Mine working apparatus
AssigneeHuwood Limited
InventorGraham J. Saunders
Life of this patent
Estimating the term…
Abstract
The invention relates to mine working apparatus including a sprag plate 21. The sprag plate 21 is included in a sprag unit 20 that can be reciprocated in the fore-and-aft direction of the canopy and the sprag unit 20 includes a sprag slide 22 and a link system 43 and 61 that can be reciprocated in the fore-and-aft sense relatively to each other. There is a range of lost motion between the slide 22 and the link system and the means 48 for moving the sprag unit between the position in which the sprag plate 21 is operative and the position in which the sprag plate 21 is inoperative also moves the sprag slide and the link system relatively to each other through their range of lost motion and this relative movement swings the sprag plate 21 between a generally upright, operative, position and a generally horizontal, retracted, position.
Claims8
Mine working apparatus provided with a sprag plate by which an upright wall adjacent, and forwardly of, the apparatus can be supported, in which the sprag plate is pivotally mounted on the forward end of a support, the support is carried by a part of the apparatus relatively to which it is reciprocable in the fore-and-aft direction, actuating means is provided to effect reciprocation of the support and is such that forward movement of the actuating means effects, except for a range of such movement when the actuating means moves relatively to the support, forward movement of the support and rearward movement of the actuating means effects, except for a range of such movement when the actuating means moves relatively to the support, rearward movement of the support, and a link is pivotally connected at spaced locations to the actuating means and to the sprag plate and is such that when the actuating means is at the forward end of the range in which it can move forwards relatively to the support, the link holds the sprag plate in an upright, wall-supporting position and when the actuating means is at the rearward end of the range in which it can move rearwardly relatively to the support, the link holds the sprag plate in a retracted position.
Dependencies are inferred from the claim text.