starter motors 4841 electrical

Stater motors

Pull in and hold in windings

This week in class we went through starter motors, we leant that when the ignition key is turned electricity from the battery triggers the starter motor solenoid that engages the pull in windings. When the pull in windings are engaged it completes a circuit on the contacts which activates the hold in winding, the plunger shifts back and moves the shift lever towards the clutch. The pinion drive gear then slide into the ring gear teeth on the flywheel, the pinion drive gear then rotates and turns the flywheel until the engine is started. When the ignition is turned off the circuit is then broken and the hold in winding are no more and the pinion drive gear is moves back in a helix rotation.

 Bench test

We first had to test the starter motor on the bench test and get a volt and amperage readings we got 11.9v and 33.8 amps which meets the specs.

Visual inspection

We then carried out visual check on the armature and field coils, pole shoes we checked for overheating, burning, physical damage and poling we found none of these in the inspection.

Readings

We got reading for the ground test from the commutator segments and the armature core shaft 1k or infinity which means that there is low resistance so more amps can flow through.

Armature continuity test

Armature continuity test gave us a reading of 0.01 ohms again good for conduction.

Commutator diameter

When we measured the diameter of the commutator we got 32mm which is above the specs of 26.8 – 31 we aren’t Shure why but could be because of overheating.

Brush readings

All our 3 brush readings were 5mm and were not worn or damaged and are in good condition.

solenoid magnetic switch

We tested the pull in winding on the solenoid by connecting negative on the M and back out the pull in windings were functioning correctly. We obtained a 10amp reading which meets the specs.

hold in test

In the hold in windings we had to connect the positive to the S terminal and earth the negative to the body of the solenoid, in result the solenoid plunger pulled in and held in we also got a reading of 8 amps which meets the specs.

Putting the alternator together

When we assembled the alternator together we accidently pulled out wirings on the brush connections. We had to solder the wire back together and assemble it. When we carried out a bench test there was an increase in voltage and amperage from the last test 33.8amps to 45.1 amps and 11.9v to 12.26v this could be a result of the soldering we did