Electrical System b. Solenoid Relay
c. Tooth to Tooth Abutment
The solenoid relay is mounted on the DE bracket with its axis parallel to that of armature. This contains a soft iron plunger, a pair of heavy duty copper studs forming fixed contacts, a moving contact made up of copper is carried on a non-magnetic spindle which is insulated to the contact plate. This also moves the drive assembly with the help of a lever and peg assembly which is pivoted on an eccentric pin screwed on the DE bracket. The electrical circuit diagram given below explains the connections of solenoid winding. The coil consists of two windings, a heavy gauge which is called pullin or series winding and a thinner gauge winding called hold-on or shunt winding. The pull in winding is connected through the field coil and armature to the ground. Whereas shunt is connected between smaller terminal on the solenoid phenolic moulded terminal base and ground. When the switch is closed both pull in and hold on windings get energised resulting in pulling in of plunger. At the end of the travel the main contacts get closed, connecting starter to battery. Simultaneously series winding gets short circuited between main contacts.
When the tooth to tooth abutment takes place the plunger movement is restricted because the drive movement is restricted. But the plunger is so designed that it can move in further closing the contacts connecting the starter to battery. When starter rotates, the pinion gets slipped into mesh by the force of the compressed engaging spring. d. The Lost Motion Device A feature of ‘Lost Motion’ is designed into engagement mechanism to allow the solenoid contacts to open before pinion retraction begins. This action depends upon the yielding of a weaker spring which forms the lost motion device, to the stronger system return spring of the plunger. The lost motion spring is carried in the plunger. The initial yielding results in the switch contacts being fully opened within the first 3.20 mm of plunger return travel- this action being followed by normal drive retraction. 3) Routine Maintenance 1)
2)
Ensure that the mounting bolts are securely fastened and all electrical connections are clean and tight. Cables should be examined for fractures.
4) STARTER MOTOR DO’S AND DONT’S DO’s
DONT’s
Ensure that all electrical connections in the circuit including the battery are clean and secure.
Do not operate the starter motor when the engine is running as this could result in damaging the starter motor and flywheel ring gear.
Observe correct polarity, i.e. connect negative to negative and positive to positive.
Do not crank continuously. If the engine does not fire immediately, allow sometime to cool the starter motor before cranking again.
For earth return system, a twin wiring system between battery and starter motor should be used.
If still the engine does not start, ascertain the cause and do not drain the battery by cranking the starter motor.
The total resistance of the starter circuit including that of return path and junctions should not exceed 0.002 Ohm 200 C.
Do not inch (move) the vehicle using starter motor.
The main feed cable should be supported to prevent the cable weight and vibrations from coming on to the electrical terminals.
Do not disconnect battery cables while the engine is running.
While washing the vehicle with high pressure gun starter motor should be suitably protected.
Do not subject the starter motor to continuous oil / water drip.
ROUTINE MAINTENANCE • Ensure that the starter motor mounting bolts are securely fastened. • Check and ensure that all electrical connections are firmly tightened. • Examine cables for fractures / cracks particularly at the terminal lugs. G-22
35 Series 4WD, Model - 3535, 4035, 4535 and 5035 SM June’08
