Pressure Taps on the ECM Manifold
The ECM manifold has pressure taps for the following functions:
(1) Charge Pressure - This pressure tap is located between the charge filter and the charge relief valve in the charge circuit. Also, this is the pressure that is sent to the implement circuit in order to be used as pilot pressure.
(2) Brake Control Pressure - This is the pressure that is being directed from the ECM manifold to the left brake and the right brake. This pressure is used to release the brakes.
(3) Left FORWARD Signal Pressure - This is the pressure that is sent from the left FORWARD steering valve to the control valves on the left drive pump and the left drive motor.
(4) Right FORWARD Signal Pressure - This is the pressure that is sent from the right FORWARD steering valve to the control valves on the right drive pump and the right drive motor.
(5) Left REVERSE Signal Pressure - This is the pressure that is sent from the left REVERSE steering valve to the control valves on the left drive pump and the left drive motor.
(6) Right REVERSE Signal Pressure - This is the pressure that is sent from the right REVERSE steering valve to the control valves on the right drive pump and the right drive motor.
Pressure Taps on the Synchronization Manifold
(7) Left REVERSE Drive Pressure - This pressure is the drive pressure from the left drive pump to the left drive motor when the left track is moving in the REVERSE direction. This is the return pressure from the drive motor to the drive pump when the left track is moving in FORWARD direction.
(8) Left FORWARD Drive Pressure - This pressure is the drive pressure from the left drive pump to the left drive motor when the left track is moving in the FORWARD direction. This is the return pressure from the drive motor to the drive pump when the left track is moving in REVERSE direction.
(9) Right FORWARD Drive Pressure - This pressure is the drive pressure from the right drive pump to the right drive motor when the right track is moving in the FORWARD direction. This is the return pressure from the drive motor to the drive pump when the right track is moving in REVERSE direction.
(10) Right REVERSE Drive Pressure - This pressure is the drive pressure from the right drive pump to the right drive motor when the right track is moving in the REVERSE direction. This is the return pressure from the drive motor to the drive pump when the right track is moving in FORWARD direction.
Pressure Tap for Charge Pressure
|(11) Charge Pump Pressure - This is the pressure between the charge pump and the charge filter.|
The charge pump is a gear pump, which is mounted in-line with the left drive pump. Charge pump (12) supplies oil to the drive loops, to the ECM manifold for the steering and braking, and to the implement hydraulic system as pilot oil.
The charge pump also supplies flushing and cooling flow to the drive pumps and motors.
Charge filter (13) provides filtration for the charge oil before the oil enters the drive loops, the ECM manifold, or the implement hydraulic system as pilot oil. If the oil is very cold or if the charge system filter is restricting flow due to contamination, the charge pump oil will be directed to the tank through the bypass valve that is located in the filter housing. The machine will not move until the oil pressure is below the bypass limit and the bypass valve closes.
The charge filter is located behind the access door on the right side of the machine.
Power Train ECM
Power train ECM (16) is located inside the left side access doors on the outside of the platform. Inputs that include switches and sensors send signals to the ECM that are based on system pressures, positions of controls, temperatures, and speeds. The AVSpare Monitoring System control also sends information to the ECM that is based on the position of service switches. The ECM processes this information. Then, the ECM sends appropriate signals to the outputs in order to control the machine.
(17) ECM Manifold
(18) Brake valve
(19) Left FORWARD steering valve
(20) Left REVERSE steering valve
(21) Right REVERSE steering valve
(22) Right FORWARD steering valve
(23) Transmission Override Valve
ECM manifold (17) is mounted to the left top side of the pump drive gear box. The ECM is located behind the forward enclosure door on the left side of the machine. The ECM manifold is made up of the following components: Charge relief valve, brake valve, transmission override valve, valves and resolvers.
Brake valve (18) controls the oil to the parking brakes. When the operator makes a demand for travel, the ECM sends a signal to the brake valve, which allows charge oil to flow to the brake pistons in order to release the brakes. When the machine stops, the brake valve shifts in order to drain the oil from the brake piston, and the spring applied brakes are engaged.
The brakes are engaged in any of the following conditions:
- the speed/direction control lever is in the PARK position.
- the center pedal is fully depressed.
- the parking brake switch is engaged.
When the speed/direction control lever is in NEUTRAL, FORWARD, or REVERSE and the center pedal is not depressed, the brakes are released.
Transmission Override Valve
Transmission override valve (23) is used in order to control the flow of oil to the four steering valves. When the operator makes a demand for travel, the ECM sends a signal to the transmission override valve. The transmission override valve then opens in order to provide charge oil to the steering valves.
There is a forward and a reverse steering valve for both the left and the right drive loops. When the operator makes a demand for travel or for a turn, the ECM shifts the appropriate steering valves. By using charge oil as a source for signal oil, the signal oil is then sent to the control valves on the drive pumps. The control valves on the drive pumps can then act on the actuator pistons. The actuator pistons have a direct mechanical connection with the swashplates in the drive pumps, which control the output of the steering pumps.
Charge Relief Valve
Excess flow from the charge pump is relieved through the charge relief valve. The charge relief valve limits the maximum pressure of the charge oil. Charge relief valve (24) is located behind the mounting plate on the top of the ECM manifold at the front end.
The resolvers direct the signal oil from the forward or reverse steering valves to the side of each valve for the drive motor control in each of the track motors. The signal oil is used to destroke the motors after the drive pumps have fully upstroked.
Synchronization manifold (25) connects the two drive loops in order to assist in straight tracking of the machine. The synchronization manifold connects the right and the left FORWARD drive loops and the two REVERSE drive loops when the machine is in motion and the operator is not demanding a turn.
When a steering input is sensed, the synchronization valve is closed and the drive pumps are allowed to change the flows independently from each other.
The synchronization manifold is mounted on top of the left drive pump.
Pump Drive Gear Box
Pump drive gear box (26) attaches to the rear of the engine. The pump drive gear box couples the engine to drive pumps (27) and (28). The pump drive gear box also drives the implement pump. The engine and the pumps are supported by the pump drive gear box, which attaches to the frame.
Each track is powered by one variable displacement pump and one variable displacement motor. Each pump, each motor, and each set of hoses forms a closed loop circuit.
The drive pump (27) and drive pump (28) are variable displacement piston pumps that have bidirectional flow. The steering valves in the ECM manifold control the output of the drive pumps and the drive motors which control the track speed. The drive pumps are mounted on either side of the pump drive gearbox.
Makeup and Line Relief Valve
There are two makeup and line relief valves (29) and (30) in each drive pump. Charge oil enters the low pressure side of the drive loop through the makeup and line relief valves. These valves limit the maximum pressure in the high pressure side of the drive loop.
Drive motor (31) and drive motor (32) are variable displacement piston motors which can turn in either direction. High pressure oil from the drive pumps turns the drive motors. The direction and rotation of the drive motors determines the direction and speed of the machine travel.
The drive motors are mounted inboard of the final drive and parking brake units.
Case Drain Filters
Case drain filters (33) and (34) provide filtration of the case drain oil from the drive pumps and motors before the oil returns to the tank. The case drain filters are located behind the access door on the right side of the machine.
Final Drive and Parking Brake
The drive motors are splined to final drive and parking brake units (35). The final drive and parking brake units cause the last speed reductions and the last torque increases in the power train. Power is transferred from the final drives to the tracks by way of sprockets.