why does clutch coil overheat and melt?

[acworthpreacher]

third new clutch after about on hour of use, coil overheats, melts, and is toast. no rubbing, not voltage problems, this is on a older gravley and the clutch is straight wired to the battery. volts vary from about 12- 13.5

HELP

 

[StarTech]

What the voltage provided by the regulator when the engine is operating at fully speed? You can't go by the battery standing voltage when the engine is not running.

I suspect voltage is above 15 VDC with the engine running at full speed. And Xtreme clutch said for the voltage to be between 13.4-14 VDC. Too low or too high will cause failure per their install sheet.

 

[Forest#2]

third new clutch after about on hour of use, coil overheats, melts, and is toast. no rubbing, not voltage problems, this is on a older gravley and the clutch is straight wired to the battery. volts vary from about 12- 13.5

HELP

You say:
clutch is straight wired to the battery.
it's melts until it's toast.

You answered your own question.
A corrects size fuse usually prevents the melting and toasting.

What is the model # of your gravely tractor and engine and the part number or model number of the clutches you are trying to use?

 

[Tiger Small Engine]

third new clutch after about on hour of use, coil overheats, melts, and is toast. no rubbing, not voltage problems, this is on a older gravley and the clutch is straight wired to the battery. volts vary from about 12- 13.5

HELP

Why do you keep throwing brand new PTO clutches at it if they fry after an hour of use? Stop, break out the multimeter and start doing some checking, or take it to a good repair shop and have them fix it.

 

[StarTech]

Hush. I am making a good money selling the OP the clutches....

 

[acworthpreacher]

You say:
clutch is straight wired to the battery.
it's melts until it's toast.

You answered your own question.
A corrects size fuse usually prevents the melting and toasting.

What is the model # of your gravely tractor and engine and the part number or model number of the clutches you are trying to use?

Straight wired but is fused at 5 amps. Nothing has changed as far as wiring since

 

[acworthpreacher]

no sure make and model of mower would help as it originally did not have a electric clutch. plan to check several things with it this afternoon. battery voltage is 12.5 volts running or with mower off. Interesting thing I found last night is that voltage at the clutch is 10.5.

with power to the clutch and letting it run engaged for 15 minutes, temp was at 140. not near enough to cause any damage.
will try and get to the low voltage problem.

 

[StarTech]

One thing stand here is the amount of voltage drop. Something is amiss with the wiring, bad connection or under sized wiring. Wiring should be at least 16 ga. as you probably a fairly long run. Being at 10.5v the clutch is probably slipping the armature and rotor contact causing excessive heating under the grass load of the deck. This would be due the magnetism is a lot weaker than normal. Another thing that can cause excessive heating is belt slipping or being way too tight.

And don't over torque the retaining screw as that can cause excessive bearing loads again causing excessive heating. Though most clutch have spacers between the bearings to limit this loading.

All this extra heat has to be heatsinked somewhere which would be the clutch assembly.

 

[slomo]

Should be roughly 13.5VDC at fast idle, highest revs as others pointed out.

A 3 volt DC drop is huge. You have wiring issues on the + side and possible the - side of the clutch. Start polishing some ground points, connections and so on.

An under volt condition will draw more current to satisfy the load. Leads to the clutch running hotter than normal. Add in some 100+ degree temps.......

I'm also guessing one or more dead deck bearings, worn belt/s and so on might be assisting this issue. Bet the deck is packed with grass and dirt. Dull blades and so on. Before the clutch smokes, do the blades come up to full speed as in normal ops?

If you are using OEM clutches then something else needs located slash investigated.

 

[StarTech]

An under volt condition will draw more current to satisfy the load. Leads to the clutch running hotter than normal. Add in some 100+ degree temps.......I

Explain.

Normally a dc inductor, coil, windings has only one resistance through it can change some from heating. As voltage drop so does the current. In this case the estimated resistance is around 2.5 ohms (actual resistance depends on the windings). So 13.5/2.5 = 5.4 amps and if the voltage drops to 10.5 / 2.5 = then the current draw is only 4.2 amps.

Now the OP has one the Warner clutches then the following table applies.


Now motors like starters are a different story as they constant changing winding when rotating and slowly rotating they do draw more current up to a point.