TM 5-3805-281-24-1
Theory of Operation
Electrical signal for rear (C) and front (J) pump
When the propel speed switch (A) is at slow speed
control pressure sensors increases because the pilot
(turtle), the electrical signal to the propel speed change
oil control signals from front and rear control valves
solenoid valve (N) coil is low. The pilot oil control
are increasing.
signal to the speed selector valve spools (E) is too low
Rear and front pump pressure sensors (K) are
to shift the spools. The propel motors (D and F) are at
sensing low pressure.
maximum displacement causing the machine to travel
at slow speed.
When the electrical signals are received at the engine
and pump controller (O), the electrical signal from the
The propel speed goes to fast with the following
controller to the solenoid valve (N) coil increases. The
operating conditions:
solenoid valve spool shifts increasing the pilot oil
Propel speed switch is at fast speed (rabbit).
control signal. The higher control signal shift the speed
Propel pressure switch (H) in closed (propel function
selector valve spool (E) causing the motor to go to
minimum displacement and the machine to travel at
actuated).
Dig pressure switch (G) is open (no dig function
fast speed. (See Propel Motor Fast Speed Operation
in this group.)
actuated).
CED,TX08227,3101
1923APR982/2
9025
05
90
6-89
