Bomag BW 156 D-3, Service Manual

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Service Training
BW 156/177 D-3/PD-3 - D 20 -
BW 178/179 D-3/PD-3
Piston position 3:
Once the piston has reached the deepest point the oil flow to the piston is cut off. The piston is no longer
driven. It has reached its dead centre. Another piston must now be driven to move the previous piston
out of dead centre position.
Piston position 4:
By driving other pistons the previous piston is moved out of dead centre position. The oil behind the
piston is connected with the low pressure side and the retracting piston presses it back to the pump.
Piston position 5:
The oil supply back to the pump comes close to an end, the connecting bore between cylinder and low
pressure side closes slowly. The piston will now reach its second dead centre position. This point is
the start of a new working cycle.
Changing the flow direction of the oil will also change the sense of rotation of the motor.
The output shaft is resting in two taper roller bearings. It transmits the rotary movement via the drive
disc and the rubber elements to the drum.