Method and apparatus for reducing the power required by an hydraulic elevator drive

摘要

An apparatus for reducing the driving power required for an hydraulic elevator in which the elevator car is suspended in the shaft by a cable connected with a piston rod of an hydraulic piston-cylinder drive providing two units of distance of car travel for each unit of distance of piston movement. A counterweight is connected to the head end of the piston rod for travel equal in distance and opposite in direction to the car travel. The counterweight is selected to balance the weight of the car and the most frequently occurring car load. A pump supplies pressured fluid to the cylinder of the drive and, during upward travel of the elevator car, a control system provides a differential circulation of the fluid whereby a smaller fluid volume can be used for the dimensioning of the pump.