US955852A

US955852A - Plunger-equalizer.

Info

Publication number: US955852A
Application number: US26958605A
Authority: US
Inventors: Andrew M Coyle
Original assignee: Otis Elevator Co
Current assignee: Otis Elevator Co
Priority date: 1905-07-14
Filing date: 1905-07-14
Publication date: 1910-04-26
Anticipated expiration: 1927-04-26

Description

- A.KM."G0YLE. v

l PLUNGERBQUALIZER.

APPL'IOATioN FILED 11114114.1905. v l 95;"1558`552;l I D Patented Apr. 26,1910.

3 SHEETS-SHEET 1.

s f A ATTO NEY.

A A'. M; COYLE.

PLUNGER EQUALIZER.

APPLICATION FILED JULY 14, 1905.

Patented Apr. 26,19170.

` 3 SHEETS-SHEET 2.

wnNEssEs:

` Patented Apr,26,191o.

l a amus-SHEET a.

WITNESSES ATTORNEY UNTTED sTATEs PATENT onFIoE.

ANDREW M. COYLE, OF NEW YORK, N. Y., ASSIGNOR TO OTIS ELEVATOR COMPANY, OIEY JERSEY CITY, NEWV JERSEY, A CORPORATION 0F NEW JERSEY.

PLUNGER-EQUALIZER.

Application filed July 14, 1905.

To all whom it may concern:

Be it known that I, ANDREW M. CorLE, a citi/.en ot the United States, residing at New York city, in the county of New York and State of New York, have invcnted'a new and useful Improvement in Flnnger-llqualizers, ot' which the following is a siiecilication.

My invention relates to plunger cqualizing mechanism and has tor its object the provision of vsimplified and etlicient means for cqualizing the motion of a plurality ot plungers to elt'ect a uniform lifting of a load by the plungcrs irrespective of the uneven distribution of said load.

More particularly it the object.- of my in vention to provide improved valves and gearing' and means for automatically Operating the same to regulate. the How of fluid under pressure to a plurality of plungers and effect the lifting of said plungers at substantially equal velocitiesirrespective of the load carried by the various plungers. i Y

To these and other-ends appearing hereinafter. my invention consists of the combination, location, construction. and arrangement of the various partsy all as more fully explained in the following description and specitically pointed out in the claims.

ln the acconn'ianying drawings, Figure 1 is a plan view and Fig. 2 an elevation of a platform and hydraulic m.hanism for 0perating the same; Fig. is a sectional view of the 'preferred form of equalizing valve and also shows the arrangement otditl'erential gears by which .said valve is operated ;'A

Fig. 3 is a view ot the ditl'erential gears.

taken on the line un of Fig. 3; Figpl is an elevation of Fig. 3 with a portion broken away to show certain details; Figs. 5 and 6 show respectively a plan and an elevation' of a modified form of my invention; Fig. 7 shows a detail of the same.; and Figs. 8, 9 and 10 are, respectively, a plan, an elevation and a detail view of my invention applied to valves of ordinary construction.

1 designates a platform to which are secured the plungers, 2, 2', 3, 3' near the four corners of the same. These pluugers are adapted to move in the hydraulic cylinders` 10, 11, 12, 13 in a wel] known manner. These cylinders are fed respectively by the

branch pipes

14, 15, 17 and 1G. Between the

pipes

14 and 15 is connected an equalizilig valve'mcchanisln 18 and between the

pipes

16 and 17 is placed a similar equalizing valve Speccaton of Letters Patent.

Patented Apr. 26, 1910. Serial No. 269,586.

mechanism 19. The

valves

18 and 19 are connected by the

pipes

22 and 23 with the main equalizing valve mechanisnr 2() which is connected to the main supply pipe 21. I associate certain differential gearing with these valves and provide. automatic means for operating the same so that the supply of tluid to the plunger cylinders shall be. so varied when any one of the plungers tends to assume a posit-ion dili'erent from that required by the conditions .of the apparatus, that the platform will always remain substanti-ally level. For instance if one end of the platform beheavily loaded and the other end lightly loaded, the former end will tend tolag behind the latter when the platform is being liftedand consequently a good landing couldnot he made nor could the load be well carried. A

In Fig. 1 I have shown three

differential gear mechanisms

24, 25 and 26 connected in line and to each other by the

shafts

26, 27, 28 and 29. suitable standards 30 (Fig. 6) heilig provided with bearings for these shafts. rigidly secured the bevel gears 31 and and at the ends of the shaft 27 are secured .the bevel gears 33 and 34. T o the inner ends of the

shafts

28 and 29 are fastened the bevel gears and 36, respectively, to face the gears 31 and 34. 'lhegears 32 and 33 face each other in a similar manner. Between each Aset ofV gears, however, there is sufficient space for a planetary bevel gear to be placed with its axis at right angles to the shafts mentioned and mounted 0n bearings in line withsaid shafts. 1n Fig. 3a is shown a bearing 183 for the arm 37 which carries the gear 39. The bearings for the

gears

32 and 33 are At the ends of the shaftl 2G are` indicated at 182 and 182', respectively. The\95 hearings for the arm 37 and the

gears

32, 33, are 1n ahnement with each other. These planetary gears are indicated by the

reference number

38, 39 and 40 and are always in

mesh withthc gears

35, 31 and 32, 33 and A34, 36, respectively, at the ends of the shafts.

4, respectively. The belt et is fastenedl to one' corner of the platform 1 at 56`and passes downwardly under the pulley 6 and then to L the right horizontally (Fig. 2)v under the pulley 47 on the shaft 29 and continues vover the pulley 9 toa weight 55. The belt 5 is fastened at 57 near the opposite corner andpasses vertically downward under the pulley 7 and over the pulley 46 on the shaft 27 to' the weight 54. At the other end of the platjgf form the belts 48 and 49 are attached respec- -be preferable in some cases. In either case it is apparent that there is a tensional recipl rocating connection between the bottom of prevent leakage.

the platform and the differential mechanlsms.

If the fluid is admitted to the three valves and the four cylinders simultaneously by opening the supply pipe 21, the platform will .be lifted. lt will be noticed that the belting is so arranged that the four shafts` will rotate alternately in opposite directions. For instance, if the platform be traveling downwardly the shaft 29 will rotate anticlockwise (Fig. 2); shaft 27, clockwise; shaft 26, anti-clockwiseg'and shaft 28 clockwise. It will be readily understood that if these shafts rotate with uniform velocities the bevel gears secured to them will simply rotate the planetary gears 38,` 39 and 40 about their centers and not tend to bodily move the same so as to operate the valves to which they are connected. vBut if one of the shafts revolves at a dilferent rate of speed'than the one next to it the planetary gears will be moved inl one direction or the' other to move the valve stem.

Before describing further the operation of the equalizing mechanism, I will explain the construction of the

valves

19, 2O and 18, one of which is shown in section in Fig. 3, say the central one of Fig. 1.

62y designates the valve chest through which longitudinally is adapted to move the valve 65, suitable stuffing boxes in the valve chest being provided for lubrication and to The valve chest is provided with five annular ports 78, 7 9, 80, 82

-and 83. The central chamber 63 communicates with the pipe 64 which leads to the supply pipe 21 and also through the valve ports 81 with the interior of the hollow feo valve 65.

Near the ends of the valve chest 62 are 19 and 18. Check

valves

70 and 71 are l placed in the

separate chambers

73 and 74, I

half covered up. That is, half of the number of holes 76 communicate with the annular port 78 when the valve 65 is in central position, while the otherhalf are closed. In a similar' manner half of the holes 77 are in communication with the annular port 79, half of the holes 93 with the port 82, and half of the holes 94 with the port 83.

The chamber 87 of the check valve box 68 communicates with the chamber 73 through the opening 72 but iiuid cannotenter the annular port 78 through the chamber below fronnchamber 73 by reason of the check valve 70. Chamber 87 also communicates with the chamber below the chamber 74 through the opening 92 and liuid can be forced thence into the chamber 74 past the check valve 71. The chamber 74 communicates with the port 63 through the port 75, half of the port holes 77, the `interior of the cylindrical valve 65, a'nd the valve ports 81.

The operation of the construction thus far described is as follows: Assuming a change valve in the supply pipe to be moved to pressure-supplying position d the

Yvalves

19, 2O and 18 in their centra positions, the fluid will flow through the central valve from annular chamber 63 through the holes 81, to v and through half of the holes 76 at one end and half of the holes 94 at the other end of the valve 65. The fluid passes also through half the holes 77 on one hand and half the holes 93 on the other hand. The fluid through the holes 77 and 93, however, cannot be forced out ,of the check valveboxes by reason of the

check valves

71 and 66. The fluid passing through the holes 76 into the annular chamber 78 will lift the check valve .against the force of gravity and flow into chamber 73, through opening 72 into chamber 87 and thence through the port 23 into the pipe 23 and through the same to the valve V19. In this valve the fluid enters the central annular chamber 63 and passes throu h the check valveboX 68, pipe 16 to the cy inder 13. The fluid also passes from the annular chamber 63 through the openings 81,half of the holes 94, chamber 83, port hole 84 into chamber 90, past the check valve 67 into the 'chamber 86, port 91, chamber 88,

port 22', pi e 22 to valve 18. Through 'this through the check valve box G9, pipe 15 to cylinder 11. Ofcourse the fluid passes also through the 'check valve box 69 of the* valve 19 to the pipe 17 and cylinder 12, and through the check valve box G87', to the pipe 14 and cylinder 10. Each valve being in central position the rate of flow of the fluid Will be the same to each cylinder and the platformlwill be lifted at substantially uniform velocities at all points. This will cause the various shafts to be rotated at equal rates of speed and consequently the planetary gears will simply rotate about their centers as before explained. Suppose, however, that a heavy load is placed over the

plungers

3 and 3 at one end of the platform and there be a light or practically no load at the other end. The end bearing the heavy load will tend to lag behind the other end. Therefore, more fluid must be supplied to the valve 19 than tothe valve 18 and this is done automatically with my arrangement. The lighter end will travel faster than the heavier end and in so doing will rotate the shaft 27 in an anti-clockwise direction faster than the shaftf26 is rotated in a clockwise direction. This will effect a movement of the planetary gear 39 bodily to the left and of the valve stem 42 to the right. A larger number of ports 6 Will then be opened into the annular -port 78 while a corresponding number of the ports 94 will be closed from' communication with the port 83. It is,

therefore, seen that iuid will flow at. a 35 greater rate of speed to the valve 19 and at a less rate of speedf to the valve 18 at this time thanswhen the valve is in central position. In a similar manner if one corner is more heavily loaded than the one next to it, as for inst-ance, if there'is a heavier load on the plunger 3 than on the plunger 3, 'the cylinder 13 Will receiveimore fluid than the cylinder 12 until the platform becomes level.

With any unequal load the equalizing action is constantly andgradually taking place in the manner 'stated so long as the platform is.

being lifted.

In the opposite direction of the platform, that is when the same is descending, the most heavily loaded part of the platform will tend to descend the faster. The plunger adjacent that point must therefore be' retarded and this is done automatically by means of the same valves as before but-using other portions of the cheek valve boxes and other elliptic-ally arranged ports in the valve cylinder Of course, in ,descending the fluid must be exhausted from the cylinders and in order to allow the lighter portions of lthe platform to descend at thesame rate of speed as the heavier portions the cylinders under the lighter portionsmust be exhausted faster and those under the heavier port1ons retarded in exhausting. Suppose, then,

that the plungers 2l and 2 are ther'more' to chamber 87, through port 92, past-(check valve '71, through chamber 74, port 75, half of the holes 77, portholcs 81, to the exhaust port of the change valve in the main supply pipe 21. The fluid is also exhausting to the supply pipe exhaust port from the cylinders 10 andv 11, through valve 18, pipe 22, chamber 88, port 95, chamber 89, past check valve 66, chamber 85, port 96 and annular charnber 82. through half the holes 93, to the ports S1 and thence to the supply pipe 21. But when the valve 65 is moved to the left theholes 93 are throttled while those at 77 will he opened wider. The exhausting of the fluid from the cylinders 1() and 11 is therefore retarded and that from the

cylinders

12 and 13 increased. This equalizing action takes place constantly as before. and maintains the platform substantially level. As in the case of the platform ascending, so

also when the same descends the valves 19 and 18vma v also be operated to allow the fluid to escape from one cylinder,V as 10, faster than the fiext adjacent one, as 11.

Figs. 5, and 7 show a modified form of valve, three of which are connected to the )latform lift-ine means Fig. 5) in exact-l f I the same manner as is done. in

F

1 and 2.

But I provide manual means for operating the valves instead of automatic means and therefore the check valve mechanism is un Fig. 6 shows the details of the valve mech-` on which is littettiacrank arm 103 which has secured at its' lciuterend a laterally projecting pin 104. From Fig. 5 it will be seen that a rod105 is connected to the pin 104 o f the crank arm of each of the valve mecha-nisms so that when said rod is moved longi- A tudinally the internal sleeve 97 of each valve will be rotated about its longitudinal axis.

-It will be noticed further, that each of the valvesmay be moved longitudinally with out interference with the operation of the crank arms for in such case the squared ends of the shafts will simply slide through the 50 set. Suppose the

plungersy

2 and 2 are b esquare holes in the hubs of said arms. The pins 104 may slide in the bar 105. A,

The inner sleeve 97 is rovided with series of circularly arranged holes which are adapted to register with corresponding holes in the cylindrical portion of the va ve 65. The valve chest 120 is provided with ports f 117, 118 and 119 which are shown inFig. 6

l tively, registerin as screw-threaded to receive the

ipes

22,64 and 23, respectively, assuming the valve to be the central one of Fig. 5. The screwthreaded ports communicate with annular chambers or

ports

121, 122 and 123 which surround the valve cylinder 65 at the openings therein.

The operation is as follows: Assuming each valve to be in the osition shown in Fig. 6 the supply Huid wil pass through the

ports

118 and 122, the

holes

114 and 115 in the valve 65, and holes 108 and 109, respectherewith, into the interior of the cylin rical'sleeve 97. The Huid ma then pass through the openings 107 an 110in the inner cylinder,

openings

113 and 116, respectively, in the outer cylin der, into the

chambers

121 and 123 and through the ports 117 and 119, pipes 22 andv 23,

valves

18 and 19, pipes 14 andv 15 to the cylinders 10 and 11 and

pipes

17 and 16, to the

cylinders

13 and 12. The fluid cannot pass through the openings 106 or 111 as they are closed at this time, that is, they do not register'with the openings 112 or 117 in the outer cylinder. Now'by moving the rod 105 longitudinally the openingsshown in Fig. 6 may be throttled to any extent desired and therefore the speed with which` the platform is being lifted may be con' trolledor it maybe stopped by rotating the inner sleeve .to entirely -close the circular series -of holes. It will be seen that when the valve is in central position the holes 113 and 116ja-re halfthrottled by the valve seat. Should, therefore, one end of the platform be lifted more rapidly than the other due to a lighter load, the planetary gear would be moved bodily and consequently the valvewould be moved longitudinally. This operation would effect a wider opening of one set of ports and a throttling of the other ing lifted faster than the

plungers

3 and 3.

)This will eect an automatic movement of the valve to the right. The openings 116 `and 110 will be opened wider while those designated by the reference numbers 113 and 107 will be throttled. The fluid can therefore flow to the valve 19 at a greaterrate'of speed than to the valve 18. This will tend to -equalize the`\rate of -speed at which the plungers are being lifted and therefore maintain the platform substantially level. IVhen the platform descends the reverse movements of the plungers tend to take place, that is, the heavier endwill tend to holes 106 must register with the holes 112 and the holes 111 with the holes 117 In central'position each of the series of'holes 112 and 117 are half throttled by the valve seat.l

In the new position of the valve sleeve, when the valve is moved to the right the exhaust from the valve 18 will be more rapidthan from the 'valve 19. The lighter end of the platform wiill then tend to descend Imore rapidly and catch u with the loaded end where the exhaust rom the cylinders will be retarded. The nal result will be to keep the platform substantiall level..

In Figs. 8, 9 and 10 I ave show-n an application of the equalizing gears to valves v of ordinary construction. This type of valve 1 s shown, m Fig. 10 in section and is what 1s known in elevator practice as a three-Wayfchange valve.

In Fig. 8 I have shown four valves, one

for ,each plunger. Upon vthe shaft 135 which extends vthroughout the length of the mechanism are fixe bevel ,gears` 136, .137, 138 and 139. 'Loosely mounted on said shaft are the bevel gears 140, 141, 142and 143 on the hubs of which are secured the pulleys 179,174, 180` and 165.

Fixed to the four corners of the platform 1 are the -

belts

171, 173, 161 and 162 which pass vertically downward to idle pulle s v170, 172, 164 and 163 and then'horizonta yl tp the

pulleys

179, 174, 180 and 165, res ectlvely. The belts pass under all the Ifast named/pulleys to additional idle or direction pulleys 178, 175, 181 and 166 and thence to vlveights 177, 176, 182and 167, respective y.

The shaft 135 may be manually rotated either bythe gearing 129 and handle 128 or by means of the handle 130 and shaft 131 arranged at a point' above the platform but within reach of the operator. This shaft 131 has fixed to it a pulley 132 which is connected by'a belt 133 to another pulley 134 fixed t9 the shaft 135. Upon movement of the shaft 135 in a clockwise direction the link 43 -will be moved toward the left asI move longitudinally in' the valve chest-152.

As shown in Fig. 10 the valves are in central or closed position so that the Huid entering the space between the valves from the cylinders` through the supply port 153 can go no farther, nor can Huid from the supply port- 157 enter the cylinders. If, however, the valve stem 160 is moved to the right the iuid can pass from the supply port 157 through 'the openings 156 in the lining and thence to and through bhe port 153 and to the cylinder connected therewith. Therefore when the shaft is turned in a clockwise direction all the change valves will be opened and the platform will ascend. As it does so, however, the valves will be again closed by the automatic movement of the planetary gears in the opposite direction. The latter movements of the planetary gears will vary with the'load on the different parts of -the platform, those parts moving the faster throttling the fluid to the 'nearest cylinders more than the slower moving` portions. will be seen, however, that the motion of the shaft 135 must be kept up, otherwise thc change valves will be closed as soon as the platform has moved sufficiently to effectthe movements of the planetaries back to their original positions. If the motion of the shaft 135 is continued manuallyT the motion of the platform will also continue only stopping`when the plungers have reached infedetermined limits- While the platform is moving .thereis always a tendency for the loose gears to catch up with the fixed gears and at rates depending upon the distribution of load on the platform, the effect being to maintain the plat-form substantially level irrespective. of such distribution of load. Of course, when the platform `is allowed to 'descend the'fluid is exhausted from the cylind'er through the exhaust ports 159 of the change valves, to the exhaust pipe 169. The operation of the equalizing apparatus would be the same in this case only in reverse direction.

While the arrangement shown in Figs. v8, 9 and 10 is not entirely automatic it employs ordinary valves and admits of very prompt governing.

As shown in F ig. 9, the plungers or rams may, 1f desired, be hinged to the platform, as by ball and socket joints, but ordinarily the iexibility of the platform willv be sufficient to take care of any tendency of an un- 'even load to bend the rams, this tendency being reduced to'a minimum by the 'use ofjmy invention.

Having thus described my invention and Without limiting myself tothe precise construction of details or arrangement of parts, what I claim and desire to secure by Letters Patent of the United States is:

1. The combination witha platform, of means for'lifting the same, means for controlling said lifting-means, 'dierential planetary mechanism for actuating said controlling-means, and means operatively connected to the platform for throwing said differential mechanism to various positions.

Q. The combination with a platform, of

means for lifting the same, means for controlling' said lifting-means, differential planetary mechanism for actuating said controlling-means, and a reciprocating tensional connection operatively connected with said platform and saidA differential mechanism for actuating the latter.

The combination with a platform,A of a plurality of lifting motors and controllingmeans therefor, diiferential planetary mechanisms for actuating said controlling-means, and a plurality of tensional connections each operatively connected with said platform and adapted to independently actuate each differential mechanism.

Ll. 'lhe combination with a plat-form, of`

said platform and said differential lnechanism to actuate the latter and throw said valve to various degreesof opening.

6. The combination with a platform, of a hydraulic motor for lifting the same, a

Valve for controlling the motor, differential planetary mechanism for operating said valve, and a reciprocating tensional connection operatively connected with said platform and differential mechanism for actuating the latter. A

7. The combination with a platform, of a plurality of lifting hydraulic motors and valves therefor, a plurality of co-acting differential planetary mechanisms for operating said valves, and a plurality of tensional connections each operativelyl connected .with said platformA and differential mechanisms for operating the latter.

v8. The combination with a platform, of

three or more hydraulic plungers connected therewith, hydraulic cylinders for said plungers, valves for controlling the passage of fluid to and from said cylinders, differential gearing arranged in alinement for actuating said valves to various degrees of opening to vary the rate of flow of fluid `to the various cylinders and means connecting said platform and differential gearing for automatically operating the latter.

9. The combination With a platform, of a plurality of motors for lifting the same, a plurality of valves for controlling said motors, planetary gearing for actuating said valves, and means connected to the platform for operating said gearing.

10. The combination with a platform, of a plurality of hydraulic motors for moving the same, a plurality of Valves for controlling saidA motors, a plurality of differential planetary mechanisms corresponding in number to lthe number of valves for actuating said Valves to various degrees of opening, and means connected With the platform for automatically operating said differential mechanisms. f

11. The combination With a platform, of three or more hydraulic motors,a plurality of valves for controlling said motors, dierential gearing coperatively connected in alinement with each other for actuating said valves to various degrees of opening, and means for operating said dierential gearing.

12. The combination yWith a platform, of hydraulic motors therefor, valve mechanism for controlling said motors, and planetary y gearing operating said valve mechanism, the latter being constructed and arranged When operated by'said gearing to simultaneously increase the rate of flow of fluid to the motors most heavily loaded and decrease the: rate of flow to the motors less heavily loaded.

l. The combination With a platform, of hydraulic motors therefor, valve mechanism for controlling said motors, and planetary gearing operating said-valve mechanism, the latter being constructed and arranged When operated by said gearing lto simultaneously increase the rate of flow of Huid to t-.he motors heavily loaded and decrease 'the rate of flow to the motors lightly loaded When the platform is being lifted and to control the exhaust reversely When the platform is descending.

14C. The combination with a platform, of distributed hydraulic motors therefor, valves for controlling said motors, diHerential gearing comprising a plurality of planetary gears, connections between said planetary gears and said valves, and means for actuating said differential gearing to effect an even lifting of the platform irrespective of .the loadv thereon.

' 15. The combination With a platform, of hydraulic motors for lifting the same, a plurality of valves forffcontrollingsaid motors,

differential gear mechanisms comprising planetary gears and corresponding in number to the number of said valves and arranged in substantial alinement with each other, valve-actuating connections 'between 'the planetary gear of each of said gear'mechanisms vand each of said valves, and connections corresponding in number with the number of hydraulic motors for operating said differential gear mechanisms. '7f3l 16. The combination with a platform, of a plurality of distributed hydraulic motors for lifting said platform, valves for controlling said motors, planetar bevel gear' mechanism with connections for operating said valves, and' means for automatically operating said planetary bevel gear mechanism and said valves to maintain the platform substantially level at all times.

17. The combination with a platform, of hydraulic motors therefor, valves for controlling said motors, a plurality of shafts m alinement with each other, bevel gears secured to both ends of the intermediate shafts and to the inner ends of the outside shafts, planetary bevel gears mounted between each pair of facing bevel gears on said shafts valve-actuating means connected to sai planetary'I gears, a pluralit of Wheels one fastened to each of said shafts, a plurality of 90 connections one for each of said Wheels and each secured to' the platform, means for d1- recting said connections, and means for keeping said connections taut.

18. The combination 'with a platform, of hydraulic means for moving the same, valve l mechanism for controlling said moving means com .rising a main valve, check valves, and sets o ports in the main' valve for operatively connecting the same with the check valves and means for automatically operating said valve mechanism to simultaneously open one set-of ports therein and closel another set and place both sets of ports in cooperative relation With half of the number 105 of said check valves.

19. The combination with a platform, of hydraulic means for moving the same, a main valve provided With a plurality of series of supply ports, a corresponding number of supply check valves to coo erate with said supply ports, said main va ve having also a plurality `of series of exhaust ports,

a plurality of exhaust check valves to c0- for moving said main valve to supply or ex,\

haust position.

20. The combination With a platform, of

hydraulic meansA for moving said platform,

a main valve provided With two series of graduated supply ports and also tWo series of graduated exhaust ports, check valves to coperate with said supply and exhaust ports, and means for simultaneously opening one series of supply ports and throttling the other series when the platform is being lifted and for simultaneously opening one series of exhaust ports and throttling the other When the platform is descending.

21. The combination with aplatform, (of '130' CII a plurality of motors for lifting the same, a plurality of valves for, controlling said motors, check valves associated with the aforesaid valves, planetary gearing for -actuating said first-named valves, and means connected to the platform for operating said gearing.

22. 1n Valve mechanism, the combination with a hollow valve having two sets of ports at each end, of a valve casing having chamberscoperating with said ports, and check valves in said chambers, the ports an d valves being constructed and arranged to cause the supply to pass into the interior of said hollow valve, out of the same through' certain sets of ports, and past certain check valves, and the exhaust lto pass the other check valvesint'o the interior of the hollow valve, and thence out of same.

23. The combination-with a platform, of

a plu lality of hydraulic motors for lifting the same, a plurality of valves each .'havmg four series of ports, planetary differential 'and said differential gear mechanisms, said tensional connections corresponding `in number to the number of sald motors, and check valves lnterposed between sald valves and said motors, the number of said check valves corresponding in number to the number of Series of ports in said first-named valve.

In testimony whereof, I have signed'my name to this specification in the presence of two subscribing witnesses.

ANDREW M. COYLE.

Titnesses CHARLES M. NIssEN, HENRY E. KIRBY.