Overcentre Valves

The hydraulic system is fitted with pilot operated over-centre valves on the crane arm cylinders which are factory preset to cope with all foreseen shock loads or attempts to lift more than the crane's maximum lifting capacity.

The over-centre valves:

• Prevent the arms from moving unless there is a pressure signal from the main hydraulic valve.
• Help keep the movement of the load controlled and constant when being lowered, regardless of the pressure that may be in the cylinder.
• Ensure that the cylinders are held in position, should the hydraulic system lose pressure. This stops the arms from dropping and thus preventing any run away of the load in the event of a hose failure.