LOAD CONTROL VALVE

Counterbalance valves are devices used to control cylinder and motor loads helping to restrict overrunning loads, assist with controlling speed and position for varying loads, and they are also used as load holding devices with built in thermal relieving functionality. Standard counterbalance valves are pilot operated devices that allow free flow in one direction and restricted flow in the opposite direction. The load is held in place until the counterbalance setting is overcome by sufficient pressure generated by the pump, thermal expansion, or from external forces acting on the actuator. Once the pressure falls below the required setting, the valve closes and holds the load in place. In order to save horsepower, pilot pressure assists in the opening of the valve allowing the load to be controlled with a lower than load induced pressure as long as the available pilot pressure is greater than the ratio between the valve setting and the selectable pilot ratio. Standard counterbalance valves are non-vented meaning the control spring chamber is connected to the valve outlet which will cause any downstream pressure to be additive the valves pressure setting. If excessive downstream pressure may be present or if the counterbalance pressure setting is critical, Parker also offers several series of externally vented counterbalance valves. Parker’s CB101, MHC-010-S, MHC-022-S, and E2 series of counterbalance valves are all standard non-vented load and motor control valves. Each series has multiple pilot ratio options, adjustment styles, and available pressure ranges. They can also be supplied with fixed factory settings, or with tamper proof caps. Typically higher pilot ratios are used for simple load holding applications where the moving load is controlled by external means and the main purpose of the counterbalance is to hold the load in position when not being operated, and to provide thermal and hose-break protection. Lower pilot ratios are typically used to assist in applications where cylinder or motor speed and positioning needs to be controlled with varying loads. Parker’s extensive line of counterbalance load and motor control valves allow design flexibility in the most demanding applications and markets including and not limited to: Power Units, Refuse, Oil and Gas, Material Handling, Construction, Drills, Presses, Mixers, Agriculture, Balers, Combines, Load Holding, Hose Break Protection, Overrunning load control