CA1158226A - Longwall jacks - Google Patents
Longwall jacksInfo
- Publication number
- CA1158226A CA1158226A CA000368617A CA368617A CA1158226A CA 1158226 A CA1158226 A CA 1158226A CA 000368617 A CA000368617 A CA 000368617A CA 368617 A CA368617 A CA 368617A CA 1158226 A CA1158226 A CA 1158226A
- Authority
- CA
- Canada
- Prior art keywords
- cylinder
- piston
- head
- jack
- longwall
- 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
Links
- 239000012530 fluid Substances 0.000 claims abstract description 11
- 239000007787 solid Substances 0.000 claims description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 11
- 239000000839 emulsion Substances 0.000 description 3
- 239000003245 coal Substances 0.000 description 1
- 239000010720 hydraulic oil Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
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
Landscapes
- 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)
- Actuator (AREA)
- Pit Excavations, Shoring, Fill Or Stabilisation Of Slopes (AREA)
Abstract
Abstract A longwall jack is provided having a telescoping cylinder and piston which can be expanded and pressurized with water or other fluids through a one-way valve in the head of the cylinder and which is provided with a pre-set pressure release means which will release fluid each time the pressure on the cylinder and piston exceeds the pre-set level and with a second release means combined with a retrieval means by which the pressure can be released and the jack retrieved by remote means.
Description
~1~82~
This invention relates to longwall jacks and particularly to hydraulically operated longwall jacks which release and yield at a preselected pressure while continuously maintaining the preselected yield pressure as they yield.
The use o~ longwall jacks has been proposed in the coal mining industry in the past as a replacement for cribbing and the like. There have been a variety of problems with the prior art longwall jacks. Many of them were expensive and complicated in structure. Generally, they were heavy and required a hydraulic oil pump for their installation. Moreover, ~;
thev had poor yield characteristics, would bend or deform rather than yield and were difficult to recover and reuse.
We have developed a yieldable longwall jack which is light in weight, very simple in structure, operates on water or other fluid pressure, yields at a preselected pressure while continuously maintaining said pressurè and which can be readily recovered and reused.
The invention provides a longwall jack comprising an elongate piston having a floor engaging base at one end, a cylinder slidingl~ surrounding substantially the length of said piston on the other end, a solid roof engaging head integrally bonded on said cylinder opposite said base, said head including a radially extending flange at the end remote from the piston, said flange extending substantially beyond the periphery of the cylinder, one-way inlet means in said head communicating with the interior of the cylinder above the piston, first outlet means in said head communicating with the interior of said cylinder above the piston, pre-set pressure release means in said outlet means releasing fluid from the cylinder each time the pressure therein exceeds a selected pre-set pressure, a second outlet means in said head spaced from said inlet means and said first outlet means communicating with the interior of ~S~2~6 the cylinder above the piston, pressure release valve means in said second outlet means and operator means pivoted on said head engaging said pressure release valve means whereby a pull on said operator means opens said pressure release valve means in said second outlet means to release fluid from the cylinder and permit it to slide over the piston, said flange on said head extending substantially over said operator means.
The pressure release valve means is preferably a spring loaded ball and a rod moves in a passage in said head against the ball at one end and at the other end against a cam actuator on a handle. Preferably, the one-way inlet means is an Alemite type one-way valve. The base on said one end of the piston is preferably slightly hemi-spherical. Preferably the cylinder is pressurized with water or a water emulsion.
In the foregoing general statement of our invention~
we have set out certain preferred embodiments and practices of our invention. Other objects, purposes and advantages of this invention will be apparent from a consideration of the follow-ing ~escription and the accompanying drawings in which:
Figure 1 is a vertical section through a longwall jack according to our invention;
Figure 2 is a top plan view of the head of the jack of Figure l;
Figure 3 is a section on the line III-III of Figure 2;
Figure 4 is a section on the line IV-IV of Figure 2;
and Figure 5 is a fragmentary side elevational view of the jack of Figure 1.
Referring to the drawings, we have illustrated an ~J
1 1 5B~26 elongate piston 10 having a base 11 at one end. An outer cylinder 12 surrounds piston 10 above base 11 and carries a head 13 with cap 13a at the end opposite base 11. Base 11 is preferably provided with a convex bottom, as shown. The end 14 of cylinder 12 opposite head 13 carries a wiper ring 15 and a wiper ring 16, which slides on piston 10. An annular stop ring 17 is provided on the piston spaced from base 11 to limit the relative movement of piston 10 and cylinder 12. The end lOa of piston 10 opposite base 11 carries annular seal 18, back up ring 19 and packing 20 which bear on the wall of cylinder 12 and seal the piston in the cylinder. The cylinder head 13 is provided with an inlet passage 21 which communicates from the side of head 13 to the interior of cylinder 12 above the piston 10. An Alemite (trademark) type inlet check valve fitting 22 is provided in the inlet passage to permit introduction of hydraulic fluid from the outside inl:o cylinder 12 above piston 10. A first outlet passage 23 is provided in head 13, spaced from and generally paralleling inlet passage 21, and communicating from the interior of cylinder 12 above piston 10 to the outside. A pressure relief valve 24 is provided in this first outlet passage and is pre-set to the pressure at which it i5 desired to cause the jack to yield, e.g., 22.5 tons. A
second outlet passage 25 is provided in head 13 communicating from the interior of cylinder 12 above piston 10 to the exterior of the head through a check valve 26 in transverse passage 26a and deflector 27. A manually operated valve 28 is provided in passage 25 in the form of a spring loaded ball 29 in a seat 30 at the connection of passage 25 to passage 26a.
An elongate handle 31 is pivoted at one end 31a in trunnions 32 on head 13 and normally lies parallel to cylinder 12. The ~,~.
~ ~58~2~
other end 31b o~ the handle has a cross rod 31c to be pulled by hand or to receive a retrieving rope or cable Inot shown). The one end 31a of handle 31 has a cam surface 34 which bears against a pin 35 in passage 3~ aligned with ball 29. When handle 31 is pulled outwardly on its pivot to a position transverse to cylinder 12, cam surface 34 forces pin 35 to press ball 29 in against spriny 29a and thus releases fluid from the interior of cylinder 12. The head 13 is provided with a radially extending flange 13b which extends radially beyond the periphery of the cylinder and substantially over handle 31 and pin 35.
In operation the jack of this invention is placed in position and extended and pressurized by introducing water under pressure through Alemite (trademark) inlet check valve fitting 22 so as to fill the area of the cylinder 12 between head 13 and piston 10 with water and to cause relative movement between cylinder 12 and piston 10, bringing cap 13a on head 13 ~ ~ -in contact with the mine roof to be supported. Water or water emulsion is added until the jack is pressurized to the desired level. In the event that the pressure of the roof on the jack exceeds the pre-selected relief pressure, e.g. 22.5 tons, the jack will automatically release water or wa~er emulsion-through first outlet passage 23 and pressure relief valve 24 to maintain a continual resistance at the pre-selected relief pressure and will not bend or deform or be destroyed as was the ~;
case with many jacks of the past.
In the event that it is desired to remove the jack and retrieve it, cross rod 31c is pulled or a rope or cable is attached around cross rod 31c in handle 31 and a workman by pulling on the cable from a safe position raises handle 31 to a ,,~
t ~5~26 position transverse to cylinder 12, causing cam surface 34 to force pin 35 against ball 29 pushing it away from its seat and releasing water or water emulsion from the interior of cylinder 12 through passages 25 and 26a, check valve 26 and deflector 27. This causes cylinder 12 to collapse over piston 10 and move away from the supported roof. Continued pulling on the rope or cable will cause the jack to fall over on its side and be pulled to the workman. ~ /:
In the foregoing specification we have set out certain preferred practices and embodiments of our invention, however, it will be understood that this invention may be otherwise variously embodied within the scope of the following claims.
~ 5 ,
This invention relates to longwall jacks and particularly to hydraulically operated longwall jacks which release and yield at a preselected pressure while continuously maintaining the preselected yield pressure as they yield.
The use o~ longwall jacks has been proposed in the coal mining industry in the past as a replacement for cribbing and the like. There have been a variety of problems with the prior art longwall jacks. Many of them were expensive and complicated in structure. Generally, they were heavy and required a hydraulic oil pump for their installation. Moreover, ~;
thev had poor yield characteristics, would bend or deform rather than yield and were difficult to recover and reuse.
We have developed a yieldable longwall jack which is light in weight, very simple in structure, operates on water or other fluid pressure, yields at a preselected pressure while continuously maintaining said pressurè and which can be readily recovered and reused.
The invention provides a longwall jack comprising an elongate piston having a floor engaging base at one end, a cylinder slidingl~ surrounding substantially the length of said piston on the other end, a solid roof engaging head integrally bonded on said cylinder opposite said base, said head including a radially extending flange at the end remote from the piston, said flange extending substantially beyond the periphery of the cylinder, one-way inlet means in said head communicating with the interior of the cylinder above the piston, first outlet means in said head communicating with the interior of said cylinder above the piston, pre-set pressure release means in said outlet means releasing fluid from the cylinder each time the pressure therein exceeds a selected pre-set pressure, a second outlet means in said head spaced from said inlet means and said first outlet means communicating with the interior of ~S~2~6 the cylinder above the piston, pressure release valve means in said second outlet means and operator means pivoted on said head engaging said pressure release valve means whereby a pull on said operator means opens said pressure release valve means in said second outlet means to release fluid from the cylinder and permit it to slide over the piston, said flange on said head extending substantially over said operator means.
The pressure release valve means is preferably a spring loaded ball and a rod moves in a passage in said head against the ball at one end and at the other end against a cam actuator on a handle. Preferably, the one-way inlet means is an Alemite type one-way valve. The base on said one end of the piston is preferably slightly hemi-spherical. Preferably the cylinder is pressurized with water or a water emulsion.
In the foregoing general statement of our invention~
we have set out certain preferred embodiments and practices of our invention. Other objects, purposes and advantages of this invention will be apparent from a consideration of the follow-ing ~escription and the accompanying drawings in which:
Figure 1 is a vertical section through a longwall jack according to our invention;
Figure 2 is a top plan view of the head of the jack of Figure l;
Figure 3 is a section on the line III-III of Figure 2;
Figure 4 is a section on the line IV-IV of Figure 2;
and Figure 5 is a fragmentary side elevational view of the jack of Figure 1.
Referring to the drawings, we have illustrated an ~J
1 1 5B~26 elongate piston 10 having a base 11 at one end. An outer cylinder 12 surrounds piston 10 above base 11 and carries a head 13 with cap 13a at the end opposite base 11. Base 11 is preferably provided with a convex bottom, as shown. The end 14 of cylinder 12 opposite head 13 carries a wiper ring 15 and a wiper ring 16, which slides on piston 10. An annular stop ring 17 is provided on the piston spaced from base 11 to limit the relative movement of piston 10 and cylinder 12. The end lOa of piston 10 opposite base 11 carries annular seal 18, back up ring 19 and packing 20 which bear on the wall of cylinder 12 and seal the piston in the cylinder. The cylinder head 13 is provided with an inlet passage 21 which communicates from the side of head 13 to the interior of cylinder 12 above the piston 10. An Alemite (trademark) type inlet check valve fitting 22 is provided in the inlet passage to permit introduction of hydraulic fluid from the outside inl:o cylinder 12 above piston 10. A first outlet passage 23 is provided in head 13, spaced from and generally paralleling inlet passage 21, and communicating from the interior of cylinder 12 above piston 10 to the outside. A pressure relief valve 24 is provided in this first outlet passage and is pre-set to the pressure at which it i5 desired to cause the jack to yield, e.g., 22.5 tons. A
second outlet passage 25 is provided in head 13 communicating from the interior of cylinder 12 above piston 10 to the exterior of the head through a check valve 26 in transverse passage 26a and deflector 27. A manually operated valve 28 is provided in passage 25 in the form of a spring loaded ball 29 in a seat 30 at the connection of passage 25 to passage 26a.
An elongate handle 31 is pivoted at one end 31a in trunnions 32 on head 13 and normally lies parallel to cylinder 12. The ~,~.
~ ~58~2~
other end 31b o~ the handle has a cross rod 31c to be pulled by hand or to receive a retrieving rope or cable Inot shown). The one end 31a of handle 31 has a cam surface 34 which bears against a pin 35 in passage 3~ aligned with ball 29. When handle 31 is pulled outwardly on its pivot to a position transverse to cylinder 12, cam surface 34 forces pin 35 to press ball 29 in against spriny 29a and thus releases fluid from the interior of cylinder 12. The head 13 is provided with a radially extending flange 13b which extends radially beyond the periphery of the cylinder and substantially over handle 31 and pin 35.
In operation the jack of this invention is placed in position and extended and pressurized by introducing water under pressure through Alemite (trademark) inlet check valve fitting 22 so as to fill the area of the cylinder 12 between head 13 and piston 10 with water and to cause relative movement between cylinder 12 and piston 10, bringing cap 13a on head 13 ~ ~ -in contact with the mine roof to be supported. Water or water emulsion is added until the jack is pressurized to the desired level. In the event that the pressure of the roof on the jack exceeds the pre-selected relief pressure, e.g. 22.5 tons, the jack will automatically release water or wa~er emulsion-through first outlet passage 23 and pressure relief valve 24 to maintain a continual resistance at the pre-selected relief pressure and will not bend or deform or be destroyed as was the ~;
case with many jacks of the past.
In the event that it is desired to remove the jack and retrieve it, cross rod 31c is pulled or a rope or cable is attached around cross rod 31c in handle 31 and a workman by pulling on the cable from a safe position raises handle 31 to a ,,~
t ~5~26 position transverse to cylinder 12, causing cam surface 34 to force pin 35 against ball 29 pushing it away from its seat and releasing water or water emulsion from the interior of cylinder 12 through passages 25 and 26a, check valve 26 and deflector 27. This causes cylinder 12 to collapse over piston 10 and move away from the supported roof. Continued pulling on the rope or cable will cause the jack to fall over on its side and be pulled to the workman. ~ /:
In the foregoing specification we have set out certain preferred practices and embodiments of our invention, however, it will be understood that this invention may be otherwise variously embodied within the scope of the following claims.
~ 5 ,
Claims (8)
1. A longwall jack comprising an elongate piston having a floor engaging base at one end, a cylinder slidingly surrounding substantially the length of said piston on the other end, a solid roof engaging head integrally bonded on said cylinder opposite said base, said head including a radially extending flange at the end remote from the piston, said flange extending substantially beyond the periphery of the cylinder, one-way inlet means in said head communicating with the interior of the cylinder above the piston, first outlet means in said head communicating with the interior of said cylinder above the piston, pre-set pressure release means in said outlet means releasing fluid from the cylinder each time the pressure therein exceeds a selected pre-set pressure, a second outlet means in said head spaced from said inlet means and said first outlet means communicating with the interior of the cylinder above the piston, pressure release valve means in said second outlet means and operator means pivoted on said head engaging said pressure release valve means whereby a pull on said operator means opens said pressure release valve means in said second outlet means to release fluid from the cylinder and permit it to slide over the piston, said flange on said head extending substantially over said operator means.
2. A longwall jack as claimed in claim 1 wherein the operator means is an elongate handle pivoted at one end to said head and normally parallel to the axis of said cylinder, the other end of said handle having means receiving a pull rope or cable, cam means on said one end and cam follower means in said head engaging said pressure release valve means, a cam surface on said cam means acting on the cam follower means to open said pressure release valve means when said handle is pivoted from its normal position to a position transverse to the cylinder axis.
3. A longwall jack as claimed in claim 1 wherein the piston base has a convex bottom surface.
4. A longwall jack as claimed in claim 1 or 2 wherein the one-way inlet means is an inlet passage having an Alemite (trade mark) fitting on the external end.
5. A longwall jack as claimed in claim 3 wherein the one-way inlet means is an inlet passage having an Alemite fitting at the external end.
6. A longwall jack as claimed in claim 1 wherein the pre-set pressure release means is a spring loaded relief valve.
7. A longwall jack as claimed in claim 6 wherein the relief valve is set to release at about 22.5 tons.
8. A longwall jack as claimed in claim 1 or 2 wherein the head has a fluid diverter means on said second outlet means diverting fluid discharged therefrom generally parallel to the axis of the cylinder and toward the base of the piston.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US11410880A | 1980-01-21 | 1980-01-21 | |
| US114,108 | 1980-01-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1158226A true CA1158226A (en) | 1983-12-06 |
Family
ID=22353397
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000368617A Expired CA1158226A (en) | 1980-01-21 | 1981-01-15 | Longwall jacks |
Country Status (5)
| Country | Link |
|---|---|
| CA (1) | CA1158226A (en) |
| DE (1) | DE3101849A1 (en) |
| FR (1) | FR2474112B1 (en) |
| GB (1) | GB2069048B (en) |
| MX (1) | MX152214A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104963706A (en) * | 2015-07-10 | 2015-10-07 | 常州市龙润机械有限公司 | Coal mine underground shoring device and shoring method |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB720361A (en) * | 1952-11-22 | 1954-12-15 | Gullick Ltd | Improvements in or relating to hydraulic pit props, hydraulic jacks and the like |
| NL191038A (en) * | 1953-09-24 | 1900-01-01 | ||
| FR1280684A (en) * | 1960-11-22 | 1962-01-08 | Sagem | hydraulic prop |
| FR1321725A (en) * | 1961-04-20 | 1963-03-22 | Bochumer Eisen Heintzmann | Improvements to hydraulic props for mines |
| GB970917A (en) * | 1962-11-20 | 1964-09-23 | Hans Joe Rheinbay | Hydraulic pit prop |
| GB1342741A (en) * | 1970-01-24 | 1974-01-03 | ||
| DE2022514C3 (en) * | 1970-05-08 | 1974-02-07 | Josef Haamann Hebe- Und Transporttechnik, 6982 Freudenberg | Hydraulically operated jack |
-
1981
- 1981-01-13 GB GB8100960A patent/GB2069048B/en not_active Expired
- 1981-01-15 CA CA000368617A patent/CA1158226A/en not_active Expired
- 1981-01-20 MX MX18562481A patent/MX152214A/en unknown
- 1981-01-20 FR FR8100971A patent/FR2474112B1/en not_active Expired
- 1981-01-21 DE DE19813101849 patent/DE3101849A1/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| FR2474112B1 (en) | 1985-10-25 |
| MX152214A (en) | 1985-06-10 |
| GB2069048B (en) | 1984-06-06 |
| GB2069048A (en) | 1981-08-19 |
| FR2474112A1 (en) | 1981-07-24 |
| DE3101849A1 (en) | 1982-01-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |