US3631761A

US3631761A - Hydraulic action devices with inertia insensitive snubbing circuit

Info

Publication number: US3631761A
Application number: US756228A
Authority: US
Inventors: Rollin Douglas Rumsey
Original assignee: Houdaille Industries Inc
Current assignee: Houdaille Industries Inc
Priority date: 1967-09-18
Filing date: 1968-08-29
Publication date: 1972-01-04
Anticipated expiration: 1989-01-04

Abstract

A hydraulic action device such as a buffer, actuator, and the like, comprises means defining a working chamber from which hydraulic fluid is arranged to be displaced through one or more passages by a member such as a wing shaft vane, and the like, operative under substantial load variables, and a valve is referenced directly to the working chamber independently of and in control of at least one of the passages for effecting a substantially uniform rate of deceleration of the member irrespective of load, force or inertia. Anticavitation valve means and speed control valve means may be provided.

Description

United States Patent 1 3,631,761

[72] Inventor Rollin Douglas Rumsey [56] References Cited 21 A l N gggg g UNITED STATES PATENTS E fig $29,196,; 2,464,283 3/1949 Adams 91/421 Patented Jan. 4 1972 3,323,422 6/1967 Freese 91/409 Assignee Houdaiue Industries, ha 3,470,792 10/1969 Darl ng... 91/408 Buffalo, 3,054,384 9/1962 Darling 9 H26 original application Sept. 18,1967, sen 3,103,281 9/1963 Rumsey et al. 91/26 No. 668,716 now Patent 3,419,114 3,303,746 2/1967 Schmoeger 91/26 dated Dec. 31, 1968, Continuation of Primary Examiner-Paul E. Maslousky applica n ,Jan- 27, AttorneyHill, Sherman, Meroni, Gross & Simpson 1966, now abandoned. Divided and this application Aug. 29, 1968, Ser. No.

756,228 ABSTRACT: A hydraulic action device such as a buffer, ac-

tuator, and the like, comprises means defining a working chamber from which hydraulic fluid is arranged to be dis- HYDRAULIC ACTION DEVICES WIT NERTIA placed through one or more passages by a member such as a INSENSITIVE N BB CIRCUIT wing shaft vane, and the like, operative under substantial load l7Claim ,2DraWing ig variables, and a valve is referenced directly to the working [52] US. Cl 91/408, chamber independently of and in Control of at least one of the 91/420 91/421 91/437 passages for effecting a substantially uniform rate of decelera- 51 lm. Cl ..Fl5b 15/22, of the member ifrfislecfi"e bad, fme inertia Flsb 11/08 Flsb 13/042 ticavitation valve means and speed control valve means may 50 Field of Search 91/405, 26, be P PATENIED JAN 4 m2 SHEET 2 OF 2 1 EN'IUR.

HYDRAULIC ACTION DEVICES WITH INERTIA INSENSITIVE SNUBBING CIRCUIT The present application is a division of my application, Ser. No. 668,716, filed Sept. 18, 1967, now US. Pat. No. 3,419,114, dated Dec. 31, 1968 which is a streamlined continuation of my application, Ser. No. 523,426, filed Jan. 27, 1966, now abandoned.

This invention relates to improvements in hydraulic action devices on the order of shock absorbers, buffers, rotary actuators, and the like, and more particularly concerns inertia insensitive snubbing circuit means especially useful with such devices.

In the operation of hydraulic action devices of the type indicated, a serious problem has existed in respect to stopping variable inertia loads. Generally a compromise setting or adjustment has been established in the associated hydraulic cir cuitry to accommodate the mean inertia force, or at least the force predominantly encountered in the use of the device. Hence, in substantially higher inertias there is a strong tendency for the hydraulic stopping means to bottom out, whereas, if the inertia load is substantially lighter excessively high deceleration forces are encountered.

For example, difiiculties are encountered in hydraulic actuators of the kind used on earth moving equipment such as the swing actuators on backhoes, If the hydraulic control circuitry is designed to stop the backhoe under an average inertia load condition, should the operator of the equipment inexpertly come into the stops with the boom fully extended and the bucket fully loaded, the hydraulic actuator generally will not stop it and the boom will ram into the solid stops with destructive force. On the other hand, if snubbing is made strong enough in the system to stop the boom under the worst condition, then when the boom is in close, or lightly loaded, the speed of operation of the backhoe will be severely limited near the ends of travel because of the high braking force exerted, resulting in excessively slow operation.

Accordingly, it is an important object of the present invention to provide in hydraulic action devices a new and improved inertia insensitive snubbing circuit in which snubbing will be in proportion to the inertia forces exerted in order always to bring the load to rest at the same rate.

Another object of the invention is to provide a new and improved snubbing circuit for hydraulic action devices of the character indicated in which the load will be brought to rest from a predetermined speed at a constant G force irrespective of the amount of inertia in the load, such that if the inertia is high the snubbing pressure will be high and if the inertia is low the snubbing pressure will be low.

A further object of the invention is to provide new and improved bufi'ing means affording the maximum efficiency at all times and capable of protecting the associated equipment from abuse by abnormal inertia load conditions, operator variation or inconsistency, and the like.

Another object of the invention is to provide new and improved inertia insensitive snubbing control means comprising novel control valve structure and pressure referencing means therefor.

Other objects, features and advantages of the present invention will be readily apparent from the following detailed description of certain preferred embodiments thereof taken in conjunction with the accompanying drawings, in which:

FIG, 1 is a schematic illustration ofa rotary hydraulic buffer or actuator including a snubbing circuit arrangement embodying features of the invention; and

FIG. 2 is a schematic illustration of a rotary buffer or actuator with a modification of the novel inertia insensitive snubbing circuit features of the invention.

Application of the principles of the present invention to a rotary vane type of hydraulic actuator 35 is represented in FIG. 1. In such an actuator a tubular housing body 37 is closed at its opposite ends by means of end closure members 38 and defines a cylindrical working chamber 39 in which is fixedly mounted at least one abutment 40 having an inwardly project- 48 is provided for selectively determining connection of thepressure and

return lines

45 and 47 with respective hydraulic fluid displacement control circuit passages 49 connected at one end with the control valve and at their opposite ends with the respective working subchambers through an orifice 50 in each instance opening through one of the end closures 38 adjacent to the abutment 40 and in that portion of the subchamber toward which the vane 43 is driven in each respective direction of oscillation in operation. In addition, each of the orifices 50 is so located and shaped that as the vane 43 approaches its respective limit at the abutment 40 the displacement orifice is progressively closed off for rapid deceleration of the wing shaft. A generally teardrop shape of each of the orifices 50 with its widest portion at the end toward which the vane approaches is desirable for progressive deceleration cutoff.

To assure constant snubbing deceleration irrespective of inertia, a reciprocable plunger valve 51 is mounted in a bore 52 which intersects the passage 49. Normally the valve 51 is biased toward one end of the bore 52 by means of a coiled compression spring 53 so as to leave the passage 49 open. At its end opposite the biasing spring 53, the valve 51 is referenced to the portion of the associated working subchamber toward which the actuator vane 43 is liable to generate pressure in response to external force through the shaft 42. Reference is effected by a pilot pressure connecting passage duct 54 having at its subchamber end an orifice 55 located beyond the orifice 50, considered with respect to the working stroke approach of the vane member 43, and adjacent to the abutment 40 clear of the vane 43 and its adjacent terminal position, as indicated in dash outline in FIG. 1. Through this arrangement, the snubbing valve 51 responds to vane generated pressure in the associated working subchamber for automatically controlling an orifice or port 57 affording communication of the passage 49 with the bore 52. For starting the wing shaft in a reverse stroke, even though the adjacent deceleration metering orifice 50 is closed off by the vane 43, each of the valves 51 is provided with an orifice 58 therethrough controlled by a ball check valve 59 at its end referenced to the subchamber through the passage 54, whereby to enable the wing shaft vane 43 to be moved rapidly away from the abutment 40, by pressure fluid introduced through the passage 49.

A further refinement of the inertia insensitive snubbing circuit is depicted in FIG. 2, in respect to a rotary vane hydraulic actuator 60 including a housing 61 defining a cylindrical working chamber 62 closed at the opposite ends by respective end closures 63 and having mounted therein at least one fixed abutment 64 with an inner edge having a seal 65 and slidably cooperating with an oscillatable wing shaft 67 having a vane 68 with an edge provided with a seal 69 slidably engaging the walls defining the working chamber 62 and cooperating with the abutment 64 to divide the working chamber into subchambers. A hydraulic pressure supply line 70 and a return line 71 are connected through a conventional four-way plunger control valve 72 with the respective subchambers of the actuator through inertia insensitive snubbing circuit passages 73, each of which communicates with its subchamber through a respective port 74 in one of the end members 63 and having a pattern of communication orifices 75 which are adapted to be progressive closed as the vane 68 approaches the terminal limit of its stroke toward the abutment 64 in order to decelerate the wing shaft rapidly. Each of the circuit passages 73 has speed control valve means 77 including an adjustable orifice or throttle valve portion 770 and a one-way check valve portion 77b. For enabling rapid movement of the actuator vane 68 away from the abutment 64 even though the port 74 is fully covered, a respective orifice 78 located in the comer of the subchamber adjacent the abutment 64 clear of the vane in its terminal position affords communication with a duct 79 which is in communication through a one-way check valve 80 with the passage 73. Anticavitation or overrun preventing means are provided comprising a pair of crossover relief valves 81 which interconnect the two subchambers in order to prevent excessive pressure being developed in the actuator in the event the control valve 72 is abruptly centered when the actuator is moving at maximum speed. These valves 81 are connected across the ducts 79 and are biased in respective opposition to the direction of pressure movement of the hydraulic fluid from the respective ducts and responsive to predetermined pressure to throttle passage of hydraulic fluid through these valves respectively. As pressure builds up in the respective subchambers incident to closing of the orifices 75 in the terminal portion of the vane stroke, a plunger-type throttle valve 82 in a bore 83 intersecting the passage 73 through which hydraulic fluid from the pressure line 70 is being delivered is pressurized through a branch 84 from the duct 79. This causes the pressurized valve 82 to move in opposition to a normally biasing coiled compression spring 85 to throttle a port 87 in the passage 73 which is in communication with the pressure line 70.

To provide constant snubbing deceleration irrespective of inertia, a plunger valve 88 mounted in the opposite end portion of the bore 83, and normally biased by the spring 85 to leave a port 89 in the associated passage 73 open, is referenced directly to its associated subchamber through a branch 90 leading from the duct 79 in its circuit. Since the biasing spring 85 bottoms under biasing compression oppositely against the companion inlet cutoff valve 82 and snubbing valve 88, these valves serve automatically to load the spring toward the opposite valve under respective pressure fluid thrust, thus attaining automatic biasing control in operation. Otherwise, functioning of the snubbing valve 88 is substantially the same as described for the snubbing valve 51 of FIG. 1.

ln all forms of the invention, an important feature resides in affording maximum efficiency in operation of the hydraulic action device, protecting the equipment from the inevitable abuses, extraordinary inertia loads either above or below the normal range, variations or inconsistencies in operators handling of the equipment, etc.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts or the present invention.

I claim as my invention:

1. A hydraulic reaction device comprising a rotary vane actuator having:

a housing providing a cylindrical working chamber having fixed abutment means therein;

a rotary wing shaft joumaled in the housing and having vane means cooperating with said cylinder and said abutment means to subdivide the working chamber into subchambers;

means providing respective hydraulic fluid displacement control circuit passages having connections with the respective subchambers for fluid driven from said subchambers by pressure generated in working strokes of said wingshaft and each including orifice means adjacent to the abutment means and located to be progressively closed off in the terminal portion of the movement of the vane means toward the abutment means,

each of said passages having a snubber valve; and

a respective pilot pressure duct connected with each of said subchambers adjacent to the abutment means and beyond the range of said vane means and referencing the respective subchamber for pressure fluid thrust to drive the snubber valve referenced to the pressure, thereby to drive the valve into throttling snubbing relation to its passage.

2. A device according to claim I, having means for delivering operating hydraulic fluid to said subchambers through said passages, said snubber valves comprising respective plungers each including a check valved passage therethrough for starting hydraulic pressure fluid flow through its associated duct to effect reversal of the wing shaft when the vane means are in closing relation to said orifice means.

3. A device according to claim I, having means for delivering operating hydraulic fluid to said subchambers through said passages, said passages and said ducts having respective check valved connections for bypassing starting hydraulic fluid from said passage to the duct in each instance for reversal of the wing shaft from the respective terminal positions of the vane means.

4. A device according to claim 1, including a respective throttle valve additionally in control of each of said passages, and a respective operating pressure fluid thrust reference connection provided between each of said throttle valves and the duct leading from the other of said subchambers than that subchamber with which the passage controlled by the valve is connected.

5. A device according to claim 4, said snubber valve and said throttle valve in each passage comprising respective plungers having a common biasing spring thrusting at its opposite ends respectively thereagainst and normally biasing the plungers into clearance relation to the passage.

6. A hydraulic action device comprising: means defining a working chamber; a relatively reciprocably movable member in said chamber adapted to be driven by hydraulic fluid pressure in respective opposite working stroke and also adapted to generate fluid pressure in response to external forces; fluid displacement passage means comprising, in communication with said chamber at each opposite side of said member, a respective normal flow passage connectable selectively through control means with a hydraulic fluid pressure source and an exhaust, and a pilot pressure passage connected with a control valve in said normal flow passage; first orifice means at the chamber end of each of said normal flow passages located to be progressively closed off by said member in a working stroke theretoward; and

second orifice means at the chamber end of said pilot passages located beyond said first orifice means, considered with respect to the working stroke approach of said member theretoward, and through which pressure is referenced to said valve to control the pressure drop across said first orifice to efiect uniform deceleration snubbing of said movable member irrespective of said external forces.

7. A device according to claim 6, having crossover relief valves interconnecting said pilot pressure passages.

8. A device according to claim 6, having check valve means permitting flow from said normal flow passage to the pilot pressure passage connected therewith.

9. A device according to claim 6, having in at least one of said displacement passage means cutoff valve means referenced to the portion of the working chamber to which the other of said displacement passage means are connected and operative to throttle said one passage means while serving to deliver hydraulic fluid from said source to said working chamber if the pressure in that portion of the working chamber to which said other passage means are connected exceeds the delivered fluid pressure.

10. A device according to claim 9, in which said control valve and said cutoff valve means comprise respective valve pistons in a valve chamber which intersects the respective main flow passage, and common biasing means which holds said plungers in respective inactive positions.

1 l. A hydraulic reaction device comprising:

means defining a working chamber having hydraulic fluid therein;

means relatively movably operative in substantial working strokes in respectively opposite directions in said working chamber and generating hydraulic pressure in respective opposite portions of the chamber;

means providing respective hydraulic fluid displacement control circuit passages connected to said portions of the chamber for fluid driven from said portions of the chamber by the pressure generated in said working strokes by said movable means and each including orifice means the effective flow area of which is progressively closed off by said movable means at least during the last part of the respective working stroke to effect snubbing deceleration of said relative movement and resulting in substantial increase in said hydraulic pressure;

respective means including ducts directly referenced to said portions of the chamber independently of said passages and responsive to said increase in pressure to throttle and control said respective passages for effecting a substantially uniform rate of deceleration of said movable means irrespective of load, force or inertia; and

anticavitation means connected between said ducts.

12. A hydraulic reaction device comprising:

means defining a working chamber having hydraulic fluid therein;

respective means directly referenced to said portions of the chamber independently of said passages and responsive to said increase in pressure to throttle and control said respective passages for effecting a substantially uniform rate of deceleration of said movable means irrespective of load, force or inertia; and

speed control valve means in said hydraulic fluid displacement control circuit passages in addition to said respective means directly referenced to said portions of the chamber.

13. A hydraulic reaction device comprising a rotary vane actuator having:

a housing defining a cylindrical working chamber;

fixed abutment means in said working chamber;

a rotary wing shaft joumaled in the housing and having vane means cooperating with said cylinder and said abutment means in a substantial working stroke under likelihood of substantial load variables and in said stroke generating hydraulic pressure in at least a portion of the chamber;

means providing a hydraulic fluid displacement control circuit passage connected to said portion of the chamber for fluid driven from said portion of the chamber by the pressure generated in said working stroke by said vane means and including orifice means the effective flow area of which is progressively closed off by said vane means at least during the last part of said working stroke to effect snubbing deceleration of said relative movement and resulting in substantial increase in said hydraulic pressure, said orifice means being closed off to attain maximum hydraulic pressure at the terminus of said working stroke; and

means spaced a substantial distance from the terminus of working stroke of said vane means and directly referenced to said portion of the chamber independently of said passage and responsive to said increase in pressure to throttle and control said passage for effecting a substantially uniform rate of deceleration of said vane means irrespective of load, force or inertia.

14. A hydraulic reaction device comprising:

means defining a working chamber having hydraulic fluid therein;

means relatively movably operative through a substantial working stroke in said working chamber under likelihood of substantial load variables and in said stroke generating hydraulic pressure in at least a portion of the chamber;

means providing a hydraulic fluid displacement control circuit passage connected to said portion of the chamber for fluid driven from said portion of the chamber by the pres sure generated in said working stroke by said movable means and including orifice means the effective flow area of which is progressively closed off by said movable means at least during the last part of said working stroke to effect snubbing deceleration of said relative movement and resulting in substantial increase in said hydraulic pressure, said orifice means being completely closed off to attain maximum hydraulic pressure at the terminus of said working stroke;

means spaced a substantial distance from the terminus of working stroke of said movable means and directly referenced to said portion of the chamber independently of said passage and responsive to said increase in pressure to throttle and control said passage for effecting a substantially uniform rate of deceleration of said movable means irrespective of load, force or inertia; and

speed control means in said fluid displacement control circuit passage in addition to said means to throttle and control said passage.

15. A hydraulic reaction device comprising:

means defining a working chamber having hydraulic fluid therein;

means providing respective hydraulic fluid displacement control pressure generated in said working strokes by said movable means and each including orifice means the effective flow area of which is progressively closed off by said movable means at least during the last part of the respective working stroke to effect snubbing deceleration of said relative movement and resulting in substantial increase in said hydraulic pressure; and

respective means including ducts directly referenced to said portions of the chamber independently of said passages and responsive to said increase in pressure in either of said passages to throttle and control the other of said passages.

16. A hydraulic reaction device comprising:

means defining a working chamber having hydraulic fluid therein;

means relatively movably operative in substantial working strokes in respectively opposite directions in said working chamber and generating hydraulic pressure in respective portions of the chamber;

means providing respective hydraulic fluid displacement control circuits connected to said portions of the chamber for fluid displaced with respect to said portions of the chamber and each circuit including orifice means connecting it with its respective portion of the chamber and the effective flow area of which orifice means is progressively closed off by said movable means at least during the last part of the respective working stroke to effect snubbing deceleration of the relative movement of the relatively movable means and resulting in substantial increase in hydraulic pressure in the respective portion of the working chamber; and

respective means referenced to said portions of the chamber independently of said orifice means and responsive to said increase in hydraulic pressure in either of said chamber portions to control the control circuit connected to the other of said portions of the chamber.

17. Pressure governing apparatus for a hydraulic actuator experiencing heavy inertia loads, which actuator includes a housing defining a working chamber having a differential pressure movable barrier traversing said chamber and dividing it into two variable volume chambers each of which alternately acts as an intake chamber having a port therein connected by an intake line to a source of hydraulic pressure, while the other acts as a discharge chamber having a port therein connected to a discharge or exhaust line, and which actuator also includes variable orificing means cooperating with the discharge port for cushioning the end of the stroke of the movable barrier, the pressure governing apparatus comprismg:

shutoff valve means positioned in said intake line, normally spring biased to an open position; valve operator means responsive to a predetermined pressure in the discharge chamber which is greater than the operating pressure in said chamber operatively connected to the shutoff valve means, which latter, upon actuation overrides the valve spring, closes the valve and maintains it closed so long as said pressure exists, and thereby blocks flow from the pressure source into the inlet chamber, which effectively reduces the maximum pressure experienced in the discharge chamber during any portion of the stroke; passage means connecting the discharge chamber with the intake chamber; and a high-pressure relief valve positioned in said passage means permitting flow only from the discharge chamber to the intake chamber to prevent excessive pressure development in the actuator.

* i i t t

Claims

1. A hydraulic reaction device comprising a rotary vane actuator having: a housing providing a cylindrical working chamber having fixed abutment means therein; a rotary wing shaft journaled in the housing and having vane means cooperating with said cylinder and said abutment means to subdivide the working chamber into subchambers; means providing respective hydraulic fluid displacement control circuit passages having connections with the respective subchambers for fluid driven from said subchambers by pressure generated in working strokes of said wing shaft and each including orifice means adjacent to the abutment means and located to be progressively closed off in the terminal portion of the movement of the vane means toward the abutment means; each of said passages having a snubber valve; and a respective pilot pressure duct connected with each of said subchambers adjacent to the abutment means and beyond the range of said vane means and referencing the respective subchamber for pressure fluid thrust to drive the snubber valve referenced to the pressure, thereby to drive the valve into throttling snubbing relation to its passage.

2. A device according to claim 1, having means for delivering operating hydraulic fluid to said subchambers through said passages, said snubber valves comprising respective plungers each including a check valved passage therethrough for starting hydraulic pressure fluid flow through its associated duct to effect reversal of the wing shaft when the vane means are in closing relation to said orifice means.

3. A device according to claim 1, having means for delivering operating hydraulic fluid to said subchambers through said passages, said passages and said ducts having respective check valved connections for bypassing starting hydraulic fluid from said passage to the duct in each instance for reversal of the wing shaft from the respective terminal positions of the vane means.

6. A hydraulic action device comprising: means defining a working chamber; a relatively reciprocably movable member in said chamber adapted to be driven by hydraulic fluid pressure in respective opposite working stroke and also adapted to generate fluid pressure in response to external forces; fluid displacement passage means comprising, in communication with said chamber at each opposite side of said member, a respective normal flow passage connectable selectively through control means with a hydraulic fluid pressure source and an exhaust, and a pilot pressure passage connected with a control valve in said normal flow passage; first orifice means at the chamber end of each of said normal flOw passages located to be progressively closed off by said member in a working stroke theretoward; and second orifice means at the chamber end of said pilot passages located beyond said first orifice means, considered with respect to the working stroke approach of said member theretoward, and through which pressure is referenced to said valve to control the pressure drop across said first orifice to effect uniform deceleration snubbing of said movable member irrespective of said external forces.

11. A hydraulic reaction device comprising: means defining a working chamber having hydraulic fluid therein; means relatively movably operative in substantial working strokes in respectively opposite directions in said working chamber and generating hydraulic pressure in respective opposite portions of the chamber; means providing respective hydraulic fluid displacement control circuit passages connected to said portions of the chamber for fluid driven from said portions of the chamber by the pressure generated in said working strokes by said movable means and each including orifice means the effective flow area of which is progressively closed off by said movable means at least during the last part of the respective working stroke to effect snubbing deceleration of said relative movement and resulting in substantial increase in said hydraulic pressure; respective means including ducts directly referenced to said portions of the chamber independently of said passages and responsive to said increase in pressure to throttle and control said respective passages for effecting a substantially uniform rate of deceleration of said movable means irrespective of load, force or inertia; and anticavitation means connected between said ducts.

12. A hydraulic reaction device comprising: means defining a working chamber having hydraulic fluid therein; means relatively movably operative in substantial working strokes in respectively opposite directions in said working chamber and generating hydraulic pressure in respective opposite portions of the chamber; means providing respective hydraulic fluid displacement control circuit passages connected to said portions of the chamber for fluid driven from said portions of the chamber by the pressure generated in said working strokes by said movable means and each including orifice means the effective flow area of which is progressively closed off by said movable means at least during the last part of the respective working stroke to effect snubbing deceleration of said relative movement and resulting in substantial increase in said hydraulic pressure; respective means directly referenced to said portions of the chamber independently of said passages and responsive to said increase in pressure to throttle and control said respective passages for effecting a substantially uniform rate of deceleration of said movable means irrespective of load, force or inertia; anD speed control valve means in said hydraulic fluid displacement control circuit passages in addition to said respective means directly referenced to said portions of the chamber.

13. A hydraulic reaction device comprising a rotary vane actuator having: a housing defining a cylindrical working chamber; fixed abutment means in said working chamber; a rotary wing shaft journaled in the housing and having vane means cooperating with said cylinder and said abutment means in a substantial working stroke under likelihood of substantial load variables and in said stroke generating hydraulic pressure in at least a portion of the chamber; means providing a hydraulic fluid displacement control circuit passage connected to said portion of the chamber for fluid driven from said portion of the chamber by the pressure generated in said working stroke by said vane means and including orifice means the effective flow area of which is progressively closed off by said vane means at least during the last part of said working stroke to effect snubbing deceleration of said relative movement and resulting in substantial increase in said hydraulic pressure, said orifice means being closed off to attain maximum hydraulic pressure at the terminus of said working stroke; and means spaced a substantial distance from the terminus of working stroke of said vane means and directly referenced to said portion of the chamber independently of said passage and responsive to said increase in pressure to throttle and control said passage for effecting a substantially uniform rate of deceleration of said vane means irrespective of load, force or inertia.

14. A hydraulic reaction device comprising: means defining a working chamber having hydraulic fluid therein; means relatively movably operative through a substantial working stroke in said working chamber under likelihood of substantial load variables and in said stroke generating hydraulic pressure in at least a portion of the chamber; means providing a hydraulic fluid displacement control circuit passage connected to said portion of the chamber for fluid driven from said portion of the chamber by the pressure generated in said working stroke by said movable means and including orifice means the effective flow area of which is progressively closed off by said movable means at least during the last part of said working stroke to effect snubbing deceleration of said relative movement and resulting in substantial increase in said hydraulic pressure, said orifice means being completely closed off to attain maximum hydraulic pressure at the terminus of said working stroke; means spaced a substantial distance from the terminus of working stroke of said movable means and directly referenced to said portion of the chamber independently of said passage and responsive to said increase in pressure to throttle and control said passage for effecting a substantially uniform rate of deceleration of said movable means irrespective of load, force or inertia; and speed control means in said fluid displacement control circuit passage in addition to said means to throttle and control said passage.

15. A hydraulic reaction device comprising: means defining a working chamber having hydraulic fluid therein; means relatively movably operative in substantial working strokes in respectively opposite directions in said working chamber and generating hydraulic pressure in respective opposite portions of the chamber; means providing respective hydraulic fluid displacement control pressure generated in said working strokes by said movable means and each including orifice means the effective flow area of which is progressively closed off by said movable means at least during the last part of the respective working stroke to effect snubbing deceleration of said relative movement and resulting in substantial increase in said hydraulic pressure; and respective means including ducts directly referenced to said poRtions of the chamber independently of said passages and responsive to said increase in pressure in either of said passages to throttle and control the other of said passages.

16. A hydraulic reaction device comprising: means defining a working chamber having hydraulic fluid therein; means relatively movably operative in substantial working strokes in respectively opposite directions in said working chamber and generating hydraulic pressure in respective portions of the chamber; means providing respective hydraulic fluid displacement control circuits connected to said portions of the chamber for fluid displaced with respect to said portions of the chamber and each circuit including orifice means connecting it with its respective portion of the chamber and the effective flow area of which orifice means is progressively closed off by said movable means at least during the last part of the respective working stroke to effect snubbing deceleration of the relative movement of the relatively movable means and resulting in substantial increase in hydraulic pressure in the respective portion of the working chamber; and respective means referenced to said portions of the chamber independently of said orifice means and responsive to said increase in hydraulic pressure in either of said chamber portions to control the control circuit connected to the other of said portions of the chamber.

17. Pressure governing apparatus for a hydraulic actuator experiencing heavy inertia loads, which actuator includes a housing defining a working chamber having a differential pressure movable barrier traversing said chamber and dividing it into two variable volume chambers each of which alternately acts as an intake chamber having a port therein connected by an intake line to a source of hydraulic pressure, while the other acts as a discharge chamber having a port therein connected to a discharge or exhaust line, and which actuator also includes variable orificing means cooperating with the discharge port for cushioning the end of the stroke of the movable barrier, the pressure governing apparatus comprising: shutoff valve means positioned in said intake line, normally spring biased to an open position; valve operator means responsive to a predetermined pressure in the discharge chamber which is greater than the operating pressure in said chamber operatively connected to the shutoff valve means, which latter, upon actuation overrides the valve spring, closes the valve and maintains it closed so long as said pressure exists, and thereby blocks flow from the pressure source into the inlet chamber, which effectively reduces the maximum pressure experienced in the discharge chamber during any portion of the stroke; passage means connecting the discharge chamber with the intake chamber; and a high-pressure relief valve positioned in said passage means permitting flow only from the discharge chamber to the intake chamber to prevent excessive pressure development in the actuator.