When the engine is running, the shaft (1) and the barrel (4) are
rotating. There are nine pistons (10) in barrel (4). The port
plate (7) and the swashplate (8) are held by the housing (5).
The port plate (7) and the swashplate (8) do not rotate. The
spring assembly (9) keeps a force on the barrel (4) in order to
make a high pressure seal between the barrel (4) and the port
plate (7). When barrel (4) is rotating, each piston (10) follows
the angle of the swashplate. If the swashplate angle is at zero,
the pistons do not move in and out of the barrel and there will
be no flow. The charge oil from the internal charge pump (14)
maintains oil pressure in the pump in order to keep the barrel
full of oil. The charge oil lubricates the pump components.
The charge oil compensates for the normal internal loss of oil
due to leakage.
The position of the swashplate (8) is controlled by the control
valve (6) and the servo piston (3). The control valve (6)
receives an electrical signal from the vibratory on/off control
and this causes the servo piston (3) to move. The control
valve (6) routes the control oil in order to move the servo piston
(3). The servo piston (3) controls the angle of the swashplate
If the machine is equipped with the variable
frequency system, the control valve receives the
electrical signal by way of the variable vibration
control knob. Refer to Variable Frequency
Electrical Control for more information.
Oil flows from the pump to the vibratory motor and back to the
main passage (12). The position of the swashplate (8)
determines the direction of flow of the two main passages (11)