Hose Failure Safety
Even smaller machines are now specifying Boom Lock. Intelligent overcentre valves are widely used to give load holding. load control and load safety in the case of hose failure. Systems which allow float are also available.
Back-up flow and pressure for braking systems and steering is supplied by accumulators which must be kept charged and, also for safety reasons, unloaded when the machine is idle. Cartridge valves are available to give any combination of control.
Sequence and diverter valves for the control of pumping circuits allowing simple pumps to be converted to achieve more complex functions.
For wheeled excavators. brakes are supplied by back-up accumulators which must be charged at all times. The dual check valve makes sure that the lower pressure accumulator is always referenced to the supply. The unloading valve will re-charge the accumulators ach time they drop below 85% of their required setting.