Service Manual

Controls and Features
Direct Displacement Control
The direct-proportional displacement control (DDC) pro-
vides a simple method of
control. Movement of the
swashplate control shaft produces a proportional swash-
plate movement and change in pump flow and/or direc-
tion.
If difficulties are encountered with the control, inspect the
connection of the control linkage to the swashplate
control
shaft to insure that the linkage is properly at-
tached. The vehicle/machine control system determines
the neutral
position of the linkage.
Charge Pumps
A fixed displacement gerotor type charge pump is pro-
vided as
part of the BDP-1 0L.
Bypass Valve
In some applications, it is desirable to move the machine
for
short distances at low speeds without operating the
engine.
A bypass valve allows oil to be routed from one
side of the pump/motor circuit to the other, thus allowing
the motor to turn with little resistance.
The
BDP variable pumps utilize a screw type bypass
valve which is
fully open when unscrewed two (2) turns
maximum. The bypass valve must
be fully closed during
normal vehicle operation.
BDP-10L Variable Pump with Charge Pump