Patent ID: 9738490
Date: 2017-08-22
CPC Classifications: B66B,E04G

Claim:
1. A platform lift apparatus, comprising; a main body having a platform receiving portion and a utility portion; a drive train substantially contained within the utility portion of the main body, the drive train comprising a rotatable shaft having plural lift drums and a motor operatively coupled to the shaft to cause selective rotation thereof, each of the lift drums having an associated lift tether coupled thereto and wound thereon; a platform coupled to respective ends of the lift tethers to suspend the platform from the platform receiving portion of the main body, the platform being selectively movable by operation of the drive train to travel vertically relative to the main body, the platform being substantially nested within the platform receiving portion of the main body when at an uppermost point of travel; at least a first sensor operatively coupled to a first one of the lift tethers and a second sensor operatively coupled to a second one of the lift tethers, the first sensor providing a first signal corresponding to slack on the first one of the lift tethers and the second sensor providing a second signal corresponding to slack on the second one of the lift tethers; and a control circuit operatively coupled to the motor and the first and second sensors, wherein the control circuit takes at least one corrective action if the first and second signals indicate slack on at least one of the first and second ones of the lift tethers; wherein the control circuit causes the platform to travel upward by driving the motor to rotate the shaft in a first direction to wind the lift tethers onto the respective lift drums and causes the platform to travel downward by driving the motor to rotate the shaft in a second direction to unwind the lift tethers from the respective lift drums.