Electrical Components
Circuit Breaker Panel
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| Illustration 1 | g01229154 |
(1) Engine circuit breaker (2) Circuit breaker "CB2" (3) Circuit breaker "CB1" (4) Circuit breaker "CB11" | |
The circuit breaker panel is located in a compartment under the instrument panel. The panel is on the right side of this compartment. Decals near each circuit breaker identify the function of the circuit breaker.
The following circuit breakers protect components in the propel circuit:
- Engine ECM circuit breaker (1)
- Circuit breaker "CB1" (3)
- Circuit breaker "CB2" (2)
- Circuit breaker "CB11" (4)
Engine circuit breaker (1) receives power when the electrical disconnect switch is in the ON position. This circuit breaker transfers power to terminal "J1-48" and to terminal "J1-52" of the engine ECM.
Circuit breaker "CB1" (3), circuit breaker "CB2" (2), and circuit breaker "CB11" (4) receive power when the main power relay is energized. Circuit breaker "CB1" distributes power to contact "2" of the shift switch. Circuit breaker "CB2" distributes power to contact "A" of the propel lever sensor and to terminal "1" of the machine ECM. Circuit breaker "CB11" distributes power to contact "2" of the flow divider switch.
Machine Electronic Control Module (ECM)
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| Illustration 2 | g01229157 |
(5) Machine ECM (6) LED display (7) Forty pin connector | |
Machine ECM (5) is a model MPC-10. This unit is located inside the compartment, under the right side of the instrument panel. The machine ECM has single 40-pin connector (7). The 40-pin connector receives input signals from sensors around the machine which monitor the current operating conditions. System software compares the gathered input to information already stored in the machine ECM's memory. The software evaluates the current conditions. The software then generates an output signal to control machine propulsion within set parameters.
The machine ECM has a self-diagnostic capability to assist in troubleshooting problems with the machine. The unit operates in one of three modes: mode "0", mode "1" and mode "2". Mode "0" is the operate mode. Mode "1" is the service mode. Mode "2" is the calibration mode.
The right side of LED display (6) on machine ECM (5) contains three indicators. The top indicator is the fault present indicator. The red fault present indicator illuminates when the machine ECM detects a fault in one of the input or output signals. The middle indicator is the calibrate mode indicator. The yellow calibrate mode indicator illuminates when the machine ECM is in mode "2". The bottom indicator is the power indicator. The green power indicator illuminates when the machine ECM receives electrical power.
When power is provided to machine ECM (5), the unit performs a self test. During the test, the number 888 flashes in LED display (6), and all three indicators illuminate. This is followed by the software version number and then "-0-". The "-0-" indicates that the machine ECM is in mode "0". After the self test is completed and if no faults are present, the LED displays the letter "P" followed by two dashes. The "P" followed by the two dashes remains on the LED until the power source is removed, or until the machine ECM mode is changed.
Note: If the machine ECM is faulty, the fault present indicator will flash, but the LED will not display a fault.
40-Pin Connector
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| Illustration 3 | g01229161 |
Illustration 3 shows the 40-pin connector of the machine ECM. Arrows which point into the connector indicate input signals to the machine ECM. Arrows which point away from the connector represent output signals from the machine ECM. Arrows that point both into and out of the connector represent data transfer lines between the machine ECM and the other electronic control modules on the machine. The machine ECM receives power at terminal "1". The unit is grounded at terminal "2".
The control functions of the machine ECM system can be divided into the following five groups:
- Propel control
- Load control
- Steering control
- Rotor control
- Water spray control
In order to control the propel system, the machine ECM gathers input from the following components:
- The propel direction switches (terminal "14" and terminal "15")
- The propel lever (terminal "27")
- The parking brake switch (terminal "25" and terminal "12")
- The Cat Data Link (terminal "8" and terminal "9")
The software analyzes the input and the software determines whether an output signal should be sent to the following components:
- The forward EDC (terminal "11")
- The reverse EDC (terminal "10")
- The backup alarm (terminal "31")
Engine Electronic Control Module (ECM)
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| Illustration 4 | g01229163 |
(8) Engine ECM (9) "J2" connector (10) "J1" connector | |
Engine ECM (8) controls the engine. The engine ECM is located on the front of the engine. Similar to the machine ECM, the engine ECM receives input from sensors around the machine. The engine ECM then compares the input signals to parameters already stored in the software. Then the engine ECM generates an appropriate output response for the current conditions.
The software inside the engine ECM stores operating maps which define horsepower, torque curves, rpm, and other operating parameters. These maps provide the logic necessary for the engine ECM to operate the engine at the proper setting.
The engine ECM has a self-diagnostic capability to assist in troubleshooting engine problems. When the Caterpillar Monitoring System (CMS) is in the diagnostic mode, the CMS panel displays fault information from the engine ECM.
Engine ECM Connectors
The engine ECM has two connectors, "J1" connector (10) and "J2" connector (9). The "J1" connector receives input signals from machine components. The "J2" connector receives input signals from engine components.
Note: Refer to the engine service manual modules for additional information about the engine and the engine ECM.
Cat Data Link
Engine ECM (8) receives power at terminal "J1-48" and at terminal "J1-52". The unit is grounded at terminal "J1-61" and terminal "J1-63". The Cat Data Link lines transfer information from terminal "J1-8" and terminal "J1-9" to the machine ECM.
Load Control Logic
In the propel system, the engine ECM transfers an engine speed signal to the machine ECM. The machine ECM uses this signal in order to evaluate the current load on the machine. The machine ECM automatically adjusts propel speed in order to maintain an optimum engine speed.
Propel Lever Sensor
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| Illustration 5 | g01229174 |
Propel Lever Sensor (11) is Located Under the Propel Lever. (11) Propel lever sensor | |
Propel lever sensor (11) is located under the left side of the instrument panel. The sensor is mounted to the pivot shaft of the propel levers.
Propel lever sensor (11) provides a pulse width modulated input signal to the machine ECM. The machine ECM then generates an output signal which is proportional to the position of the propel levers. The output signal controls the pump EDC.
Circuit breaker "CB2" transfers power to contact "A" of the propel lever sensor. Contact "B" of the sensor is grounded at terminal "39" of the machine ECM. Contact "C" of the sensor sends an input signal to terminal "27" of the machine ECM.
Hydraulic Components
Charge Filter
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| Illustration 6 | g01229232 |
The Charge Filter is Located Left of the Center Pedestal in the Engine Compartment. (12) Charge Filter | |
Charge filter (12) is located in the engine compartment. The charge filter is on the left side of the center pedestal. The charge pump directs oil through the charge filter.
Filtered oil is directed to the following locations:
- Port "M3" of the propel pump
- Port "P2" of the center manifold
- Port "S" of the flow divider valve
The base of charge filter (12) contains a bypass valve. If the pressure differential across the filter is greater than 345 kPa (50 psi), the bypass valve will open. Charge oil is sent directly to the hydraulic tank.
Center Manifold
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| Illustration 7 | g01229234 |
(13) Charge pressure tap (14) Shift solenoid | |
Charge pressure tap (13) is located on the right side of the center manifold. The ports on the center manifold are marked for identification. The charge pressure tap is installed in port "CH" of the manifold.
Charge pressure is equal to the pressure differential between port "CH" of the center manifold and the case drain of the propel pump. The differential pressure should be 2410 ± 69 kPa (350 ± 10 psi).
Shift solenoid (14) is located on the front face of the center manifold. This solenoid controls the flow of charge oil to the shift passages of the propel motors. The shift switch on the instrument panel controls the shift solenoid. When the shift switch is in the HIGH position, the shift solenoid is energized.
Rear Manifold
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| Illustration 8 | g01229237 |
(15) Pressure reducing valve (16) Parking brake solenoid | |
The rear manifold is mounted to the leg tower which is located at the rear left corner of the machine. Parking brake solenoid (16) is mounted to the right face of the manifold.
The parking brake switches on the instrument panel control parking brake solenoid (16). When both parking brake switches are in the OFF position, the brakes are released.
Pressure reducing valve (15) limits the pressure which is available to release the parking brakes. This pressure is limited to 6900 kPa (1000 psi).
Flow Divider
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| Illustration 9 | g01229259 |
Behind the Engine at the Right Side of the Machine (17) Flow divider valve (18) Block (flow divider solenoid) (19) Line relief and makeup valves | |
Flow divider valve (17) is located behind the engine on the left side of the machine. The ports on the manifold are marked for identification.
Flow divider valve (17) is equipped with the following components:
- Four line relief and makeup valves (19)
- Flow divider control spool
- Flow divider solenoid
The flow divider solenoid is located on the bottom of block (18) .
The line relief and makeup valves direct pressure surges in the motor supply lines into the charge circuit. Also, if the pressure in any of the supply lines falls below charge pressure, the makeup section of the valve opens, and charge oil is directed into the supply line.
The flow divider switch on the instrument panel controls the flow divider solenoid. When the switch is in the OFF position, the flow divider solenoid is de-energized. When the flow divider switch is in the ON position, the flow divider solenoid is energized. When the flow divider solenoid is energized, an equal amount of oil flows through each propel motor.
Undercarriage Components
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| Illustration 10 | g01229022 |
(19) Spring (20) Track Tension Cylinder (21) Track Shoes (22) Final Drive (23) Sprocket (24) Track Rollers (25) Front Idler | |
The machine is equipped with four legs. Each leg is equipped with an undercarriage group. The rotating components of each undercarriage group include the following components that are mounted to final drive (22) .
- A single piece drive sprocket (23)
- Four track rollers (24)
- Front idler (25)
The track group is made up of 26 padded track shoes (21) which are mounted to the drive chain assembly. The drive chain assembly consists of two chains which are joined with pins and bushings through a compression fit.
Front idler (25) and track rollers (24) ride on the rails of the chains. Drive sprocket (23) rides on the bushing which connects the chains together.
Track tension is achieved through the use of tension cylinder (20) with shock absorbing spring (19). Each undercarriage is equipped with a track tension cylinder. Each cylinder is equipped with a spring. The tension cylinders are mounted between the track frame and the front idler shaft. The tension cylinder is filled with grease.