US3182456A

US3182456A - Remote control mechanism

Info

Publication number: US3182456A
Application number: US279133A
Authority: US
Inventors: Elmer B Burnett
Original assignee: Ingersoll Rand Co
Current assignee: Ingersoll Rand Co
Priority date: 1963-05-09
Filing date: 1963-05-09
Publication date: 1965-05-11
Anticipated expiration: 1982-05-11

Description

May 11, 1965 E. B. BURNETT 3,132,456

REMOTE CONTROL MECHANISM Filed May 9, 1963 5 Sheets-Sheet 1 v INVENTOR. ELMER B. BURNETT ATTORNEY y 1, 1965 E. B. BURNETT 3,182,456

REMOTE CONTROL MECHANI SM Filed May 9, 1965 5 Sheets-Sheet 2 F I3 I I I4 y 1965 E. B. BURNETT 3,182,456

EEEEEEEEEEEEEEEEEEEEE SM Filed May 9, 1965 5 Sheets-Sheet 3 INVENTO EL Mil 31;? B. BUR/VET y 1, 1965 E. B. BURNETT 3,182,456

REMOTE CONTROL MECHANISM Filed May 9, 1965 5 Sheets-Sheet 4 INVENTOR. ELMER B. BURNETT I I), I! 2 ATTORNEY May 11, 1965 E. B. BURNETT REMOTE CONTROL MECHANISM 5 Sheets-Sheet 5 Filed May 9, 1963 V ra/fl!!! INVENTOR. ELMER B. BURNETT ATORNEY United States Patent C 3,182,456 REMOTE CONTROL MECHANISM Elmer B. Burnett, Monroeton, Pa., assignor to Ingersoll- Rand Company, New York, N .Y., a corporation of New Jersey Filed May 9, 1963, Ser. No. 279,133 3 Claims. (Cl. 60-545) This invention relates to control mechanisms and more particularly to a hydraulic control device for remotely regulating the operation of another element or mechanism, such as a motor.

Presently in the control of overhead supported power hoists driven by air motors, pendent control devices are provided, which devices are air operated and require three relatively large diameter hoses, one hose leading from a source of pressurized air to the device, a second hose extending between the device and the hoist for effecting the lifting of a load, and a third hose extending between the device and the hoist for effecting the lowering of a load. With hoses of relatively large diameter and relatively long length, large volumes of compressed air must fill the hoses and be evacuated therefrom to effect appropriate response of the hoist motor. The necessity of moving large volumes of air through the hoses to effect a desired response of the hoist motor results in a time lag between actuation of the pendent control device and the appropriate response of the hoist motor. This disadvantage of present pendent control devices for overhead supported hoists is more pronounced with larger size hoists since hoses of increased diameter are required.

Another disadvantage of the present air operated pendent control assemblies is that they cannot be readily substituted for the mechanical pull chain type of remote control means employed in some hoists.

It is, therefore, an object of the present invention to provide a remote control assembly which effects rapid response of a slave mechanism.

It is another object of this invention to provide a pendent remote control assembly which is capable of being relatively quickly and easily installed on an overhead power hoist in place of a mechanical pull chain type remote control device.

A further object of the present invention is to provide a hydraulic control assembly of simplified construction which efiects quick and accurate response of a mechanism whose operation is controlled by the hydraulic control assembly.

A still further object of this invention is to provide a hydraulic control assembly which is a closed system requiring a relatively small amount of hydraulic fluid under relatively low pressure.

In view of the foregoing, the present invention contemplates a novel hydraulic remote control system or assembly comprising, a control device in combination with a slave mechanism such as a double-acting piston-cylinder unit which is, in turn, constructed and arranged to actuate another'mechanism, such as an electric switch, fluid valve, or the like.

The control device comprises a housing forming a liquid reservoir chamber in which is disposed means for constantly maintaining the liquid in the chamber under a slight pressure. The housing also provides a pair of identical and independently controlled piston valve assemblies. Each piston valve assembly has a piston chamber which communicates with the liquid reservoir chamber and with a slave mechanism through conduits of relatively small flow areas. A piston is disposed for reciprocation in each piston chamber, which piston has a piston bypass passage therein and a check valve to control flow of liquid through the by-pass passage. An axially movable plunger is slidably disposed in the housing adjacent ice each of the pistons to engage and cause movement of the associated piston in the piston chamber. A by-pass valve control plate is mounted on the plunger for restricted slidable movement relative to the plunger and piston. The control plate is constructed and arranged to coact with the check valve so that the check valve is maintained in an open position, and when .the plunger moves the piston, the check valve is allowed to close.

A biasing means, such as a spring, is provided to urge the check valve in a closed position. Another biasing means which may be in the form of a spring is disposed in each piston chamber to bias the associated piston in a direction toward one end of the piston chamber.

In operation of the control device, a plunger of one of the piston valve assemblies is slid by a manually actuated lever or by other suitable means. The movement of the plunger efiects slidable movement of the piston. The initial movement of the plunger and piston is relative to the control plate which permits the check valve to move to a closed position under the urging of its biasing means. Further movement of the piston effects displacement or" liquid which is immediately transmitted through the conduit to the slave mechanism to actuate the latter. Actuation of the slave mechanism causes actuation of another mechanism, such as an electric switch, fluid valve, or the like, to which the slave mechanism is connected. If the slave mechanism is in the form of a double-acting pistoncylinder unit, the displaced liquid moves the piston of the double-acting piston-cylinder unit commensurate with the amount of liquid displacement. This piston movement displaces a similar amount of liquid at the opposite end of the double-acting piston-cylinder unit, which liquid displacement is immediately transmitted through the conduit associated with the other piston valve assembly and through the check valve and bypass passage in the piston to the liquid reservoir chamber.

The invention will be more fully understood from the following detailed description thereof when considered in connection with the accompanying drawing wherein one embodiment of the invention is illustrated by way of example and in which:

FIG. 1 is a View in elevation of the hydraulic remote control device according to this invention as applied to an air motor operated overhead supported hoist.

FIG. 2 is a view in section taken along line 22 of FIG. 1 on an enlarged scale,

FIG. 3 is a view in perspective of the by-pass valve control plate,

FIG. 4 is a transverse sectional view taken along line 44 of FIG. 2,

FIG. 5 is a view in elevation of the remote control assembly shown in FIG. 1 on an enlarged scale and with parts in cross section for illustrative purposes, and

FIG. 6 is a view similar to FIG. 3 showing another operative position of the remote control assembly of this invention.

Now referring to the drawings and more specifically to FIG. 1, the reference numeral 10 generally designates the hydraulic remote control assembly according to this invention as applied to controlling the operation of an air motor driven hoist 11. While the hydraulic remote control assembly 10 is shown and will be described as applied to an overhead suspended power hoist 11, such application of the present invention is solely for illustrative purposes. The invention has application to many different apparatuses wherein remote control of the operation of a device or mechanism is desired as will be apparent hereinafter.

As shown in FIG. 1, the hydraulic remote control assembly 10 comprises a manually operated control device 12 connected by pendent hydraulic lines or

conduits

13 and 14 to a slave mechanism 15 secured to the air motor driven hoist 11 which is of conventional construction 3,. well known to those skilled in the art. struction of hoist 11 is of conventional design well known to those skilled in the hoist art and the construction of Since the conhoist 11 forms no part of the invention, hoist 11 will not be described in detail.

Slave mechanism The slave mechanism 15 is illustrated as comprising two piston-cylinder units 16, each of which is secured at a fiange. 17 to'a mounting bracket 18 bolted to a valve chest 19 of hoist 11. The piston-cylinder units 16 are I mounted in juxtaposed relation to each otheron opposite sides of a lever 20 which is connected to a reversing and throttle valve (not shown), the reversing and throttle".

unit 16 comprises a housing 22 of which flange 17 is inte-- gral. Housing 22 is provided with an end wall 23 and a bore 2 extending from the opposite end of the housing to a point short of end wall 23. Bore 24is counterbored and threaded at 25 to receive a threaded end cap 26. Cap

26 is providedwith a bore 27 havingthe same diameter as bore 2 2- so that, when the cap is turned into counterbore 25 of housing 22,,the surfaces of

bores

24 and 27 are coincident and form a piston chamber 28. A hole 31 of substantially smaller diameter than the diameter of bore 24 is provided in end wall 23 of housing 22.

, A piston 32 having a head portion 33 and a stem portion34 is disposed for reciprocation in piston chamber. 28 with the stern portion 34 extending through hole 31 and projecting a substantial distance from end wall 23. Cap 26 is provided with a suitable threaded hole 35 which communicates with piston chamber 28 and is adapted to receive a threaded hose connection 36 of the associated

hydraulic line

13 or 14.

To seal the space between the piston head 33 and the walls of piston chamber 23, a cup-shaped rolling diaphragm 37, known in the trade by the trademark Bellotram, is secured to the piston head 33 by a cup-shaped retainer plate 38 and a screw 39 turned into a threaded axial hole in the piston head to squeeze the rolling diaphragm 37 between the retainer plate 38 and piston head 33. The periphery ofdiaphragm 37 is provided with a head 29. which is compressed in an annular groove formed in shoulder by cap 26. The bead 29 also serves as a seal to prevent leakage of fluid from piston chamber. 28 between housing 22 and cap 26. While a Bellofrarn type of sealing means is shown and described, any other type. of seal means may be employed without departing from the scope and spirit of this invention.

A vent hole 4i) is provided in the end wall 23 of housing 22 to vent the piston chamber on the non-working side of piston .32 and thereby provide free. reciprocation of piston 32.

As shown in FIGS. 1, 5, and 6, each of the pistoncylinder units 16 is mounted onthe valve chest 19 of hoist 11 so that the distal ends-of stem portions 34 of pis-.

tons 320i each piston-cylinder unit 16 abut opposite sides of lever 20. As can be readily seen, slidable movement a .of one of the pistons 32 will cause the lever 2010 pivot and the other piston 32 to slidably move a distance corresponding to the distance of'movernent of the first men-- tioned piston. Pivotal movement of lever 20 willefte'ct movementot the throttle valve (not shown) of the hoist so that the speed and direction of operation of the hoist motor (not shown) are achieved.

Control device comprises a body portion or housing 41 and an elongated handle 42. A pair of plunger and

piston assemblies

43 and 44 are disposed within body portion 41, each of which assemblies controls actuationof a piston-cylinder unit 16' of slave mechanism 15. Plunger and piston a'ssembly 44 controls actuation of piston-cylinder unit 16 through line 14, while plunger and piston unit 43 controls actuation of the other piston-cylinder. unit 16 through line 13. Since each of the plunger and

piston assemblies

43 and 44 is identical in construction, only assemblyp44 will be hereinafter described in detail.

Body portion 41 is provided with a bore 45 which has a counterbored portion 46-adapted to receive therein a cylinder sleeve 47; Bore 45 is provided with another counterbored portion 48 which is=internally threaded at 49 to receive anexternally threaded'plunger housing 50, the latter being turned into threads '49 and into abutment against the end of cylinder sleeve 47 to; firmly hold the 3 cylinder sleeve in position between the plunger housing and the shoulder 51 formed at the juncture of bore. 45 and counterbored portion 46. a The inner surfaces of cylinder sleeve 47 and bore, 45 define a vpistin chamber in which is disposed for reciprocative movement a piston 52.

As best illustrated in FIG. 2, piston 52 is provided with an axial .bore 53 which has a counterbored portion 54 and a valve seat 55 formed at the juncture of bore 53 and counterbored portion 54'. The outer end part of counterbored portion 54 is threaded to receive a screw 56 which has an axial opening 57 extending therethrough. Screw 56 when turned into thethreaded part of counterbored portiorrS i engages a retainer cap 58 to urge the latter toward the working face of piston 52 and thereby secure one end of a cup-shaped rollingdiaphragm 59 which is disposed between the working face of piston 52 and retainer cap 58. The periphery of diaphragm 59' the tradeby the trademark .Bellofrarn and serves to seal the space between piston 52 and the inner surface of cylinder sleeve 47. The rolling diaphragm 59' also functions to divide the piston chamber formed by bore 45 and cylinder sleeve 47 into a working chamber 66 and a nonworking chamber 61. The piston is biased in a direction toward plunger housing .50 by a spring 62 which bears at one end against the bottom surface of bore 45 and at the opposite .end against retainer cap 58. Bore 55, counterbored portion 54, and axialopening 57 constitute a piston by-pass'line. To control flow of fluid through the by-pass line, a ball valve 63 is disposed in counterbored portion 54. Ball valve 63 is biased in a direction toward seat 55 by a spring 64 which is disposed between ball valve 63 and the inner end of screw 56.

The seating and unseating of ball valve 63 is achieved by a control plate 65 which is carried by a plunger 66 and disposed between the latter and piston 52. The construction and function of control plate 65 willjhereinafter be more fully described.

Plunger 66 'is disposed 'forslidable movement in an axial recess 67 'formed in plunger housing 56. An axial opening 68 of smaller diameter thau'recess 67v and com municating with the latter is provided in plunger'housing 56' to slidably receive therethrough a reduceddiameter stem portion 69 ofplunger66." A cup-shaped rolling diaphragm type seal '70,

similarto rolling diaphragrns

37 and 59, is secured to the endof plunger 66 by a retainer screw 71 and a cup-shaped retainer plate 72. Retainer screw 71 is turned into a'threaded axial recess73' so as to urge retainer plate 72 toward plunger 66 and clamp rolling diaphragm 7 0 between the retainer plate 72 and the end of plunger 66. The outer peripheral end portion of the diaphragm is clamped .between the end of plungerhousing 51 and an 0 ring seal disposed in the annular space formed between counterbored portion 48 .1 and plunger housing 50. Seal Stifunctions to prevent fluid leakage from annular groove.81 through the interstices between cylinder sleeve 47, counterbore 46, and threads 49 to atmosphere.

Retainer plate 72 is provided, as best shown in FIGS. 2 and 4, with two spaced, axially extending guide walls 74. Guide walls 74 are arcuate in shape to receive and support therebetween control plate 65 so that limited relative axial movement of control plate 65 and plunger 66 is permitted. As shown in FIG. 3, control plate 65 has a circular central portion 75 and integral Wing portions or tabs 76 extending radially from opposite sides of the central portion and partly lying in planes oflset from the plane of the central portion 75. In addition, control plate 65 has a pin 77 suitably secured at one end in an opening in the central portion 75 and extending normal to the plane of the central portion. As shown in FIG. 2, control plate 65 is positioned and dimensioned so that one side of tabs 76 abuts against the inner end of plunger housing 50 and the opposite sides of tabs 76 abut the end of piston 52, with pin 77 extending coaxially within bore 53 to maintain ball valve 63 unseated. Also as shown in FIG. 2, guide walls 74 of retainer plate 72 abut the end of piston 52.

T o slidably move plunger 66 within recess 67 of the plunger housing 50, a trigger or lever '78 is pivotally mounted at one end to housing 41 with the free end portion of the lever engaging the distal end of stem portion 69 of plunger 66. In operation, when lever 78 is depressed or pivoted inwardly toward housing 41, plunger 66 is moved in recess 67. A vent hole 79 is provided in plunger housing 50, which hole extends from the bottom of recess 67 to atmosphere.

Cylinder sleeve 47 is provided with an annular groove 81 in the peripheral surface thereof and a radial hole 82 extending from groove 81 through the inner surface of cylinder sleeve 47 so as to communicate non-working chamber 61 with groove 81. The purpose of groove 81 and hole 82 will be hereinafter more fully explained.

To provide a reservoir of fluid under slight pressure for both piston and

plunger assemblies

43 and 44, a fluid reservoir chamber 83 is provided. Chamber 83 is defined by a recess 84 formed in housing 41, which recess is counterbored and threaded at 85 to receive the externally threaded end portion of handle 42. Handle 42 has an axially extending bore 86 which, when handle 42 is turned into the counterbored portion of recess 84, registers with recess 84 so that the respective surfaces of recess 84 and bore 86 lie in coplanar relationship to each other. A piston 87 is disposed for axial movement within chamber 83 and is biased by a spring 88 toward the bottom of recess 84. Piston 87 is provided with a cup-shaped rolling diaphragm 89, similar to rolling diaphragm type seals 37, 59, and 70, to seal the space between the piston and the inner surface of chamber 83. Rolling diaphragm 89 is secured to piston 87, in the same manner as rolling

diaphragms

37, 59, and '70, by a cup-shaped retainer plate 90 and a screw 91 turned into a threaded opening 92 in piston 87. The outer periphery of the diaphragm is provided with a bead 42A which is clamped in a groove formed in the end surface of handle 42 between the latter and the shoulder at the juncture of recess 84 and counterbore 85. As shown in FIG. 5, the bottom of bore 86 is closed by a threaded plug 93 which is provided with an axial vent passage 94 to maintain the chamber below piston 87 at atmospheric pressure. As is best shown in FIG. 4, fluid reservoir chamber 83 is in communication with annular groove 81 of each of the piston and

plunger assemblies

43 and 44 through a pair of passageways 95.

In the neutral position of piston and plunger assembly 44 of control device 12, as shown in FIGS. 2 and 5, working chamber 60 is in communication with reservoir chamber 83 via passageway 95, annular groove 81, radial opening 82, non-working chamber 61, and the piston by-pass line consisting of bore 53, counterbored portion 54, and opening 57. Communication of the piston bypass line with non-working chamber 61 is effected through 5 the spaces between control plate 65 and guide walls or arms '74 as can best be seen by viewing PEG. 4.

To convey fluid displaced in working chamber 68 to line 14 when piston 52 is moved to the right as viewed in FIGS. 2 and 5, housing 41 is provided with a passageway 96 which is counterbored and threaded at 97 to receive a hose connection 98 of line 14.

Operation In operation of control device 12, depression of one of the levers 78, as for example lever 78 associated with piston and plunger assembly 44, causes plunger 66 to move in axial recess 67 of plunger housing in a direction to the right as viewed in FIG. 2. Since piston 52 is in abutment against the ends of guide walls 74 of the retainer screw 71, movement of plunger 66 forces piston 52 to move to the right as viewed in FIG. 2, thus displacing hydraulic fluid in Working chamber 60. Since control plate 65 is in abutment against plunger housing 50 and is urged thereagainst by spring 64 through ball valve 63, plunger 66 and piston 52 move relative to the control plate until plunger 66 butts against the circular portion 75 of the control plate. With the movement of piston 52 relative to control plate 65, ball valve 63 is brought into seating relationship with seat to thereby close the piston by-pass line and prevent flow of hydraulic fluid from working chamber 68 into reservoir chamber 83. When the piston by-pass line is closed, further movement of plunger 66 and piston 52 against the force of spring 62 displaces fluid in working chamber 60, which fluid displacement is immediately transmitted by the fluid through passageway 96 and line 14 to one of the piston-cylinder units 16 of the slave mechanism 15 to thereby cause a corresponding movement of piston 32 in a direction to the left as viewed in FIGS. 5 and 6.

As best shown in FIG. 6 in which the extreme opposite operative position of piston and plunger assembly 44 of control device 12 is illustrated, the fluid displaced in working chamber 68 forces fluid into piston chamber 28 of the right-hand piston-cylinder unit 16 through line 14, thereby causing piston 32 to move in a direction to the left as viewed in FIG. 6. This movement of piston 32 actuates lever 28 and, in turn, effects movement of a throttle valve (not shown) of hoist 11. Simultaneous with movement of piston 32, piston 32 of the other piston-cylinder unit 16 is moved to displace fluid in its associated working chamber 28 (not shown). The fluid displaced in piston chamber 28 of the other piston-cylinder unit 16 is transmitted through line 13 to piston and plunger assembly 43 of control device 12. Since the components of piston and plunger assembly 43 are in the positions shown in FIG. 2, the fluid will flow from line 13, through passage 96, and into working chamber 60. From working chamber 69 the fluid will flow through the piston by-pass line consisting of opening 57 in screw 56, counterbored portion 54, and bore 53. From the piston by-pass line the fluid will flow in the space between control plate and guide arm-s 74 into non-working chamber 61. Thereafter, the fluid will flow into reservoir chamber 83 via hole 82, an-

nular groove 81, :and passageway 95. Flow of fluid into reservoir chamber 83 exerts a pressure on piston 87, forcing the latter to compress spring 88.

When the pressure exerted by the operator on lever 78 is released, spring 62 of plunger and piston assembly 44 returns piston 52 and plunger 66 to the position shown in FIG. 2. At the latter part of the movement of piston 52 and plunger 66 to the left as viewed in FIG. 2, the movement of control plate 65 is restrained by its abutment against the end of plunger housing 58 so that plunger 66 and piston 52 continue to move relative to control plate 65. This relative movement between the piston, plunger, and control plate 65 brings pin 77 of the control plate into engagement with ball valve 63, causing the latter to be unseated from seat 55 and thereby opening the piston by-pass line to allow flow of fluid from chamber 28,

ansa rso through line 14, working chamber 66, the piston by-pass line, non-working chamber 61, hole 82, groove 81, and

passageway 95, into reservoir chamber 83. Simultaneous with movement of the piston SZand plunger 66 of piston and plunger assembly 44 to the left-as viewed in FIGS. 2 and 6 and before the piston by-pass line is opened, fluid in reservoir chamber 33 is forced therefrom under the urging of spring 88 against piston 87 through passageway 95, groove 81, hole 82, non-working chamber 61, the piston by-pass line, working chamber 60, passageway 96, 'line a 13, and thence into chamber 28 of piston-cylinder unit 16 on the left as viewed in FIG. 6. The entry of fluid into the piston chamber 28 of this latter mentioned unit forces the associated piston 32 to the right as viewed'in FIG. 6 and thereby returns lever 20 and the other piston-cylinder unit 16 to the neutral position shown in FIG. 5.

Actuation of lever 78 of piston and plunger assembly 43 will result in the same operation as herein above described except that such movement will result in actuation of leverZtl in a direction opposite to that shown in FIG. 6.

It is believed readily apparent that the remote control mechanism or system herein described provides a novel combination of a control device and slave mechanism, which system quickly and accurately responds to an operators wishes and requires the movement of relatively small quantities of fluid. The invention also provides in the control device a small lost motion wherein initial depression of lever 78 will not effect operation of slave mech-' anism 15 so that the operator has an opportunity to. realize his error should he begin to depress the wrong lever. Furthermore, the invention provides a completely closed hydraulic system which operates under relatively low fluid pressures, thus providing a system where sealing problems are negligible and the possibility of leakage is minimal. In addition, since both ball valves 63 in plunger and

piston assemblies

43 and 44 are open when control device 12 is in the neutral or non-operating position, the remote control assembly 10 is self-compensating to pressure changes caused by temperature variationsor small fluid leakage. Also with both ball valves 63 in the open position, lever 20 is unrestrained and may be moved with-' out interference from slave mechanism 15.

In addition to the foregoing, the invention provides a hydraulic remote control'mechanism which can be quickly and easily substituted for a mechanical pull chain type of hoist control by merely substituting lever 29 for the throttle control :arms at the ends of which are suspended pull chains and mounting piston-cylinder units 16 to brackets 18 bolted to the valve chest 19 of the hoist.

Although but one embodiment of the invention has been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. Various changes can be made in the arrangement of parts without departing from the spirit and scope of the invention as the same will now be understood by those skilled in the art.

I claim:

1. A hydraulic control device for transmitting liquid to and receiving liquid from a slave mechanism to selectively effect operation of the latter comprising,

(a) a housing having a liquid reservoir therein,

(b) said housing having at least one piston chamber therein,

(0) a piston disposed for axial movement in said piston chamber and biased toward one end of the piston chamber to define between the piston and the.

opposite end of the piston chamber a working 7 chamber,

(d) a by-pass passage extending axially through said piston communicating at one end with the working chamber and at the opposite end with the liquid reservoir to provide flow of liquid past the piston,

(e) actuating means for axially moving said piston in said piston chamber to displace liquid in the working chamber,

(f) a check valve in said by-pass passage for controlling flow of liquid through the latter, and

(g) means cooperatively associated with said actuating means and said checkvalve to maintain said check valve open when said piston is at said one end of the piston chamberand to allow said check valve to close when the piston is moved toward said opposite end of the piston chamber,

(12) said last mentioned means comprising a plate carried by said actuating means for restricted slidable imovementrelative thereto,

(1') said plate having a projection disposed to extend into said by-pass passage to engage the check valve and maintain said check valve in an open position when said piston is at said one end of said piston chamber and disengage from'said check valve to allow the latter to close when the piston is moved toward said opposite .end of said piston chamber.

2. A hydraulic control device for transmitting liquid to andreceiving liquid from a slave mechanism to selectively to effect operation of the latter comprising,

(a) a housing having a liquid reservoir therein,

(b) said housing having at least one piston chamber therein, v

(c) a piston disposed for axial movement insaid piston chamber,

(d) biasing means for urging said piston in a direction toward one end of the piston chamber to define between the piston and the opposite end of the piston chamber a working chamber,

(e) a coaxial thy-pass passageway formed in said piston communicating at one end with the. working chamber and at the opposite end with said liquid reservoir to providefiow of liquid past the piston,

(f) a plunger disposed in said housing adjacent said piston for axial movement to engage and axially move said piston toward said opposite end of the piston chamber,

(g) trigger means disposed to engage said plunger and to axially move the latter,

(h) a valve seat formed in'said by-pass' passageway,

(i) a ball valve'disposed in said by-pass passageway and biased toward said valve seat in said by-pass passageway, and I .(j) a ball valve control plate carried by said plunger adjacent said piston,

(k) said ball valve control plate, having a projection disposed to extendpinto said .by-pass passageway and. into engagement-with said ball valve to maintain said ball off said Valve seat when the piston is at the said one end ofthe piston chamber,

(1) said ball valve control plate carried by said plunger and capable of restricted axial movement relative to the plunger so that, upon movement of the plunger 7 and the piston, the control plate and its projection move relative to the plunger and piston to allow the ball valve to rest against the valve seat and thereby prevent flow of liquid through the by-pass passageway.

3.'A hydraulic control devicecomprising in combination with a double-acting piston-cylinder. unit having a piston chamber means and a piston means reciprocable in said piston chamber means and wherein said piston means is connected to another element to operate the latter, said hydraulic control device comprising,

(a) a housing having a liquid reservoir therein,

(b) said housing being: provided with a first piston valve assembly and a second piston valve assembly,

(0) each of said first and second piston valve assembliescomprises a piston chamber,

(d) a piston disposed for reciprocation in said piston chamber and biased toward one end of said,

piston chamber to define between the piston and the opposite end of the piston chamber a working chamber,

(e) a by-pass passage in said piston communicating at one end with the Working chamber and at the opposite end with the liquid reservoir to provide for flow of liquid past said piston,

(f) a valve disposed in said by-pass passage for controlling flow of liquid past said piston,

(g) plunger means disposed for slidable movement in said housing adjacent said piston for moving said piston in said piston chamber, I

(h) manually controlled means for slidably moving said plunger,-

(i) valve actuating means cooperatively associated with said plunger and said valve to maintain said valve means open when said piston is at said one end of said piston chamber and to permit said valve to close when said piston is moved toward said opposite end of the piston chamber,

(j) said valve actuating means comprising a plate carried by said plunger and having a projection disposed to extend in said by-pass passage to engage and maintain said Valve open when the piston is at said one end of the piston chamber,

(k) a first passage means in communication at one end with the working chamber of the first piston valve assembly and at the opposite end with one end of said piston chamber means of the piston-cylinder unit to transmit liquid displaced by the piston of said first piston valve assembly to the said one end of the piston chamber means to actuate the piston means of the doubleacting cylinder-piston unit, and

(l) a second passage means in communication at one end with the working chamber of the second piston valve assembly and at the opposite end with the other end of the piston chamber means of the piston-cylinder unit to receive liquid displaced by said piston means of the piston-cylinder unit and transmit the same through the by-pass passage in the piston of the second piston valve assembly to the liquid reservoir.

References Cited by the Examiner UNITED STATES PATENTS 1,693,068 11/28 Cowles 60-54.6 X 2,189,013 2/40 Loweke 6054.5 2,246,140 6/41 Main 6054.6 2,847,827 8/58 Johnson 6054.6 2,871,662 2/59 Nagel et al. 6054.5 2,946,196 7/60 Myetrs 6054.6 X 2,968,154- 1/61 Richey 6054.5 3,120,244- 2/64 Hahn 60-545 X 3,125,200 3/64 Kaman 60--54.6 X

FOREIGN PATENTS 626,073 7/ 49 Great Britain. 765,301 1/ 57 Great Britain.

JULIUS E. WEST, Primary Examiner.

'30 ROBERT R. BUNEVICH, Examiner.

Claims

2. A HYDRAULIC CONTROL DEVICE FOR TRANSMITTING LIQUID TO AND RECEIVING LIQUID FROM A SLAVE MECHANISM TO SELECTIVELY TO EFFECT OPERATION OF THE LATTER COMPRISING, (A) SAID HOUSING HAVING A LIQUID RESERVOIR THEREIN, (B) SAID HOUSING HAVING AT LEAST ONE PISTON CHAMBER THEREIN, (C) A PISTON DISPOSED FOR AXIAL MOVEMENT IN SAID PISTON CHAMBER, (D) BIASING MEANS FOR URGING SAID PISTON IN A DIRECTION TOWARD ONE END OF THE PISTON CHAMBER TO DEFINE BETWEEN THE PISTON AND THE OPPOSITE END OF THE PISTON CHAMBER A WORKING CHAMBER, (E) A COAXIAL BY-PASS PASSAGEWAY FORMED IN SAID PISTON COMMUNICATING AT ONE END WITH THE WORKING CHAMBER AND AT THE OPPOSITE END WITH SAID LIQUID RESERVOIR TO PROVIDE FLOW OF LIQUID PAST THE PISTON, (F) A PLUNGER DISPOSED IN SAID HOUSING ADJACENT SAID PISTON FOR AXIAL MOVEMENT TO ENGAGE AND AXIALLY MOVE SAID PISTON TOWARD SAID OPPOSITE END OF THE PISTON CHAMBER, (G) TRIGGER MEANS DISPOSED TO ENGAGE SAID PLUNGER AND TO AXIALLY MOVE THE LATTER, (H) A VALVE SEAT FORMED IN SAID BY-PASS PASSAGEWAY, (I) A BALL VALVE DISPOSED IN SAID BY-PASS PASSAGEWAY AND BIASED TOWARD SAID VALVE SEAT IN SAID BY-PASS PASSAGEWAY, AND (J) A BALL VALVE CONTROL PLATE CARRIED BY SAID PLUNGER ADJACENT SAID PISTON, (K) SAID BALL VALVE CONTROL PLATE HAVING A PROJECTION DISPOSED TO EXTEND INTO SAID BY-PASS PASSAGEWAY AND INTO ENGAGEMENT WITH SAID BALL VALVE TO MAINTAIN SAID BALL OFF SAID VALVE SEAT WHEN THE PISTON IS AT THE SAID ONE END OF THE PISTON CHAMBER, (L) SAID BALL VALVE CONTROL PLATE CARRIED BY SAID PLUNGER AND CAPABLE OF RESTRICTED AXIAL MOVEMENT RELATIVE TO THE PLUNGER SO THAT, UPON MOVEMENT OF THE PLUNGER AND THE PISTON, THE CONTROL PLATE AND ITS PROJECTION MOVE RELATIVE TO THE PLUNGER AND PISTON TO ALLOW THE BALL VALVE TO REST AGAINST THE VALVE SEAT AND THEREBY PREVENT FLOW OF LIQUID THROUGH THE BY-PASS PASSAGEWAY.