Piston and cylinder devices.

摘要

A load bearing piston and cylinder device (50) for use with low pressure air, particularly in glassware manufacturing machines, is provided with a bypass (52) which, at some stage in the movement of the piston (48), interconnects opposite sides of the piston to enable the passage of air from one side to the other. By appropriate positioning of the bypass (52), movement of the piston (48) can be made more uniform, cycle time can be reduced and cushioning improved. On-off valves and one way valves may be positioned in the bypass if required.