GB2115046A

GB2115046A - Self-advancing roof supports

Info

Publication number: GB2115046A
Application number: GB08201227A
Authority: GB
Inventors: Kenneth David Prescot; Charles John Holland
Original assignee: Dobson Park Industries Ltd
Current assignee: Joy Global Industries Ltd
Priority date: 1982-01-16
Filing date: 1982-01-16
Publication date: 1983-09-01
Also published as: GB2115046B; ZA827321B; DE3301262A1; IN156673B; AU8949082A; AU540247B2

Abstract

A self-advancing mine-roof support 10 has a double acting hydraulic ram 28 within the support connected to the support base 12 and to a relay bar 24 for coupling to an anchorage forward of the support and a ram 31 for lifting of the support base in relation to the relay bar. The rearward end of the relay bar is pivotally connected approximately to the midpoint of the hydraulic ram 28 and the relay bar 24 is of box section construction. <IMAGE>

Description

SPECIFICATION Self-advancing roof supports This invention concerns self-advancing mineroof supports.

Self-advancing mine-roof supports often operate by way of fore-and-aft (double) acting advancing rams operative between the support and a forward anchorage therefor, such as a snakable face conveyor. Thus when the support is in a roof supporting condition the anchorage can be moved forwards and, when the support is released from roof supporting and the anchorage secured by other supports, the support can be moved toward the anchorage. Such supports have floor-engaging and roof-engaging structures, i.e. a base and canopy which are urged apart by props in order to support a roof.

Connection between the support and the anchorage is by way of a relay bar coupled to the ram and the anchorage.

Such mine-roof supports can be difficult to advance if the mine floor is uneven or is covered with soft debris. The support base can then become stuck. Proposals have been made for lifting of support bases to facilitate advancing of the support. These proposals have not been entirely satisfactory and so various improvements to mine-roof supports are proposed herein.

According to this invention there is provided a self-advancing mine roof support having advancing ram means within the support connected to the support base and to a relay bar for coupling to an anchorage forward of the support, and one or more of the following features: (1) means for lifting of the support base in relation to the relay bar; (2) the rearward end of the relay bar being pivotally connected approximately to the midpoint of the advancing ram means; (3) the relay bar being of box-section construction.

The lifting means is preferably a single acting hydraulic ram connected to a forward part of the support base its lower end being slidable along the relay bar. The lifting ram may be vertical but is preferably downwardly and forwardly inclined.

The inclination of the lifting ram can improve its travelling way.

In a preferred embodiment the lifting ram has inner (piston) and outer (cylinder) telescopic members, the inner of which is connected at its upper end to a generally cylindrical casing in which the ram operates which cylindrical casing is mounted on the support base. The outer member of the lifting ram has its lower end connected to a pad, which is preferably of brass, which is slidable along the relay bar.

Such an arrangement of lifting ram has a number of advantages. Firstly, the cylindrical casing in which the lifting ram operates can compensate for any side loads and also provides a good bearing length. Secondly, the thrust of the lifting ram will be at the bottom. Thirdly, if using a brass pad, this will be self-aligning on the relay bar.

The lifting ram will usually be used when the support is being advanced, i.e. after advancement of the relay bar, so that the base can be lifted slightly to avoid being caught by an uneven mine floor. The pressure of the ram will also help to keep the relay bar in contact with the floor during advance of the support.

Connection of the midpoint of the advancing ram to the relay bar can prevent fouling of the mine floor by the rear end of the advancing ram when the reiay bar is in an advanced position.

Preferably the relay bar has at or near its forward end fins to guide the support as it is being advanced. The fins preferably extend outwards horizontally and may taper rearwardly. A box section relay bar may well be stronger than solid bar and will be of benefit if used in conjunction with the previously mentioned support lifting means because a wider upper surface of the relay bar can be provided on which the lifting ram can slide.

This invention will now be further described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a side view of a self-advancing mine roof support; Figure 2 is a side view of the ram and relay bar assembly of the support of Figure 1; Figure 3 is a longitudinal section showing detail of the ram of the support of Figure 1; Figure 4 is a longitudinal section showing detail of a lifting ram of the support of Figure 1; and Figures 5 and 6 are side and plan views of the relay bar of the support of Figure 1.

Referring to the drawings a self-advancing mine roof support 10 has a base 12 and a canopy 14 supported in cantilever fashion by a pair of forwardly inclined hydraulically extensible props 13 acting between the base 12 and the canopy 14.

The rear of the canopy 14 has pivotally connected thereto downwardly and rearwardly inclined members carrying rear and side shielding 1 8. The lower end of each shielding carrying member is connected to the rear of the base by a pair of pivotally connected members 19, 20.

The base 12 is in the form of a pair of skids 22 having arched cross connections at the front 23 and rear (not shown). Between the skids is a relay bar 24 having at its forward end a clevis type connector 25 for connection of the relay bar to an anchorage such as a conveyor. The rear of the relay bar is pivotally connected to the midpoint of cylinder 27 of double acting hydraylic ram 28.

The forward end of piston 29 of the ram 28 is pivotally connected to the rear of the forward cross connection 23 of the support skids 22.

Attached to the front of the forward cross connection 23 is a generally cylindrical housing 30 for a lifting ram 31. Piston 32 of the lifting ram is connected to the upper end of the housing 30 and cylinder 33 of the lifting ram is connected to a brass pad 35 which rests on and is slidable along the upper surface of the relay bar 24.

Detail of the double acting ram 28 is shown in Figure 3. The piston 29 is slidable within cylinder 27 and has two hydraulic fluid ports 40, 41 which act as both inlets and outlets depending upon whether the ram is being extended or retracted.

To extend the ram hydraulic fluid is forced into port 40 and through connected bore 42 into chamber 43 formed between the cylinder end and the piston end. An annular seal provided at 44 between wider end portion 49 of the piston and the cylinder. To retract the piston, hydraulic fluid is forced through port 41 and connected bore 47 into annular chamber 48 surrounding the piston.

One end of the chamber 48 is formed by the wider end portion 49 of the piston which as stated above is sealed at 44 and an annular plug 50 fixed in the neck of the cylinder and in which the piston moves, an annular seal being provided between the plug and piston at 52.

A hole 53 is provided in the outer end of the piston for attachment thereof to the support base and a pair of holed flanges 54 are provided at the midpoint of the cylinder for attachment of the cylinder to the relay bar.

Referring to Figure 4, the lifting ram 31 has a cylinder 33 in which slides a piston 32. Annular seals are provided at 63 and 64 between the piston and the cylinder. Extension of the ram is limited by an annular extension near inner end 66 of the piston 32 which can abut against the end of an annular sealing plug 67 in the end of the cylinder 33. To extend the ram, hydraulic fluid is forced into chamber 69 between the end 66 of the piston and the cylinder via port 70 and bore 71.

Attachment of the piston 32 of the cylindrical housing 30 (Figures 1 and 2) is by hole 73 through the outer end of the piston 32. The closed end of the cylinder 33 has attached thereto brass pad 35 which is to slide on relay bar 24 when in position.

Turning to Figures 5 and 6, relay bar 24 has sides 80, 81 and upper and lower surfaces 82, 83 respectively welded together to form a boxsection. The forward portion of the relay bar is deeper and wider than the rearward position since that is the position on which the lifting ram will slide. Also at the forward end of the relay bar are welded on a pair of tapered fins 85 extending outwards in the horizontal plane one on each side of the relay bar. The fins are flattened at 86 to locate between the skids of the support base.

These fins assist in guiding the support base into position as it is advanced.

Attachment of the relay bar to an anchorage at one end is by means of hole 88 in extension piece 89 fitted into and welded to the relay bar.

Attachment of the relay bar to the advancing ram is by hole 90 in extension piece 91 fitted into and welded to the other end of the relay bar.

Operation of the mine roof support 10 will be conventional except that, during advance of the support base the lifting ram will be extended to raise the front of the base of the floor to avoid it being obstructed by debris or unevenness of the floor. As the support base is advanced, the brass pad on the lifting ram will slide along the relay bar keeping the front end of the base up at the same time as keeping the relay bar on the floor.

Claims

1. A self-advancing mine roof support having advancing ram means within the support connected to the support base and to a relay bar for coupling to an anchorage forward of the support, and one or more of the following features; (1) means for lifting of the support base in relation to the relay bar; (2) the rearward end of the relay bar being pivotally connected approximately to the midpoint of the cylinder of advancing lam means; (3) the relay bar being of box section construction.

2. A mine roof support as claimed in Claim 1 wherein the lifting means is a single acting hydraulic ram connected to a forward part of the support base its lower end being slidable along the relay bar.

3. A mine roof support as claimed in Claim 2 wherein the lifting ram is downwardly and forwardly inclined.

4. A mine roof support as claimed in Claim 2 or 3 wherein the lifting ram has inner and outer telescopic members, the inner of which is connected at its upper end to a generally cylindrical casing in which the ram operates.

5. A mine roof support as claimed in Claim 4 wherein the outer member of the lifting ram has at its lower end a pad slidable along the upper surface of the relay bar.

6. A mine roof support as claimed in Claim 5 wherein the relay bar has at or near its forward end fins to guide the support as it is being advanced.

7. A mine roof support as claimed in Claim 6 wherein the fins extend outwards horizontally and taper rearwardly.

8. A self advancing mine roof support substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.