CUSHION AS 9C4130 - Caterpillar

Start Circuit
The 3Y7571 Start Switch sends power to activate the starter relay. The starter relay sends power to activate the starter solenoid and motor, to start the vehicle engine.On machines with a 3 forward-1 reverse speed transmision, there is a 9P9520 transmission switch that is closed when the transmission is in neutral, and open when the transmission is in gear. The switch is in series with the start relay so that it will not activate if the transmission is in gear.
Figure 1. Start CircuitStarting Aid Circuit
The starting aid circuit has a switch on the instrument panel. There is also a 5N5899 Temperature Switch in the circuit. The temperature switch opens when the engine temperature goes up to 100°F (38°C) and closes when the temperature goes below 80°F (27°C).When the starting aid switch is pushed, power is sent to the solenoid of the ether aid valve assembly. If the temperature switch is closed it makes a ground for the circuit, the solenoid is activated, and the valve assembly sends a specific volume of ether to the engine. The temperature switch opens (when the engine is hot) so that ether can not be put in a hot engine.
Figure 2. Starting Aid CircuitBack-Up Alarm
The back-up alarm system has a 5P8845 Alarm below the battery at the rear of the machine. Current for the alarm is sent through an oil pressure switch and activated, the oil pressure switch must be closed (engine in operation) and the reverse switch must be closed (transmission in REVERSE). The reverse switch is on the inside of the left hand control console and is activated by the transmission shift linkage.
Fig. 3. Back-up Alarm CircuitFront Horn Circuit
Power for the attachment front horn is sent through the main circuit breaker, through the ammeter, through the ON-START key switch, through a 10 amp fuse and through the horn switch. The horn switch is located on the left hand control console. The 10 amp fuse is in the left console. The key switch must be in the ON position for the horn to work.
Figure 4. Front Horn CircuitService Meter
Operation of the service meter is controlled by the 6N2466 Engine Oil Pressure Switch. When the engine is in operation, and the oil pressure gets to approximately 21 psi (145 kPa), the normally open contacts of the switch close and send power to the service meter. The current for the service meter is sent from the 40 amp main circuit breaker through the oil pressure switch, to the meter.The D3B and 931B use a 7N864 Electronic Service Meter. This meter has a solid-state (no moving parts) circuit which sends a timing pulse (current for a short time) every 3.6 seconds to the solenoid that moves the counter. The meter works on 12 or 24 volt negative ground systems.The 7N864 Meter has a very good service record. If the meter does not work, make sure that the red wire to the meter has + 12 volts with the machine in operation, and that the