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UNITED STATES PATENT oFFlca

BRUNO V. NOlitDBlîllEtGr,• DECEASEI), LATE OF MILWAUKEE, WISCONSIN, BY HELENA. C. NORDBERG, EXECUT'RIX, OF MILWAUKEE, WISCONSIN REVERSIBLE ROLLING MILL ENGINE Application ?led May 21, 1925. Serial No. 31,954. This invention relates to steam engines and the proper speed until the pass is completed. particularly to reversible engines for roll As the work leaves the rolls, the develop ing mill duty, ment of power must be suddenly checked so So far as applicant is advised, no one has that the engine will not race. Moreover, it heretofore produced a reversible engine forA 1s sometimes necessary to reverse or to start rolling mill service using high initial pres under full load, and this means that the cyl sure and a high ratio of expansion. The inders must develop ample power in the worst present invention produces an engine of such possible crank position. type which is now in successful operation, The customary solution of this problem is 60 'Il and which, as a result of high pressure, super to use two double-acting cylinders with the heat, and expansion, is giving good steam cranks set quartering. Such an engine is or economy. Furthermore, this engine is con dinarily equipped with slide valves of either trolled directly by manipulation of the re the .flat or piston type, and the cut-oil is ordi vel-sing gear and has no regulation by throt narily at about 90% of the stroke. Slide tle such as has been the universal practice in valves give large cylinder clearances and 65 rolling mill engines heretofore. long’cut-offs preclude economical steam eX Many of the features of this new engine, pansion, so these two factors combine to pro individually considered, are not new in other duce gross waste. A consideration of the relations. These elements are, however, crank effort diagram of any two-cylinder, combined in a new relation to produce the double-acting reversible rolling mill engine7 desired result, and certain of them are modi with the cranks at 90°, shows that the crank ‘ fied to give them new and heretofore unde eífortt‘ends to be very irregular. yAccord sired characteristics, adapting them to this 1ngly,_1n order to secure relatively smooth particular field of use. In order that the operation (in the absenceof the regulative importance of these various adaptations and efl’cct of a fly wheel) it is necessary to throt 75 modilications of detail may be fully appre tle the inlet steam. ciated, it is desirable iirst to outline the re The combined eli’ect of a long cut-od, large quirements of the service and the manner in clearance spaces and throttled inlet is neces` which these have heretofore been met. In sarily very poor efliciency, and it is a fact this way the important considerations con notorlous in the art that reversible rolling 80 trolling the design of an engine constructed mill engines are among the least economical according to the present invention may be steam prime movers now in use. Neverthe made clearer than is otherwise possible. less, engines of this type of extremely large In the operation of two-high rolling mills power are extensively-used in the steel in« it is necessary to reverse the rolls and conse dustry. ~ ' quently to reverse the engine. rl‘his reversal It follows that the production of an eco must be quickly eifected, and that fact, as nomical reversible engine of this type which well as the necessity of quick stopping and will meet the severe requirements of rolling starting, precludes the use of fly wheels. In millservice is a matter of considerable eco 90 fact. the ideal reversible rolling mill engine nomic importance. has the minimum possible momentum in pro It is obvious that7 if an engine ­is to oper portion to the power which it develops. ate smoothly without a fly wheel and without This means that the entire torque must at throttling regulation at’relatively short cut all times be developed by the engine without ofîs, it must have a relatively large number i assistance from the momentum of moving masses. The engine must be capable of of cylinders, and almost the first considera starting and running smoothly before the tion in the development of an engine of this billet enters the roll. It must develop im type is to determine how many cylinders shall mediately an increase of power as the piece be used. On this will turn a number of im enters, and must then continue to operate at portant details añecting'the type of cylinder 2

and the nature of the steam valves and the Having arrived at the conclusion that four valve-actuating gear. or more cylinders are desirable, the next The controlling factor in the size of the en question is as to the type of cylinder. It is gine, i. e., the total cylinder volume, is the lli hl important to reduce clearance in the ratio of thc minimum crank effort- to the aver cy in er and the conventional types of ex age, for as has been stated, the engine must haust valve are the greatest sources of such be able to start under full load with the clearance. This suggests the desirability of cranks in the most unfavorable position. The using the so-called unifiow or terminal ex first step is to lay out a diagram showing the 10 haust type of cylinder. This type is well starting crank effort. Such a diagram must adapted to large power units, and has been 75 ignore all the efforts produced by each cylin adopted for use in the present engine. » Be der beyond its point of longest cut~oif, for in side the reduction of clearance which it er starting only those cylinders which have not mits, it has the additional advantage ofp re yet reached such oint of cut-0E are effective. 15 quiring no reversing gear for actuatin eX The following ta le gives the resulting val haust valves. Such gear, because of the Targe 80 ues for engines having, two, three, four and Size of the valves and the power necessary to five cranks, the cranks being assumed to be actuate them, would be cumbersome and so arranged that the dead center positions would greatly complicate the maneuvering of the pistons are spaced equally in a revolu of the engine. 20 tion. Since the piston in a uniflow engine alone controls the exhaust, and since a rolling mill Ratio {AverageMinimum starting starting efîort eñ'ort engine must stop, start, and reverse in every Point of cut-on! position of the pistons, some means must“ 25 2 cranks 3 cranks 4 cranks 5 cranks be provided to unload the cylinders at the time of starting and reversal, as otherwise 90 0. 90 0. 58 0.81 0. 79 0.83 the confined steam would render maneuver 0, 80 0.»43 0. 55 0. 70 0. 78 ing impossible. This unloading must occur 0. 70 ______0.30 0. 48 0.62 0.70 o. 6o ______o. 16 o. 44 c_sî o. 65 automatically as an incident to starting the 30 0.50 ______._ 0. 0.38 0. 44 0.55 engine in either direction. Generally stated, 0.40 0. 27 0. 39 0. 40 this problem is solved by actuating the inlet 0. 30 0. 057 0. 30 0.35 valves by a reversing valve gear which has The data for two cranks shows clearly a greater travel in full gear position both forward and reverse than it has in interme why approximately 90% cut-off is customary diate positions. This greater travel in these 35 with such engines, and why shorter than 80% cut-off is not used. The table shows that four two extreme positions is used to actuate un 100 engines of approximately the same total cyl­` loading valves associated with the inlet inder volumes, but differing in the number valves. . of cylinders, will have approximately the A number of reversing valve gears having 40 same starting effort with the following cut this characteristic of increased motion are offs: known, and the selection of any particular type of gear is affected by considerations Two crank engine, 90%. Which are dependent on the particular type Three crank engine, 80%. of valve used. There is illustrated in the pres 45 Four crank engine, 60%. ent application, a poppet valve mechanism F ive crank engine, 50%. of the equilibrium type actuated through 110 a known cam mechanism by a modified form `It follows that the three cylinder engine of Marshall valve gear, the modification giv has no great advantage over the twin, while mg increased `lead toward full gear positions the four cylinder engine has a very great ad 50 instead of constant lead as is usual. vantage. The economy gained by the adop The purpose of giving the variable lead 115 tion of five cylinders is ordinarily not suf characteristic is to insure that the inlet valves ficient to justify the extra complication, and will all be closed in mid-gear position so that it is believed that for usual service the four this becomes a neutral position and conse cylinder arrangement with variable cut-oftl 55 quently this is hereinafter referred to as and maximum cut~of`f at 5;/8 stroke will prove “neutral”. Similarly the full gear positions 120 a satisfactory standard. as maximum positions are designated turn It is important to note that the above fig ing “over” and “under” to avoid any im ures are based on equal spacing of dead cen plication that the engine has any normal ters, and this means that, in a four cylinder direction of rotation. 60 engine, there will be two units, each con The modification of the Marshall gear to sisting of two cylinders set quartering, the give variable lead preferably consists in a two units being displaced 45° from each change in the length of the radius rod, so other. This crank arrangement, while not that the arc which its swinging end describes broadly new, is believed to be new as applied does not ass through the axis of the are 65 to a reversible engine having no fly wheel. along whlch its pivoted end is adjusted to 130 3

set the valve gear. ­The link may be either end inlet valve bonnet and indicating how shorter or longer than the radius of the arc the reach rod to the head end inlet valve is or quadrant, but a quadrant whose radius ex supported and guided. ceeds the length of the radius rod is preferred Fig. 5 is a fragmentary plan view showing and hence illustrated. the relative locations of the inlet, unloading 70 This characteristic of variable lead pre and relief valves. f cludes the use of a single eccentric and valve Fig. 6 is a section on the line 6--6 of Fig. 5 .gear for both ends of a cylinder, as one end showing an inlet valve and its associated re would be given excessive lead. Hence there lief valve. Figs. 7 and 8 are respectively plan and ele 10 are used for each cylinder two eccentrics as set at 180° from each other, two eccentric vation diagrams showing the preferred straps and two radius rods. The radius rods crank arrangement for a four cylinder dou of each pair are carried by a single quadrant ble acting engine. . ­ yoke. Thus each inlet valve has a corre Fig. 9 is a sectional view showing the mo sponding inlet valve gear. tor for actuating the main throttle valve and 80 15 Since the crank shaft is large in rolling its relation to the reversin valve-gear. This mill engines, it is impracticable to put the view shows the floating linîage through which valve actuating'eccentrics in it, and a lay the throttle is closed as a precautionary meas shaft is desirable to permit the use of small ure in neutral position of the valve gear. Fig. 10 is a detail View of one unit 0f the 20 eccentrics and a correspondingly compact valve gear. This lay shaft is necessarily Marshall valve gear specially adapted to give ` parallel with the crank shaft and must be variable lead, as herein explained with a dia driven in absolute unison with the crank gram of the cranks and pistons and of the lay shaft. All back lash or lost motion must _be shaft and its driving connections. On this N) CA. eliminated in a reversible engine, as reversal view is imposed a motion diagram showing 90 precludes any compensatory setting of the the positions of the quadrant and the operat eccentrics. This excludes all gear trains. ing lever in the neutral and both maximum Two parallel rods set quartering are bet positions and the three resulting paths of the ter, but not satisfactory, as the rods act head of the eccentric rod. alternately in tension and compression so Fig. 1l is a sectional view showing the mo 95 that the effects of worn journals are additive tor for maneuvering the quadrant shaft. or cumulative. Hence the expedient of using This is the motor which controls the starting, an odd number of cranks equally spaced in. stopping and reversing of the engine. each shaft and a corresponding number of Fig. 12 is a fragmentary plan showing a - parallel rods, each of which always acts in portion of a quadrant with radius rods, ec compression has been adopted. Three is the centric straps, &c. theoretical minimum, but in practice three Fig. 13 is a fragmentary view showing the develops excessive friction at certain crank throttle valve and its actuating connections. angles. Five cranks is a satisfactory stand-_ The engine illustrated is provided with four identical cylinders, one of which is illus 40 ard and is preferred. 105 As an incidental feature there is combined trated in detail at 11 in Fig. 1,. This cylinder with the valve controlling gear a throttle is of the terminal exhaust or uniíiow type hav valve and mechanism for closing the throttle ing central exhaust ports 12 controlled by when the valve controlling gear is in neutral the elongated piston 13. The exhaust ports 12 45 position. This is merely a safety device to lead by way of branch ports 141 to the main im _provide secondary stopping means in case of exhaust line 15. failure or wrong adjustment of the valve The cylinder l1 has the heads 16 provided gear. The throttle preferably has no regu with packing glands 17 to seal the joint with lative effect on the engine when running. the piston rod 18 and tail rod 19. These parts The preferred embodiment of the invention are of ordinary construction as are the inlet is illustrated in the accompanying drawings, steam ports 2O and the cylinder drain cocks in which :- ' 21, crossliead 22, crosshead guides 23 and con Fig. 1 is a longitudinal axial section necting rod 24. through one cylinder and its inlet valve gear. Each connecting rod 24 is connected to a The relation of the plane of section to the in corresponding crank 25 on crank shaft 26 let and unloading valves is indicated by the running in main bearings 27. The shaft 26 i line 1-1 in Fig. 5. ' is shown in Fig. 2, while the angular ar Fig. 2 is a transverse section through a rangement of the cranks is illustrated dia portion of the engine on the line 2-2 of grammatically in Figs. 7 and 8. In the pre Fig. 1. ferred arrangement the spacing is 90°, 45°, Fig. 3 is a fragmentary view showing a 90°, 135°, because a desirable balancing char portion of Fig. 1 enlarged to show the details acteristic is thus secured. From the last of the inlet and unloading valves with the ac 'named figures it will be observed that the tuating mechanism therefor. eight dead points for the four double-acting Fig. 4 is a perspective view showing a crank cylinders are equally spaced in a rotation of 4 1,811,02o

the crank shaft, this being an important the Working spaces and allows the engine to factor. in securing satisfactory starting and start without opposition therefrom. The ac reversing. tion is secured by the excess travel of the v Since the shaft 26 is large and is inconven valve actuating mechanism when the valve ìently located it is desirable to place the valve gear is in the two extreme settings. actuating eccentrics 28 on a lay shaft 29 The unloading valves are shown in Figs. 1 driven in the same direction and at equal and 3 as single-beat poppet valves 47 which speed by the crank shaft. The shaft 29 turns open inward (toward the cylinder) into ports in a series of aligned bearings 30 and is 10 48 which communicate with the steam inlet driven by a series of parallel rods 31, íive be ports 20 by way of ports 44 (see Figs. 3 75 ing shown and preferred, each rod connect and 6). They are provided with stems 49 ing a corresponding pair of eccentrics 32 and which project upward through guides, and 33 placed respectively in the crank lshaft 26 they are urged upward in closing direction and on the lay shaft 29. Outboard bearings 15 each by a spring 50. A tappet 51 is guided 34 and 35 are provided to steady each group and sealed in the bonnet 52. The lower end 80 of five eccentrics 32 and 33 respectively, and of the tappet 51 abuts against valve stem 49 the eccentrics of each group are spaced at and the upper end is actuated by a roller on uniform angular intervals and all have the the inlet-valve actuating-cam, later to be de same eccentricity. As explained this connec 20 scribed, when the latter moves through its tion ensures accurate transmission of rotary extreme range. The spaces above valves 47 85 motion from the crank shaft to the lay shaft are connected to the exhaust port 14 through in both directions, and without any lost mo pipe connections 53 (for valves at the head tion at reversal. end) and 54 (for valves at the crank end). The steam inlet valves are shown in Figs. 1, 25 Mounted on each steam chest 38 is a frame 3, and 6 and are balanced double beat poppet 55 which carries the valve actuating mecha 90 valves with quick motion cam actuation de nism. One such frame 55 is shown in Fig. 4 signed to permit over-travel of the actuating in detail. This view shows the frame usedL cam in valve-open and valve-closed positions. at the crank end, but the head end frame is This valve and the actuating cam mecha 30 identical except that it lacks the trunnion nism are known but because of its quick open 56. This trunnion 56 is used on the crank 95 ing and closing characteristics and the pos end frame to carry the swinging arm 57 which sibility of over-travel of the actuating gear, guides the reach rods, hereinafter described, the combination is eminently suitable to the for driving the actuating cam of the head end purpose. 35 inlet valve. The head end and crank end The steam chests are shown generally at actuating mechanisms are identical but are 10G 38, the valve cage at 39 and the valve at 40. actuated individually by separate eccentrics The valve 40 is actuated by reciprocating and straps. valve stem 41 with lost motion spring con Vertica-lly guided in the top of each frame nection 42 which ensures a moderate yield 40 55 is a plunger 58 which is connected to the ing seating pressure on the valve when closed. corresponding inlet valve stem 41. A cylin The stem 41 passes through the bonnet 43, drical pin 59 is journaled in plunger 58 and the usual sealed joint being afforded. The eccentrically pinned thereto at 60 is the cam space below the cage 39 communicates di follower 61 which is itself pivoted in frame ­ rectly with the steam port 20 leading to the 45 55 at 62. The follower 61 carries two rollers cylinder, and a by-pass port 44 leads past 63 and 64 positioned on opposite sides of 110 valve 40 to the space within chest 38 above pivot 62 and contacting with the periphery valve 40. A relief valve 45 normally held of actuating cam 65 which is itself pivoted at closed by pressure in chest 38 obstructs port 44. It opens automatically when cylinder 66. The cam 65 is so formed that as it swings 50 alternately back and forth through a rela pressure exceeds main steam pressure as it tively small angle it imparts sudden positive i115 might do in case of accident or maladJustment of the valve gear. Valve 45 is purely a safety movements in alternate directions to cam fol device and normally remains closed. The lower 61. The follower 6l through the con nections described opens and closes the inlet position of valve 45 is indicated on Fig. 6 by valve 40. the enlargement 46 formed on the side of the 120 steam chest 38 to receive it. The cam 65 is so formed that it may have In additon to the relief valve just de considerable over-travel while the valve re scribed, there is an unloading valve asso mains open and while it remains closed and ciated with each steam chest and inlet valve. this property permits a variable timing of 60 This valve is designed to be opened by the the cut-off by varying the action of the valve 125 actuating mechanism of each inlet valve while actuating eccentrics as is hereinafter de the inlet valve is closed, when the valve gear scribed. The over-travel in valve-closed con~ is set in its maximum position either turn~ dition is also availed of to actuate the un ing over, or turning under, but not other 65 loading valve by placing a roller 67 on the wise. This vents the confined steam from cam 65 in position to strike tappet 51 and 130 1,811,020 5

open valve 47 when the cam has its extreme the axis of pivot 75 is shown for all three po over-travel in inlet-valve-closed condition. - sitions and this last-named detail shows the The valve actuating eccentrics 28 are ar variable lead characteristic and how the valve ranged in pairs, the eccentrics of each pair cams 65 must travel further and further in being at 180° to each other. One eccentric valve closing direction as the operating lever 70 of each pair drives the crank end inlet valve moves from neutral toward its two maxi and the other drives the head end inlet valve mum positions. ' l through independent eccentric st-raps 70. Since only that art of the motion t0 the These straps 70 are of the type customarily right of line A-B 1s effective to open the in used in Marshall valve gears and have a rod let valves, it vfollows that in the neutral posi 75 portion 71 guided by a radius bar 72. The tion the inlet valves do not open at all. rod portion 71 i-s bifurcated as shown in Hence the engine mustvstop when the valve Fig. 2 and t-hus straddles the end of the cor gear is set in neutral position and it is there responding radius bar 72 (see Fig. 12). fore possible to control the engine solely by 15 The crank end eccentric rod 7l is connected the action of the cylinder 80 acting on the re 80 to its cam 65 by a single reach rod 73. The versing valve gear. ` ’ head end eccentric strap- 70 is connected to its The actuating mechanism for the ma cam 65 by a two part reach rod consisting of neuvering shaft 78 is shown in Figs. 1, 2 two members 7 4, connected together, sup and 11. The piston 7 9 which works in the 20 ported and guided by the arm 57 above de cylinder 80 is of the `differential, type and is 85 scribed. 'l‘he pivot connection to the eccen connected by the rod 81 with the arm 82 fast tric rod 71 is shown at 75. on the shaft 78, as already described. The Aside from this slight difference in the con left hand smaller face of the piston 79 is con struction of the reach rods, and the placing stantly subject to fluid pressure, usually hy 25 of their actuating eccentrics at 180° from draulic pressure. Pressure fluid is admitted 90 cach other the head 4end and crank end valve to and discharged from the right hand larger gears are identical and operate in the same face of the differential piston 79 by means of way. The use of' independent drives for the an enlarged inlet and discharge valve, indi two valves is made necessary by the asym cated generally by the- numeral 80 and hav 30 metric operating characteristic of the par ing an inlet poppet valve 80i and an exhaust 95 ticular modified Marshall valve gear chosen poppet valve 80x arranged to be unseated for illustration, for if a single gear of this alternatively by a cam 85. An arm 86, fast on modified type were connected in the conven shaft 78 and so arranged as to be'horizontal tional manner so as to operate both the head when the shaft 78 is in mid-gear position, as 35 _ end and crank end inlets, one inlet valve must shown in Fig. 11, is connected by a floating 100 have excessive lead. lever 87 and link 88 with the actuating arm The radius bars 72 are pivoted at 76 to so of the cam 85. The floating fulcrum 89 of . called quadrant yokes 77. There is one quad lever 87 is guided by a link 90 pivoted to arm rant yoke 77 for each cylinder, each yoke 91 on the valve gear maneuvering shaft 92. 40 supporting two radius bars 72, one for the Maneuvering leve-r 93 is fast on the shaft 92 _105 crank end eccentric and the other for theI and is the means by which the entire engine head end eccentric (see Figs. 1, 2, 10 and 12). is controlled under normal conditions. If rl`hese quadrant yokes 77 are carried by a sec the lever 93 be swung to the right, the arm 91 tional reverse-shaft 78, the quadrant yokes swings down, lowers the fulcrum 89 and thus 45 with the reverse shaft elements forming a results in swinging cam 85 counter-clockwise rigid unitary structure. rll‘his is angularly to open the exhaust valve 80X. This causes shif‘table by the maneuvering motor which has the piston 79 to move to the right, swinging a piston 79, working in a cylinder 80, and the shaft 78 clockwise and causing the arm connected by piston rod 81 and lever 82 with 86 to move downward. This lowers the left 50 the reverse shaft 78 (see Figs. 1, 2 and 11). hand end of the lever 87, causing the right The usual construction of Marshall valve hand end torise and restore­ the cam 85 to its gear is such that the effective length of radius normal position in which botlî the valves 801 bar 72 is equal to the radial distance from and 80X are closed. lf the lever 93 be moved the axis of reverse shaft 78 to the axis of pivot to the left the inlet valve 80i will be opened, 55 support 76 on the quadrant. Under these the piston 79 will move to the left, the arm 86 conditions constant lead is secured. The va will rise and restore the valve 80ì to its closed riable lead desired to secure over travel of position. It follows that for every posi the inlet valve gear in valve closing direction tion of the lever 93 there is a correspond can be had by using longer or shorter radius ing position for the piston 79 and conse 60 bars, the parts being appropriately arranged, quently for the shaft 78. Remembering that 125 but the use of shorter radius bars is illus in mid-gear position of the shaft 78, which is trated. Fig. 10 is a diagram of crank and the position shown in Fig. 11, all the steam in piston positions and of the two maximum let valves of the cylinder are closed, it will be and the neutral positions of the operating observed that the engine may be stopped by 65 lever 82 ard quadrant yokes 77. The path of setting the lever 93 in its mid position, and 130 6 1,811,020

caused to operate in either of its two direc The parts are dimensioned to meet the fol~ tions of rotation by moving the lever 93 in lowing requirements: one or another direction from such mid posi lVhen the lever 101 is in the horizontal posi tion. To start the engine the lever 93 is tion shown in Fig. 9, the lever 99 is shifted moved in one or another direction to its limit in a counterclockwise direction so far that ofmotion so as to shift the shaft 78 to one or whether the lever 103 be in the open position another full gear position in which the un« shown in Fig. 9 or in its extreme left hand loading valves are operated. The valve gear position, indicated by the legend “closed” on is only retained in full gear position for a Fig. 9, the reach rod 98 will be so far to the 10 brief period and is thereafter moved to vary left that the cam 96 holds the throttle valve the cated according to the load. 95 closed. This action is possible because of In the event of maladjustment of some part the characteristic of the cam 96 of permitting ofthe valve gear a serious accident might oc over~travel while holding the valve closed cur if the entire reliance were placed on the However, if the lever 103 is in the open posi inlet valve gear to stop the engine. Conse tion shown in Fig. 9 and the arm 101 be swung quently as a secondary means and solely as a up or down from its horizontal position, the safety device a mechanism is provided which reach rod 98 will be drawn to the right far closes the main throttle valve when the inlet enough to open the throttle 95. This means valve gear is in neutral position. that when the arm 103 is in its open position This mechanism is shown in Figs. 9 and 13 of Fig..9, the cam 96 is so positioned that 85 and may be readily understood from these fig slight motion of the rod 98 to the right will ures considered in connection with Figs. 1 ­open the throttle valve 95. and 2. The main throttle valve is indicated It follows from the above that if the lever generally at 95 (Fig. 13) and consists of a 103 be moved from the open position shown 25 double beat poppet valve, larger than, but in Fig. 9, to the closed position indicated by 90 structurally identical with, the steam inlet the legend “Closed” on Fig. 9, the reach rod valves for the cylinders, already described. 98 will be moved so far to the left that no The throttle valve is actuated by a ­cam 96 and motion of arm 101 above or below its horizon cam follower 97, similar to the parts 61 and 65 tal position can shift the reach rod 9,8 far ao alreadyodescribed. The follower 97 has two enough to the right to open the throttle valve. 95 rollers through which the cam 96 imparts pos~ The throttle actuating lever 103 is shifted to itive motion to the follower in-both direc its closed position only to shut the engine tions. The cam 96 turns in a clockwise direc down. During ordinary stoppages it remains tion to close the valve and after the valve has in the open position of Fig. 9, but despite this closed may over-travel while maintaining the fact the movement of the arm 101 to hori 100 valve closed. Similarly, the valve is opened zontal mid-gear position closes the throttle 95 by counter-clockwise motion of the cam 96 independently of the action of the lever 103. and the cam may over-travel after the valve This is merely a safety feature, because as al is closed, maintaining said valve closed dur ready explained, when the arm 101 and the ing the over-travel of the cam.l The cam 96 is shaft 78 are in mid-gear position the inlet actuated by means of a reach rod 98 connected valve to the cylinders can not open in any po to the lower end of the cam 96, from which it sition of the engine so that by the simple act follows that the throttle valve is closed by of setting shaft 78 in mid-gear position the motion of the reach rod 98 to the left and engine is stopped. The only purpose in clos 45 opened by motion of the reach rod to the right. ing the throttle 95 at such a time is to avoid 110 The other end of the reach rod 98 is con a wreck in the event that the inlet valves nected to the upper end of a floating lever 99 should be improperly set and hence not func whose lower end is connected by link 100 with tion to stop the engine.I an arm 101 fast on' the reverse shaft 78. The The throttle actuating lever 103 is shifted '50 arm 101 is so positioned on the shaft 78 that by a servo-motor essentially identical with 115 when’this shaft is in mid-gear position thel that used to maneuver the reverse shaft 78. arm 101 is substantially horizontal, as shown The cylinder of the servo-motor is shown at in Fig. 9. The floating lever 99 is pivoted 105, the piston at 106, and the piston rod at ` near its mid-length on a journal 102 carried 107. The rod 107 is connected directly to the by the throttle actuating lever 103 a short lever 103. The piston is of the differential distance above the fulcrum on which that type, its smaller left hand face being con leverturns. At its upper end the lever 99 is stantly subject to fluid pressure, usually hy provided with a bearing block 104 which is draulic pressure. The pressure acting on the adjustable, on occasion, in a radial direction larger right hand face of the differential pis 60 in the lever 99 so as to determine the effective ton is alternately admitted by an inlet valve ' length of this lever above the journal 102. It 108 and discharged by an exhaust valve 109, will be understood that the arm 101 swings which are actuated alternatively by a cam _ above or below the horizontal position shown 110. The lever 103 carries an arm 111 to in Fig. 9, according as the engine is running which is pivoted a Heating lever 112. The ­under or over. other end of the floating lever 112 isconnected 130 ì 1,811,020

by a link_113 to the valve actuating cam 110. latter has the full travel produced in full gear The lever 112 has a floating fulcrum 114:l position; and automatic means serving to re supported by the upper end of link 115 whose lieve said cylinders of pressure in excess of lower end is ñxed on the arm 116 fast on the inlet steam pressure. throttle maneuvering shaft 117. . 3. A rolling mill engine comprising in com 70 The shaft 117 may be shifted by hand lever bination not less than three double-acting cyl 118 "(see Fig. 9). If the lever 118 be moved inders of the terminal exhaust type; revers to the right the link 115 moves the fulcrum ino` variable c_ut olf inlet valve gear for said 114` upward, rocks the cam 110 in a clockwise cylinders said gear being .of the variable 10 direction, opens the inlet valve 108 and admits travel link type and having insufficient travel Ul additional fluid pressure against the right in mid-gear position to open the inlet valves, hand side of piston 106. Piston 106 then and suiiicient travel in other positions to give moves to the left, swings lever 103 in a coun variable cut off with and maximum cut olf in ter-clockwise direction, and this causesarm both directions 'of running at about % stroke; 15 111 to swing upward, raising the left hand and unloading valves operable by said valve 80 end of floating lever 112 and depressing the gear at said maximum cut oils. right hand end to restore cam 110 and cause 4. The combination with an engine hav valve 108 to close. Thus as the lever 118 is ing a cylinder of the terminal exhaust type swung to the right, the piston 106 moves to the and inlet valves, of a reversing valve gear 20 left, assuming a corresponding position for said gear being of the variable travel link each position ot the lever 118. Movement of type and having increasing travel from mid the lever 118 to the left produces a. similar lgear toward both full gear positions, and be result in the reverse sense, the cam 110 being ing connected to actuate said inlet valves; and rocked downward to open the discharge valve unloading valves operable by said valve gear 25 109, the piston 106 moving to the right unt-il, when the latter .has substantially its maxi through the action of the arm 111, floating mum travel. link 112 and cam 110, it restores the normal 5'. The combination with an engine having closed condition of the valve 109. . a cylinder of the terminal exhaust type and The operation of the various parts has been inlet valves, of a reversing valve gear said 30 described in connection with the discussion gear being of the variable travel link type above given, and no elaborate description of and having increasing travel from mid gear the operation of the engine is necessary. The toward both full gear positions, and being important feature is that it is so de’signed that connected to actuate said inlet valves; and it will start at maximum cut olf under full unloading valves of the inward opening pop 35 load, and that it is controlled both as to speed pet type mounted in the path of a portion of and direction of running and as to stopping said valve gear and in position to be engaged exclusively by the valve gear. Obviously and forced open thereby when the valve gear various changes can be made without depart has its maximum travel. ‘ ing from the inventive principle involved and 6. The combination with an engine having 40 therefore no limitation to the structure illus a cylinder of the terminal exhaust type and trated is implied except to the extent specified inlet valves, of a reversing valve gear said in the following claims. gear being of the variable travel link type What is claimed is: and having increasing travel from mid-gear 1. A rolling mill engine comprising in com towardv both full gear positions, and being 45 bination a plurality of double-acting cylin connected to actuate said inlet valves; un- 1E ders of the terminal exhaust type; reversing loading valves arranged to be operated by variable cut olf inlet valve gear for said cyl said valve gear when the latter has substan inders, said gear being of the variable travel tially its maximum travel; and relief valves link type and having insufficient travel in interposed between said cylinder and the 50 mid-gear position to open the inlet valves,` steam supply and arranged to open auto- lí and sufficient travel in other positions increas matically when cylinder pressure predomi ing toward both full gear positions; and un nates. loading valves operable by said valve gear 7 . The combination with an engine having when the latter has the full travel produced ac-ylinderofthe terminal exhaust type and in 55 in full gear positions. dividual steam inlet valves, of two Marshall 2. A rolling mill engine comprising in com type variable cut off reversing valve gears, bination a plurality of double-acting cylin one for each inlet valve, said gears each in ders of the terminal exhaust type; reversing cluding an eccentric strap, radius bar and 'variable cut oil' inlet valve gear for said cylin quadrant, the radius of the quadrant and the 60 ders, said gear being of the variabletravel link length of the bar being unequal, and the ïïï‘ï' type and having insuflicient travel in mid parts being so arranged as to afford a neu gear position to open the inlet valves, and tral mid-gear position in which both inlet suiiicient travel in other positions increasing valves are maintained closed. toward both full gear positions; unloading 8. The combination with an engine having 65 valves operable by said valve gear when the a cylinder of the terminal exhaust type and 8 1,811,020

individual steam inlet va.lves,of twoMarshall individual steam inlet valves of the poppet type variable cut off reversing valve gears, type and individual actuating cams therefor one for each inlet valve, said gears each in of two Marshall type variable cut oíi‘ revers cluding an _eccentric with strap, radius bar ing valve gears each connected to actuate a and quadrant, the radius of the quadrant and corresponding cam, said gears each includ 70 ‘the length of the bar being unequal, and the ing an eccentric with strap, radius bar and parts being so arranged as to afford a neutral quadrant, the radius of the quadrant and mid-gear position of minimum travel in the length of the bar being unequal, and the which both inlet valves are maintained s parts being so arranged as to aíord a neutral 10 closed; and unloading valves for the two ends mid-gear position of minimum cam travel 75 of the cylinder arranged to be opened by in which both inlet valves are maintained said valve gear through its increased travel closed; and inward opening poppet unload when in full gear positions. ing valves for the two ends of the cylinder 9. The combination with an engine hav arranged to be actuated by said cams when 15 ing a cylinder of the terminal exhaust type the latter have their maximum travel occa 80 and individual steam inlet valves, of two sioned by the placing of the valve gear in its Marshall type variable cut oft' reversing valve full gear positions. gears, one for each inlet valve, said gears each 13. The combination of an engine includ including an eccentric with strap, radius bar ing a cylinder and steam inlet valves there 20 and quadrant,tlie radius of the quadrant and for; a throttle valve controlling the flow of 85 the length of the bar being unequal, and the steam to said inlet valves; a variable cut oiï parts being so arranged as to afford a neutral reversing inlet valve gear connected to actu mid-gear position of minimum travel in ate said inlet valves and having settings for which both inlet valves are maintained forward and reverse running and an inter 25 closed; unloading valves for the two ends of mediate neutral position in which all said 90 the cylinder arranged to be opened by said inlet valves are closed; and >operative con valve gear through its increased travel when nections between said valve gear and said in full gear positions; and relief valves .nor throttle valve for closing said throttle valve mally held closed by the pressure of steam when said valve gear is in its neutral posi 30 supply interposed between the cylinder and tion. 95 steam supply. ‘ 14. The combination of an engine includ 10. The combination with an engine hav ing a cylinder and steam inlet valves there ing a cylinder of the terminal exhaust type, for; a throttle valve controlling the flow of individual steam inlet valves of the poppet steam to said inlet valves; a variable cut oil' 35 type and individual actuating cams therefor, reversing inlet valve gear connected to actu 100 of two Marshall type variable cut oii revers ate said inlet valves and having settings for ing valve gears each connected to actuate a forward and reverse running and an inter corresponding cam, said gears each includ ~ mediate neutral position in which all said in ing an eccentric with strap, radius bar and l let valves are closed; operative connections quadrant,.the radius of the quadrant and between said valve gear and said throttle 105 the length of the bar being unequal, and the valve for closing said throttle valve when parts being so arranged as to afford a neutral said valve gear is in its neutral position; mid-gear position oiE minimum cam ltravel in and independently operable means for clos which both inlet valves are maintained ing said throttle valve regardless of the set closed. ting of the valve gear. 110 11. The combination with an engine hav 15. The combination of an engine including ing a cylinder of the terminal exhaust type, . a cylinder and steam inlet valves therefor; a individual steam inlet valves of the poppet throttle valve controlling the flow of steam type and individual actuating cams therefor to said inlet valves; a variable cut oil" re 50 of two Marshall type variable cut oit revers versing inlet valve gear connected to actuate 115 ing valve gears each connected to actuate a said inlet valves and having settings for for corresponding cam, said gears each including an eccentric with strap, radius bar and quad ward and reverse running and an intermedi rant, the radius of the quadrant and the ate neutral position in which all said inlet 55 length of the bar being unequal, and the parts valves are closed; a throttle valve actuator; 120 being so arranged as to afford a neutral -mid and :floating connections between said actu gear position of minimum cam travel in ator, throttle valve and inlet valve gear. which both inlet valves are maintained 16. The combination with an engine char closed; and unloading valves for the two ends acterized by low inertia masses and having of the cylinder arranged to be actuated by at least four double-acting cylinders and pis 125 said cams when the latter have their maxi tons therein, of a multiple throw crank shaft mum­ ¿travel occasioned by the placing of the operatively connected with said pistons, the valve gear in full gear positions. various throws of said crank shaft being so 12. The combination with an engine hav angularl spaced relatively to each other that _ ing a cylinder of the terminal exhaust type, the deady points for the diíïerent worklng 130 1,811,020 9

spaces occur successively and are uniformly having more than three double-acting cyl- - spaced throughout a revolution. . `inders, and having cranks arranged to cause / 17. The combination with an engine hav the individual working spaces to deliver their , ing more than six Working spaces and driving impulses serlatim at uniform' intervals; of connections arranged to deliver the driving cam actuated inlet valve mechanisms control 70 impulses of the individual spaces seriatim at ling the inlets to said working spaces; the ` umform intervals; of valves controlling the actuating cams of said valves being capable` admission to said Working spaces; and a re of over-travel after the valve is closed and versing valve gear of the'link type arranged after it has been opened; a reversing valve 10 to give a variable cut-oft in both directions of gear of the Marshall type including a swing 75 running and to have a mid-gear position lin ing yoke and radius bars, the radius bars and which said valves are closed. yoke being of unequal radii; means for con 18. The combination with a simple engine trolling all said yokes simultaneously to vary having more than three double-acting cylin the cut-oil when running in either direction; 15 ders, and having cranks arranged to cause and unloading valves one adjacent each in 80 the individual Working spaces to deliver their let valve and each serving the same working impulses seriatim at uniform intervals; of space as the adjacent inlet valve, said unload valves controlling the inlets to said working ing valves being arranged to be opened by spaces; reversing valve gears of the link type, the over-travel of the inlet valve actuating 20 one for each inlet valve; and means for con cam beyond inlet valve closing position. 85 trolling all said gears simultaneously, said 22. The combination with an inlet valve gears and controlling means being arranged serving a Working space, of a reversing valve to give variable cut-oill in both directions of gear of the link type capable of giving vari running with a mid-gear position in which able cut-off in both directions of running, and said valves are closed. characterized by over-travel in valve-clos 90 19. The combination with a simple engine ing direction in full-gear settings; and an having more than three double-acting cylin unloading valve adjacent the inlet valve` ders, and having cranks arranged to cause the serving the same Working space and arranged individual working spaces to deliver their im to be opened by the inlet valve gear when the 30 pulses seriatim at uniform intervals; _ of same over-travels in full gear settings. 95 valves controlling the inlets to said Working 23. The combination of an inlet valve in spaces; reversing valve gears of the link type, cluding a valve actuating cam capable oÍ one for each inlet valve; means for control over-travel after the valve has opened and ling all said gears simultaneously, said gears after the valve has closed; a Working space 35 and controlling means being arranged to give fed by said valve; a reversing valve gear of 100 variable cut-oft' in both directions of running the Marshall ltype including a yoke and a with Iexcess travel in full-gear settings and radius bar of unequal radii; and an unload with a mid-gear position in which said valves ing valve adjacent the,k inlet valve, serving are closed ; and unloading valves, one adjacent the same Working space and arranged to be 40 each inlet valve and each serving the same opened by the inletA valve actuating cam l05 Working space as the adjacent inlet valve, when the same overtravels in inlet valve clos said unloading valves being arranged to be ing direction in full gear settings. opened by over-travel of the inlet valve gear _ 24. The combination of an inlet valve hav in a closing direction in full gear settlngs. ing an inlet steam passage leading thereto; 45 20. The combination with a simple engine a Working space fed by said valve; of a re having more than three double-acting cyl versing valve gear of the link type arranged inderso? the terminal exhaust type, and hav to give variable cut-ottl in both directions of ing cranks arranged to cause the individual running, and characterized by over-travel in Working spaces to deliver their impulses seri a valve closing direction in full gear settings; 50 atim at uniform intervals; of valves control an unloading valve adjacent the inlet valve 115 ling the inlets to said Working spaces; re serving the same Working space and arranged versing valve gears of the link type, one for to be opened by the inlet valve gear when each inlet valve; means for controlling all the same over-travels in full gear settings; said gears simultaneously, said gears and con and a relieî'r` valve controlling the passage be 55 trolling means being arranged to give vari tween said working space and said inlet steam 120 able cut-off in both directions of running with passage and normally held closed by pre excess travel in full gear settings, and ,withv ponderating inlet steam pressure. a mid-gear position in which said valves are 25. The combination of an inletfvalve in closed; and unloading valves, one adjacent cluding an inlet steam passage leading there 60 each inlet valve and each serving the same to and a valve actuating cam capable of over Working space as the adjacent inlet valve, travel after the valve has opened and after said unloading valves being arranged to be the valve has closed; a working space fed by opened by over-travel of the inlet valve gear said valve; a reversing valve gear of: the in a closing direction in full gear settings. Marshall type including a yoke and a radius 21. The combination with a simple engine bar or unequal radii; an unloading valve ad t Gi 'Lei 1,02@ jacent the inlet valve serving the same work gine; reversing variable cut-olf inlet valve ing space and arranged to be opened by the gears for said cylinders, said valve gears be- ­ inlet valve actuating cam when said cam lng characterized by a different range of over-travels in inlet valve closing direction travel in mid-gear and in full gear positions; in full gear settings; and a relief valve con and unloading means for said c linders ren trolling the passage between said working dered alternately operative an inoperative space and said inlet steam passage and nor by said variable travel according as the gear mally -held closed by preponderating steam is set in one or another position. pressure. Y , ‘ 31. A reversible rolling mill engine com 26. In an engine, the combination of a plu prising ­in combination, four double-actin rality of cylinder Working spaces,­ exhaust cylinders; pistons therein; cranks to Whici valve means for said Working spaces indif said pistons are respectively connected, said ferent to the direction of rota-tion of the en cranks being spaced 90°, 45°, 90° and 135°; » gine, an individual steam inlet valve for each exhaust valve means indifferent to the direc Working space; individual Marshall type tion of running; inlet valves for each end sol variable cut-oit' reversing valve gears, one of each cylinder; and reversing variable cut connected to operate each steam inlet valve, off valve mechanism controlling Said inlet said gears each including an eccentric strap, valves and having a maximum cut-off of the radius bar and quadrant, the radius of the order of 60% and having a variable lead 20 quadrant and the length of the bar belng characteristic such that at substantially mid- «‘ unequal and the parts being so arranged as gear position the inlet valves do not open. to afford a neutral mid-gear position in which 32. A reversible rolling mill engine com all inlet valves are maintained closed. prlsing in combination, four double-acting ' 27. In an engine, the combination of a plu cylinders; pistons therein; cranks to which rality of cylinder Working spaces; exhaust said pistons are respectively connected, said 00 valve means for said spaces indifferent to cranks being spaced 90°, 45°, 90° and 135°; the direction of rotation of the engine; in exhaust valve means indifferent to the direc dividual steam inlet valves of the poppet type tion of running; inlet valves for each end for said working spaces; individual actuat of each cylinder; a reversing variable cut-oil' 30 ing cams for each inlet valve; Marshall type valve mechanism controlling said inlet valves 95 variable cut-cti reversing valve gears, one and having a maximum cut-off of the order connected to each of said individual actuat of 60% and having a variable lead character ing cams, said gears each including an eccen istic such that at substantially mid-gear posi tric with strap, radius bar and quadrant, the tion the inlet valves do not open; a throttle 85 radius of the quadrant and the length of the valve; and connections between said valve '100 bar being unequal and the parts being so ar gear and throttle to hold the latter closed ranged as to aiiord a neutral mid-gear posi when the former is in substantially mid-gear . tion of minimum cam travel in which all in position. let valves are maintained closed. 33. A reversible rolling mill en ine com 40 28. ln an engine, the combination of a plu prising in combination, four dou le-acting 105 rality of cylinder working spaces, exhaust cylinders; pistons therein; cranks to which valve means for said spaces indifferent to said pistons are respectively connected, said the direction of rotation of said engine ; steam cranks being spaced 90°, 45°, 90° and 135°; inlet valves, one for each said Working space; exhaust valve means for each end of each and variable cut-ofi' reversing valve gears of cylinder; a reversing variable cut-oft` valve 110 the link type, one for each inlet valve and mechanism controlling said inlet valves and each characterized by greater lead in mid having a maximum cut-oli' of the order of gear than in full gear positions. ' 60% and having a variable lead character 29. In an engine, the combination of a plu istic such that at substantially mid-gear posi 50 rality of cylinder Working spaces; exhaust tion thecinlet valves do not open; a throttle 115 _valve means for said spaces indifferent to valve; connections between said valve gear the direction of rotation of the engine; steam and throttle to hold the latter closed when inlet valves oí’ the poppet type, one for ­each the former is in substantially mid-gear posi or" said Working spaces; actuating cams, one tion; and independent means for closing said 55 associated with each inlet valve to actuate throttle valve regardless of the setting of said 120 the same; and variable cut-oit reversing valve valve gear. gears of the link type each operatively con 34. A reversible rolling mill en ine com nected With a corresponding actuating cam prising in‘combination, :tour dou le-acting and each characterized by a greater lead char cylinders; pistons in said cylinders; cranks 60 acteristic in mid-gear than in full gear posi to which respective pistons are connected 125 tions. spaced successively 90°, 45°, 90° and 135°;_ 30. ln a rolling mill engine, the combina exhaust valve means indifferent to the direc tion of a plurality of double-acting cylinders; tion of rotation; inlet valves, one for each exhaust valve means for said cylinders indif end of each cylinder; and a separate variable 65 ferent to the direction of rotation kof the en cut-off reversing valve gear for each inlet 130 1,811,020 11

valve, all giving a maximum cut-off of the order of 60% and having a variable lead characteristic such thatat substantially mid gear position the inlet valves do not open. 35. A reversing rolling mill engine, com prising in combination, four double-acting cylinders; pistons in said cylinders; cranks spaced successively 90°, 45°, 90° and 135° to which said pistons are respectively connect ed; exhaust valve means indifferent to the 10 direction of rotation; inlet valves, one for each end of each cylinder; an unloading valve associated with each inlet valve; and a separate variable cut-oil' reversing valve linkage for each inlet valve, each character 15 ized by a maximum cut-oil' of the order of 60% and having variable travel and variable lead characteristics, such that With minimum travel substantially at mid-geaìr the inlet valves do not open and at maximum travel, 20 substantially at full gear positions, the link age engages and opens said unloading valves. In >testimony whereof I have signed my name to this specification. , HELENA C. NORDBERG, 25 Emeoutm'œ of the Estate of Bru/no V. Nowi bef'g. -

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