Bomag BW 156 D-3, Service Manual

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Service Training
BW 156/177 D-3/PD-3 - D 10 -
BW 178/179 D-3/PD-3
Description of function
The drive shaft (1) is directly driven by the diesel engine via an elastic coupling and transfers the rotary
motion to the cylinder block (5) via a splined connection.
The cylinder block rotates with the drive shaft (1), thereby carrying the working pistons (4). The pistons
rest with their slipper pads on the sliding face of the swashing cradle (3). When actuating the swash
plate out of neutral position to one of the two possible flow directions, the working pistons perform a full
stroke movement in the cylinder block with every complete revolution.
The slipper pads are hydrostatically balanced and are retained on the sliding face of the swashing cradle
by a retaining device.
During a complete rotation of the cylinder block each piston moves through the bottom and top dead
centre back to its initial position. Between those two dead centres the piston performs a complete
stroke.
During this stroke movement the appropriate amount of fluid with respect to piston area and stroke
length is drawn in through the two control slots in the valve plate (8) and displaced into the pressure side.