RA1.2, R1.4, R2.0, R2.2, R2.5, R2.7, R3.0, R4.5 and R5.5 Series Reduction Starting Motors Caterpillar

A visual check of the field windings should be done first. Check for wear and damage. Check all of the connections for imperfections in the solder joints.

Field Winding Ground - Test

Illustration 1	g00584871
Field Winding Ground Test (1) Field winding leads. (2) Motor (Mtr) terminal lead.

1. Place the multimeter in the "20M" position. Touch the multimeter leads between each field winding lead (1) and the case of the starting motor.

2. Touch the multimeter leads between the motor terminal lead (2) and the case of the starting motor.

3. Each reading should be greater than 100,000 ohms. The multimeter should read "0.10" or a value that is greater.

4. If the meter reading is less than 100,000 ohms, the field winding is grounded. The case of the starting motor and field windings must be replaced.

Field Winding Continuity - Test

Illustration 2	g00584873
Field Winding Continuity Test (1) Field winding leads. (2) Terminal lead.

1. Place the multimeter on the "200 ohm" scale. Touch the meter leads between field winding leads (1).

2. Touch the meter leads between each field winding lead (1) and motor terminal lead (2).

3. Each reading should be 00.0 to 00.1 ohms.

4. If the meter reading is higher than the meter reading in 3, there is an open in the field winding. The case of the starting motor and the field windings must be replaced.

Armature Short Circuit - Test

Illustration 3	g00584876
Armature Short Circuit Check (3) Armature. (4) Growler tester.

1. Place armature (3) on growler tester (4). The tester needs to be turned to the ON position.

2. Hold a hacksaw blade against the armature core. Slowly rotate the armature while the blade is against the core.

3. The blade should not vibrate or the blade should not be attracted to the armature core.

4. If the blade vibrates or the blade is attracted to the core, the armature has a short. The armature must be rebuilt or replaced.

Armature Ground - Test

Illustration 4	g00584879
Armature Winding Ground Test (3) Armature.

1. Place the multimeter in the "20M" position. Touch one meter lead on each commutator bar and the other lead on the armature core.

2. Each multimeter reading should be greater than 100,000 ohms. A meter reading of "0.10" or a value that is greater is acceptable.

3. If the meter reading is lower than 100,000 ohms, the armature is grounded. The armature must be rebuilt or replaced.

Armature Continuity - Test

Special equipment is needed to test the armature for an open. If the commutator is pitted or the bars are burned, the armature has an open. The armature must be replaced.

Armature Runout - Check

Illustration 5	g00584880
Armature Runout Check (5) Commutator.

1. Check the runout of the armature (TIR) of the commutator (5). The maximum TIR that is allowed is 0.05 mm (0.0020 inch).

2. If the TIR is too great, the armature must be replaced.

Commutator Outside Diameter - Check

Illustration 6	g00584882
Commutator Outside Diameter Check (5) Commutator.

1. Check the outside diameter of commutator (5). The new diameters of the commutator and the minimum diameters of the commutator are provided in the Specifications section.

2. If the armature is worn, the armature must be replaced.

Show/hide table



Illustration 7	g00584885
Depth Of Segment Mica (X) Depth of segment mica.

3. Measure the depth of commutator segment mica. The minimum depth should be 0.20 mm (0.008 inch).

Show/hide table

NOTICE
Keep all parts clean from contaminants. Contaminants may cause rapid wear and shortened component life.

4. If the depth is under the minimum, the mica can be undercut. If the mica is undercut, remove all shavings and mica particles.

Brush Holder - Test

Illustration 8	g00584915
Brush Holder Insulation Test (6) Brush holder plate. (7) Brush holder. (8) Brush spring.

1. Check the brush holder springs (8) for damage or rust. If necessary, replace the brush holder springs.

2. Place the multimeter in the "20M" position. Touch one meter lead to each positive brush holder (7) and the other lead to brush holder plate (6). Check both positive brush holders.

3. Each multimeter reading should be greater than 100,000 ohms. A meter reading of "0.10" or a value that is greater is acceptable.

4. If the meter reading is less than 100,000 ohms, the brush holder is grounded. The brush holder must be replaced.

Brush Length - Check

Illustration 9	g00584917
Brush Length Measurement (X) Brush Length.

1. Measure brush length (X) for wear. The new brush lengths and the minimum brush lengths are provided in the Specifications section.

2. If the brushes are worn below the minimum length, replace the brush holder and starting motor case.

Overrunning Clutch - Check

Illustration 10	g00584919
Overrunning Clutch Check (9) Housing (10) Pinion.

1. Visually inspect the overrunning clutch for damage.

2. Hold housing (9) and turn pinion (10) in the direction of operation. A clicking noise should be heard during this check.

3. Hold housing (9) and turn pinion (10) in the opposite direction of operation. In order to prevent rotation, the pinion should be locked.

4. Hold housing (9) and press pinion (10) into the housing. The pinion should be pressed completely into the housing. The pinion must spring back into the rest position.

5. If any of the checks in 1- 4 are not correct, replace the overrunning clutch.