ELBOW 8T6684 - Caterpillar

Illustration 1 g03157018
Typical example
(1) Pilot air solenoid
(2) Starter inlet
(3) Exhaust muffler
(4) Controller The Integral Electronic Controller (IEC) shares control with the engine control system. This control sharing helps provide consistent operation and greater starter reliability. The IEC provides Electronic Starter Protection (ESP) by monitoring starter performance and operation to help prevent damage and excessive wear.Pressurized supply air that is present at the starter inlet valve is routed by a control line to the normally closed pilot air solenoid valve.When the pilot air solenoid is activated for start-up, the solenoid opens the connected valve. The valve allows the pressurized pilot air to engage the air starter pinion gear.When the pinion is fully engaged, pilot air pressure is directed to the starter relay valve. The supply air pressure fully opens the starter relay valve which allows pilot air pressure to flow through the turbine and crank the engine.When the engine starts to run, the engine ring gear will back drive the starter pinion gear. When the pinion speed reaches 2800 rpm, the starter ESP interrupts the electronic signal to the air solenoid. The interruption prevents excessive back driving, and starter overspeed. When the ESP interrupts the signal, the main relay valve closes and disengages the pinion.When the engine control senses the crank terminate speed, the starting motor solenoid is de-energized. The control valve closes in order to shut off the main supply of pressurized air to the starting motor.A manual bypass button on the pilot air solenoid will allow the starter to be operated without electrical power and control voltage.
When using the manual bypass, starter overspeed and/or improper starter engagement can occur. Only use the manual bypass in emergencies. Do not use the manual bypass for normal starting.