US3281107A

US3281107A - Hydraulic support prop

Info

Publication number: US3281107A
Application number: US514090A
Authority: US
Inventors: Warren J Lewis
Original assignee: Ohio Brass Co
Current assignee: Ohio Brass Co
Priority date: 1965-12-15
Filing date: 1965-12-15
Publication date: 1966-10-25
Anticipated expiration: 1983-10-25

Description

Oct. 25, 1966 w. J. LEWIS HYDRAULIC SUPPORT PROP 5 Sheets-Sheet 1 Filed Dec. 15, 1965 FIG. 3

INVENTOR. WARREN J. LEW/S 24m w ATTORNEY Oct. 25, 1966 'w. J. LEWIS 3,281,107

HYDRAULIC SUPPORT PROP Filed Dec. 15, 1965 5 Sheets-Sheet 2 IN VEN TOR. WARREN J. LEW/5 FIG.4 M

ATTORNEY Oct. 25, 1966 Filed Dec. 15, 1965 f I I. A

W. J. LEWIS HYDRAULIC SUPPORT PROP .3 Sheets-Sheet 5 INVENTOR. WARREN J. LEW/5 WbM AT TORNE Y United States Patent O 3,281,107 HYDRAULIC SUPPORT PROP Warren J. Lewis, Mansfield, Ohio, assignor to The Ohio Brass Company, Mansfield, Ohio, a corporation of New Jersey Filed Dec. 15, 1965, Ser. No. 514,090 13 Claims. (Cl. 248354) This application is a continuation-in-part of application Serial No. 407,143, filed October 28, 1964, by Warren J. Lewis.

The invention relates to supports for mine roofs and, more particularly, to an extensible hydraulic support prop therefor.

A principal object of the invention is to provide a portable light weight device useful for temporary support of roofs, floors, shoring, and the like.

Another object of the invention is to provide a hydraulic support prop for mine roofs which will accommodate substantial shifting and settling of the roof and will distribute the load over a plurality of similar props.

Still another object of the invention is to provide a hydraulic support prop, for the purposes above described, which is self-contained and economical to manufacture and use.

It is known to use hydraulic props for supporting mine roofs which have provisions for equalizing the loads carried by a number of the prop during roof movement so that the props can be set in convenient positions during installation without overloading during subsequent roof movement. This is accomplished ordinarily by providing a relief valve, or like device, which acts to release a portion of the hydraulic fluid from the prop when the pressure developed in the internal fluid system exceeds a certain magnitude required to actuate the relief device. Such support props have, in general, required filling -by hydraulic pumps during installation and have required relatively precisely fitting parts. The devices are useful for mine roof control although large installation and replacement costs are incurred.

According to the present invention, a hydraulic support prop is provided in which the hydraulic system is entirely self-contained, the hydraulic fluid being retained within the prop upon activation of a relief device during overload conditions. This result is accomplished by utilizing a novel arrangement of a fixed base cylinder and a movable cylinder telescoping therein with a fixed piston in the movable cylinder and a movable piston in the base cylinder to constitute a constant volume system for the hydraulic fluid. The spaces between the fixed and movable pistons are connected by hydraulic circuits incorporating, in one embodiment of the invention, a by-pass valve in one conduit thereof to permit extension of the prop and a relief valve in another conduit to relieve excess pressures for load distribution during roof movement. A manual valve in parallel with the relief valve permits manual collapse of the prop. In another embodiment of the invention, a hydraulic pump is incorporated in one hydraulic circuit for forced extension of the movable cylinder with respect to the base cylinder. A relief valve connected in shunt with the hydraulic pump is arranged for operation in response to over-pressures in the base cylinder or manually for collapse of the prop.

Manufacture of the prop is facilitated by the use of standard tubular sections and O-ring seals.

The support prop of the invention will be more clearly understood by reference to the following detailed specification and claims, taken with the appended drawings in which:

FIG. 1 is a vertical sectional view of the hydraulic support prop of the invention;

FIG. 2 is a transverse sectional view, taken in the direc- 3,281,107 Patented Got. 25, 1966 tion 22 in FIG. 1, showing the construction of the base part of the prop;

FIG. 3 is a transverse sectional view, taken in the direction 3-3 in FIG. 1, showing the arrangement of the bypass valves of the prop;

FIG. 4 is a vertical sectional view showing another hydraulic support prop embodying the principles of the invention;

FIG. 5 is a sectional view, taken along the line 5-5 in FIG. 4, showing the pump of the prop of FIG. 4; and

FIG. 6 is a sectional view, taken along the line 66 in FIG. 4, showing the relief valve of the prop of FIG. 4.

The support prop 10 comprises a base 11, a base cylinder 12, a base head 13, a top cylinder 14, a top head 15, a cross head or movable piston 16 at the lower extermity of the top cylinder, a fixed piston 17 in the top cylinder, and a stand pipe 18 extending from the base head 13 through the movable piston to the fixed piston. The support prop 10 is adapted to be filled with hydraulic fluid in the chamber 19 between the base head 13 and the movable piston 16 and in the chamber 20 between the movable piston 16 and the fixed piston 17. With this arrangement, a substantially constant total volume of hydraulic fluid is contained in the two chambers, whatever the position of the top cylinder 14 with respect to the base 11 and base cylinder 12.

The support prop 10 is adapted for placement in a tunnel or other opening by engagement of the base 11 with the floor or ground part of the excavation and extension of the prop until the top head 15 engages the roof or overburden. As so arranged, the prop 10 supports the roof or overburden and will continue to do so upon downward movement or collapse of the overburden. Collapse of the overburden will be resisted by the support prop until the load exerted by the roof or overburden produces a hydraulic pressure sufficient to actuate a relief valve 21 which permits the top cylinder 14 to retract into the base cylinder 12 a distance suflicient to reduce the pressure in the prop and permit the relief valve 21 to close. A manual valve 22 is provided for retracting the top cylinder to lower the prop during disassembly or moving operations.

The specific construction of the support prop 10 is such that the prop may be manufactured and assembled from standard shapes and component parts of standard design. Thus, the base 11 comprises a base plate 23 welded to a cylindric metal body 24 which constitutes the base head 13 and the body 24. A cylindric metal tube 25 comprising the base cylinder 12 is threaded into an opening in the top extremity of the body 24 and is provided with a seal 26 to constitute a fluid pressure-tight joint between the tube 25 and the body 24. The tube 25 may be welded to the body 24 in an alternate design of the support prop.

The top cylinder 14 comprises a first cylindric tube 27 threaded into an opening in the lower extremity of the top head 15, and a second cylindric metal tube 28 received within the tube 27 and secured thereto by a circumferential weld 29 which also provides a fluid-tight joint between the tubes. The top head is constituted as a cylindric metal tube welded to an end plate.

All of the tubes and joints of the prop are designed as pressure chambers to accommodate interior pressures substantially in excess of the pressure at which the relief valve 21 is designed to operate.

The movable piston 16 at the lower extremity of the top cylinder 14 is constituted by a circular plate 30 received in the end of the tube 28 and attached thereto by a peripheral weld 31. An O-ring 32 is received in a groove extending circumferentially about the exterior periphery of the plate 30 to comprise a fluid sealing means closing the chamber 19 of the base cylinder 12. An 0- ring 33 is received in a groove extending circumferentially about the interior periphery of the plate 30, and to constitute a fluid sealing means between the plate 30 and the stand pipe 18, and to separate the chamber 19 from the chamber 20. A plurality of openings 34 extend longitudinally through the plate 30 to comprise fluid conduits between the chambers 19 and 20. The openings 34 are closed by a plurality of by-

pass valves

35, 36, and 37. As shown for the valve 35, the by-pass valves comprise a valve element 38 held in engagement with the plate 30 by a spring carrier 39. The valve element 38 is maintained in contact with the plate 30 to close the opening 34 by the force of the spring carrier 39 and pressure of fluid in the chamber 19, and is moved away from the plate 30 in response to pressure of fluid in the chamber 20. This arrangement permits elongation of the prop by extension of the top head and top cylinder 14 relative to the base cylinder 12.

The stand pipe 18 comprises a hollow metal tube 40 threaded in the base head 13 at one extremity and having the fixed piston 17 attached to the remaining extremity by the rivet 41. The tube 40 is formed with ports 42 comprising openings radially through the wall of the tube and providing fluid communication between the interior opening 43 of the tube and

chambers

44 and 45 in the body 24, and ports 46 comprising openings radially through the wall of the tube 40 and providing fluid communication between the interior opening 43 and the chamber 20 of the top cylinder.

The fixed piston 17 is constituted by a circular plate 47 and an O-ring 48 received in a groove extending circ'umferentially about the exterior periphery of the plate. The O-ring 48 comprises a sealing means between the plate 47 and the interior wall of the cylinder tube 27, and the piston 17 closes the top cylinder 27 at the upper extremity thereof, whatever the position of the top head 15 and the cylinder 27.

The chamber 44 is formed as transverse and longitudinal openings in the body 24 to constitute a valve opening 59 and a valve seat 51. A spherical valve element 52 and a spring 53 are received in the openings and held in place by a cap screw 54 threaded into the body 24 and arranged for adjustable compression of the spring 53 to determine the relief pressure of the valve.

The chamber 45 is formed as transverse and longitudinal openings in the body 24 to constitute a valve seat 55 and a valve opening 56. A needle valve element 57 is received in the transverse opening and threaded into the body 24 with an O-ring 58 received in a groove extending circumferentially about the exterior periphery to provide a seal between the valve element and body 24. Fluid communication from the opening 42 of the stand pipe 18 to the chamber 19 is determined in accordance with the position of the needle valve 57.

The fluid conduit which comprises the stand pipe 18, the ports 42 and 46, the chamber 44, and the valve 21 accommodates fluid flow from the chamber 19 to the chamber 20 in response to an excess of pressure in the chamber 19 because of an overload on the prop. A shunt conduit is provided by the chamber 45 and the valve 21 which accommodates a fluid flow from the chamber 19 to the chamber 20 when the valve 21 is closed and the valve 22 is opened by rotation of the handle 59. Accordingly, the prop 18 may be extended for installation and retracted for removal without accessory apparatus.

Adjustment of the relief valve 21 by means of the screw closure 54 suflices to determine load distribution among several props which are grouped under a portion of a mine roof or overburden.

The effective area of the movable piston 16 and the base cylinder 12 is the same as the effective area of the fixed piston 17 in the top cylinder 14. With this arrangement, the total volume of the two spaces 19 and 20 is constant and the pressure in the top cylinder remains substantially constant whatever the position of the top cylinder in the base cylinder 12. Accordingly, the prop may be operated without substantial entry of foreign matter into the spaces 19 and 20 or substantial loss of hydraulic fluid during extension or retraction of the prop. Small differences in cross sectional area .are useful in certain circumstances and are Within the invention and claims herein.

In the embodiment of FIG. 4, the prop 60 comprises a base 61, a base cylinder 62, a base head 63, a top cylinder 64, a top head 65, a cross head or movable piston 66 at the lower extremity of the top cylinder 64, a fixed piston 67 in the top cylinder 64, and a stand pipe 68 extending from the base head 63 through the movable piston 66 to the fixed piston 67. A pump 69 functions to transfer hydraulic fluid through the stand pipe 68 from the space 70 in the top cylinder 64 between the movable piston 66 and the fixed piston 67 to the space 71 in the base cylinder 62 between the base head 63 and the movable piston 66, for extending the top cylinder 64 and top head 65 with respect to the base cylinder 62 and base 61. A relief valve 72 functions to permit return of the fluid from the base cylinder 62, through the stand pipe 68, to the top cylinder 64 when there is a compressive load upon the prop sufficient to create a pressure on the interior of the base cylinder 62 in excess of the operating pressure of the relief valve. A by-pass valve 73 in the movable piston 66 functions to return fluid from the top cylinder 64 to the base 62 when extending the prop by elongating movement of the top cylinder 64 with respect to the base cylinder 62.

The base 61 comprises a base plate 74 and a cylindric metal body 75, comprising the base head 63, welded to the plate 74 at the top side thereof. The body 75 has a recessed upper extremity, and a cylindric metal tube 76, comprising the base cylinder 62, is received over the body and secured thereto by a circumferential weld 77.

The top cylinder 64, top head 65, movable piston 66, fixed piston 67, and stand pipe 68 are all generally similar to the

parts

24, 23, 15, 17, and 16, respectively, of the embodiment of FIG. 1. The by-pass valves 73 are constructed and function in the same way as the bypass valves 35 of FIG. 1.

The pump 69 is constituted by a pump cylinder 78 received in a transverse opening 79 in the body 75, a piston 80 received in an opening 81 in the cylinder 78, an intake valve 82, and an exhaust valve 83. The intake valve 82 is connected to the stand pipe 68 by an axial opening 84 and cross openings 85 in the piston 88, a space 86 between the piston 80 and the cylinder 78, defined by 0-

rings

87 and 88, transverse openings 89 in the cylinder 78, a space 91 between the cylinder 78 and the body 75, defined by O-

rings

91 and 92, and a longitudinal opening 93 from the opening 79 in the body 75 to the interior of the stand pipe 68. The exhaust valve 83 is connected from the piston opening 81 through the cylinder 7 8 to the space 94, from the O-ring 91 to the body 75 at the interior end of the opening 79, which is connected to the interior of the base cylinder 62 by the longitudinal opening 95, from the opening 79 to the interior of the cylinder tube 76. Accordingly, alternating transverse movement of the piston 80 draws oil from the space 70 within the top cylinder 64, through the ports 96 in the stand pipe 68, through the opening 97 of the stand pipe 68 and the opening 93 in the body 75, to the pump 69, and drives oil from the pump 69, through the space 94 and the opening into the space 71 in the base cylinder 62.

The pump 69 has a handle 98 which is supported from the body 75 by a plug 99, a connecting link 1416, and two pins 101 and 102, and from the piston 80 by a pin 103.

The overpressure relief valve 72 comprises a slide 104 received in an opening 105 which extends transversely through the body 75 and has the plug 99 threaded in the extremity thereof adjacent the handle 98. A spring 106 received in the opening 107 of the opening 105 is compressed between the extremity of the slide 104 and the plug 99, and holds a land 108 at the end of the slide 104 in fluid-tight engagement with a shoulder 109. A land 110 of the slide 104 engages a shoulder 111, which defines an opening 112 of reduced diameter with respect to the opening 113, defined by the shoulder 109. The opening 112 is closed by an O-ring 114 extending peripherally about the land 110 in a groove formed in the exterior periphery thereof.

The opening 105 extends transversely through the body 75 of the base head 63 and intersects the

longitudinal openings

93 and 95 so that fluid communication is provided between the opening 93 and the opening 95, through the

openings

107 and 113 of the opening 105 when the slide 104 is displaced toward the plug 99 by reason of an excess pressure in the space 71 of the base cylinder 62. Movement of the slide 104, due to an excess pressure in that space, results from the difference in diameters of the land 108 and the land 110 so that the differential of force, due to the pressure of fluid in the enclosed space, is directed against the force of the spring 106. A force by the piston in excess of that exerted by the spring 106 causes the slide 104 to move toward the plug 99, connecting the

openings

93 and 95 and permitting hydraulic fluid to flow from the space 71, through the stand pipe 68 to the space 70, with a consequent retraction of the top cylinder 64 and cross head 65 with respect to the base cylinder 62 and base 61.

A handle 115, for manual operation of the slide 104, is carried by two laterally spaced guard members 116 welded to the side of the body 75. The handle 115 is pivoted upon a pin 117 and has the interior extremity shaped as a cam so that rotation of the handle moves the slide 104 inward or outward to open or close the relief valve. The guard members 116 extend outwardly from the body 75 and are spaced from the cylinder tube 76 to protect the valve handle 115.

In operation the prop 60 is conveniently positioned between the floor and roof or floor members and roof members of a mine tunnel by drawing the top cylinder 64 outward from the base cylinder 62 until the top head 65 engages the associated working member. The pump 69 is then actuated by lateral movement of the handle 98 to further elongate the prop by forcing hydraulic fluid into the space 71. The prop may be left in place for long periods of time and will collapse upon occurrence of a sufiicient over-pressure, determined by the slide 104 and spring 106, so that the prop is not damaged. The prop may be removed from the working position by operation of the handle 115 to permit retraction of the top cylinder 64 into the base cylinder 62.

The hydraulic support props and 60 are useful when inverted from the positions shown in FIG. 1 and FIG. 4 of the drawing. Accordingly, it is to be understood that the specific terminology of the description and of the claims does not restrict or limit the scope of the invention. The claims are directed to combinations of elements which embody the invention or inventions of this application.

I claim:

1. A hydraulic device comprising a base, a base head, a base cylinder on the base head, a top cylinder telescoping into the base cylinder at the end thereof away from the base, a top head on the top cylinder at the end thereof away from the base, a cross head on the head cylinder at the end thereof adjacent the base, comprising a movable piston, a stand pipe extending from the base head longitudinally through the base cylinder and movable piston into the top cylinder, a cross head in the top cylinder secured to the stand pipe and comprising a fixed piston, fluid sealing means between the top cylinder and the base cylinder, between the fixed piston and the top cylinder and between the movable piston and the stand pipe, means including a conduit through the movable piston determining flow of hydraulic fluid between the base cylinder and top cylinder in one direction thereof, and means including a conduit through the stand pipe determining flow of hydraulic fluid between the base cylinder and top cylinder in the direction opposite thereto.

2. A hydraulic prop comprising a base, a base head, a base cylinder on the base head, a top cylinder telescoping into the base cylinder at the end thereof away from the base, a top head on the top cylinder at the end thereof away from the base, means fluid sealing the interior of the said two cylinders from the exterior, a movable piston at the end of the top cylinder separating the interiors of the said two cylind:-rs, a fluid conduit through the movable piston and one-way valve means closing the conduit and only permitting the flow of hydraulic fluid from the top cylinder to the base cylinder in response to an excess of fluid in the top cylinder, a fixed piston in the top cylinder and fluid sealing means on the fixed piston engaged with the top cylinder on the interior thereof, a stand pipe extending from the base head through the movable piston to the fixed piston, and fluid sealing means on the movable piston engaged with the stand pipe, a fluid conduit from the top cylinder along the interior of the stand pipe to the base head, and a relief valve in the base head closing the conduit and permitting flow of hydraulic fluid from the base cylinder to the top cylinder upon excess pressure in the base cylinder.

3. A hydraulic prop in accordance with claim 2, in which the base head is constituted by a cylindric body having the base cylinder aflixed thereto, and the lastnamed conduit comprises an opening in the said body, and the relief valve comprises a valve element in contact with the said body, a spring for holding the valve element in a closed position and determining the relief pressure thereof, and a closure for the opening.

4. A hydraulic prop in accordance with claim 3 with means for manually moving the valve element against the spring to open the relief valve and collapse the prop.

5. A hydraulic prop in accordance with claim 2 with a fluid conduit in parallel with said last-named fluid conduit and a manual valve in series with said shunt conduit for manual control of flow of fluid from the head cylinder to the base cylinder to retract the prop.

6. A hydraulic prop in accordance with claim 5, in which the base head comprises a cylindric body extending transversely across the base cylinder, and said parallel fluid conduit comprises an opening in the said plate, and the manual valve comprises a valve element in contact with the said body, and actuating means for operating the valve element from the exterior of the base head to open and close the valve.

7. A hydraulic prop in accordance with claim 2 with a fluid conduit in parallel with the last-named fluid conduit, and a hydraulic pump means in the base head in series with the said parallel fluid conduit for pumping fluid from the top cylinder to the base cylinder to extend the top cylinder with respect to the base cylinder.

8. A hydraulic prop in accordance with claim 7, in which the base head comprises a cylindric body having the base cylinder aflixed thereto, the said parallel fluid conduit comprises at least an opening in the said body longitudinally of the cylinders, and the hydraulic pump means is constituted by cylinder means and piston rneans extending transversely of the body, and openings therein.

9. A hydraulic prop in accordance with claim 2, in which the top cylinder comprises a first cylindric metal tube, a second cylindric metal tube fitted within the first tube at the extremity thereof adjacent the base, and a mechanically rigid fluid-tight joint between the tubes, and the base head cylinder comprises a third cylindric metal tube with the second tube received concentrically within the third tube and sliding therein, all with the effective cross sectional area of the movable piston and second tube in the third tube equal to the effective cross sectional area of the fixed piston in the first tube.

10. A hydraulic prop in accordance with claim 9, in

which the movable pistoncomprises a circular plate extending across the second tube at the extremity thereof adjacent the base and secured thereto in a mechanically rigid fluid-tight joint, a circumferential groove on the exterior peripherally of the plate, and an O-ring received therein in fluid sealing contact with the interior of the third tube, a central opening for receiving the stand pipe, and a circumferential groove on the interior periphery of the plate about the opening, and an O-ring received in the last-named groove in fluid sealing contact with the stand pipe.

11. A hydraulic prop comprising a base, a base head, a base cylinder on the base head, a top cylinder telescoping into the base cylinder at the end thereof away from the base, a top head on the top cylinder at the end thereof away from the base, a cross head on the head cylinder at the end thereof adjacent the base comprising a movable piston, a stand pipe extending from the base head longitudinally through the base cylinder and movable piston into the top cylinder, a cross head in the top cylinder secured to the stand pipe and comprising a fixed piston, the effective cross sectional area of the movable piston in the base cylinder being substantially equal to the effective cross sectional area of the fixed piston in the top cylinder, the stand pipe and base head having openings providing fluid communication between the base head and the space in the top cylinder between the fixed and movable pistons, fluid sealing means between the top cylinder and the base cylinder, between the fixed piston and the top cylinder and between the movable piston and the stand pipe, hydraulic pump means in the base head, conduit means connecting the stand pipe with the inlet of the pump means, and conduit means connecting the outlet of the pump means to the interior of the base cylinder in the space between the movable piston and the base head, all for operatively extending the top head and the top cylinder with respect to the base and base cylinder by actuation of the pump means While maintaining a substantially constant volume of fluid in the spaces between the fixed and movable pistons and movable piston and base head.

12. A hydraulic prop in accordance with claim 11, with a valve in the base head connecting the named two conduit means for transmitting hydraulic fluid from the base cylinder through the stand pipe to the head cylinder to collapse the prop.

13. A hydraulic prop in accordance with claim 11 or claim 12, With a bypass valve in the cross head for relieving excess pressure in the top cylinder.

References Cited by the Examiner FOREIGN PATENTS 1,249,070 11/ 1960 France.

CLAUDE A. LE ROY, Primary Examiner.

Claims

1. A HYDRAULIC DEVICE COMPRISING A BASE, A BASE HEAD, A BASE CYLINDER ON THE BASE HEAD, A TOP CYLINDER TELESCOPING INTO THE BASE CYLINDER AT THE END THEREOF AWAY FROM THE BASE, A TOP HEAD ON THE TOP CYLINDER AT THE END THEREOF AWAY FROM THE BASE, A CROSS HEAD ON THE HEAD CYLINDER AT THE END THEREOF ADJACENT THE BASE, COMPRISING A MOVABLE PISTON, A STAND PIPE EXTENDING FROM THE BASE HEAD LONGITUDINALLY THROUGH THE BASE CYLINDER AND MOVABLE PISTON INTO THE TOP CYLINDER, A CORSS HEAD IN THE TOP CYLINDER SECURED TO THE STAND PIPE AND COMRISING A FIXED PISTON, FLUID SEALING MEANS BETWEEN THE TOP CYLINDER AND THE BASE CYLINDER, BETWEEN THE FIXED PISTON AND THE TOP CYLINDER AND BETWEEN THE MOVABLE PISTON AND THE STAND PIPE, MEANS INCLUDING A CONDUIT THROUGH THE MOVABLE PISTON DETERMINING FLOW OF HYDRAULIC FLUID BETWEEN THE BASE CYLINDER AND TOP CYLINDER IN ONE DIRECTION THEREOF, AND MEANS INCLUDING A CONDUIT THROUGH THE STAND PIPE DETERMINING FLOW OF HYDRAULIC FLUID BETWEEN THE BASE CYLINDER AND TOP CYLINDER IN THE DIRECTION OPPOSITE THERETO.