Lift cylinder i.e. free lift cylinder, for triplex lifting gear of reach fork lift truck, has mechanical pump device attached to shut-off valve device and arranged in piston to convey leakage of agent from air chamber into pressure chamber

摘要

The cylinder (2) has a cylinder housing (2b), and a piston rod provided with a piston (2d), and a pressure chamber (2c) pressurized with a hydraulic pressurizing agent. A shut-off valve device (20) connects an air chamber (2e) with the pressure chamber. A mechanical pump device (21) attached to the shut-off valve device is arranged in the piston for conveying leakage of the agent from the air chamber into the pressure chamber by a sealing device (16). The pump device comprises a pump pressure chamber, and a pump piston is arranged in the pump pressure chamber.