GB1205931A - Improvements in or relating to building apparatus - Google Patents

Abstract

1,205,931. Hoists; winches. P. N. EVANS. 30 Nov., 1967 [7 Sept., 1966], No. 39924/66. Headings B8B and B8H. A hoist for raising tiles or slates to a roof comprises a sectional track 10-13, Figs. 2-9 (not shown), having the upper sections supported on the rafters of the roof under construction, a carriage 35 movable on the track by means of a winch assembly 18, and a knock-off device 43 which is adjustably locked to the track and which is clamped to a winch control cable 40 to prevent movement of the cable to apply the winch brake, the knock-off device including a trigger mechanism to release the lock when the carriage engages the device to cause the winch brake to be applied. The winch drum shaft 65 is mounted in eccentric bearings 101 controlled by a lever, to which the control cable is attached, by which it can be moved to bring the drum into contact with a friction drive wheel 64 or with a friction brake 105. A sprocket 103 on the shaft 63 of friction wheel 64 drives, through a chain 66, a pawl plate 67 free on the shaft 65 but having sprocket teeth. The plate carries pawls which engage ratchet teeth formed on an inside surface of the winch drum, the ratcheting direction being such that the pawls slide over the teeth when the winch is winding in. On lowering the carriage, when the friction wheel is not engaging the drum, the pawls continue to slide over the ratchet teeth when the pawl plate is running faster than the drum, but engages the teeth to restrain the drum speed to that at which it can be driven by the motor. The knock-off device, Fig. 15, comprises plates 80-82 supporting rollers 83a which rest on one of the track members. An arm 87, pivotally mounted on an eccentric bush 86 is connected by a spring 88 to a trigger 89 pivoted on one end of a bar 110 linearly movable between plates 80, 82. In the " automatic " position, a projection 114 on the trigger is latched over a separator 83 between plates 80, 82 to tension the spring 88 so that the arm 87 is forced against the lowermost surface of the track, thereby allowing downward but not upward movement of the device on the track. The return run of the control cable 40 from the head gear is secured to the knock-off device by a clamp 115. When the operator pulls the control cable to start the winch, the device moves down the track and thereafter the tension is retained in the cable until the carriage engages the trigger 89, which is thereby unlatched allowing the bar 110 to move to the right to release the tension in the spring 88 and free the knockoff device. The tension in the control rope is thereby released allowing the winch control lever to move to the " brake " position. The knockoff device is reset by means of a knob on the bar 110 extending through an opening 113 in the plate 80. A tile-carrying trolley, Figs. 18-20 (not shown), is associated with the hoist and is adapted to be moved horizontally along the roof from a position adjacent the knock-off device.