Includes Control For Power Source Of Drive-means Patents (Class 187/276)
With specific electrical component (Class 187/277)
Actuated by presence of obstruction in shaft (Class 187/300)
Actuated by location of access barrier or its lock (Class 187/301)
Actuated by load support contacting trip in shaft (Class 187/302)
Actuated by load support speed sensor or governor (Class 187/305)
Actuated by human operator engaging specific input part (Class 187/306)
  • Elevator control valve assembly
    Patent number: 5374794
    Abstract: A control valve assembly for an hydraulically operated elevator includes separate control valve units for controlling upwards and downwards movements of the elevator. The up valve unit is connected to a pump output and controls connection of the pump output to the elevator cylinder via a check valve. The up valve unit includes an orifice for connecting the pump output to a reservoir, and a valve member for varying the size of the orifice to control the amount of fluid passed to the reservoir, and thus the amount of fluid supplied to the elevator cylinder. The down valve unit has an inlet for connection to the elevator cylinder, a variable orifice connected to a reservoir, and a valve member for controllably varying the size of the orifice to control the rate of descent of the elevator.
    Type: Grant
    Filed: December 9, 1993
    Date of Patent: December 20, 1994
    Assignee: United States Elevator Corp.
    Inventor: William K. Holmes