Troubleshooting Electromagnetic Clutches and Brakes

This 22 minute video will help you on your way to troubleshooting electromagnetic clutch and brake issues. The video is conveniently broken down into sections. You can jump to the following sections that deal with slippage: Excessive slipping - 16:45
Excessive slipping from electrical - 17:19 Excessive slipping from contamination - 18:32
Excessive slipping from the application or lack of burnishing - 19:08

Potential Problem Possible Reason Solution
Low voltage going into the clutch. Defective battery. Check with voltmeter, battery should be 8-16 volts. (Assuming 12 volt battery.)
Lead wire cut which could be intermittently grounding out the lead wire causing the clutch to turn on and off or not to give full voltage.
Fix or replace lead wire.
Erratic engagement. If lead wire is kinked or pinched and the break is internal, the clutch operation may show up as being erratic engagement.
Fix or replace lead wire.
Clutch is contaminated. Oil or other lubricant has been sprayed on the clutch surface. Sometimes this shows up after the clutch is disassembled. Physical evidence is either burnt oil or a greasy metallic surface showing oil still present.
Clean off surfaces with solvent and re-burnish. Replace the clutch if damage is severe enough.
Clutch overloaded. Output torque required is greater than what the clutch can handle. If input torque going into clutch is greater than the output torque required, the clutch will slip. If it slips too long, the clutch surfaces will be galled Size clutch correctly for the application. Replace clutch.
Output stalled. If output is stalled, clutch could slip to the point where it will burn up and destroy either bearings or the field. Replace clutch.
If voltage is going to the clutch, but the clutch will still not engage. Coil open or shorted. Check coil with ohmmeter. A range close to 3 to 4 ohms should be present at an ambient coil temperature of 70\uffffF. Replace coil.
Clutch not burnished. If full torque is required immediately and clutch is not burnished, it will slip and could become galled. Try to re-burnish clutch. If slipping is to severe, clutch will have to be replaced.