Hydraulic Logic Valve

Pilot-to-close Hydraulic Logic Valves are primarily used for bi-directional flow switching applications. The poppet in the pilot-to-close Hydraulic Logic Valve is spring biased to the closed condition. With no pilot signal at port 3, the Hydraulic Logic Valve will open allowing flow in either direction between work ports 1 and 2 once pressure at one of the work ports reaches the biased spring setting. Applying a sufficient externally generated pilot force to port 3 of the Hydraulic Logic Valve closes the poppet creating a low leak seal between port 1 and port 2. Poppet Hydraulic Logic Valves are typically used to perform high flow directional switching operations using small low power pilot valves to control the sequence of the directional operation.

• A single logic valve can be used to control 2-way, on/off switching.
• Multiple elements in a bridge arrangement can control 3-way or 4-way directional switching.
• Since each logic valve is individually controlled, the timing, sequence, and overlap of directional functions can be controlled very precisely.
• Uni-directional or bi-directional flow can be achieved, depending on the valve selected.
• Flows in excess of 80 gpm can be controlled through a single logic element, and more than one logic valve can be used in parallel to control flow in excess of the rated flow of a single element.
• Poppet construction provides a low leak directional control.

Spool Type Spool type Hydraulic Logic Valves can also be used for directional switching, however, they are typically used in modulating applications to control flow or regulate pressure. Virtually any pressure or flow control function can be achieved with a spool type Hydraulic Logic Valve including; restrictive or priority flow control, pressure relief, pressure reducing, sequencing, and unloading. The spools in this category of Hydraulic Logic Valves are balanced designs; the spool area at the work port (port 1) and the pilot port (port 3) are equal (1:1). The spool is held in a biased condition by a spring. Venting the pilot at port 3 creates an unbalanced condition causing the valve spool to modulate open or close, depending on the valve chosen. This spool design makes the valve very stable because the forces acting to open and close the valve are in balance. Normally closed spool Flow Control / Compensators Parker offers two types of logic valves for flow control functions.

• Normally open spools function as a restrictive type compensator.
• Normally closed spools function as a priority or by

Minimum Order Quantity : 5