Directional Valves

Directional control valves – flow direction in the hydraulic circuit

Directional control valves determine in which direction the hydraulic fluid flows to the cylinders – and thus whether the platform of a tail lift is raised, lowered, tilted or held. They connect, block or cross the ports through defined switching positions. At SULEJ Ladebordwand you will find directional control valves in 4/3 and 4/2 designs, with electromagnetic or manual actuation, matched to the installed component – as the central switching element between pump, cylinders and tank.

4/3 and 4/2 valves – ports, switching positions and neutral position

The designation 4/3 stands for four ports and three switching positions: lifting, lowering and a centre position. In the centre position the ports are either blocked or connected via the pump return circulation. 4/2 valves operate with four ports and only two switching positions, often in combination with an additional lowering valve. The spool runs precision-hardened in the housing bore and defines the transitions between the P, T, A and B ports via its control edges – the basis for clean switching processes without pressure peaks.

Selection and replacement – the details that matter

When replacing a directional control valve, the switching symbol, the nominal flow rate and the connection pattern are decisive. Pay attention to a smoothly moving spool, intact springs in the centring units and matching solenoid coils with correct on-board voltage. Signs of wear often show up as sluggish switching, audible oscillation or slight leakage at the end faces. After installation a functional test in all switching positions with slow platform movement follows.

Benefits at a glance

• Central directional control for lifting, lowering and holding the platform
• 4/3 and 4/2 designs for different hydraulic concepts
• Precisely hardened control spools for long service life and sealed switching positions
• Compatible with common connection patterns and solenoid coils

A precisely switching directional control valve is the prerequisite for clear, predictable movement sequences – during lifting as well as when lowering under load.