Title of Invention	AN IMPROVED PIT PROP FOR SUPPORTING MINE/TUNNEL ROOFS
Abstract	An improved Pit Prop for supporting mine/tunnel roofs which comprises an upper pipe (1) telescopically fitted into a lower pipe (2), the top portion of the upper pipe (1) being provided with internal threads for fitting an externally threaded bar (3), the top of the bar (3) having a bearing plate (5), the bottom end of the upper pipe (1) being provided with a block (4) having means for swiveling such that the block (4) remains stationary when the pipe (1) is rotated, the upper pipe (1) being also provided with a plurality of holes (7) for rotating the pipe (1) by means of a rod, the lower pipe (2) having a matching bush (6), the inner space of the lower pipe (2) partitioned into two chambers by means of a circular separating disc (8) having a concentric hole, the upper chamber filled with sand and the lower chamber provided with a key-pipe (10) matching the concentric hole in the disc (8), the bottom of the key-pipe (10) fixed to a horizontal rod (12) passing through a vertical slot (13) made on the side of the lower chamber of pipe (2), the lower pipe (2) provided with a bottom plate (15) having a concentric hole, the said upper pipe (1) and lower pipe (2) also provided with external handles (14) for carrying in dismantled condition.

Title of Invention

AN IMPROVED PIT PROP FOR SUPPORTING MINE/TUNNEL ROOFS

Abstract

An improved Pit Prop for supporting mine/tunnel roofs which comprises an upper pipe (1) telescopically fitted into a lower pipe (2), the top portion of the upper pipe (1) being provided with internal threads for fitting an externally threaded bar (3), the top of the bar (3) having a bearing plate (5), the bottom end of the upper pipe (1) being provided with a block (4) having means for swiveling such that the block (4) remains stationary when the pipe (1) is rotated, the upper pipe (1) being also provided with a plurality of holes (7) for rotating the pipe (1) by means of a rod, the lower pipe (2) having a matching bush (6), the inner space of the lower pipe (2) partitioned into two chambers by means of a circular separating disc (8) having a concentric hole, the upper chamber filled with sand and the lower chamber provided with a key-pipe (10) matching the concentric hole in the disc (8), the bottom of the key-pipe (10) fixed to a horizontal rod (12) passing through a vertical slot (13) made on the side of the lower chamber of pipe (2), the lower pipe (2) provided with a bottom plate (15) having a concentric hole, the said upper pipe (1) and lower pipe (2) also provided with external handles (14) for carrying in dismantled condition.

Full Text	This invention relates to an improved pit prop for supporting mine/tunnel roofs. More particularly it relates to a sand filled yielding prop. The device of present invention i.e Sand Filled Pit Prop is specially useful in depillaring operation as well as in development workings to support exposed mine roof against dislodging of roof rocks. This device is an alternative to other known conventional woodenorsteelprops. There are many types of pit props viz. wooden props, steel props etc. being used in coal mines. But Sand Filled pit prop based on a new concept (using sand for yielding, height adjustment and recovery) is a novel pit prop. No where in Indian coal mines it is inuse nor it is used in mines abroad In underground coal mining operation, the developing galleries (tunnels) and space caused by depillaring operation (taking out coal) are generally supported with wooden pit props or steel pit props. Wooden pit props are becoming scare day by day becauseof depletion in our forest reserves. Moreover, when in use, it requires frequent replacement because of its decaying properties. Steel pit props being used in mines are of two types- rigid type and yielding type. Rigid type props are simpleanddo notprovide yield or setting load Moreover, it can be withdrawn under excessive loading condition. In friction and hydraulic pit props generally in use abroad, there are arrangements for yield, setting load and withdrawal facilities. But these are very costly and many mines can not afford to have such props. Friction prop provides yield because of mechanical sliding, where as hydraulic prop provides yield because of hydraulic compression. But sand filled pit prop provides yield because of compression in sand. The main objective of the present invention is to provide an improved pit prop useful for supporting mine/tunnel roots. Another objective of the present invention is to provide a simple steel pit prop which is economically viable and does not incorporate the drawbacks of all other known pit props. In fig-1 of the drawing accompanying this specification the schematic diagram of the sand filled pit prop of the present invention is depicted. Accordingly, the present invention provides an improved pit prop for supporting mine / tunnel roots which comprises an upper pipe (1) telescopically fitted into a lower pipe (2), the top portion of the upper pipe (1) being provided with internal threads for fitting an externally threaded bar (3), the top of the bar (3) having a bearing plate (5), the bottom end of the upper pipe (1) being provided with a block (4) having means for swiveling such that the block (4) remains stationary when the pipe (1) is rotated, the upper pipe (1) being also provided with a plurality of holes (7) for rotating the pipe (1) by means of a rod, the lower pipe (2) having a matching bush (6), the inner space of the lower pipe (2) partitioned into two chambers by means of a circular separating disc (8) having a concentric hole, the upper chamber filled with sand and the lower chamber provided with a key-pipe (10) matching the concentric hole in the disc (8), the bottom of the key-pipe (10) fixed to a horizontal rod (12) passing through a vertical slot (13) made on the side of the lower chamber of pipe (2), the lower pipe (2) provided with a bottom plate (15) having a concentric hole, the said upper pipe (1) and lower pipe (2) also provided with external handles (14) for carrying in dismantled condition. The sand Filled Pit Prop of the present invention is described below with reference to fig of the drawing accompanying this specification. The Pit Prop of the present invention consists of two pipes (1) and (2) telescopically fitted with each other. The upper pipe (1) is of smaller dia. Compared to bottom pipe (2). The top portion of the upper pipe (1) is fitted with a square threaded steel bar (3). The bottom portion of this threaded bar (3) remains inside the pipe (1) while the top protruded portion is engaged with a small pipe with a bearing plate (5). The bottom end of the pipe is attached with a bearing block (4) with swiveling arrangement. This block (4) remains stationary. On the outer surface of the pipe (1) few small holes (7) are provided to rotate the pipe (1) by means of an external iron rod at the time of fixing it for use. The bottom bigger dia. Pipe (2) is fitted with a bush (6) matching with the dia. Of the upper pipe (1). The inner space of this pipe (2) is separated into two parts by welding a circular separating disc (8). Thus the inner space of the bigger bottom pipe (2) has two chambers. The top chamber contains sand (9) while the smaller bottom chamber houses a small key-pipe (10). In working condition this key-pipe (10) remains inside the sand (9) kept in the top bigger chamber. But in release condition, the key-pipe (10) remains in the smaller chamber. At the bottom portion of the key-pipe (10) a iron rod (12) is welded for moving the key-pipe (10) up and down through a slot (13) made on the pipe (2) i.e. in the bottom chamber of the pipe (2). This is made like this for release purpose. The bottom portion of the pipe (2) is fitted with a circular disc with a central hole for taking out the key-pipe (10) when there is need be. Both the pipe (1) and (2) are provided with handles (14) for the purpose of easy handling. The operation of the Sand Filled Pit Prop of the present invention is as follows : The key-pipe (10) is pushed inside the bigger chamber of the pipe (2) and locked in the slot (13). Sand (9) is filled in the pipe (2) as per height requirement. Then the small pipe (1) is pushed inside the bigger pipe. The steel circular block (4) now rests on the sand. This whole assembled unit becomes a pit prop which is erected straight and fixed between roof and floor of a mine gallery (tunnel). Now a small iron rod is pushed inside the hole (7) of the upper pipe (1) and rotated. In so doing the square threaded iron bar (3) gets extended and tightly fix the prop between roof and floor of a mine gallery to support the loose roof rock against dislodging. In this position it can takes 20 to 30 tone rock load of mine roof. If it is required to release for reuse, the key-pipe (10) is disengaged by means of a handle (12) and is brought down in the bottom chamber of the pipe (2). This creates a void in the sand which ultimately gets collapsed resulting in lowering of the pipe (1) in the bigger dia. pipe. Now the prop is released and ready for reuse. Under high roof loading condition it gives yield which is not possible in the available steel pit except in the costly friction and hydraulic props. The pit prop of the present invention was tested in the laboratory under universal testing machine. The main findings are as follows : a] Setting load - 2 t to 5 t b] Load bearing capacity - 20 t to 30 t c] Yield - 4 cm d] Quickly ly released under excessive loading condition e] Reuse many times. The Main Advantages of the invention are : 1] It is very cheap and effective compared to other steel props like friction props and hydraulic props. 2] It provides initial setting load, withstands high load with yielding arrangement and can be withdrawn even under high loading condition. 3] It is made of two separate steel pipe, handling of such prop is easier in transportation. We Claim: 1. An improved Pit Prop for supporting mine/tunnel roofs which comprises an upper pipe (1) telescopically fitted into a lower pipe (2), the top portion of the upper pipe (1) being provided with internal threads for fitting an externally threaded bar (3), the top of the bar (3) having a bearing plate (5), the bottom end of the upper pipe (1) being provided with a block (4) having means for swiveling such that the block (4) remains stationary when the pipe (1) is rotated, the upper pipe (1) being also provided with a plurality of holes (7) for rotating the pipe (1) by means of a rod, the lower pipe (2) having a matching bush (6), the inner space of the lower pipe (2) partitioned into two chambers by means of a circular separating disc (8) having a concentric hole, the upper chamber filled with sand and the lower chamber provided with a key-pipe (10) matching the concentric hole in the disc (8), the bottom of the key-pipe (10) fixed to a horizontal rod (12) passing through a vertical slot (13) made on the side of the lower chamber of pipe (2), the lower pipe (2) provided with a bottom plate (15) having a concentric hole, the said upper pipe (1) and lower pipe (2) also provided with external handles (14) for carrying in dismantled condition. 2. An improved Pit Prop for supporting mine/tunnel roofs, substantially as herein described with reference to the drawing accompanying this specification.

Full Text

This invention relates to an improved pit prop for supporting mine/tunnel roofs. More particularly it relates to a sand filled yielding prop.
The device of present invention i.e Sand Filled Pit Prop is specially useful in depillaring operation as well as in development workings to support exposed mine roof against dislodging of roof rocks. This device is an alternative to other known conventional woodenorsteelprops.
There are many types of pit props viz. wooden props, steel props etc. being used in coal mines. But Sand Filled pit prop based on a new concept (using sand for yielding, height adjustment and recovery) is a novel pit prop. No where in Indian coal mines it is inuse nor it is used in mines abroad
In underground coal mining operation, the developing galleries (tunnels) and space caused by depillaring operation (taking out coal) are generally supported with wooden pit props or steel pit props. Wooden pit props are becoming scare day by day becauseof depletion in our forest reserves. Moreover, when in use, it requires frequent replacement because of its decaying properties. Steel pit props being used in mines are of two types- rigid type and yielding type. Rigid type props are simpleanddo notprovide yield or setting load Moreover, it can be withdrawn under excessive loading condition. In friction and hydraulic pit props generally in use abroad, there are arrangements for yield, setting load and withdrawal facilities. But these are very costly and many mines can not afford to have such props. Friction prop
provides yield because of mechanical sliding, where as hydraulic prop provides yield because of hydraulic compression. But sand filled pit prop provides yield because of compression in sand.
The main objective of the present invention is to provide an improved pit prop useful for supporting mine/tunnel roots. Another objective of the present invention is to provide a simple steel pit prop which is economically viable and does not incorporate the drawbacks of all other known pit props. In fig-1 of the drawing accompanying this specification the schematic diagram of the sand filled pit prop of the present invention is depicted.
Accordingly, the present invention provides an improved pit prop for supporting mine / tunnel roots which comprises an upper pipe (1) telescopically fitted into a lower pipe (2), the top portion of the upper pipe (1) being provided with internal threads for fitting an externally threaded bar (3), the top of the bar (3) having a bearing plate (5), the bottom end of the upper pipe (1) being provided with a block (4) having means for swiveling such that the block (4) remains stationary when the pipe (1) is rotated, the upper pipe (1) being also provided with a plurality of holes (7) for rotating the pipe (1) by means of a rod, the lower pipe (2) having a matching bush (6), the inner space of the lower pipe (2) partitioned into two chambers by means of a circular separating disc (8) having a concentric hole, the upper chamber filled with sand and the lower chamber provided with a key-pipe (10) matching the concentric hole in the disc (8), the bottom of the key-pipe (10) fixed to a horizontal rod (12) passing through a vertical slot (13) made on the side of the lower chamber of pipe (2), the lower pipe (2) provided with a bottom
plate (15) having a concentric hole, the said upper pipe (1) and lower pipe (2) also provided with external handles (14) for carrying in dismantled condition.
The sand Filled Pit Prop of the present invention is described below with reference to fig of the drawing accompanying this specification. The Pit Prop of the present invention consists of two pipes (1) and (2) telescopically fitted with each other. The upper pipe (1) is of smaller dia. Compared to bottom pipe (2).
The top portion of the upper pipe (1) is fitted with a square threaded steel bar (3). The bottom portion of this threaded bar (3) remains inside the pipe (1) while the top protruded portion is engaged with a small pipe with a bearing plate (5). The bottom end of the pipe is attached with a bearing block (4) with swiveling arrangement. This block (4) remains stationary. On the outer surface of the pipe (1) few small holes (7) are provided to rotate the pipe (1) by means of an external iron rod at the time of fixing it for use.
The bottom bigger dia. Pipe (2) is fitted with a bush (6) matching with the dia. Of the upper pipe (1). The inner space of this pipe (2) is separated into two parts by welding a circular separating disc (8). Thus the inner space of the bigger bottom
pipe (2) has two chambers. The top chamber contains sand (9) while the smaller bottom chamber houses a small key-pipe (10). In working condition this key-pipe (10) remains inside the sand (9) kept in the top bigger chamber. But in release condition, the key-pipe (10) remains in the smaller chamber. At the bottom portion of the key-pipe (10) a iron rod (12) is welded for moving the key-pipe (10) up and down through a slot (13) made on the pipe (2) i.e. in the bottom chamber of the pipe (2). This is made like this for release purpose. The bottom portion of the pipe (2) is fitted with a circular disc with a central hole for taking out the key-pipe (10) when there is need be. Both the pipe (1) and (2) are provided with handles (14) for the purpose of easy handling.
The operation of the Sand Filled Pit Prop of the present invention is as follows :
The key-pipe (10) is pushed inside the bigger chamber of the pipe (2) and locked in the slot (13). Sand (9) is filled in the pipe (2) as per height requirement. Then the small pipe (1) is pushed inside the bigger pipe. The steel circular block (4) now rests on the sand. This whole assembled unit becomes a pit prop which is erected straight and fixed between roof and floor of a mine gallery (tunnel). Now a small iron rod is pushed inside the hole (7) of the upper pipe (1) and rotated. In so doing the square threaded iron bar (3) gets extended and tightly fix the prop between roof and floor of a mine gallery to support the loose roof rock against dislodging. In this position it can
takes 20 to 30 tone rock load of mine roof. If it is required to release for reuse, the key-pipe (10) is disengaged by means of a handle (12) and is brought down in the bottom chamber of the pipe (2). This creates a void in the sand which ultimately gets collapsed resulting in lowering of the pipe (1) in the bigger dia. pipe. Now the prop is released and ready for reuse. Under high roof loading condition it gives yield which is not possible in the available steel pit except in the costly friction and hydraulic props.
The pit prop of the present invention was tested in the laboratory under universal testing machine. The main findings are as follows :
a] Setting load - 2 t to 5 t
b] Load bearing capacity - 20 t to 30 t
c] Yield - 4 cm
d] Quickly ly released under excessive loading condition
e] Reuse many times.
The Main Advantages of the invention are :
1] It is very cheap and effective compared to other steel props like friction props and hydraulic props.
2] It provides initial setting load, withstands high load with yielding arrangement and can be withdrawn even under high loading condition.
3] It is made of two separate steel pipe, handling of such prop is easier in transportation.

We Claim:
1. An improved Pit Prop for supporting mine/tunnel roofs which comprises an upper pipe (1) telescopically fitted into a lower pipe (2), the top portion of the upper pipe (1) being provided with internal threads for fitting an externally threaded bar (3), the top of the bar (3) having a bearing plate (5), the bottom end of the upper pipe (1) being provided with a block (4) having means for swiveling such that the block (4) remains stationary when the pipe (1) is rotated, the upper pipe (1) being also provided with a plurality of holes (7) for rotating the pipe (1) by means of a rod, the lower pipe (2) having a matching bush (6), the inner space of the lower pipe (2) partitioned into two chambers by means of a circular separating disc (8) having a concentric hole, the upper chamber filled with sand and the lower chamber provided with a key-pipe (10) matching the concentric hole in the disc (8), the bottom of the key-pipe (10) fixed to a horizontal rod (12) passing through a vertical slot (13) made on the side of the lower chamber of pipe (2), the lower pipe (2) provided with a bottom plate (15) having a concentric hole, the said upper pipe (1) and lower pipe (2) also provided with external handles (14) for carrying in dismantled condition.
2. An improved Pit Prop for supporting mine/tunnel roofs, substantially as herein described with reference to the drawing accompanying this specification.

Documents:

2454-del-1995-abstract.pdf

2454-del-1995-claims.pdf

2454-del-1995-complete specification (granted).pdf

2454-del-1995-correspondence-others.pdf

2454-del-1995-correspondence-po.pdf

2454-del-1995-description (complete).pdf

2454-del-1995-drawings.pdf

2454-del-1995-form-1.pdf

2454-del-1995-form-2.pdf

2454-del-1995-form-3.pdf

2454-del-1995-form-4.pdf

2454-del-1995-form-9.pdf

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Patent Number

193307

Indian Patent Application Number

2454/DEL/1995

PG Journal Number

46/2012

Publication Date

16-Nov-2012

Grant Date

16-Dec-2005

Date of Filing

29-Dec-1995

Name of Patentee

COUNCIL OF SCIENTEFIC AND INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG, NEW DELHI-110001, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	BIRENDRA PRASAD VERMA	CENTRAL MINING RESEARCH INSTITUTE, DHANBAD-826 001, BIHAR, INDIA.
2	BHARAT BHUSHAN DHAR	CENTRAL MINING RESEARCH INSTITUTE, DHANBAD-826 001, BIHAR, INDIA.
3	AJOY KUMAR SINGH	CENTRAL MINING RESEARCH INSTITUTE, DHANBAD-826 001, BIHAR, INDIA.

PCT International Classification Number

E21D 15/18

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA