GB635854A - Improvements in and relating to mine and like props - Google Patents

Abstract

635,854. Mine-props. PARRY, E. Sept. 25, 1947, No. 26001. [Class 20 (ii)] A mine prop comprises two lengths 1, la pivotally connected at 4 to form with their male and female members 2, 2a a rigid prop when in the working position, being releasably locked together by a main catch 9 pivoted to the female member and engaging the male member and releasably locked by an auxiliary catch 10 pivoted thereto and engaging the female member. A female portion 2c in the member 2a receives a male portion 2b on the member 2 which is slotted to receive a portion of a catch lever 9 hooked to engage a transverse pin 6 in the slot, the catch lever being pivoted at 9a to lugs 8 on the member 2a so that it may be pulled out of engagement, by a chain 12, to an extent limited by'a stop 9c: A second catch 10 is pivoted to the catch 9 and hooked to engage an edge of the slot in the member 2 and is provided also with a hook 10a over which is looped a spare link 12a of the chain whereby the pull first disengages the catch 10 and then the lever 9. Further locking means consists of a pin passing through a hole in the catch lever 9 and lying across the catch 10 so that it cannot rise until the pin is withdrawn. This pin I may be secured against loss by a chain 11b. The edges of the portion 2c and of the member 2 which are in contact are curved to allow the portions of the prop to swing apart, and these curves may be such that there is a slight wedging action when the prop is in the working position. The pivot 4 may be off-set from the main axis of the prop so as to increase the effort required to collapse it. Downward projecting walls 2i form a shield for the curved faces.