PLATE-FRICTION 0998183 - Caterpillar

Armature Short Circuit Test
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Armature short circuit check (3) Armature assembly (A) Armature Testing Gp
Place the armature assembly (3) on the Armature Testing Gp (A). Turn on the tester.
Hold a hacksaw blade against the armature core. Slowly rotate the armature.
The blade should not vibrate. The blade should not be attracted to the armature core.
If the blade vibrates or if the blade is attracted to the core, the armature assembly has a short. The armature assembly must be rebuilt or replaced.Armature Ground Test
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Armature winding ground test (3) Armature assembly
Put the Digital Multimeter on the "20M" resistance scale. Touch one meter lead on a commutator bar and the other lead on the armature core.
Each reading should be greater than 100,000 ohms.
If the meter reading is lower than 100,000 ohms, the armature assembly is grounded and the armature assembly must be rebuilt or replaced.Armature Continuity Test
Testing for an open circuit in the armature is difficult without special equipment. If the commutator shows signs of pitting, the armature assembly has an open circuit and the armature assembly must be replaced. If any of the commutator bars are black, the armature assembly has an open circuit and the armature assembly must be replaced.Armature Runout Check
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Armature runout check (4) Commutator (5) Core
Check the armature assembly runout (TIR). The maximum indication that can be measured is given below: (4) Commutator ... 0.03 mm (0.001 inch) (5) Core ... 0.10 mm (0.004 inch)
If the armature assembly runout is greater than the values above, the armature assembly must be replaced.Commutator Outside Diameter Check
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Commutator outside diameter check (4) Commutator
Check the outside diameter of the commutator (4) with the Dial Caliper As. The diameter should have a value:New diameter ... 45 mm (1.77 inch)Minimum diameter ... 42.5 mm (1.67 inch)
If the armature assembly is worn, the armature assembly must be replaced.
Illustration 5 g00720043
Depth of insulation between commutator bars (X) 0.8 mm (.03 inch)
Measure the depth of insulation between the bars of the commutator (4). The minimum depth (X) should be 0.8 mm (0.03 inch).
Failure to remove the insulation shavings and particles will cause the brushes to wear at a fast rate.
If the depth is under the minimum, the insulation must be undercut. If the insulation is undercut, remove all shavings with forced air and remove all insulation particles with forced air.