiced view of the APT by this time, fed by the ever cynical attitude of the media, and it was hoped that the tests could take place in a certain amount of secrecy. The Power Cars had had the E1 bogie air springs' ride height lowered by approximately 2” as aerodynamic measurements at the Old Dalby track had showed there to be slight advantage in doing this, this being termed the 'Speed Mode', and for this series of tests the Power Cars would be run with their tilt systems passive and locked-off parallel with the track surface. There was an even smaller aerodynamic advantage in doing this but more importantly load measurements made during the tilt failure tests indicated that the tilt jack brackets on the Power car bodies were approaching their strength limits and it was decided to run passively and strengthen the brackets prior to the planned London – Leicester runs later in the year.

On the first Sunday runs the train reached a maximum speed of 149.8 mph on the last run of the day and the whole train had behaved perfectly. This speed was a new British Rail speed record, beating the HST's record run of 144 mph on the ECML in 1973, but BR did not release the news to the public this time as greater things were expected. The test team went home to Derby for their delayed weekend and returned to Old Oak Common later in the week to continue the tests. The Thursday test of the second week went well until the WR Inspector exceeded his brief and gave the train an unauthorised brake test near Reading. In attempting to re-start the train refused to move despite the turbines being heard to power up as expected, and it took some time to isolate the fault with the self-same Inspector giving dire warnings about the prospects of delaying service trains! After some 15 mins. or so it was discovered that while PC2 was in 'forward gear', PC1 was in 'reverse' so PC1's turbines were shut down and the journey continued on five turbines. Back at the depot a burned out relay was replaced and the Inspector reminded of the limits of his responsibilities. On the second Sunday's runs the 150 mph. 'barrier' was breached on the second run at 151.3 mph. And despite some high anomalous high lateral track and bogie forces over the complex pointwork at Didcot clearance was given for an increased speed limit to 155 mph. for the third weekend, this being closer to the designed maximum speed of 250 km/hr.

By the third weekend a considerable amount of work had been carried out on all ten turbines using a portable load bank that had been brought down from the RTC. As this was to be the final weekend of the high speed tests it was essential that all the turbines were on top form for the last Sunday's runs. On the first run some aerodynamic drag measurements were taken, limiting the maximum speeds to some 143 mph. but the next two runs were dogged by alternator control issues and the 150 mph. barrier was not reached. It was notable that the word had got around about the tests being carried out, fuelled no doubt by the ever vigilant masses of railway enthusiasts in the UK, and there were numerous small groups of people standing on bridges and around the few stations on that stretch of track, the public being prevented from access to the platforms themselves by BR staff and barriers for the duration of the tests.

13 The fourth and last run was luckily scheduled to start over an hour after the train's arrival back at Uffington and this was to stand the turbine team in good stead as their spare control board turned out to already have a fault when used to replace the faulty item that had caused problems on the previous two runs. By a fluke the Head of APD's Electrical Section was on board the train at the time and he got to work building a manual control board from spare components and some Vero board that he happened to have with him. There was no time to connect the board remotely in TC2 and so Ray Coleman, the on-board electrical engineer operated it while standing alongside the recalcitrant turbine at the rear of PC2! Ray took his instructions on the required settings from Alan Goodley, who monitored all the turbine's outputs from the TC2 Control Centre, via the train's on-board intercom system. With such a Heath Robinson control system Britain's fastest train set off toward Goring and a place in history. With all ten turbines giving maximum power Didcot was passed at exactly 150 mph. and over the next few miles the speed built up extremely slowly in the warmth of that summer morning. At the braking point the train reached 152.3 mph, a speed that still stands to this day for non-electrified rail travel in the UK.

A question that has often been asked amongst the many people interested in high speed rail travel since that summer's day in 1975 is that could APT-E have reached the designed speed of 155 mph, and it could be argued that the 152 mph was effectively the balancing speed at the time. However it's open to conjecture that if the alternator control board had not failed on runs 2 and 3 that day the cooler air earlier in the day maybe have enabled the turbines to give that last fraction of power to gain the extra 3 mph required to reach 155 mph during an earlier test run. It's a question that's never likely to be answered as although the train still exists at the NRM Locomotion Museum, and in a remarkable state of preservation due to the supreme and ongoing efforts of the APT-E Conservation and Support Group, it's extremely unlikely that it will ever run again under its own power. Not only had the train been neglected for a very long time during its tenure at NRM York, but the forcible separation of the vehicles during the move to Shildon in September 2004 unfortunately resulted in the cutting of all the control cables so essential to the running of the train. In addition the large number of people with the necessary expertise who would be required to even re-commission the train are just not available any more. The great majority of the original test team are now in their 60s and 70s, and others having been scattered to the four winds after the project was transferred to the CM&EE's Dept. after APT-E was delivered to the NRM at York means that the required detailed knowledge is no longer available. Unless a benevolent billionaire with access to a time machine comes along APT-E is only likely to move by external means in the future.

After the resounding success of the 150 mph tests E-Train returned to the RTC for the strengthened tilt jack brackets to be fitted to the Power Cars and it was then taken to Old Dalby to test these before the final demonstration of the limits of such a high performance train. This was to be an attempt to run from London to Leicester in under an hour, and as the distance between the two stations was just over 99 miles this required an average speed of 100 mph from start to stop, something that was completely outside the limits of any other railway vehicle in the UK. Even the HST, to be brought into service on the same line in future years, would be unable to reach such speeds as it was unable to corner at higher than normal line limits. The Midland Main Line was quite sharply curved and included a number of reasonably steep banks, although nothing like as severe as those on the WCML. There were quite sharp speed restrictions in some places and a considerable

14 number of meetings took place between APD Support Group, R&D Field Trials, the LMR CCE's Dept., the overall BR CCE's Dept., the BR CM&EE's Dept. and the Chief Signalling and Telecommunications Dept. to work out how much the restrictions could be upgraded to cater for the APT's improved curving and acceleration abilities. One cannot help but be amazed that a consensus of opinion on the various issues was agreed with such a varied group of people all with their respective axes to grind.

A number of exploratory test runs were made along the route while measuring the lateral forces on the bogies through the curves and across point and crossing work and as a result of these a comprehensive, albeit complex, set of higher speed restrictions were determined for the whole distance. Overall this amounted to no less than 23 different restrictions, every one of which required a separate and easily identifiable commencement and termination board so the train crew would know which of the speed restrictions applied at that particular point. To check on the effect of such high speeds on the track a specially equipped track survey train ran behind E-Train during the work- up runs to ensure that the track still remained on its original alignment. It says much for the diligence of all people concerned that no significant alignment errors were recorded.

Once the boards were placed in position the way was open for the initial runs to be made over the critical Kettering – Leicester section of the line and these were to take place in late October. Two such runs were made initially and both were unsuccessful, the first due to high HK brake temperatures and the second due to the cab steps falling down, this triggering a train 'STOP' alarm. The cab steps were more reliably latched and the HK brake problems traced to cooling fans running the wrong way round! After further runs on that section of track the train was deemed ready to tackle the 1 hour record run itself and the first one of these was scheduled to take place on October 27th. The train ran into St. Pancras after fuelling at Cricklewood depot and this time the strident exhaust note of the ten turbines caused a lot of interest from the public as by now the whole project had high visibility after the Western Region speed record runs. For these runs TC2 was very heavily staffed, every system on the train being required to be monitored comprehensively, much more so than on the 150 mph. runs. The windows of TC2 were mirrored and totally impenetrable from the outside so the test staff were treated to the view of a number of flattened noses as the public tried to get a glimpse of what was going on inside. As the runs were quite important within the higher levels of BR the TC1 VIP compartment carried a number of high ranking passengers on each of the three runs and these exalted personages found themselves under public scrutiny as their windows were not mirrored. Unlike the potential 'passenger' on POP Train at Peterborough none of the public attempted to gain entry to the train, perhaps because the central joint module entrance doors were manned by fierce looking APT Support Group members.

The first run left on time at 12.40 and was looking good until another failure of the cab steps occurred only 14 miles out from St. Pancras. This entailed a notch 8 brake application but as the train slowed the cab staff were able to raise the steps again, but by then too much time had been lost and Leicester wasn't reached until some 65 mins. after departure. The second attempt was made on the 29th October and even more BR Board notables rode aboard the train. The BR Chairman himself, Sir Richard Marsh, travelled aboard the train from Cricklewood into St. Pancras and wished the whole train crew well on their second attempt. This time the run went very well indeed reaching a maximum speed of 136 mph. but as the train approached Leicester with the record well in hand it

15 received a signal check to allow a Birmingham – Norwich DMU to enter the station ahead of the APT, despite the Special Notice stating that such checks should not take place. As one of the passengers in the VIP compartment on the attempt was the BR Board member for Signalling and Telecommunications one wonders at the prospects of the signalman concerned after the event.

The third and last attempt was to be made on the 30th October and special measures were put in place to ensure that the best possible conditions existed for a successful run, and to this end the APT needed to leave St. Pancras as late as possible after the preceding train had left for Leicester, but not so late as to lose the path. This minimised the chances of catching up with the earlier train and being slowed by signals. It was arranged that a spurious instrumentation 'fault' would be found on the centre E1T bogie and that would not be 'solved' until just before the optimum time for departure. This procedure worked very well and despite pleas from the cab Inspector and an anxious Station Master the 'problem' was found and 'fixed' at just the right time and the train left London in fine style. This despite a wallet belonging to the poor instrumentation engineer, Derek Camp, falling out of his pocket as he scrambled aboard the train and down onto the track bed! The wallet followed the APT to Leicester but at a somewhat slower speed on a following train. This time everything went perfectly, helped by the driver, Ken Austin, who always got the very best out of E-Train. Ken was a master of anticipating the need to open the throttle ahead of a particular restriction termination board enabling the turbines slow throttle response to be minimised and thus achieving the highest possible speeds in any section. When the train arrived at Leicester the stop-watches read 58 mins and 30 seconds and the average speed stood at 101.6 mph. This compared with the fastest current service train average speed of 70.8 mph. showing an improvement of 45% over a relatively short line.

After such a successful demonstration of the technology's capability there was little else for APT-E to prove and the three APT-P trains then in their early stages of production were so different to the E-Train that very little further work was possible for Britain's fastest train, and it was offered in its entirety to the National Railway Museum at York, and was duly accepted. Some final tests with load measuring wheelsets took place on the Old Dalby track during November and December and these were extended onto the Midland Main Line early in 1976. The last runs at Old Dalby after those tests resulted in a remarkable maximum speed of 143.6 mph, which considering the very sharply curved line and the gradients at the south end compared very favourably with the Western Region tests and maintained the discussion concerning the train's possible ability to have reached 155 mph.

APT-E returned to Derby for the last time on 2nd April and was then prepared for its change of ownership to the NRM. This encompassed the removal of much of the instrumentation although somewhat surprisingly the REDCOR computer remained in place. Eventually APT-E left Derby for its last powered run on 11th June and it carried possibly its largest ever passenger load, many of the support staff who'd remained at Derby or at the test track Control Centre managing to find well earned places aboard for the very last time. On arrival at York the train was held on the centre road of the station for a considerable time with the turbine exhausts notably heating up the enclosed volume inside the station and drawing enormous crowds and photographs taken at the time show the bridge and adjacent platforms packed with spectators. Eventually a path was cleared to enter the

16 NRM Yard and after a number of reverses the train came to a halt for the last time at 10.48, having covered almost 23600 test miles since that first run in 1972, only some four years before.

At the time it seemed that E-Train was destined for a life as a museum exhibit where the public could view it and wonder at the advanced technology enclosed within its aluminium shell, but that was not to be, at least not for many years. Soon after the train's arrival at the NRM TC2 was removed from the consist and exhibited inside the Great Hall supported by an E1T bogie at one end and the last remaining SA bogie, the centre bogie from POP Train, at the other. A small capacity hydraulic power pack was installed in the inspection pit beneath the coach and an NRM staff member could demonstrate the static tilt capability of the coach at intervals through the day. The remainder of the train was parked outside in the NRM Yard in a variety of locations, slowly deteriorating even though covered by tarpaulins. No attempt was made to preserve the train, possibly due to a change in management at the NRM, but in any case no work on the train ever took place after its arrival at York in 1976 apart from an notional repaint that it was given in the 1990s.

All was not lost however as one notable spectator was looking on as the APT-E slowly ran into the NRM Yard that day in June 1976.. The spectator, Paul Leadley, was 9 years old at the time and he's described his first view of E-Train as '…a spaceship on wheels...' That view quite literally changed Paul's life and without his efforts in the following years the train would probably have been scrapped by now. As it was Paul formed the APT-E Conservation and Support Group in 2000, resulting in the train being in its current state of preservation, albeit in non-running form and some distance from its original resting place as it's now at the NRM's Locomotion Museum at Shildon. The long story of the trains restoration is the subject of a different story published elsewhere, but it is spelled out in fine detail on the Group's web site at http://www.apt-e.org/ as well.

As APT-E had a very limited public showing, and as it only ran for four years, it was never modelled by any of the major manufacturers in any scale, although a number of attempts have been made to scratchbuild models of the train, some good, some not so good, in various scales. Unlike the APT-P which was modelled by Hornby firstly in 1981, coinciding with the real train's entry into service, there was little demand for a model of APT-E. With the current increased interest in the train, due to the public's ability to view the train itself now that its preservation has reached a good level, perhaps the time is ripe for such a model to be produced?