3.SELF-STARTER REMOVAL & DISASSEMBLY
An internal combustion (IC) engine converts the chemical energy of fuel to mechanical energy when it is running on the power developed in its own cylinders. An internal combustion engine, however, cannot start by itself and needs to be cranked before the four operations of suction, compression, power and exhaust take place. These days, the process of cranking is achieved with the help of an electric starter motor which is also called the self-starter.
3.0
Objectives After going through this lesson, you will be able to: Remove the self starter from the engine Disassemble the self starter Inspect commutator, armature, field coil, brush, brush holder, springs, magnetic switch and other mechanical components of the self starter.
i. ii. iii.
3.1
Introduction
The starter motor, shown in Fig. 3.1, draws a heavy current, of the order of 350 ampere, from the battery in order to produce a torque that is sufficient to crank the engine. This heavy current is conveyed to the motor by a heavy duty switch called the magnetic switch or the solenoid switch. In this lesson we will study the overhauling of the self-starter in detail and testing of the magnetic switch.
3.2 • •
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Fig. 3.1: Starter motor.
Removal Unlock the bonnet, lift it up and then hook it. Loosen the clamp at the negative terminal of the battery and disconnect the cable from the battery. Unscrew the nut at the heavy duty terminal ‘B’ at the magnetic switch, with the help of a No.12 ring spanner. Fig. 3.2: ‘S’ Terminal.