345B, 345B Series II and W345B Series II Excavators Engine and Pump Control Start and Stop Circuit Caterpillar


Start and Stop Circuit
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345B, 345B Series II and W345B Series II Excavators Engine and Pump Control [SENR1935]
ELECTRICAL AND STARTING SYSTEM
ALTERNATOR GP-CHARGING
345B, 345B Series II and W345B Series II Excavators Engine and Pump Control General Information (Electrical System)
345B, 345B Series II and W345B Series II Excavators Engine and Pump Control Start and Stop Circuit

Note: The following schematics are typical examples. Refer to the Electrical System Schematic for the machine that is being serviced for the most updated information.




Illustration 1g00672484

Schematic For The Start/Stop Circuit For The 345B

(5) Main relay

(10) Engine ECM

(11) Starter switch

(12) Neutral start switch

(19) Starter motor

(20) Starter relay

(29) Timer relay

(30) Neutral start relay

(36) Starter solenoid




Illustration 2g00672625

Schematic For The Start/Stop Circuit For The 345B

(5) Main relay

(10) Engine ECM

(11) Starter switch

(12) Neutral start switch

(19) Starter motor

(20) Starter relay

(29) Timer relay

(30) Neutral start relay

(36) Starter solenoid

The start/stop circuit is used to start the engine and the start/stop circuit is used to stop the engine. The following items are included in the start/stop circuit:

  • Starter control relay

  • Starter relay

  • Starter motor

  • Timer relay

  • Start switch

  • Governor actuator

  • Neutral start relay

  • Neutral start switch

Current is allowed to flow through the timer relay and the neutral start switch to the neutral start relay when the starter switch is placed in the ON position and the control lever is in the LOCKED position. The coil of the neutral start relay is energized. Current flows through the neutral start relay to the starter relay when the starter switch is placed in the START position. The contacts of the starter relay close and current flows to terminal "S" of the starter solenoid from the starter relay.

Note: Current will not pass through the starter relay if the starter switch is placed in the ON position and the control lever is NOT in the LOCKED position.

Current from the battery will flow through the starter solenoid to the starter motor when the contacts of the starter solenoid are closed.

After the engine has started, the alternator will begin to produce electricity. A current signal is sent from the "P" terminal of the alternator to the "P" terminal of the starter relay. Terminal "S" of the starter control relay will open and the coil of the starter relay will be deactivated. Then, the starter motor will stop operating. This action is designed to prevent the starter motor from rotating too fast.

The timer relay will supply power for a specific amount of time after the start switch is placed in the OFF position. When the starter switch is moved to the START position, the engine receives fuel from the injectors.

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