How to test an armature - Motorsports

Measuring across the commutator opposites is a rough check - if each pair has the same resistance it is probably good but even then there are no guarantees. I have never seen the armature resistance stated for any motor though that doesn't mean such figures don't exist.

It would seem logical that each pair should be isolated but that generally is not how the armature is wired and each commutator segment is the termination of two coils.

In reality there is only three ways to test an armature - either build it into a motor and see if it performs ok, use an automated motor fault analysis machine or one of the dedicated armature testers such as an armature growler.

If it hasn't been used for a while, the contacts on the armature may have oxidized. Use a pencil eraser or 1000 grit emery cloth to make the area where the brushes contact the armature SHINY. If the armature rotor contacts are shiny and it still sparks, make sure that all of the windings measure the same. Excessive sparking is a sign the armature is going

it is most likely the armature. You can test the coils with a meter set to ohms. http://www.appliancepartspros.com/motor-control-parts-for-whirlpool-k5ss.html

YES
starters can develop a dee bar on the commutator where that circuit is not completed to allow the current to flow
pull it and have an accredited bike electrician bench test it and test armature and field coils

I would be prepared to pull the starter and have it bench tested for a dry joint on one of the windings of the armature. If the armature stops spinning and this winding is under the brush there will be nothing until the armature moves until the brush can make contact with the next winding and then it will spin. The test will show if the solenoid is faulty

Go on E-bay for electrical test equipment and look for growler.or go google and type in armature growler test equipment and see what you get.

I would like you to make sure that the brushes are indeed touching the armature. It is possible that the brush holder is not allowing free brush movement through them, and that would cause this problem. If that checks ouf fine, I would make sure the cord is in good condition, and you are certain you dont have an intermittant break in the cord. Your next step will be checking the condition of the field leads, and continuity of the bars on the armature. Pull the brushes, and remove the 4 long bolts that hold the motor housing on to the saw. There will be another bolt that connects the housing to the upper guard. After you slide that back(if you meet resistance it is the 608 bearing on the back of the armature). The armature will stay fixed to the rest of the tool. You will then take a continuity tester and test from one copper communtator bar to another, until you have tested them all. I would imagine you have a dead bar on the armature, and you will know this when you test between it, and another bar, and there is no response from the tester. Let me know if this works. If not, please post back.

put your test probs on the armature and hold them were the brushes tuch on eather side you should get a reading from all of them "one at a time" check the commutator for burn marks or big gaps,,,if there there scrap the motor,

Starter - There are like 2 or 3 bolts on most starters that are long and go into the engine block. Then there is the electrical positive connection which should be removed only after the battery has been disconnected to avoid shock and fire caused by a short in the electrical system when disassembling or assembling (warning: this a safety measure designed to keep you from hurting yourself or the car). Assembly is the reverse of the removal.
TESTING No-Load Test Make the connections as shown in the illustration. Close the switch and compare the rpm, current and voltage readings with the specifications found in the chart located in this section. Fig. 1: Proper connections for the starter no-load test

• Current draw and no load speed within specifications indicates normal condition of the starter motor.
• Low free speed and high current draw indicates worn bearings, a bent armature shaft, a shorted armature or grounded armature fields.
• Failure to operate with high current draw indicates a direct ground in the terminal or fields, or frozen bearings.
• Failure to operate with no current draw indicates an open field circuit, open armature coils, broken brush springs, worn brushes or other causes which would prevent good contact between the communtator and the brushes.
• A low no load speed and low current draw indicates high internal resistance due to poor connections, defective leads or a dirty commutator.
• High free speed and current draw usually indicate shorted fields or a shorted armature.

check the thrust plate at the end of the armature inside the gearbox any sign of wear replace, take the gear and lever out and test to see if the noise is still there if it is it could be either a faulty bearing or a faulty armature (armatures can run out of balance) all clipper repair parts for the oster are at www.angliaclipperservices.com .