TM 5-2410-240-23-1
0010
ELECTRO-HYDRAULIC CONTROLS CONTINUED
Parking Brake Machine ECM Inputs and Outputs and Hydraulic Oil Flow
00010
N OT E
The following description assumes the transmission is in NEUTRAL and the service brake
pedal is fully released.
The parking brake switch (Figure 5, Item 8) has a normally open contact and a normally closed contact. The
contacts provide switch ground inputs to the machine ECM (Figure 5, Item 7) in order to indicate switch position.
When the parking brake switch is in the ON position, the machine ECM de-energizes the parking brake solenoid
(Figure 5, Item 5). Oil flows from the fan motor and passes through the left side hydrostatic pump into the line
(Figure 5, Item 9). The oil then flows through the check valve (Figure 5, Item 10) and into the powertrain return
manifold (Figure 5, Item 4), where the parking brake solenoid blocks the flow of oil to the brake pistons (Figure 5,
Item 1). Oil from the brake pistons flows into the lines (Figure 5, Item 2) and then the line (Figure 5, Item 6), and
then into the powertrain return manifold. The oil then flows through the parking brake solenoid and into the line
(Figure 5, Item 3), where the oil returns to the hydraulic tank.
N OT E
The following description assumes the machine is in forward or reverse travel.
When the parking brake switch (Figure 5, Item 8) is in the OFF position, the machine ECM (Figure 5, Item 7)
energizes the parking brake solenoid (Figure 5, Item 5) with a 12 Volt signal and the solenoid shifts downward. Oil
flows from the fan motor and passes through the left side hydrostatic pump into the line (Figure 5, Item 9). The oil
then flows through the check valve (Figure 5, Item 10) and into the powertrain return manifold (Figure 5, Item 4).
Since the parking brake solenoid is de-energized, the oil flows through the solenoid into the line (Figure 5, Item 6)
and then into the lines (Figure 5, Item 2), where it returns to the pistons (Figure 5, Item 1). The oil from the parking
brake solenoid also flows through the line (Figure 5, Item 3), where it returns to the hydraulic tank.
N OT E
The parking brake solenoid will not engage when the neutral interlock is active, or the park
brake lockout configuration is locked, or when an electronic pressure override calibration
or stall test is being performed.
0010-10
