PWM solenoids: failure due to contamination
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1. Contamination sources of PWM solenoids are the same as on/ off solenoids.
- parts failure
- fuzzy magnet
- solenoid screen filter contamination
- permagunk (friction material accumulating in low flow areas)
2. Tiny particles of metal and other debris will erode the sealing surfaces of a solenoid. The rapidly cycling armature pounds the particles into the sealing surfaces.
3. Excessive wear in the seat area can add additional stroke. These charts are for the F4EAT EPC solenoid. The lower chart was a solenoid that had its seat worn. .003 extra stroke caused pressure to drop too quickly. It gave too fast a drop in main line and a 1-2 slide bang.
4. As compared to the previous slide, the solenoid is so plugged with debris and contamination thatthe armature is hanging up, binding and preventing proper pressure regulation.
Click on an illustration to see an enlargement.
© Scott Kirkendall
Other related articles:
On-off solenoids: Failure due to contaminationOn-off solenoids: Failure due to wear
On-off solenoids: Failure due to abuse
On-off solenoids: Failure due to heat
On-off solenoids: Failure due to electrical causes
PWM solenoids: Failure due to wear
PWM solenoids: Failure due to abuse
PWM solenoids: Failure due to heat
Proportional solenoids: Failure due to contamination
Proportional solenoids: Failure due to wear
Proportional solenoids: Failure due to abuse
Proportionalsolenoids: Failure due to heat
Replace and reuse rules
Failure review chart