US3000358A - Hydraulic props or struts - Google Patents

Hydraulic props or struts Download PDF

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Publication number
US3000358A
US3000358A US8796A US879660A US3000358A US 3000358 A US3000358 A US 3000358A US 8796 A US8796 A US 8796A US 879660 A US879660 A US 879660A US 3000358 A US3000358 A US 3000358A
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US
United States
Prior art keywords
valve
prop
pressure
hydraulic
ram
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US8796A
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English (en)
Inventor
Michael J Marlow
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Dowty Mining Equipment Ltd
Original Assignee
Dowty Mining Equipment Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB618959A external-priority patent/GB901168A/en
Application filed by Dowty Mining Equipment Ltd filed Critical Dowty Mining Equipment Ltd
Application granted granted Critical
Publication of US3000358A publication Critical patent/US3000358A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D15/00—Props; Chocks, e.g. made of flexible containers filled with backfilling material
    • E21D15/14—Telescopic props
    • E21D15/44—Hydraulic, pneumatic, or hydraulic-pneumatic props

Definitions

  • HYDRAULIC PROPS OR STRUTS lNvEN-roR la/ufl. -T- MKLov/ BY y gina,
  • This invention relates to hydraulic telescopic props comprising a cylinder member and a ram member together enclosing a liquid pressure chamber into which hydraulic liquid is transferred yfor extending the prop, and from which the liquid under the hydraulic pressure caused by excessive longitudinal compression loads applied to ⁇ the prop, can escape through a relief valve.
  • the present invention utilizes the longitudinal strain of the ram member under the opposed forces of externally applied load and hydraulic pressure to open the relief valve.
  • FIGURES l and 2 respectively of the accompanying drawings.
  • FIGURE 'l shows a hydraulic prop comprising a cylinder member having a cylinder with a floor-engaging base 1f1 fixed at its lower end and a bearing ring 12 fixed at its upper end.
  • the ram member comprises a tube 13 which slidably enters the bearing ring 12, wherein a wiper ring 14 is iitted, while its lower end carries an inner bearing ring 15 and a piston head 1'6 both slidable in the bore 17 of the cylinder 10.
  • a high pressure packing gland ⁇ assembly 18 is seated against a shoulder 19 on the lower side of the piston '16 land is located by a retaining ring 21 which is part of a cap fixed to the piston 16.
  • a head 22 ixed to the upper end of the ram tube 13 is surmounted by a roof-engaging cap 23 which is replaceably secured by a bolt 24.
  • the cavity 25 within the ram tube is open to atmosphere through a hole 26 in the 'head 22 and then through the clearance in the hole 27 4in the :head 22 and cap 23 through which the bolt 24 is iixed.
  • the pressure chamber 28 enclosed ybetween the cylinder 10, the base 11 and the piston 16 is connected by a feed tube 29 with an inlet valve 31 which is fixed in the head 22 and contains a spring-loaded non-return ball valve 32.
  • the inlet valve 31 is adapted for connection with an external source of hydraulic fluid under pressure from an appliance which may be readily attached or disengaged from the groove 33 in the inlet valve 31.
  • a cylindrical valve housing 34 is fixed centrally in the piston 16 and is provided with a central bore 35 leading to a circular valve seat 36 which is of less diameter than the lbore 35.
  • a ball valve 37 located in a cylindrical guide member 38 which is slidable -in the bore 35 is urged upwardly against the seat 36 by a spring 39 interposed between the guide member 38 and an apertured retaining plug 41.
  • the retaining plug 41 is secured in the retaining ring by a spring circlip 42.
  • a channel 44 between the piston 16 and housing 34 leads to a recess 45 in the bore 35 to provide communication between the pressure chamber 28 and the surface of the ball 37 on the pressure side of the valve seat 36.
  • a push rod 46 extending substantially throughout the length of the ram tube 13 is effectively fixed but axially adjustable in the head 22 by means of a screw driver engaged in notch 48 in the end of rod 46, and the screw thread 47, and is secured by la lock nut 49.
  • the lower end of the push rod 46 comprises ya portion 51 of reduced diameter which extends with clearance through the upper part of the valve housing 34, this clearance 52 opening into the cavity 25 through -a cross drilling 53 in the upper part of the valve housing 34.
  • FIGURE 1 does not show a valve lwhich enables the prop to be collapsed when it is withdrawn, but is intended simply to show the ⁇ operation of an excess pressure relief valve which is opened when the ram tube yields compressively Iunder liquid pressure.
  • FIGURE 2 -illustrates a hydraulic pit prop having a relief valve operable in similar manner but also including supplemental means whereby the relief valve can be opened under manual control to enable the pit prop to be withdrawn.
  • the cylinder member comprises a cylinder 60 having -a floor-engaging base 61 secured to its lower end, an upper bearing ring 62 together with a wiper ring 63 secured at its upper end, and a lower bearing ring 64 secured in au intermediate position within the cylinder 60.
  • the ram member comprises an outer tube r65 slidable within the bearings 62 and ⁇ 64, a roofengaging cap 66 iixed at its upper end, a circlip 67 let into its lower end to co-operate with the lower bearing ring 64 in providing an extension limit stop, a ring 68 is secured within the lower end of the outer tube 65, and an inner tube 69 is fixed within the ring 68 co-axial with but spaced from the outer tube 65.
  • the inner tube 69 is closed at its upper end by a head 71 to separate a liquid reservoir 72 within the outerY tube -65 from lthe interior of the inner tube ⁇ 69.
  • a pressurechamber 73 within the latter is closed lfrom below by a piston tubeY 74 which is slidable in the inner tube 69 and secured at its lower end to the licor-engaging base 61.
  • a housing 76 for valve-operating mechanism is mounted transversely in the upper part of the outer tube 65. At one end of the housing 76 a non-return inlet valve 77 is provided. This inlet valve 77 is urged against a seat 78 by a spring 79 but is movable olf Vits seat by the application of air pressure from an external source to a nozzle 81, this air pressure passing into the reservoir The push 72 through an opening 82 in the housing.
  • 2i's partially lled with hydraulic liquid and a liquid supplyV pipe 86 opening from the lower part of the reservoir 72 is xed in the head 71 to supply hydraulic liquid under air pressure applied at the nozzle 81 toa central bore- 87 behind a valve. seat 88.
  • a ball valve 89 lightly loadedv against the valve.v seat 88 by a spring 91 opens under pressure in the reservoir 72 to. admit hydraulic liquidl to the pressure chamber 73.
  • This ballvalve 89- is alsov arranged to operate both as an excess pressure relief Avalveand as a pressure release valve by the mechanism now to be described.
  • This mechanism comprises a push rod 92 mounted in the bore 87' and extending upwardly to a head portion 93 which entersy the housing 76, While a compression spring 94 seated against the head Y71V of the inner tube 69 acts upwardly on the headv 93 of the ⁇ pin 92.
  • the head 93 supports a steel ball 95 which is guided within a vertical bore 96 in the housing 76 and which projects partly into a horizontal bore 97 formed in the housing 76. Two similar steel balls.
  • the plunger 104 is slidable in a counterbore 105 which is co-axial with and of larger diameter than the bore 97, while a spring 106 seated against the step between the bores 97 and 105 urges the plunger 104 outwardly.
  • a slottedy lug 107 projects outwardly from the housing 76 and supports a pin 108 on which a release cam l109 is pivoted.
  • the release cam also carries a pivot 110 on which a release shackle 111 is mounted.
  • the compressive strain of the ram tube 13 can be calculated from its length, net'cross-sectional area, elastic modulus and applied load.
  • a hydraulic prop for the support of an externally applied load from a resisting base through pressurization of contained liquid said propl comprising4 at least two telescopic cylinder and ram members mounted slidably- ⁇ one in the other and together enclosing a liquid' pressure chamber, one part of the ram member having a passageway connecting the inside and the outside of the pressure chamber, a valve disposed in saidV passageway, and'v a valve-operating'element eiectively fixed in another part of the ram member separated from the one part in which the valve is disposed by a portion of the ram: member whichA is subject to longitudinal strain under the opposed forces of the externally applied loady on the ram member and the resulting liquid pressure in the pressure chamber, the valve-operating element being disposed in co-operative association with the valve to open same as an excess pressure relief valve when the longitudinal strain in the ram member exceeds a predetermined value.
  • valve comprises a valve seat fixed in the said one part of the ram tube, and a movable Valve element engageable with that side of the valve seat which is subject tol liquid pressure in the pressure chamber, and wherein the valveoperating element comprises a push rod which, under said longitudinal strain in said portion of the ram member, is. movable relatively to the valve seat in a direction to displace the movable valve element off said seat.
  • a hydraulic prop according ⁇ to claim 1, wherein the portion of the ram tube which is subject to longitudinal strainV comprises concentric tubes joined together at adjacent ends, the other ends. of the concentric tubes being joined respectively to the one andl other said parts of the ram tube, and the inner tube at least being subjectto liquidl pressure in the pressure chamber whereby it is strained longitudinally in tension while the outer tube to which it is joined is strained longitudinally in compress1on.
  • a hydraulic prop for the support of an externally applied load from a resisting base through pressurization of contained liquid, said prop comprising telescopic cylinder and ram members for engagement the onek with the load and the other with the resisting base, and mounted slidably one in the other and together enclosing a liquid pressure chamber, a valve disposed in one part of the ram member, a passageway closable by said valve and extending between the inside and the outside of the pressure chamber, a valve-operating element disposed in another part of the ram member'separated from the one part by a portion of the ram member which is'subject to longitudinal strain under the opposed forces of the externally applied load on theram member and the resulting liquid pressure in the pressure chamber, adjustable stop means fixed in said other part of the ram member, the valve-operating element being disposed in co-operative association with the adjustable stop means and with the valve to open same when the longitudinal strain in the ram member exceeds a predetermined value for which the adjustable stop means is set.
  • a hydraulic prop according to claim 4 including manually operable valve release mechanism mounted in the ram member in operative connection with the valveoperating element to displace same from the adjustable stop means in the valve-opening direction.
  • a hydraulic prop for the support of an externally applied load from :a resisting base through pressuriza-V tion of contained liquid, said prop comprising a cylinder member having a 4base and a piston abutting at one end against the base, a ram member slidably mounted in the cylinder member, said ram member including an outer tube having a cap at the end thereof remote from the base, an inner tube secured to the oppositey end of the, outer tube and extending inv spaced relation within the.
  • outer tube a head xed to the other end of the inner tube, said head, inner tube ⁇ and the piston slidably mounted therein together enclosing a pressure chamber, a passageway in the head including a valve seat therein, a Vale element closable on the valve seat under liquid pressure in the pressure chamber, and a push rod mounted in fixed location Within the outer tube adjacent the end thereof having a cap, the push rod extending into co-operative association with the valve element to lift same ott the valve seat under the combined movement of compressive strain in the outer tube and tensile strain in the inner tube caused by an excessive externally applied load on the cap and the resulting liquid pressure in the pressure chamber acting against the head of the inner tube.
  • a hydraulic prop comprising at least a cylinder and a cooperating tubular ram member closed at their pposite ends and telescopingly slidable one Within the other, one being arranged to react from a floor as a resisting base and the other to react from a roof which constitutes an applied external load to be supported from the floor, and together enclosing a liquid pressure charnber, the liquid wherein is pressurized to resist such loading, land at least one of said members being subject to strain under the influence of the opposed forces of the applied external load and the resisting internal hydraulic pressure, a passageway formed in the latter member connecting the inside and the outside of the pressure chamber, a valve normally seated in and closing said passageWay, and a valve-operating member supported in the same member, but at a location distant from the valve and where it is not itself subject to such strain, and extending into the vicinity of said valve to contact the latter when the strain exceeds a predetermined value, and thereby to unseat the valve.

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  • Engineering & Computer Science (AREA)
  • Mining & Mineral Resources (AREA)
  • Mechanical Engineering (AREA)
  • Structural Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Geology (AREA)
  • Safety Valves (AREA)
US8796A 1959-02-23 1960-02-15 Hydraulic props or struts Expired - Lifetime US3000358A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB618959A GB901168A (en) 1959-02-23 1959-02-23 Improvements in hydraulic props or struts
GB1755159 1959-05-22

Publications (1)

Publication Number Publication Date
US3000358A true US3000358A (en) 1961-09-19

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ID=26240510

Family Applications (1)

Application Number Title Priority Date Filing Date
US8796A Expired - Lifetime US3000358A (en) 1959-02-23 1960-02-15 Hydraulic props or struts

Country Status (4)

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US (1) US3000358A (sl)
DE (1) DE1145122B (sl)
FR (1) FR1249070A (sl)
NL (1) NL248713A (sl)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3202233A (en) * 1962-05-07 1965-08-24 Lansing Bagnall Ltd Pallet or stillage trucks
US3357313A (en) * 1964-02-11 1967-12-12 Dowty Mining Equipment Ltd Roof support assemblies suitable for use in mines

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3281107A (en) * 1965-12-15 1966-10-25 Ohio Brass Co Hydraulic support prop

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1699917A (en) * 1924-11-08 1929-01-22 Jeremiah E Madden Hydraulic apparatus
US1899534A (en) * 1930-05-05 1933-02-28 Curtis Mfg Co Automobile lift
US2402265A (en) * 1945-02-15 1946-06-18 Globe Hoist Co Vehicle lift
US2621631A (en) * 1948-01-12 1952-12-16 Dowty Equipment Ltd Telescopic hydraulic mine roof support
US2638075A (en) * 1948-03-06 1953-05-12 Mavor & Coulson Ltd Pneumatically controlled hydraulic prop

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE928945C (de) * 1951-06-09 1955-06-16 Eisenwerk Wanheim G M B H Verstellbarer hydraulischer Grubenstempel
DE1044003B (de) * 1952-06-16 1958-11-20 Mining Engineering Co Ltd Hydraulische Hangendtragvorrichtung bzw. Grubenstempel
DE1020945B (de) * 1955-03-14 1957-12-19 Ewald Wiemann Maschf Setz- und Raubventil fuer hydraulische Grubenstempel
NL230401A (sl) * 1957-08-13

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1699917A (en) * 1924-11-08 1929-01-22 Jeremiah E Madden Hydraulic apparatus
US1899534A (en) * 1930-05-05 1933-02-28 Curtis Mfg Co Automobile lift
US2402265A (en) * 1945-02-15 1946-06-18 Globe Hoist Co Vehicle lift
US2621631A (en) * 1948-01-12 1952-12-16 Dowty Equipment Ltd Telescopic hydraulic mine roof support
US2638075A (en) * 1948-03-06 1953-05-12 Mavor & Coulson Ltd Pneumatically controlled hydraulic prop

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3202233A (en) * 1962-05-07 1965-08-24 Lansing Bagnall Ltd Pallet or stillage trucks
US3357313A (en) * 1964-02-11 1967-12-12 Dowty Mining Equipment Ltd Roof support assemblies suitable for use in mines

Also Published As

Publication number Publication date
FR1249070A (fr) 1960-12-23
NL248713A (sl)
DE1145122B (de) 1963-03-14

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