My Simplicity mower has started blowing the 20 amp fuse when my PTO is engaged. After reading many posts regarding this common problem to so many, I purchased and installed a new PTO clutch (expensive..$260), also a new PTO switch and inspected most of my wiring harness as best I could, with no worn insulation discovered. After my installation of the new PTO clutch and switch, the 20 amp fuse lasted for app. 50 feet of mowing from cold start then blew. I replaced 20 amp fuse, disconnected the PTO electrical connection at the clutch, started the mower and engaged the new PTO switch and the fuse did not ever blow, which might indicate that the wiring insulation and new switch is good but the new PTO clutch might be bad? I can't imagine that the new clutch is no good or needs an air gap adjustment already being a new OEM Briggs Stratton product, nor the new PTO switch is bad. This problem appears to be so common to so many people regardless of mower brand and model, that it seems these manufacturers cannot remedy such a common DESIGN problem to the masses! WTF? I thought about trying a 25 amp fuse but did not want to risk 'frying' my new $260 PTO clutch...Help please!! This is BS as it is such a common problem to so many!
Mower Blows 20 amp fuse when PTO when PTO is engaged
- Thread starter JeffNC
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bertsmobile1
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There are 2 ways to approach a problem.
Toss parts at it till it goes away or find where the actual problem is and rectify it.
A solenoid draws POWER ( Watts ) and it does not care how it gets them
So 12V x 10A or 6 V x 20A or 3 V x 40A is all the same to it.
However Amps = heat.
Heat = RESISTANCE
RESISTANCE = VOLTAGE DROP
VOLTAGE DROP = more AMPS to make the same WATTS
And thus the self feeding loop continues till the fuse can't take it any more.
Much like the self feeding loop of face book morons makes bigger & more face book morons.
9 out of 10 mowers that come in here have disgusting battery connections and in particular the ground connection
Next is the actual fuse holder itself which is not waterproof because cheapskate owners & Face Book whingers will not pay the extra 50¢ to get waterproof connectors so the factories no longer fit them.
A proper search of this site will find around 2/3 of the blowing fuses problems were fixed by replacing the fuse holder.
Half of the remaining were fixed by cleaning or even replacing the battery cables & connections.
FWIW I do around 300 service / repairs a year and am yet to need to replace a clutch but I have gone through several 50 packs of fuse holders .
You are correct about their being a conspiracy out there.
It is called a free market lead economy
So whoever makes a mower with the lowest Hp to $ ratio or the lowest blade inch to $ ratio will outsell all others and prosper while the factories that make high quality mowers that sell for a fair & reasonable price will bob along being just barely profitable while the family that runs them continues to believe in the value of making quality over cost or go bankrupt.
That is the conspiracy, got nothing to do with badly designed PTO clutched except in the narrow minds of the technically if not totally ignorant who make 99% of cyber space.
The chances of you getting a dud PTO clutch if you bought it from a mower shop is about the same as winning the lottery
The chances of you getting a dud PTO clutch if you bought it from an on line Amazon or ebay vendor is about the same as it raining on any particular day.
All of the reject PTO clutches that are made in CHina end up being sold on line cheaply, usually because they are faulty .
Toss parts at it till it goes away or find where the actual problem is and rectify it.
A solenoid draws POWER ( Watts ) and it does not care how it gets them
So 12V x 10A or 6 V x 20A or 3 V x 40A is all the same to it.
However Amps = heat.
Heat = RESISTANCE
RESISTANCE = VOLTAGE DROP
VOLTAGE DROP = more AMPS to make the same WATTS
And thus the self feeding loop continues till the fuse can't take it any more.
Much like the self feeding loop of face book morons makes bigger & more face book morons.
9 out of 10 mowers that come in here have disgusting battery connections and in particular the ground connection
Next is the actual fuse holder itself which is not waterproof because cheapskate owners & Face Book whingers will not pay the extra 50¢ to get waterproof connectors so the factories no longer fit them.
A proper search of this site will find around 2/3 of the blowing fuses problems were fixed by replacing the fuse holder.
Half of the remaining were fixed by cleaning or even replacing the battery cables & connections.
FWIW I do around 300 service / repairs a year and am yet to need to replace a clutch but I have gone through several 50 packs of fuse holders .
You are correct about their being a conspiracy out there.
It is called a free market lead economy
So whoever makes a mower with the lowest Hp to $ ratio or the lowest blade inch to $ ratio will outsell all others and prosper while the factories that make high quality mowers that sell for a fair & reasonable price will bob along being just barely profitable while the family that runs them continues to believe in the value of making quality over cost or go bankrupt.
That is the conspiracy, got nothing to do with badly designed PTO clutched except in the narrow minds of the technically if not totally ignorant who make 99% of cyber space.
The chances of you getting a dud PTO clutch if you bought it from a mower shop is about the same as winning the lottery
The chances of you getting a dud PTO clutch if you bought it from an on line Amazon or ebay vendor is about the same as it raining on any particular day.
All of the reject PTO clutches that are made in CHina end up being sold on line cheaply, usually because they are faulty .
99% of the pto clutches get replaced because of mechanical failures (bearing failures, or wires getting pulled out when the anti spin tab breaks) The rest because they are either not bad, but people though it was. And in the cases where the clutch is bad majority of those never blow the fuse. They will take out the pto switch first by overheating the internal contacts, but will never blow the fuse. The only time the pto clutch will blow the fuse is in the case of a dead short to ground.
In this case I would be looking for a wiring diagram and found out what else is connected to the fuse because there could be something else causing problems but the clutch just puts it over the top.
In this case I would be looking for a wiring diagram and found out what else is connected to the fuse because there could be something else causing problems but the clutch just puts it over the top.
As an electrical engineer for over 40 years, I want to provide a bit of clarification to what berts said about solenoids. All a solenoid consists of electrically is simply a coil of wire. It creates a magnetic field when, in this case, a DC current passes through it. The amount of current it draws is determined by the resistance of the coil, which is typically under 5 ohms for a PTO. A solenoid does not draw watts per se. It draws a specific current based on its resistance and the voltage applied. When you multiply the voltage across the solenoid by the current through the solenoid, you will know the wattage or energy being used. A solenoid may specify a wattage in its spec sheet, but that is only when the unit is operated at its rated voltage, and when it is cold. [as a side note, the resistance of a coil actually rises as its temperature rises, causing less current to be drawn]
A solenoid does not behave in such a way as to draw the same number of watts, regardless of the voltage applied. In other words, if you took a perfectly good 12V PTO clutch and connected it to a 12V battery, it will draw a certain amount of current(likely to be in the 3-4 amp range based on a coil resistance in the 3-4 ohm range). If you take that exact same PTO clutch and connect it to a 6V source, it does NOT draw twice the current. In fact, it will draw half the current. The power is also halved. Why? Because the resistance of the coil remains the same in both cases. Ohm's law still applies. Current=Volts/Resistance
Specific to your problem, I'd suggest using your ohmmeter and checking the circuit(with battery disconnected of course). Disconnect clutch and check its resistance first. If the value you measure is significantly below the 3-4 ohm level, then it would appear your PTO is hosed. If it's good, then I'd work my way back looking for short of some kind to ground.
I submit this with the deepest respect for berts and his extensive experience! Not trying to start a flame war, rather I just want to give Ohm's Law its due!
Keep us posted!
A solenoid does not behave in such a way as to draw the same number of watts, regardless of the voltage applied. In other words, if you took a perfectly good 12V PTO clutch and connected it to a 12V battery, it will draw a certain amount of current(likely to be in the 3-4 amp range based on a coil resistance in the 3-4 ohm range). If you take that exact same PTO clutch and connect it to a 6V source, it does NOT draw twice the current. In fact, it will draw half the current. The power is also halved. Why? Because the resistance of the coil remains the same in both cases. Ohm's law still applies. Current=Volts/Resistance
Specific to your problem, I'd suggest using your ohmmeter and checking the circuit(with battery disconnected of course). Disconnect clutch and check its resistance first. If the value you measure is significantly below the 3-4 ohm level, then it would appear your PTO is hosed. If it's good, then I'd work my way back looking for short of some kind to ground.
I submit this with the deepest respect for berts and his extensive experience! Not trying to start a flame war, rather I just want to give Ohm's Law its due!
Keep us posted!
NorthBama
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Now I have to correct my own response!
In my example of connecting a PTO clutch to first a 12V source, then a 6V source, I indicated the power would be halved also. Not true, the power is 1/4 as much. Duh! Power=Volts x Current. Half of the voltage results in half of the current.
Example: Let's say PTO has a 3 ohm coil. Put 12VDC across it and it will draw 4 amps (12/3=4 amps). The power is 12 x 4 = 48 watts. Same PTO, but put 6VDC across it. It will draw 2 amps (6/3=2 amps) because the resistance is the same. The power is 6 x 2 =12 watts.
Current is half (4 vs 2 amps), while the power is one-fourth (48 vs 12 watts).
Sorry for the confusion. Time for another coffee!
In my example of connecting a PTO clutch to first a 12V source, then a 6V source, I indicated the power would be halved also. Not true, the power is 1/4 as much. Duh! Power=Volts x Current. Half of the voltage results in half of the current.
Example: Let's say PTO has a 3 ohm coil. Put 12VDC across it and it will draw 4 amps (12/3=4 amps). The power is 12 x 4 = 48 watts. Same PTO, but put 6VDC across it. It will draw 2 amps (6/3=2 amps) because the resistance is the same. The power is 6 x 2 =12 watts.
Current is half (4 vs 2 amps), while the power is one-fourth (48 vs 12 watts).
Sorry for the confusion. Time for another coffee!
NorthBama
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nice i like it
bertsmobile1
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I can be just as wrong as the next person so never worry about correcting me it is always appreciated.
History ( well western history to be precise ) only records a single person who was never wrong & he got crucified for that.
So with a big mouthful of humble pie , I will still put money on a foul fuse holder creating a very high resistance causing the fuse to blow.
It is nothing odd to find wires on mowers corroded a dozen or so places along their length due to water wicking up under the insulation.
For that reason I never like to rely on resistance readings cause one single strand of good wire in an otherwise corroded through cable will ohm up as being good, till you try to pass some current through it.
For the same reason the test lamp in the workshop is connected to a headlamp globe
No worries Berts... I do the exact same thing when trying to track down an open circuit. For 12v stuff I use a headlamp also. When I work on home electrical (12vac rms mains here of course!) I use an incandescent bulb as a test load. In neither case do I use a digital volt meter alone. Too many times you can be deceived into thinking the circuit is just fine up to your test point only to find you have a marginal safety switch, seat switch, ignition switch etc. DVM says 12 volts but put a nice headlamp on it and the voltage across it drops dramatically because of the resistance of the bad switch!
FWIW....
FWIW....