The 3-way pressure reducing valve type 3 DREP 6.. is direct operated by proportional solenoids. It is intended for the conversion of an electric input signal into a proportional pressure output signal. The proportional solenoids are controllable, wet-pin DC solenoids with a central thread and a detachable coil. The solenoids are controlled optionally either by external control electronics (type 3DREP) or by the integrated control electronics (type 3DREPE).
The valve basically consists of:
Housing (1) with connection surface Control spool (2) with pressure measuring spool (3, 4) Solenoids (5, 6) with central thread optional integrated control electronics (7)
The pressure in A or B is set by means of the proportional solenoids. The amount of the pressure depends on the current. With de-energized solenoids (5, 6), the control spool (2) is held in the central position by means of the compression springs (8). Ports A and B are connected with T so that the hydraulic fluid can flow to the tank without obstructions. By energizing a proportional solenoid, e.g. solenoid "a" (5), the pressure measuring spool (3) and with it the control spool (2) are moved to the right. This opens the connection from P to B and A to T via orifice-type cross-sections with progressive flow characteristics. With the surface of the pressure measuring spool (4) the pressure that builds up in channel B acts on the control spool and against the solenoid force. The pressure measuring spool (4) is supported by solenoid "b". If the pressure exceeds the value set at solenoid "a", the control spool (2) is pushed back against the solenoid force and connects B with T until the set pressure is reached again. The
pressure is proportional to the solenoid current. When the solenoid is switched off, the control spool (2) is returned into the central position by the compression springs (8). An optional hand override (9, 10) allows control spool (2) to be moved without solenoid energization.
Accidental activation of the hand override may lead to uncontrolled machine movements!
Valve with two spool positions (type 3DREP..A.. or 3DREP..B..):
The function of this valve version basically corresponds to the valve with three spool positions. The 2 spool position valve is, however, only equipped with solenoid “a” (5) or solenoid “b” (6). Instead of the 2nd proportional solenoid, a plug screw (11) is installed.
The tank line must not be allowed to run empty. With corresponding installation conditions, a preload valve (preload pressure approx. 2 bar) must be installed.