GEAR (25T.) 1H8438 - Caterpillar

7N9720 Alternator 24V 35A (Bosch Number 0-122-469-001); 9G9538 Alternator 24V 50A (Bosch Number 0-122-469-002)
7N9720 AlternatorThe solid state regulator used with the Bosch Alternator is totally enclosed and non-adjustable. If the rate of charge is not correct a replacement of the regulator is necessary.9G4574 24V 35A (Nippondenso Number 100211-0860); 6T7223 24V 50A (Nippondenso Number 100211-0890)
9G4574 AlternatorNo adjustment can be made to change the rate of charge on the alternator regulator. If rate of charge is not correct, a replacement of the regulator is necessary.Starting System
Use the multimeter in the DCV range to find starting system components which do not function.Move the start control switch to activate the starter solenoid. Starter solenoid operation can be heard as the pinion of the starter motor is engaged with the ring gear on the engine flywheel.If the solenoid for the starter motor will not operate, it is possible that the current from the battery did not get to the solenoid. Fasten one lead of the multimeter to the connection (terminal) for the battery cable on the solenoid. Put the other lead to a good ground. A zero reading is an indication that there is a broken circuit from the battery. More testing is necessary when there is a voltage reading on the multimeter.The solenoid operation also closes the electric circuit to the motor. Connect one lead of the multimeter to the solenoid connection (terminal) that is fastened to the motor. Put the other lead to a good ground. Activate the starter solenoid and look at the multimeter. A reading of battery voltage shows the problem is in the motor. The motor must be removed for further testing. A zero reading on the multimeter shows that the solenoid contacts do not close. This is an indication of the need for repair to the solenoid or an adjustment to be made to the starter pinion clearance.Make a test with one multimeter lead fastened to the connection (terminal) for the small wire at the solenoid and the other lead to the ground. Look at the multimeter and activate the starter solenoid. A voltage reading shows that the problem is in the solenoid. A zero reading is an indication that the problem is in the start switch or the wires for the start switch.Fasten one multimeter lead to the start switch at the connection (terminal) for the wire from the battery. Fasten the other lead to a good ground. A zero reading indicates a broken circuit from the battery. Make a check of the circuit breaker and wiring. If there is a voltage reading, the problem is in the start switch or in the wires for the start switch.A starter motor that operates too slow can have an overload because of too much friction in the engine being started. Slow operation of the starter motor can also be caused by a short circuit, loose connections and/or dirt in the motor.Pinion Clearance Adjustment (Delco-Remy)
When the solenoid is installed, make an adjustment of the pinion clearance. The adjustment can