Automatic locking of high-level luminaires

Claim 1

Means for positively supporting a member, having a centre opening and suspended from hoisting ropes at an elevated position around a mast, which includes a similar number of co-acting first and second parts rigid with the mast and the member; each first part comprising a substantially vertically disposed mounting plate having a pair of transversely spaced and outwardly projecting guide ribs, a sloping guide-in portion at the lower end of the mounting plate, and a bracket of connected rigid fins arranged according to a sloping Z which is secured by one face to the mounting plate in spaced relationship between the spaced ribs and presenting a pair of connected spaced and sloping radially disposed faces at different heights and a recess between said pair of faces; whereas each co-acting second part comprising a robust cantilever pin; the arrangement being such that during the final stage of hoisting of the member the pins are received with clearance between the guide ribs and are drawn onto sloping underfaces of the lower fins of the brackets whereby rotational movement is applied to the member and deflection of the hoisting ropes against gravitational bias by a camming action which is followed by a reverse movement of the member and the ropes by the gravitational bias on disengagement of the pins from the sloping faces and, on lowering of the member, the pins are received in the recesses for support of the member while, for lowering of the member, the member is lifted by the hoisting ropes and by camming with the underfaces of the upper fins of the brackets rotational movement is applied to the member and deflection of the ropes against gravitational bias and on movement of the pins across the upper ends of the said fins a reverse rotational movement is applied to the member by gravitational bias whereafter the member is lowerable.