ELECTRICAL SYSTEM CONTINUED
Solenoid Valves (Transmission)
The ECM uses solenoid valves to shift the transmission. The solenoids control the hydraulic circuits that modulate
transmission clutch pressures. Each transmission clutch solenoid has a connector with two contacts. One contact
is the PWM signal contact and the other is the return to ECM ground contact.
The ECM applies electrical current to the appropriate transmission clutch solenoids. This is based on the
operator's request from the upshift switch, the downshift switch, or the transmission direction control lever. For the
movement of the machine, two clutch solenoids are activated. One solenoid is activated for direction and one for
speed. None of the transmission solenoids is energized when the transmission is in the NEUTRAL position.
Solenoid Valve (Proportional, Secondary Brake, Parking Brake)
Refer to Table 4.
Both service and parking brake systems share the same oil-bathed, multiple-disc arrangements. One brake
assembly is contained in the steering differential and brake assembly located on the right side of the machine. The
other brake assembly is contained in the planetary and brake assembly located on the left side of the machine.
Both brake assemblies are spring applied and hydraulically released. A foot pedal is used to apply the service
brakes for slowing and stopping machine. Parking brakes are controlled by an operator controlled parking brake
switch on the left console. When the parking brakes are engaged, hydraulic pressure to the brake assemblies is
released causing spring pressure to apply the brakes. The electronic brake control valve is mounted on top of the
main case underneath the operator's floor plate.
Figure 18. Electronic Brake Control.
Table 4. Electronic Brake Control.
Secondary brake ON/OFF solenoid
Parking brake solenoid
Proportional brake solenoid