Load control valves meet new demands

Sterling Hydraulics has extended its range of load control valves to meet changing customer demands.

Sterling Hydraulics has extended its range of load control valves to meet changing customer demands.

Load control valves, also known as over centre valves, counter balance valves or boom lock valves, are used to control the movement of a hydraulically supported load as a guard against the consequences of hose failure.

In most operations they are connected to the loaded port of an actuator to allow unrestricted input flow via an integral check valve to raise the load.

And then to control the outlet flow via the pilot assisted integral relief valve to lower the load.

In many cases, a cross line pilot supply from the actuators other port is connected to the valve pilot port to give a feedback signal that causes the valve to modulate the load, lowering pressure and preventing a runaway situation.

The new Sterling Hydraulics E6C1 is a three-port load control valve with the added benefit of being independent of the return pressure in the directional control valve port.

It has a special seating arrangement and a chamber that is vented to the atmosphere.

This enables the sum of pilot and relief areas to be vented to the atmosphere without the need for a fourth port and associated vent line.

This latest load control valve is particularly suited for use with a service line relief valve on the directional control valve, in that the service line relief setting is not additive to the load control valve setting.

The E6C1 incorporates a direct acting relief valve for overload protection and a reverse check valve within the body thus saving space and minimising installation costs.

While providing the relief function, the adjustable spring loaded main poppet is lifted by the actuator-induced pressure on port 3 allowing relief flow to port 2.

During the piloted open function, the main poppet is shifted by pilot pressure on port 1; this is usually connected to the actuator's load lowering feed line.

The actuator load induced pressure on port 3 also acts to assist in lifting the main poppet allowing actuator flow to pass from ports 3 to 2.

The pilot area is generally greater than the relief area, as defined by the pilot ratio.

In application, the load control valve operates in conjunction with the main directional control valve to modulate flow from the actuator and prevents the load from running ahead of the input flow command.

In the event of hose failure, the valve will hold the load safely when the directional control valve is closed.

During the free reverse flow function, in the reverse direction, a spring loaded-check poppet is opened at low pressure on port 2 allowing free-flow to port 3.

The E6C1 has a pilot ratio of 1:1 but also available in the range is E6K1, with a pilot ratio of 3:1 and E6P1 with a pilot ratio of 5:1.

All three variants fit the new CAVT11A cavity making it interchangeable with other load control valves on the market.

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