Screed Lift Circuit
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| Illustration 1 | g01189837 |
Note: The electrical system on this machine is wired according to the Caterpillar corporate wiring system. In Caterpillar corporate wiring each wire has a color and a number. Each color and number has a specific meaning.
The color system is as follows:
- Red wires are positive
- Black wires are negative
- Orange wires are found in starting circuits
The numbering system is as follows:
- 100 wires are power circuits
- 200 wires are ground
- 300 wires are machine basic circuits
- 400 wires are monitoring circuits
- 500 wires are accessory circuits
- 600 wires are lighting circuits
- 700-999 wires are control circuits
When the main power relay is energized, power is available at the implement circuit breaker and at the propel circuit breaker. The implement circuit breaker transfers power to contact "5" of the left screed lift switch. Power also transfers from the implement circuit breaker to contact "30" of the number three operator station select relay. The propel circuit breaker transfers power to the left operator station status indicator and to the right operator station status indicator. The propel circuit breaker also transfers power to contact "2" of the operator station selector switch.
The machine ECM monitors the circuits at terminal "J2-30" and terminal "J2-31" in order to determine the position of the operator station selector switch. When the operator station selector switch is in the LEFT position, the circuit at terminal "J2-30" is complete. When the operator station selector switch is in the RIGHT position, the circuit at terminal "J2-31" is complete.
The machine ECM analyzes the input from the operator station selector switch in order to control the following components:
- The number three operator station select relay
- The left operator station status indicator
- The right operator station status indicator
The condition of the number three operator station select relay determines whether the screed lift control at the left control station or the screed lift control at the right control station is active.
When the operator station selector switch is in the LEFT position, the machine ECM does not energize the coil of the number three operator station select relay. Under this condition, the machine ECM closes the circuit at terminal "J2-32", and the left operator station status indicator illuminates.
When the operator station selector switch is in the RIGHT position, the machine ECM generates an output signal from terminal "J2-14" to the coil of the number three operator station select relay. Under this condition, the machine ECM also closes the circuit at terminal "J2- 33", and the right operator station status indicator illuminates.
When the operator station select relay is de-energized, power transfers from contact "30" to contact "87a" of the relay. This power becomes available at contact "2" of the left screed lift switch. When the operator station select relay is energized, power transfers from contact "30" to contact "87" of the relay. This power becomes available at contact "2" of the right screed lift switch.
The screed lift function is controlled across the following switch contacts:
- Contact "1" of the right screed lift switch
- Contact "2" of the right screed lift switch
- Contact "2" of the left screed lift switch
As previously described, the operator station select relay controls the power supply to contact "2" of the screed lift switches. When the active screed lift switch is in the LIFT position, power transfers from contact "1" of the active switch to the screed lift solenoid.
The screed float function is controlled by the following switches:
- The left screed lift switch
- The right screed lift switch
- The screed counterbalance switch
These switches are wired in series. Therefore, all three switches must be in the FLOAT position in order for the screed float solenoid to be energized.
When the left screed lift switch is in the FLOAT position, contacts "5" and "6" of the switch are closed. Under these conditions, power is transferred to contact "5" of the right screed lift switch. When the right screed lift switch is in the FLOAT position, contacts "5" and "6" of the switch are closed. Under these conditions, power is transferred to contact "2" of the screed counterbalance switch. When the screed counterbalance switch is in the FLOAT position, contacts "2" and "3" of the switch are closed. Under these conditions, current is conducted through the screed float solenoid.
Note: The operator station selector switch has no impact on the screed float function.
The screed assist function is controlled by the following switches:
- The left screed lift switch
- The right screed lift switch
- The screed counterbalance switch
The switches that are listed above are wired in series.
The screed assist function will operate under the following conditions:
- Both screed lift switches must be in the FLOAT position
- The screed counterbalance switch must be in the ON position
When the left screed lift switch and the right screed lift switch are in in the FLOAT position, power is transferred to contact "2" of the screed counterbalance switch. When the screed counterbalance switch is in the ON position, contacts "1" and "2" of the switch are closed. Under these conditions, current is conducted through the screed float solenoid.
Note: The operator station selector switch has no impact on the screed assist function.
Screed Extend Circuit
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| Illustration 2 | g01189840 |
When the main power relay is energized, power is available at the implement circuit breaker and at the propel circuit breaker. The implement circuit breaker transfers power to contact "30" of the number three operator station select relay. The implement circuit breaker also transfers power to contact "2" of the following switches:
- Right screed extension switch on the right extension control box
- Right screed extension switch on the right screed operator station
- Left screed extension switch on the left extension control box
- Left screed extension switch on the left screed operator station.
The propel circuit breaker transfers power to the left operator station status indicator and transfers power to the right operator station status indicator. The propel circuit breaker also transfers power to contact "2" of the operator station selector switch.
The machine ECM monitors the circuits at terminal "J2-30" and terminal "J2-31" in order to determine the position of the operator station selector switch. When the operator station selector switch is in the LEFT position, the circuit at terminal "J2-30" is complete. When the operator station selector switch is in the RIGHT position, the circuit at terminal "J2-31" is complete.
The machine ECM analyzes the input from the operator station selector switch in order to control the following components:
- The number three operator station select relay
- The left operator station status indicator
- The right operator station status indicator
The condition of the number three operator station select relay determines whether the screed extension controls on the left control station or the screed extension controls on the right control station are active.
Note: The number three operator station select relay does not control the screed extension controls which are located on the screed.
When the operator station selector switch is in the LEFT position, the machine ECM does not energize the coil of the number three operator station select relay. Under this condition, the machine ECM closes the circuit at terminal "J2-32", and the left operator station status indicator illuminates.
When the operator station select relay is de-energized, power transfers from contact "30" to contact "87a" of the relay.
This power becomes available at contact "2" of the following components:
- Right screed extension switch on the left instrument panel
- Left screed extension switch on the left instrument panel
When the operator station selector switch is in the RIGHT position, the machine ECM generates an output signal from terminal "J2-14" to the coil of the number three operator station select relay. Under this condition, the machine ECM also closes the circuit at terminal "J2- 33", and the right operator station status indicator illuminates.
When the operator station select relay is energized, power transfers from contact "30" to contact "87" of the relay.
This power becomes available at contact "2" of the following components:
- Right screed extension switch on the right instrument panel
- Left screed extension switch on the right instrument panel.
The extension control switches on the instrument panel are wired in parallel circuits with the extension control switches on the screed. When a right screed extension switch is in the EXTEND position, power transfers to the right screed extend solenoid. When a right screed extension switch is in the RETRACT position, power transfers to the right screed retract solenoid.
When a left screed extension switch is in the EXTEND position, power transfers to the left screed extend solenoid. When a left screed extension switch is in the RETRACT position, power transfers to the left screed retract solenoid.
Grade Control Circuit
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| Illustration 3 | g01189841 |
The grade circuit breaker distributes power to the following components:
- Contact "2" of the left tow point switch which is on the tractor
- Contact "2" of the right tow point switch which is on the tractor
- Contact "30" of the grade and slope relay
- Contact "B" of the right grade and slope interface connector
- Contact "B" of the left grade and slope interface connector.
The left extension circuit breaker distributes power to the following components:
- Contact "2" of the left tow point switch which is on the screed
- Contact "2" of the right tow point switch which is on the screed.
The right tow point switch which is on the screed is wired in a parallel circuit with the right tow point switch which is on the tractor. The left tow point switch which is on the screed is wired in a parallel circuit with the left tow point switch which is on the tractor.
When either left tow point switch is in the UP position, the K793-BU wire transfers power to the left tow point raise solenoid. When either left tow point switch is in the DOWN position, the K792-GN wire transfers power to the left tow point lower solenoid.
The right tow point switches operate in the same manner as the left switches. The K795-BR wire transfers power to the right tow point raise solenoid when one of the right tow point switches is in the RAISE position. The K794-YL wire transfers power to the right tow point lower solenoid when one of the right tow point switches is in the LOWER position.
The machine ECM controls the coil of the grade and slope relay. This relay controls the automatic grade and slope controls, if equipped. The machine ECM provides a three to five second delay between the time the propel lever is moved into the FORWARD range and the time the grade and slope system is allowed to take over control. When the coil of the grade and slope relay is energized, current is conducted through the coil of the automatic grade and slope relay.
Truck Hitch, Auger Lift, and Hopper Circuits
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| Illustration 4 | g01189844 |
When the main power relay is energized, power is available at the implement circuit breaker and at the propel circuit breaker. The implement circuit breaker transfers power to contact "30" of the number three operator station select relay.
The propel circuit breaker transfers power to the left operator station status indicator and to the right operator station status indicator. The propel circuit breaker also transfers power to contact "2" of the operator station selector switch.
The machine ECM monitors the circuits at terminal "J2-30" and at terminal "J2-31" in order to determine the position of the operator station selector switch. When the operator station selector switch is in the LEFT position, the circuit at terminal "J2-30" is complete. When the operator station selector switch is in the RIGHT position, the circuit at terminal "J2-31" is complete.
The machine ECM analyzes the input from the operator station selector switch in order to control the following components:
- The number three operator station select relay
- The left operator station status indicator
- The right operator station status indicator
The condition of the number three operator station select relay determines whether the screed extension controls on the left control station or the screed extension controls on the right control station are active.
Note: The number three operator station select relay does not control the screed extension controls which are located on the screed.
When the operator station selector switch is in the LEFT position, the machine ECM does not energize the coil of the number three operator station select relay. Under this condition, the machine ECM closes the circuit at terminal "J2-32", and the left operator station status indicator illuminates.
When the operator station select relay is de-energized, power transfers from contact "30" to contact "87a" of the relay.
This power becomes available at contact "2" of the following components:
- Auger lift switch on the left instrument panel
- Hopper control switch on the left instrument panel
- Truck hitch control switch on the left instrument panel.
When the operator station selector switch is in the RIGHT position, the machine ECM generates an output signal from terminal "J2-14" to the coil of the number three operator station select relay. Under this condition, the machine ECM also closes the circuit at terminal "J2- 33", and the right operator station status indicator illuminates.
When the operator station select relay is energized, power transfers from contact "30" to contact "87" of the relay.
This power becomes available at contact "2" of the following components:
- Auger lift switch on the right instrument panel
- Hopper control switch on the right instrument panel
- Truck hitch control switch on the right instrument panel.
The active truck hitch switch controls the truck hitch solenoids. When the active truck hitch switch is in the OPEN position, the 872-YL wire transfers power to the truck hitch open solenoid. When the active truck hitch switch is in the CLOSE position, the 870-OR wire transfers power to the truck hitch close solenoid.
The active hopper switch controls the hopper solenoids. When the active hopper switch is in the UP position, the A859-PU wire transfers power to the hopper raise solenoid. When the active hopper switch is in the DOWN position, the A858-GN wire transfers power to the hopper lower solenoid.
The active auger switch controls the auger solenoids. When the active auger switch is in the UP position, the 787-WH wire transfers power to the auger lift solenoid. When the active auger switch is in the DOWN position, the 781-PK wire transfers power to the auger lower solenoid.