65 New Developments in Railcar Trucks WILLLU1 W. DICKHART III ABSTRACT In this paper the results of the develop­ ment of the ASDP truck for heavy rail tran­ sit applications are discussed. The ASDP truck has a truck-frame-hung monomotor and a very soft secondary air suspension. Also, DloC a number of options that have been devel­ BRA.KE oped for the basic Budd P-III railcar truck, of which some 10,000 have been built for transit, commuter, and main-line ser­ MOTOR A.'5'5'{ vice, are discussed. The modifications or 1'2.00 options that have been developed include a soft primary suspension, a steerable truck, a simplified secondary suspension, and a tilt truck for high-speed corridor operation. In this paper the results of the development of the ASDP truck for heavy rail transit applications are discussed. Also discussed are a number of options that have been developed for the basic Budd P-III railcar truck. ASDP TRUCK The ASDP truck (Figure 1) is a monomotor truck wi tt. a very soft secondary suspension that was developed FIGURE 1 Monomotor truck. under an UMTA subcontract. The monomotor gearbox assembly is supported from the truck frame, thereby reducing the unsprung weight. The primary suspension uses a chevron-style rubber sandwich design in an tain, three-piece truck. Approximately 10,000 trucks outside bearing configuration. Two primary suspen­ have been built for transit, commuter, and main-line sion spring rate sandwiches were used to investigate service, even for the super-speed linear induction the effect on wayside vibration during tests. The motor research vehicle (LIMRV) , which established secondary suspension is very soft around the operat­ the world's speed record of 256 mph in 1972. The ing height: however, the rate increa\.es with travel P-III truck has a stiff primary suspension with a from the mean position, which prevents overshoot. spring rate of approximately 150,000 lb/in. The development of the ASDP truck, including In general, the secondary suspension is soft ver­ static and fatigue tests, has been documented (1:_) • tically and laterally. A number of options have been Subsequently, one car set of trucks was fabricated, developed recently for this basic P-III truck. These applied to one of the state-of-the-art cars (SOACs) , options retain the basic softer primary suspension and tested by the Budd Company at Pueblo, Colorado, or steering. under an UMTA contract. The ride data (Figure 2) indicated reduced vertical accelerations compared with the standard truck, as was forecasted in the SOFT PRIMARY TRUCK computer simulations. Wayside data (Figure 3) also revealed the reduction in accelerations with the Data from the ASDP test and computer results from softer 60, 000 lb/in. primary springs compared with the Budd Company vehicle dynamics and right-of-way the 180, 000 lb/in. primary springs, as was fore­ interaction simulations have indicated that small casted by the Budd wayside/vehicle interaction com­ reductions in primary spring rate can result in puter simulation. This truck could be equipped with large reductions in both rail forces and truck frame a Simotrac propulsion package. accelerations. One modification developed for the P-III truck is the soft primary P-III truck. The journal end of the truck frame has been redesigned P-III TRUCK (Figures 6 and 7) to accommodate a horseshoe-shaped elastomeric sandwich, which results in primary The P-III truck (Figures 4 and 5) was developed by spring rates of approximately 25, 000 lb/in. verti­ the Budd Company more than 25 years ago. It was the cally and 60,000 lb/in. longitudinally. This ar­ first application of air springs for railcar trucks. rangement provides controlled longitudinal motion of The P-III truck features a direct load path from the the wheels and can allow some steering in large car body through the air springs to the bolster and radii curves. Prototype trucks were tested in a side bearers to the truck frame and wheels. The bol­ joint program with the National Passenger Railroad ster rests on the twin side frames, which also serve Corporation (Amtrak). Measurements of a train pass­ as equalizers. The result is a simple, easy-to-main- ing at 100 mph verified that the wayside accelera- 66 Transportation Research Record 953 -- ASOP TRAILlllG HARO PRIMARY .... --- SOAC TRAILING ~ 60 MPH <.:> STATION 6 10 OF UMTA TEST LOOP WELDED RAIL WOODEN TIES i.ll SO AC..,A EFFECTIVE BAND WIDTH • .16Z Ha. ~ >- I\ t: II VJ 11 Z .01 LlJ ~ 0 (\ 1'I __J I I <i: I I I 0: r- I I v lJJ t 1 Cl. ·00 - 1 lf) I a: w > I ~ 0 c.. \ I ti ~ i\ ' "', }\ ii I "• I / If f 10 15 20 FREQUENCY- Hz FIGURE 2 Comparison of ASDP to SOAC midcar vertical acceleration levels. 40 MPH HARD PRIMARY I- 0 . 2. s t't:-1 40 MPH SOFT PRIMARY 60 MPH HARO PRIMARY ,0 MPH SOFT PRIMARY 70 MPH HARD PRIMARY 70 MPH SOFT PRIMARY 7G NP H HARO PR IMARY 76 M P ll SOFT PRIMARY LEAD AXLE OF '0.7 FT FROM OUTSIDE RAIL TRAILING TRUCK WELDED RAIL CONCRETE TIES PASSING WAYSIDE SCALE = 0.1 G/IN LOCATION PAPER SPEED= 5 IN/SEC DATA FILTERED AT 5 0 H.,, FIGURE 3 Effect of primaries on ASDP wayside vibrations, ASDP trailing truck data. tions were indeed reduced by the softer primary sus­ A powered truck version of the soft primary was pension (Figure 8) • developed for the self-propelled M-1 Long Island Data from the road tests with instrumented cars - . Railroad (LIRR) cars. Initial tests also indicated Cl.JIU, Ll.Ul.:~::i ..LJlU..L\..:ct i... ~ ct Lt:=UUC..:LJ.VII J.Il Ll.Ul.:I'\. l.Ldlll~ a<.,;- that the accelerations of the frame were signifi­ celerations with the softer primary, as was also cantly reduced. This car has been in revenue service forecasted (Figure 9). Currently, the prototype trucks have accumulated more than 350, 000 miles in for more than 1.5 years and has accumulated approxi­ the several years of revenue service. This design mately 100,000 miles, with essentially no flange is now the standard truck f or the Amfleet II cars. wear. Dickhart 67 SHOCK SO:CONDARY TRUCK l.BSOR BER AIR SP'11t!G EOLSTER BODY ANC HOR BRAKE THI RD RAIL SIGNAL PRll.iARY ROD ASSEMBLY COLLECTOR PICK OP 1iPAING FIGURE 4 PATCO P-III truck (side). THIRD RAil lRuCI\ BOLSTER ------------...'....J .W .~~~~~~~~~~~~-~COLLECTOR SICiNAI.. PICK OP TRUCK SIDE FRAME RICHT SIDE 1.10TOR ANO CEAA BOX MOTOR •NO GEAR BOX ' \ I ,,' -1--·, I TRUCK StDE •I ---< ~r - - -r '1- t-..:::::=::_,.~- F'RAl.<E i 'I I I f LEFT HANO ~, 1s;::::::;:=====t;• · , 1 • ,, ~ \ / r 1 BODY .i.NCHOR 1', l r, ,, 1 ROO L - -::-.:\.. .I FIGURE 5 PATCO P-III truck (plan). SOFT BUSHING TRUCK Corporation (PATCO) for more than a year. The verti­ cal spring rate is 70,000 lb/in. and the longitudi­ Another modification reduces the primary stiffness nal rate is 40,000 lb/in. The modification has both vertically and longitudinally without modifying resulted in reduced wheel wear, especially on the the truck frame. This is accomplished by substitut­ face of the flange (Figure 10) when compared with ing a sculpted bonded bushing in place of the con­ the married car with the standard bushing (Figure ventional hard primary bushing. The soft bushing 11). modification, as it is called, had been tested in a This same principle has also been applied to the cooperative effort with the Port Authority Transit trucks on Washington Metro, alth~ugh the trucks were 68 TRUCK FRAME crn6"'TIJTllj!'[ I FIGURE 7 Primary suspension and journal assembly. FIGURE 6 Soft primary. l_ 10 I l I l I §_J 1§1 1U 1li AXLE AXLE AXLE AXLE zli._D 21i.P 21i.P 2 t.!P zl:!il AXLE AXLE AXLE AXLE AXLE Dickhart 69 SOf"T fRIMAl'.1' .-,. ::· ... · . : A~lf... a_.~··1.•1\\\l'tfl.l ~""'.._J~,1:,\,.._·~-J.-.~'•. .;,-~::;<'.l',\.- . ., --r----..--......... CAR.A SllFF PRIMARY ....,j .. \/ ' '~_/\./' CAR 9 SOFi PR.IMAP-.'1' -~ ...... ~~-- ·-:.. ~'"~.,,--.--~::..::.;,,,.--. • ..:--. -~· .-~ "TltU<K !'£•<-IE 1I SOFi PRIMAR.'f ..,,.,...._....__ ... .__ ,..£> · ~- .. -~------------- FIGURE 9 Soft primary tests. 16,358 MILES 9-17·82 33,896 MILES 2·1·83 CN PROFILE BUDD SOFT BUSHING JOURNAL SUSPENSION CAR NO. 284 SCALE 2X FIGURE 10 Wheel profile wear-soft bushing. 16,358 MILES 9-17-82 33,886 MILES 2·1·83 AAR 1: 20 PROFILE STD. PID JOURNAL RUBBER CAR NO . 283 SCALE 2X FIGURE 11 Wheel profile wear-standard car. not produced by the Budd Company. In tests sponsored be parallel, which results in wheel wear, rail wear, by UMTA Cll , Budd soft bushings tested on Washington and noise in sharp curves. Allowing longitudinal Metropolitan Area Transit Authority (WMATA) trucks compliance in the primary suspension, as in the soft reduced the lateral track forces in curves up to 75 primary of soft bushing truck, alleviates this con­ percent (Figure 12). The soft bushings have been in dition somewhat . However, only with a steerable revenue service at WMATA for more than 12 months truck can the axles assume a radial position with with about 60,000 miles. One of the significant dif­ respect to the truck in the tight curves. ferences between the standard bushings and the re­ The steerable truck, by reducing the angle of at­ placement is lack of settlement (Figure 13). In the tack between the wheel and the rail, eliminates the past year the settlement of the standard bushings on noise and reduces track and 'wheel wear.