Additional steered axle straight-running stability, function

W46.80-0002-09

1 Front axle steering

2 Master cylinder

2.1 Pressure limiting valve

2.2 Replenishing valve

3 Centering cylinder

4 Hydraulic accumulator

5 Hydraulic line

6 Pressure switch

A Front axle steering operating pressure

B System pressure

C Accumulator pressure (gas fill)

Z1 Cylinder chamber (master cylinder)

Z2 Cylinder chamber (master cylinder)

Z3 Cylinder chamber (centering cylinder)

Z4 Cylinder chamber (centering cylinder)

Z5 Cylinder chamber (centering cylinder)

Z6 Cylinder chamber (centering cylinder)

Function

Cylinder chambers Z1 and Z2 of the master cylinder (2) are connected to each other when driving straight-ahead and at steering angles less than 5°.

This pressurizes cylinder chambers Z5 and Z6 of the centering cylinder (3).

With the master cylinder (2) in this position cylinder chambers Z3 and Z4 are pressurized by the hydraulic accumulator (4).

This causes the trailing axle to be moved and held in the straight-ahead position.

A short-circuit in cylinder chambers Z1 and Z2 as well as the centering of the trailing axle also causes synchronization of the master and centering cylinder (2 and 3).

This compensates any hydrostatic offsets (leakage) occurring.

To protect the hydrostatic system against unacceptably high pressures which may cause damage, pressure limiting valves (2.1) are installed in the master cylinder (2).

In addition, replenishing valves (2.2) are fitted in the master cylinder (2). These prevent a vacuum in the non-pressurized cylinder chamber, making it easier to move the steering.