Neutral self-centering, function

W26.60-1086-05

Neutral position auto-centering at the transmission device/ shifting cylinder

5 Transmitter device

7 Coupling shifting cylinder

N Neutral position without error position

N1 Neutral position with error position in the shifting cylinder

N2 Neutral position with error position in the transmission device

Operation

The auto-centering is carried out in the transmission device. This functions makes the shift lever return to the central position, where the dead center (N) fails to correspond to the dead center in the gearbox. The mismatched position is caused by differences in the existing volumes in the hydraulic circuits (gears/coupling mouth). These differences may happen because of hydraulic oil expansion, oil return caused by changes in temperature and also because of small internal leakages, liquid exchange, repair work in the hydraulic circuit and in the gearbox control.

In any situation it is necessary to carry out the auto-centering. The auto-centering is carried out through the repeated actuation of the shift lever, overrunning the pressure point up to the stop towards the gears and the coupling mouth. Because of that, the hydraulic oil flows through the balancing holes in the case and the axial grooves. The volume remaining in the opposite circuit returns through the pressure balancing valves.

W26.60-1061-12

The auto-centering servo-regulating function is achieved through the combination of axial grooves (3.1) of a certain width in the pistons (3) and the arrangement of the primary shutter fixture (7.1) that actuates as a one-way valve. The axial grooves (3.1) in the pistons (3) are arranged so that under all normal positions, they reach only the primary shutter fixture (7.1). If the shift lever is outside its normal positions, the axial grooves (3.1) in one of the pistons (3) overrun the primary shutter fixture (7.1) and open communication with the hydraulic circuit and the balancing reservoir. In this state, the liquid continues flowing. When the shift lever is repositioned again, the first movement will only be an adjusting, through which, because of the axial grooves (3.1), the liquid flows from one circuit to the balancing reservoir and from that it is taken to the lip (through a single passage) from the shutter fixture (7.1) to the contrary circuit. With that the shift lever is always in the correct position.