TWO OR THREE ROPE FRICTION HOIST HAVING A WHEEL FOR EACH ROPE

摘要

A friction hoist has two or three friction wheels and each friction wheel carries a rope. The ropes support a pair of counter balanced conveyances. In one form of the invention having two friction wheels, one friction wheel is fixed to a common shaft and a motor rotates the common shaft to drive the wheel. The other friction wheel is an idler wheel mounted adjacent the driven wheel and free to rotate on the common shaft. Because one wheel is free to rotate it can make adjustments tending to equalize differential winding tension in the ropes. A braking material is fixed to one of the friction wheels on the facing adjacent rim portions. A braking assembly has a braking device adjacent each outwardly directed rim face. A braking control actuates the braking devices causing the devices to engage the outwardly directed rim face of each friction wheel. This engagement of the braking devices with the outwardly directed rim faces provides a braking action for each friction wheel and also urges the friction wheels towards one another into engagement with the braking material between adjacent facing rim portions tending to lock the two friction wheels together. If one of the ropes should break, the conveyances are still supported by the other rope and the total braking forces on both the friction wheels are available for the unbroken rope.