US2738770A

US2738770A - Hydraulically lockable ram and control therefor

Info

Publication number: US2738770A
Application number: US320485A
Authority: US
Inventors: Clarence E Granzow
Original assignee: International Harverster Corp
Current assignee: Navistar Inc
Priority date: 1952-11-14
Filing date: 1952-11-14
Publication date: 1956-03-20
Anticipated expiration: 1973-03-20

Description

March 20, 1956 c GRANZQW 2,738,770

HYDRAULICALLY LOCKABLE RAM AND CONTROL THEREFOR Filed Nov. 14, 1952 3 Sheets-Sheet 2 MM h.

March 20, 1956 c E.IGRANZQW 2,738,770

HYDRAULICALLY LOCKABLE RAM AND CONTROL THEREFOR United States Patent HYDRAULICALLY LOCKABLE RAM AND CONTROL THEREFOR Clarence E. Granzow, Chicago, 111., assignor to International Harvester Company, a corporatlon of New Jersey Application November 14, 1952, Serial No. 320,485

11 Claims. (Cl. 121-38) This invention has to do with hydraulic lift apparatus and relates more particularly to an improved hydraulic ram wherein the control valve mechanism is incorporated within the movable working member.

Apparatus constructed according to the'principles of this invention has particular advantageous utility when mounted on a tractor for use in elevating tractor mounted implements to transport position or lowering the implements to a predetermined depth ground engaging position. Such application of hydraulic lift apparatus to tractor mounted implements has been used heretofore. It is also well known with regard to such employment of power-lift apparatus upon vehicle mounted implements to dispose a valve in series with the hydraulic circuit which carries operating fluid to and from a ram of the power lift apparatus, and to provide means for closing the control valve when the ram has reached a predetermined position. However, the control valve mechanism is usually a separate unit in the hydraulic circuit and mounted either remotely from the ram or on the outer casing of the ram. An important object of the present invention, however, is to provide an improved type of an hydraulic ram wherein the control valve mechanism is constructed within the Connecting rod or movable work member of the said ram.

A further object is to provide an improved type hydraulic ram having substantially instantaneous control as difierentiated from the follow-up type.

Another object is to provide an hydraulic ram having a control valve mechanism which establishes an hydraulic lock for preventing movement of the piston in either direction when the valve mechanism is in neutral position.

Still another object is to provide a ram having an hydraulic valve mechanism which upon failure of the source of hydraulic pressure serves to establish an hydraulic lock to prevent movement of the associated piston in either direction and that the said valve becomes inoperable during such pressure failure. Thus the mechanism provides a safety feature in that the position of the ram remains unchanged in the event of fluid pressure failure thereby preventing the accidental and sudden dropping of the implement from a transport position to the ground.

A further object is to provide an hydraulic ram wherein the operators control lever serves as an indicator of the position of the rams working member.

A different object is to provide a self-contained, corn pact hydraulic ram having all its control elements, except a source of fluid under pressure, constructed within the ram to reduce construction cost and space requirements.

These and other desirable objects inherent in and encompassed by the invention will be more readily understood from the ensuing description, the appended claims and the annexed drawings, wherein:

Figure 1 is a side elevational view illustrating a ram constituting a preferred form of the invention including control lever and schematic diagram of the pump and its conduit connections to the invention.

2,738,770 Patented Mar. 20, 1956 Figure 2 is a side elevational view in section taken on a vertical plane through the longitudinal axis of the ram.

Figure 3 is a longitudinal sectional view taken through the axis of the ram as indicated by the line 33 of Figure 2, the outer casing of the ram being excluded therefrom.

Figure 4 is a transverse sectional view taken through line 4-4 of Figure 2.

Figures 5, 6, 7 and 8 are views of each of the four sides of the body member of the rams working member showing various fluid passages opening on the respective surfaces thereof.

Figure 9, is a schematic diagram showing the flow of fluid in the ram when the control valve is in neutral position.

Figures 10 and 11 are schematic diagrams showing the flow of fluid actuating movement of the rams working member in left or rearward and right or forward directions respectively.

Referring now to Figure 1 the hydraulic lift apparatus will be seen to include an hydraulic ram 10 mounted on a stationary support 11 and having its movable work member or connecting rod 12 pivotally connected at 13 to a driven member 14. A source of fiuid pressure comprising an ordinary hydraulic pump 15 and fluid delivery conduit 16', shown diagrammatically, is connected to the ram at 17. Similarly the fluid return conduit 18, shown di agrammatically, is connected to the ram at 19. A control rod 20 is pivotally connected to an operators control lever 21 mounted on a quadrant 22 the other end of the control rod being pivotally connected to a control element 23 on the ram 10.

Referring now to Figures 2 and 3 the ram comprises a cylindrically shaped casing 24 connected at its left end to rear end Wall 25 and at its right end to front end wall 26. A piston 27 is fitted within the casing 24 in the usual manner and may be provided with a sealing ring 28 to prevent leakage of fluid between the cylinder casing 24 and the piston 27. A similar sealing ring 29 may also be used to prevent leakage of fluid between the front end wall 26 and the movable work member 12.

The movable work member 12 comprises a body member 30 fitted snugly into a cylindrically shaped sleeve 31 and welded or rigidly fastened to the body member 30 at 32. The other end of the sleeve 31 abuts the piston 27 at 33. A cap nut 34 is thread fitted to the body member 30 at 35 so that the cap nut 34 abuts the piston 27 at 36. The body member 30 is provided with a large or first longitudinal bore 37, an intermediate or second bore 38 with shoulder at 39 and a small or third bore 40 with shoulder at 41.

A servo-valve member 42 is slidably fitted into the large or first bore 37 of the body member 30. The servovalve member 42 essentially comprises a partly hollow cylindrically shaped member having circumferentially spaced

grooves

43, 44, 45, 46 and 47 providing

lands

86, 87, 88, 89 disposed therebetween and

longitudinal bores

48 and 49. Bore 49 communicates with circumferential groove 44 through a transversely bored hole or passage 50. Similarly bore 49 communicates with

circumferential grooves

46 and 47 through transversely bored holes or

passages

51 and 52 respectively.

A first helical spring 53 is held captive and is titted in a left or rear servo-chamber 55 at the left or rear end of the servo-member 42. A guide pin 56 abuts against the cap 34 and is adapted to slidably fit into the bore 48 during leftward or rearward movement of the servo-valve member 42. Similarly at the right end of the servo-valve member 42 is a second helical spring 54 held captive and is fitted in a right or forward servochamber 55 at the right or forward end of the servovalve member 42. A guide pin 57 abuts the right or fora ward end of the servo-valve member 42 and is adapted to slidably fit into the bore 58 of a plug 59. The plug 59 is adapted to fit snugly into the large or first bore 37 and recess snugly into the intermediate or second bore 38 of the body member and longitudinal movement of the plug 59 to the right or forward direction is prevented by the shoulder 39. Thus it can be seen that the captive springs urge the servo-valve member 42 to a center position with reference to the large or first bore 37 of the body member 30.

The piston 27 is provided with annular grooves 60 and 61. Fluid communication from annular groove 60 to the rear or left end cylinder chamber 63 is by means of longitudinal bore 62 and intersecting transverse bore 62 in piston 27. Similarly, fluid communication from annular groove 61 to the front or right end cylinder chamber 64 is by means of longitudinal bore 65 and intersecting transverse bore 65' in piston 27.

Into second or intermediate and third or small bores 38, 40 of the body member 30 is fitted a control valve element generally indicated at 66. The control valve element 66 is solid and cylindrically shaped. On the left end portion of the element 66 are two large diameter spaced lands 67 and 68 slidably fitted to move longitudinally in the intermediate or second bore 38 of the body member 30. Between the two

lands

67 and 63 is a circumferential groove 69. A shank 70 of the element 66 is slidably fitted into the small or third bore 40 of the body member 30. The shank 70 is provided with circumferential grooves 71, 72 and 73 and lands 74, 75 and 76 which are adapted to register with certain ports in the body member 30 as hereinafter discussed.

The control element 23 is rigidly connected to the control valve element 66 by means of a set screw 77 suitably fitted in the control element 23 as shown. The body member 30 is provided with a transversely bored elongated hole 78 to accommodate longitudinal movement of the control element 23.

In order that the control element 23 and control valve element 66 be held normally in a central position with respect to the elongated hole 78 (neutral position as shown in Figure 2) there is provided an ordinary detent mechanism generally indicated at 79. The detent mechanism may be comprised of a bracket 80 rigidly connected to the body member 30, a second bracket 81 rigidly connected to a conduit connecting member 82, a rod 83 rigidly connected to bracket 81 at one end and the other end rigidly connected to bracket 80, said rod 83 slidably passing through a bore of the control element 23. A pair of

cap tive springs

84 and 85 disposed on the rod 83 one on each side of the control element 23 co-acts to urge the said control element 23 in a central or neutral position with respect to the elongated hole 73.

Concerning means for connecting inlet and outlet eondults for fluid to actuate the ram a conduit connecting member 82 is provided. As best shown in Figure 4 the connecting conduit member is U-shaped and bored to fit snugly over sleeve 31 adjacent to the right or forward end of said sleeve and is frictionally secured thereto by means of bolts 90. The fluid under pressure delivery conduit 17 1s connected to an inlet bore 91 in the conduit connectrng member 82 which is in registry with a fluid passage 92 through sleeve 31. Similarly fluid return or discharge connection 19 is connected to an outlet bore 93 in the conduit connecting member 62 which is in registry with passage 94 through sleeve 31.

As best shown in Figures 5, 6, 7 and 8 the body member 30 is essentially cylindrically shaped and fits snugly into the sleeve 31. A section of body member 30 is cut away to form generally rectangular flat surfaces on four sides thereof and designated as surfaces A, B, C and D. Surfaces A and C are parallel to each other. Surfaces B and D are parallel to each other but at right angles with respect to surfaces A and C. It should be noted however, that the cut-away forming each surface is large but not large enough to remove the circular surfaces 121 adjoining the flat surfaces A, B, C and D. Thus it can be seen from Figure 4 that when the body member 30 is fitted into the sleeve 31 four separate chambers or passages A, B, C and D' hydraulically sealed from each other by circular surface 121 are formed by surfaces A, B, C and D respectively with the inner wall surface of the sleeve 31. The end portions of body member 30 being cylindrical and the length of surfaces A, B, C and D being less than the length of sleeve 31 as shown in Figures 2 and 3, the chambers or fluid passages A, B, C and D are closed at their respective ends.

Referring to Figure 5 side A of body member 30 has three transversely bored ports or

passages

95, 96 and 97. Port 95 communicates chamber A with the large or first bore 37 and is positioned to communicate with circumferentially spaced

grooves

46 or 47 or land 89 of the servovalve member 42. Port 96 communicates chamber A with intermediate or second bore 38 and positioned to communicate with circumferential. groove 69 or large diameter land 67 of the control valve element 66. Port 97 communicates chamber A with the small or third bore 40 and positioned to communicate with circumferential grooves 72 or 73 or land 75 of the control valve element 66. On the leftward or rearward portion adjacent the end of body member 30 are two ports or

passages

98 and 99 over which the piston 27 is fitted. The port 98 is positioned for communication with the annular groove or passage 60 on the piston 27 and circumferential grooves 43- or 44 or land 86 of the servo-valve member 42. The port 99 is positioned for communication with annular groove or passage 61 of piston 27 and circumferential grooves 44 or 45 or land 87 of the servo-valve member 42.

Referring to Figure 6 side B of the body member 30 has four transversely bored ports or

passages

100, 101, 102 and 102. The port 100 communicates chamber B with large or first bore 37 and is positioned to communi-- cate with the right or forward servo-chamber 55. The port 102 communicates chamber B with the small or third bore 40 and is positioned to communicate with circumferential groove 72 or land 75 of the control valve element 66. The port 102 communicates chamber B with the smallor third bore 40 and is positioned to register with circumferential groove 72 or land 74 of the control element 66. The port 101 communicates chamber B with small bore 40 and is positioned to register with the shank 70, circumferential groove 71 or land 74 of the control valve element 66.

Referring to Figure 7 side C of body member 30 has four ports or

passages

103, 104, and 106. On the leftward or rearward portion adjacent the end of body member 30 is the port or passage 107 over which the piston 27 is fitted. The port 107 is transversely bored to communicate with the large or first bore 37 and is positioned to register with circumferential grooves 43 or 44 or 45 as well as lands 86 or 87. The port 107 communicates with port 103 by means of longitudinal bore 108 shown in dotted lines in Figure 7. The port 104 is transversely bored to communicate chamber C with the intermediate or second bore 38 and is positioned to register with circumferential groove 69 or large diameter land 68. The port 105 is transversely bored to communicate chamber C with the small bore 40 and is positioned to register with circumferential groove 72 or land 74 of the control valve element 66. Similarly the port 106 is transversely bored to communicate chamber C with small bore 40 and is positioned to register with circumferential groove 73 or land 76. The

ports

105 and 106 are fitted with ordinary ball-type check valves 109 and 1.10. The halls of

check valves

109 and 110 are seated in a recessed portion of the ports or

passages

105 and 106 of body member 30 and are held in position by a leaf spring 111 rigidly fastened by screw 112 to the body member 30 in a threaded bore as shown in Figure 3.

Referring to Figure 8 side D of body member 30 has four ports or

passages

114, 115, 116 and 116'.- The port 114 is bored transversely to communicate chamber D with a longitudinal bore 117 shown in dotted lines which extends leftward or rearward to the left or rear end of body member 30 where it communicates with a transverse groove or passage 113 also shown in dotted lines. The transverse groove 113 extends inwardly to large or first bore 37 of the body member 30 for fluid communication to the left servo-chamber 55. From this it can be seen that a fluid passage is established which communicates chamber D' to the large or first bore 37 at the left end of body member 30. The port 115 is a transverse bore communicating chamber D' with small bore 40 and positioned to register with the shank 70, circumferential groove 71 or land 74 of the control valve element 66. The port 116 is transversely bored and positioned to communicate chamber D with circumferential groove 73 or register with land 76 of the control valve element 66. The port 116' is transversely bored and positioned to communicate chamber D with circumferential groove 73 or register with land 75 of the control valve element 66.

Having now described the construction details of the invention the following discussion is intended to illustrate the operating characteristics of the assembled mechanism.

Operation Figure 1 illustrates the ram wherein the movable work member 12 is positioned midway between the limits of its stroke. In this position the operators control lever 21 is in a. vertical or midway position between its limits on quadrant 22. It will be readily appreciated that the control element 23 moves with the working member 12 and since it is connected to the operators control lever 21 by the rod 20, the relative position of the working member 12 in the limits of its stroke will be correspondingly indicated by the position of lever 21 with reference to the quadrant 22. Thus the operator at a glance can determine the position of the working member 12 by the corresponding position of lever 21.

Assuming that the hydraulic ram with working member 12 is at rest, the control valve element 66 and the servo'valve member 42 will be in neutral position as shown in Figures 2 and 3. When the servo-valve member 42 and control valve element 66 are in neutral position two separate hydraulic circuits must necessarily be in operation, one circuit being formed to by-pass hydraulic fluid under pressure to relieve the pump 15 from unnecessary load and the other circuit formed to connect the left or rearward servo-chamber 55 with the right or forward servo-charnber 55' so that the

helical springs

53 and 54 may react to position the servo-valve member in the neutral position shown in Figures 2 and 3. All other fluid passages are blocked when the servo-valve member 42 and control valve element 66 are in neutral position.

Reference is now made to Figure 9 which illustrates schematically the flow of hydraulic fluid in the various passages when the servo-valve member 42 and control valve element 66 are in neutral position. The fluid under pressure from pump 15 is conducted through conduit 16 through the fluid delivery connection 17 into inlet bore 91 of the conduit connecting member 32, thence through passage 92 in sleeve 31 into the chamber or passage A. The side A of body member with the sleeve 31 forms the fluid confining walls of chamber or passage A and it will be seen fro-m Figure 5 that the said side A is provided with three transversely

bored ports

95, 96 and 97. The flow of fluid through port 95 is blocked due to its registry with land 89 of the servo-valve member 42. Similarly the flow of fluid through port 97 is blocked due to its registry with land 75 of the control valve element 66. In order to relieve pump 15 from unnecessary load, the fluid is by-passed through port 96 which is in registry with circumferential groove 69 thence through port 104(side C of Figure 7) also in registry with groove 69 into chamber C'. From chamber or passage C the fluid is conducted throughv passage 94 in sleeve 31 into the outlet bore 93 of the conduit connecting member 82 thence into the fluid return connection 19 and through return conduit 18 to the pump 15. Thus it can be seen that an hydraulic by-pass circuit is established to relieve the pump from unnecessary overload when the servo-valve member 42 and control valve element 66 are in neutral position.

From Figure 7 it will be seen that side C has

ports

103, and 106 in addition to the above discussed port 104 and since chamber or passage C is part of the fluid

bypass circuit theports

103, 105 and 106 are necessarily blocked. It will be seen from Figure 3 that check valves 109 and block any fluid flow from chamber C into

ports

105 and 106 respectively. The port 103 communicates with longitudinal bore 108 in the body member 30 which in turn communicates with the port 107. The port 107 is in registry with circumferential groove 44 of the servo-valve member 42 and communicates with longitudinal bore 49 of the said servo-valve member 42 through transversely bored hole 50. From the longitudinal bore 49 communication exists with

circumferential grooves

46 and 47 through the transversely

bored holes

51 and 52 respectively of the servo-valve member 42. However, fluid flow is blocked at this point because

circumferential grooves

46 and 47 are not in registry with any ports when the servo-valve member 42 is in neutral position.

From the above discussion it will be seen that when the servo-valve member 42 and control valve element 66 are in. neutral position, there is no fluid communication between the chambers or passages A and B or A and D. Similarly there is no fluid communication between chamhers or passages C and B or C and D. Further, it will be seen that fluid flow from the left or rear cylinder chamber 63 through the longitudinal bore 62 and the annular groove 60 in piston 27, thence through port 98 into circumferential groove 43 of the servo-valve member 42 in registry with port 98, is blocked due to the fact that groove 43 is not in registry with any other port. Similarly fluid flow from the right or forward cylinder chamber 64 through longitudinal bore 65' and annular groove 61 in piston 27, thence through port 99 into circumferential groove 45 of the servo-valve member 42 in registry with port 99, is also blocked due to the fact that groove 45 is not in registry withany other port. Thus it can be seen when the servo-valve member 42 is in neutral position the working member 12 is hydraulically locked from movement in either direction.

in order to properly position the servo-valve member in the neutral position as shown in Figures 2 and 3, it is necessary to provide communication between the left or rearward servo-chamber 55 and right or forward servochamber 55' so that

helical springs

53 and 54 can maintain the servo-valve member 42 in the neutral position. From Figure 2 it will be seen that the left or rearward servo chamber 55 is in communication with transverse bore 113 in the body member 30 which in turn communicates with longitudinal bore 117 also in body member 30, thence to port 114 (side D of Figure 8) and into the chamber or passage D.

It will be observed from Figure 8 that side D of body member 30 has

ports

115, 116 and 116' in addition to the above discussed port 114. The ports 116 and 116' are in registry with circumferential groove 73 of the control valve member 66. But fluid flow is blocked at this point because circumferential groove 73 is not in registry with any other port. Hence there is no fluid flow from chamher or passage D through the ports 116 and 116'. However, circumferential groove 71 is in registry with port 115 leading from chamber or passage D and port 101 (side B of Figure 6) leading to chamber or passage B. From chamber B communication is made through the port 100 (side BFigure 6) into the right or forward servo-chamber 55'. The remaining two ports 102 and 102' (side E- Figure 6) are in registry with circumferential groove 72 of the control valve element 66 and since groove 72 is not in registration with any other port there is no fluid flow from chamber or passage B through the ports 102 and 102'. Thus fluid communication is established between the left or rearward servo-chamber 55 and the right or forward servo-chamber 55".

Now referring back to Figure I, suppose the operator desires to actuate the ram 10 to move the movable work member 12 in a forward direction to the right. The operator grasps the control lever 21 and pushes it to the right or forwardly as shown by the arrow labelled X. The control rod connected to the control element 23 will also move to the right and overcome the detent mechanism 79. The control element 23 being rigidly connected to the control valve element 66 will then move in a forward direction to the right. Referring to schematic Figure 11 it will be seen that the pump by-pass circuit is immediately closed because large diameter land 67 of the control valve element 66 is moved into registry with port 96. Since the circumferential groove 69 of the control valve element 66 is not in communication with any other port except port 104, no fluid flow occurs through port 104. The shank moves into registry with

ports

101 and 115 thus blocking fluid communication between left or rearward servo-chamber 55 and right or forward servo-chamber 55. The circumferential groove 72 of the control valve element 66 moves to register with

ports

97 and 102 while circumferential groove 73 moves to register with

ports

106 and 116. The land of the control valve element 66 moves to register with port 116'.

The fluid under pressure from the pump 15 enters chamber or passage A exactly in the same manner previously described as when valves 42 and 66 are in the neutral position. The fluid under pressure is first conducted to the chamber or passage B through port 97 which is in registry with circumferential groove 72 and thence into port 102 also in registry with groove 72. From the chamber or passage B there is no flow of fluid through

ports

102 and 101 as they are blocked by registration with land 74 and shank 70, respectively, of control element 66. However, fluid under pressure is conducted from the chamber or passage B through port to the right servo-chamber 55 which forces the servovalve member 42 to the extreme leftward or rearward position and compressing the left or rear helical spring 53. The servo-valve member 42 having now been moved to its extreme leftward or rearward position effects registration of port 95 with circumferential groove 47. The fluid under pressure is then conducted from chamber A through port 95 into groove 47 thence through transversely bored hole 52 into longitudinal bore 49 of the r servo-valve member 42. From longitudinal bore 49 no fluid flow will occur through transversely bored hole 51 leading to circumferential groove 46 because no port is in registration with groove 46. However from longitudinal bore 49 fluid under pressure is conducted through transverse hole 50 into circumferential groove 44 in the servo-valve member 42 which groove is in registration with port 93 in the body member 30. Port 98 is in constant communication with the annular groove or passage 60 of the piston 27, which in turn communicates with left or rear longitudinal bore 62 in piston 27 thence into the left end cylinder chamber 63. Thus fluid under pressure is conducted from longitudinal bore 49 through transverse hole 50 into circumferential groove 44, thence through port 98, annular groove 60 and left longitudinal bore 62 into the left cylinder chamber 63 thereby exerting pressure against piston 27 to move the work member 12 in a forward direction to the right.

Thus far means have now been described for communicating fluid under pressure from the pump 15 to that the leftward or rearward movement of the serve valve member 42 requires discharge of fluid from the left servo-chamber 55. Similarly movement of the piston 27 and movable work member 12 in a forward direction to the right necessitates discharge of fluid from the right cylinder chamber 64. The means for discharging fluid from

chambers

55 and 64 are described as follows.

As the servo-valve member 42 moves rearwardly or leftwardly fluid from the left or rear servo-chamber 55 passes through transverse groove 113 into longitudinal bore 117 thence through port 114 into the chamber or passage D. From the chamber or passage D the discharge fluid passes through port 116, circumferential groove 73 which is in registry with port 116, thence through port 106 also in registry with circumferential groove '73, unseating the ball in check valve and into the chamber or passage C. The ports 116 and leading from the chamber or passage D are blocked due to registration with land 75 and shank 70, respectively, of the control valve element 66. From the chamber or passage C the discharge fluid flows through passage 94 in the sleeve 31 through bore 93 of the conduit connecting member 32 back to the pump 15 through fluid return connection 19 and conduit 18. It will be noted that port 164 leading to the chamber or passage C is blocked due to registration with the circumferential groove 69 which in turn is not in registration with another port. Also the port 105 communicating with the chamber or passage C through check valve 109 is blocked due to registration with land 74 of the control valve element 66. The remaining port 103 leading to the chamber or passage C is in communication with the right or for ward cylinder chamber 64 for discharge of fluid therefrom.

The discharge fluid from right or forward cylinder chamber 64, during movement of the piston 27 and movable work member 12 in a forward direction to the right flows through the right longitudinal bore 65 and the annular groove 61 in the piston 27 through port 99 into circumferential groove 45 of the servo-valve member 42 in registry therewith, thence into port 107 also in registry with groove 45 and into the chamber or passage C through longitudinal bore 108 and port 103. From the chamber or passage C the discharge fluid flows through the passage 94 in sleeve 31 into bore 93 of the conduit connecting member 82 back to the pump 15 through fluid return connection 19 and conduit 18.

Now again referring back to Figure I, suppose the operator desires to actuate the ram 10 to move the work member 12 in a rearward direction to the left. The oporator grasps the control lever 21 and pulls it rearwardly to the left as shown by the arrow labelled Y. The control rod 20 connected to the control element 23 will also move to the left and overcome the detent mechanism 79. The control element being rigidly connected to the control valve element 66 will then move in a rearward direction to the left. Referring now to schematic Figure 10 it will be seen that the pump by-pass circuit is immediately closed because large diameter land 68 of the control valve element 66 is moved into registry with port 104. Since the circumferential groove 69 of the control valve eiement is not in registry with any other port except port 96, no fluid flow occurs through ports 96 and 104. The land 74 moves into registry with

ports

101 and 115 thus blocking fluid circuit between the left or rearward servo-chamber 55 and right or forward scrvo chamber 55. The circumferential groove 72 of the control valve element 66 moves to register with

ports

102 and 105 while the circumferential groove 73 moves to register with

ports

97 and 116. The land 75 of the control valve element 66 moves to register with port 102 and land 76 moves into registry with

ports

116 and 106.

The fluid under pressure from pump 15 enters the chamber or passage A exactly in the same manner previously described as when the servo-valve member 42 and the control valve element 66 are in the neutral position. The fluid under pressure is first conducted to the chamber or passage D' through port 97 which is in registry with circumferential groove 73 and thence into port 116 also in registry with groove 73. From the chamber or passage D there is no flow of fluid through

ports

116 and 115 as they are blocked by registration with lands 76 and 74, respectively, of the control valve element66. However, the fluid under pressure is conducted from the chamber or passage D to the left or rearward servochamber 55 through port 114, longitudinal bore 117 and transverse groove 113 of the body member 30 which forces the servo-valve member 42 to the extreme rightward or forward position and compresses the right helical spring 54. The servo-valve member 42 having now been moved to its extreme rightward or forward position effects registration of port 95 with circumferential groove 46. The fluid under pressure is then conducted through transversely bored hole 51 into longitudinal bore 49 of the servo-valve member 42. From the longitudinal bore 49 no fluid flow will occur through transversely bored hole 52 leading to the circumferential groove 47 because no port is in registration with groove 47. However, from the longitudinal bore 49 fluid under pressure is conducted through the transverse hole 50 into circumferential groove 44 in the servo-valve member 42 which groove is in registration with port 99 in the body member 30. The port 99 is in constant communication with annular groove or passage 61 of the piston 27, which in turn communicates with the right or forward longitudinal bore 65 in piston 27 thence into the right or forward end cylinder chamber 64. Thus the fluid under pressure is conducted from the longitudinal bore 49 through transverse hole 50 into circumferential groove 44, thence through port 99, annular groove 61 and right longitudinal bore 65 into the right cylinder chamber 64 thereby exerting pressure against piston 27 to move the work member 12 in a rearward direction to the left.

Thus far means have now been described for communicating fluid under pressure from the pump 15 to the left or rearward servo-chamber 55 for moving the servo-valve member 42 in a rightward or forward direction and also fluid under pressure to the right or forward end cylinder chamber 64 for exerting pressure against the piston 27 to move the movable work member 12 in a rearward direction to the left. it will again be appreciated that the rightward or forward movement of the servo-valve member 42 requires discharge of fluid from the right or forward servo-chamber 55'. Similarly, movement of the piston 27 and work member 12 in a rearward direction to the left necessitates the discharge of fluidfrom the left or rearward cylinder chamber 63. The means for discharging fiuid from chambers 55' and 63 are described as follows.

As the servo-valve member 42 moves rightwardly or forwardly fluid from the right or forward servo-chamber 55 passes through transverse port 100 into the chamber or passage B. From the chamber or passage B' the discharge fluid passes through port 102', circumferential groove 72 which is in registry with port 102, thence through port 105 also in registry with circumferential groove 72, unseating the ball in check valve 109 and into the chamber or passage C. The

ports

101 and 102 leading from the chamber or passage B are blocked due to registration with lands 74 and 75, respectively, of the control valve element 66. From the chamber or passage C, the discharge fluid flows through passage 94 in the sleeve 31 through the bore 93 of the conduit connecting member 82 back to the pump 15 through the fluid return connection 19 and conduit 18. It will be noted that port 104 leading to the chamber or passage C is blocked due to registration with large diameter land 68. Also the port 106 communicating with the chamber C throughcheck valve 110 is blocked due to registration with land 76 of the control valve element. The remaining port 103 leading to the chamber or passage C is in communi- 10 cation with the left cylinder chamber 63 for discharge of fluid therefrom.

The discharge of fluid from the left or rearward cylinder chamber 63, during movement of the piston 27 and work member 12 in a rearward direction to the left, flows through the left or rear longitudinal bore 62 and the annular groove or passage 60 in the piston 27 into circumferential groove 43 of the servo-valve member 42 in registry therewith, thence into port 107 also in registry with groove 43 and into the chamber or passage C through longitudinal bore 108 and port 103. From the chamber or passage C the discharge fluid flows through passage 94 in sleeve 31 into bore 93 of the conduit connecting member 82 back to the pump through the fluid return connection 19 and conduit 18.

If at any time the operator releases the control lever 21 the detent mechanism 79 returns the control element 23 and control valve member 66 to neutral position. Thereupon the hydraulic circuit between the left and right servo-

chambers

55 and 55 is re-established and the helical springs co-act to urge movement of the servo-valve member 42 back to the neutral position thereby terminating. further movement of the work member 12.

It will be appreciated from the foreging description that in order to actuate the servo-valve member in either direction from the neutral position, it is necessary that the chamber or passage A be provided with fluid under pressure. Thus it can be seen that should there occur a failure in fluid pressure from the pump, the ram remains in an hydraulically locked position irrespective of the position of the movable work member 12 with reference to the limits of its stroke. This novel feature prevents the operator from accidentally releasing the ram when under load, such as when implements are in a raised or transport position, thereby safeguarding said implements from damage through inadvertent and sudden drop ping to the ground. Also the novel arrangement of the control valve mechanism within the rams movable work member not only requires less construction materials and thus lower construction cost but is compact and space saving which is believed highly significant.

It can now be seen that the objects of the invention have been fully achieved and it must be understood that changes and modifications may be made which do not depart from the spirit of the invention as disclosed nor from the scope thereof as defined in the appended claims.

What is claimed is:

1. An hydraulic ram and control therefor comprising a casing including a front end wall and a rear end wall, a piston adapted to reciprocate in said casing, a movable work member connected to said piston and projecting through said front end wall, front and rear cylinder chambers adapted to accommodate fluid under pressure for urging movement of said piston and movable work member, a conduit connecting member mounted on the external portion of said movable work member having fluid inlet and outlet means, a first conduit adapted to connect communicatively to a source of fluid under pressure said first conduit being communicatively connected to said fluid-inlet means, a second conduit adapted for accommodating fluid discharge communicatively connected to said fluid outlet means, a control valve means disposed in said movable work member, said control valve means adapted for alternately establishingcommunication between the said source of fluid under pressure and one cylinder chamber and simultaneously establishing communication between said fluid outlet means and the other cylinder chamber thereby urging movement of said piston and movable work member, said control valve means including a fluid pressure responsive servo-valve member, said servo-valve member adapted for automatically locking the position of said piston and movable work member when said source of fluid under pressure is terminated.

2. An hydraulic ram and control therefor having a casing including a front end wall and a rear end wall, a

piston adapted toreciprocate in said casing, a movable work member connected to said piston and projecting through said front end wall, said movable work member having a first, second and third longitudinal bores, front and rear cylinder chambers adapted to accommodate fluid under pressure for urging movement of said piston and movable work member, a conduit connecting member mounted on the external portion of said movable work member, a conduit adapted for connection to a source of fluid under pressure said conduit being communicatively connected to an inlet bore, a conduit adapted for connection to a fluid return said conduit being communicatively connected to an outlet bore in said conduit connecting member, a plurality of passages disposed within said piston and movable work member communicatively connectable to said inlet and outlet'bores and said cylinder chambers, a control valve means including a servo-valve member and a manually operable control valve element disposed within said movable work member, said servo-valve member disposed in said first longitudinal bore in one end portion of said movable work member and said control valve element disposed in said second and third longitudinal bores in the other portion of said movable work member, said servo-valve member comprising a partly hollow cylindrically shaped member having circumferentially spaced grooves and a longitudinal bore with transverse passages adapted to communicatively interconnect a plurality of said circumferential grooves with said longitudinal bore for fluid flow therebetween, a pair of servo-chambers disposed at each end of said servo-valve member including a pair of springs adapted to urge said servo-valve member toward a closed position, a'plurality of ports communicatively connected with said passages in said movable workmember adapted to register with at least one of said circumferential grooves in said servo-valve member, said servo-valve member advanceable in a forward direction from a normally closed position communicatively connecting said inlet bore with one cylinder chamber and simultaneously communicatively connecting said outlet bore with the other cylinder chamber for actuating movement of said piston and work member in a rearward direction and alternately retractable in a rear ward direction from a normally closed position communicatively connecting said outlet bore with one cylinder chamber and simultaneously communicatively connecting said inlet bore with the other cylinder chamber for actuating movement of said piston and Work member in a forward direction, said control valve element comprises a solid cylindrically shaped member having one end portion thereof adapted to reciprocate in said second longitudinal bore in the center portion of said movable work member and the other portion adapted to reciprocate in said third longitudinal bore in the end portion opposite the piston end of said movable work memher, said one end portion having a circumferential groove adapted to register with transverse ports in said movable Work member for establishing by-pass communication between the inlet and outlet bores of said conduit connecting member while said control valve element is in a neutral" position, a circumferential groove in said other portion of the control valve element adapted to register with a plurality of transverse ports in said movable work member for establishing fluid communication between the servo-valve chambers while the control valve element is in a neutral position and a plurality of circumferentially spaced grooves in said other portion of the control valve element adapted to register with a plurality of transverse ports in said movable work member for establishing fluid communication between one servochamber and the said inlet bore and simultaneously establishing fluid communication between the other servochamber and the said outlet bore for actuating the servovalve member in a rearward direction while the control valve element is advanced in a forward direction. and alternately adapted to register with a plurality of transverse ports in said movable work member for establishing fluid communication between one servo-chamber and the said outlet bore and simultaneously establishing fluid communication between the other servo-chamber and said inlet bore for actuating the servo-valve member in a forward direction While the control valve element is retracted in a rearward direction.

3. An hydraulic ram and control therefor having a casing including a front end wall and a rear end wall, a piston adapted to reciprocate in said casing, a movable member connected to said piston and projecting through said front end wall, front and rear cylinder chambers adapted to accommodate fluid under pressure for urging movement of said piston and movable work member, a conduit connecting member mounted on the external portion of said movable work member, a conduit adapted to connect to a source of fluid under pressure said conduit being communicatively connected to an inlet bore, a conduit adapted to connect to a fluid return said conduit being communicatively connected to an outlet bore in said conduit connecting member, a plurality of passages disposed within said piston and movable work member communicatively connectable to said inlet and outlet bores and cylinder chambers, control valve means disposed within said movable work member, said control valve means including a servo-valve member and a manually operable control valve element, said servovalve member disposed in one portion of said movable work member and having front and rear servo-chambers adapted to accommodate fluid under pressure for actuating said servo-valve member, said servo-valve member adapted to connect for fluid flow one cylinder chamber with said inlet bore for urging movement of said piston and movable work member in one direction while simultaneously connecting for fluid flow the other cylinder chamber with said outlet bore and alternately connect for fluid flow one cylinder chamber with said outlet bore while simultaneously connecting for fluid flow the other cylinder chamber with said inlet bore for urging movement of said piston and movable work member in the other direction, said control valve element disposed in the other portion of said movable work member and connected to manually operable external control means, said control valve element adapted to by-pass fluid under pressure from said inlet bore to fluid return outlet bore and simultaneously establishing means for fluid communication between said front and rear servo-chambers While said control valve element is in a neutral position, said control valve element being advanceable in a forward direction from said neutral position to communicate said inlet bore with the forward servo-chamber while simultaneously communicating the rearward servochamber With'said outlet bore for actuating said servovalve member in a rearward direction and alternately retractable from said neutral position to communicate said inlet bore with the rearward servo-chamber while simultaneously communicating the forward servo-chamher with said outlet bore for actuating said servo-valve member in a forward direction.

4. An hydraulic ram according to claim 3 having a manually operable control lever remotely positioned and connected to the control valve element, and indicating means associated with said ram and control lever for determining remotely the position of the said movable work member with reference to operable limits of said movable work member.

5. In an hydraulic ram having a piston and connecting rod adapted for reciprocation, a conduit connecting member mounted on said connecting rod, said conduit connecting member having fluid inlet and outlet means, a source of fluid under pressure including fluid return means adapted for connection to said conduit connecting member, a plurality of fluid passages disposed in said connecting rod communicatively connectable with said source of fluid. underpressure and fluid return means ofsaidram for actuating movement of said piston and connecting rod, a control valve means disposed within said connecting rod, said control valve means being movable from a neutral position to interconnect said passages for actuating movement of the said pistonand connecting rod in one direction and alternately being movable reversedly from said neutral position to interconnect said passages for actuating movement of said piston and connecting rod in the other direction, said control valve means including a fluid pressure responsive servo-valve member, said servo-valve member adapted for automatically locking the position of said piston and connecting rod when said source of fluid under pressure is terminated.

6. In an hydraulic ram according to claim said control valve means including by-pass means adapted to connect communicatively said source of fluid under pressure with said return means when said control valve means is in a neutral position.

7. An hydraulic ram and control therefor having a casing including a front end wall and a rear end wall, a piston adapted to reciprocate in said casing, a connecting rod connected to said piston and projecting through said front end wall, front and rear cylinder chambers adapted to accommodate fluid under pressure for urging movement of said piston and connecting rod, a conduit connecting member mounted on the external portion of said connecting rod, said conduit connecting member having an inlet bore adapted for connection to a source of fluid under pressure and an outlet bore adapted to connect means for accommodating fluid discharge, a plurality of passages disposed in said piston and connecting rod communicatively connectable to said inlet and outlet bores and cylinder chambers, control valve means disposed in said connecting rod, said control valve means including a servo-valve member and a manually operable control valve element, said servo-valve member being disposed in one portion of said connecting rod and having front and rear servo-chambers adapted to accommodate fluid under pressure for actuating longitudinal movement of said servo-valve member, spring means mounted within said servo-chambers, said spring means being positioned for urging said servo-valve members to a neutral position, said servo-valve member adapted to connect communicatively for fluid flow one cylinder chamber with said inlet bore for urging movement of said piston and connecting rod in one direction and alternately connect communicatively for fluid flow the other cylinder chamber with said inlet bore for urging movement of said piston and connecting rod in the other direction, said servo-valve member adapted to prevent communicative fluid flow from said cylinder chambers when said servo-valve member is in neutral position, said control valve element being disposed in the other portion of said connecting rod, said control valve element adapted to connect communicatively for fluid flow one servochamber with said inlet bore for urging movement of said servo-valve member in one direction and alternately connect communicatively the other servo-chamber with said inlet bore for urging movement of said servo-valve member in the other direction.

8. An hydraulic ram according to claim 7 having a manually operable control lever remotely positioned and connected to the control valve element, and indicating means associated with said ram and control lever for determining remotely the position of the said piston and connecting rod with reference to operable limits of said piston.

9. An hydraulic ram and control therefor including a reciprocable piston and connecting rod connected to said piston, front and rear cylinder chambers adapted to accommodate fluid under pressure for urging movement of said piston and connecting rod, means including a conduit connecting member mounted externally on said connecting rod for communicatively connecting said ram to a source of fluid under pressure and accommodating fluid discharge, said source of fluid under pressure comv 14 municatively connectableto one cylinder chamber for urging movement of said piston and connecting rod in one direction and alternately communicatively connectable to the other cylinder chamber for urging movement of said piston and connecting rod in the other direction, a plurality of fluid passages disposed in said connecting rod communicatively connectable to the said source of fluid under pressure to one cylinder chamber for urging movement of said piston in one direction and alternately into the other cylinder chamber for urging movement of said piston in the other direction, control valve means disposed in said connecting rod, said control valve means including a servo-valve member and a control valve element, said servo-valve member disposed in one portion of said connecting rod, a front servo-chamber disposed adjacent the forward end of the servo-valve member and a rear servo-chamber disposed adjacent the rearward end of said servo-valve member, said servo-chambers being adapted to accommodate fluid under pressure for actuating movement of said servo-valve member, means for urging said servo-valve member to a neutral position, said servo-valve member adapted to connect communicatively for fluid flow one cylinder chamber with said source of fluid under pressure for urging movement of said piston in one direction and alternately connect communicatively for fluid flow the other cylinder chamber with said source of fluid under pressure for urging movement of said piston in the other direction, said control valve element disposed in the other portion of said connecting rod, said control valve element adapted to connect communicatively for fluid flow one servo-chamber with said source of fluid under pressure for urging said servo-valve member in one direction and alternately connect the other servo-chamber with said source of fluid under pressure for urging movement of said servovalve member in the other direction.

10. An hydraulic ram and control therefor including a reciprocable piston and connecting rod connected to said piston, a cylinder chamber adapted to accommodate fluid under pressure for urging movement of said piston, said connecting rod including a conduit connecting member adapted to connect communicatively to a source of fluid under pressure, a plurality of fluid passages disposed in said connecting rod communicatively connectable to said source of fluid under pressure and said cylinder chamber, control valve means disposed in said connecting rod, said control valve means including a servo-valve member and a control valve element, said servo-valve member being disposed in one portion of said connecting rod, a servo-chamber disposed adjacent to one end of said servo-valve member, means mounted in said servochamber adapted to urge said servo-valve member to a neutral position, said servo-chamber being adapted to accommodate fluid under pressure for actuating movement of said servo-valve member to connect communicatively for fluid flow one cylinder chamber with said source of fluid under pressure for urging movement of said piston in one direction, said servo-valve member adapted to lock hydraulically the position of said piston When said servo-valve member is in neutral position, said control valve element disposed in the other portion of said connecting rod, said control valve element adapted to connect communicatively for fluid flow said servochamber with said source of fluid under pressure for urging movement of said servo-valve member in one direction.

11. An hydraulic ram and control therefor including a reciprocable piston and connecting rod connected to said piston, a conduit connecting member mounted on said connecting rod, said conduit connecting member being adapted to connect communicatively to a source of fluid under pressure, a cylinder chamber adapted to accommodate fluid under pressure for urging movement of said piston, a plurality of fluid passages disposed in said connecting rod connectable communicatively to said source of fluid under pressure and said cylinder chamher, a control valve means includinga manually operable control valve element disposed within said connecting rod adapted to connect communicatively said passages for fluid flow between said source of fluid under pressure and said cylinder chamber thereby urging movement of said piston and connecting rod, said control valve means including a fluid pressure responsive servovalve member, said servo-valve member adapted for automatically locking the position of said piston and connecting rod when said source of fluid under pressure is terminated.

References Cited in the file of this patent UNITED STATES PATENTS Blessing May 2, 1882 Allen et a1. Jan. 29, 1918 Davis Jan. 27, 1931 Bragg Oct. 6, 1931 Bragg et a1. Nov. 3, 1931 Onions Mar. 12, 1940 Orshansky, Jr May 22, 1945 Ecker Feb. 14, 1950 Dempsey Mar. 17, 1953 Burns Sept. 14, 1954