Hoist employing a multiple piston cylinder

Abstract

A vehicle includes a vehicle chassis, a load support body connected to the chassis and movable between a lowered position and a raised position, and a hoist operable to forcibly move the load support body from the lowered position to the raised position. The hoist includes a cylinder and a pressurized drive fluid supply system. The cylinder includes a housing assembly and a shaft assembly. The housing assembly defines first and second cylinder chambers separated by a center cap. The shaft assembly is slidably mounted in the housing assembly and includes a shaft and first and second pistons affixed to the shaft at axially spaced apart locations along the shaft. The first piston is disposed in the first cylinder chamber and the second piston is disposed in the second cylinder chamber. The pressurized drive fluid supply system is operable to supply a pressurized fluid into each of the first and second cylinder chambers to forcibly extend the shaft assembly relative to the housing assembly in an extension direction to forcibly move the load support body from the lowered position to the raised position. The cylinder is configured such that, when the shaft assembly is fully extended, a volume of the pressurized drive fluid in the second cylinder chamber exerts an offset force on the center cap in a direction opposite the extension direction to offset axially expansive counter-forces on the cylinder housing.

Dependencies are inferred from the claim text.