The clutch in your Husqvarna lawn mower is there to stop the blades when the engine is on. This important safety feature ensures you can safely operate around the machine without having to turn it off each time you get up. At the same time, clutches are prone to failure and problems with the clutch might mean you either can’t turn the blades off or you can’t turn them on. In either case, electric PTO troubleshooting is normally relatively easy.
In most cases, lawn mower clutch problems relate to power issues, belt installation, and electrical issues like ground issues. Taking time to look for electrically or mechanically caused problems can allow you to fix it yourself without buying a replacement.
Troubleshooting Husqvarna Electric Clutch
Husqvarna normally uses a Power Take Off or PTO clutch to electromagnetically prevent the blades from turning. PTO clutches are made up of an actuator to mechanically transmit torque up a PTO drive. This includes an output, with a pulley or timing belt, an armature, a rotor, and a field coil. When voltage is applied to the clutch, the coil becomes a field magnet, creating electromagnetic flux, which magnetizes the coil and pulls the armature against the hub, creating a holding force. When power is cut, springs push the armature away from the hub, preventing the drive shaft from spinning freely. Here, most lawn mower clutches have a friction area, in which the panels touch at all times.
This allows the blades to turn freely when the clutch is disengaged. It also means they lock up when the engine is turned on, until the safety switch on the mower is depressed. For example, in the case of most Husqvarna riding mowers, that means the break switch, the handlebar switch, and the under-seat switch.
Troubleshooting lawn mower clutch problems is normally relatively simple, providing you have the right tools. These common issues are a good place to start.
Check If You’re Getting Power First
Clutches can have electrical problems from a number of causes. Often the problem starts in the switches, the solenoid, and the wiring, all of which can cause clutch problems. Checking if the clutch is getting power should always be the first step. Normally, a simple multimeter is all you need to do so. It’s almost always advisable to take the clutch out of the engine when testing it. Why? If the clutch works, the blades will start spinning. So, if you fix the problem while it’s in the motor, testing it can put you in danger.
Take the PTO clutch out following your user’s manual.
You want between 2 and 4 Ohms of resistance. Use a battery powered meter.
Hook the clutch to a 12-volt battery from the mower to ensure the clutch works.
If the solenoid is defective, the clutch is worn out, or the clutch is not getting power, the blades won’t engage. Here, you should always start out checking for blockages in the pulleys etc.
Check the switches
Use a multimeter to check for power continuity to the switches. Switch problems are the most common reason for your clutch to not engage.
Check for debris
Look for blockages and debris that might stop the clutch or the pulley from spinning.
Check the discs
You could have mechanical related problems. For example, if the actuator surface is worn down, the clutch might not make contact like it should. You’ll have to adjust the discs or replace the clutch.
Check the solenoid
Touch the metal shaft of a screwdriver to the metal terminals on the solenoid. If the engine turns over and starts, the solenoid should be replaced.
Will Not Stay Engaged
In most cases, if your clutch is engaging but won’t stay engaged, you have a battery issue. However, it might also relate to breaks in the wires, power continuity, or even disk slippage.
- Set the multimeter to 13 using a DC or “A” test.
- Place the leads.
- If your battery is between 12.4 and 12.9, your battery is good. Any other charge indicates over or under charging. Anything under 10.5 is an indicator to replace the battery.
Check the wires between the switches, the solenoid, and the PTO clutch. If there are breakages, hard kinks, or loose wires, fix the issue.
If switches are loose and slide in an out of position, wires are loose, etc., your clutch can stop engaging once you turn it on.
Will Not Disengage
Clutches can stop disengaging due to a number of mechanical or electrical issues. For example, wear, if the clutch is loose or needs to adjust pedal height, or other similar problems.
Shim the Clutch
Check the tension between the actuator and the pulley on all sides of the clutch. Use the bolts to tighten or loosen the actuator to ensure they are the same. In most cases, a loose clutch will result in some rattling at startup.
Check the cable
Check the pulley cable and the pulley housing. Make sure nothing is stuck and that the pulley turns freely.
Check Clutch Pads
If clutch pads are too worn or improperly adjusted, they might not disengage.
In almost every case where a clutch is slipping, you have to tighten or shim it. Use the video above for instructions. If that doesn’t solve the issue, the problem is likely that the actuator is too worn and must be replaced.
Vibrating or Making Noise
If your PTO clutch is vibrating or making noise, it normally means you have to tighten or shim it. Alternatively, it could mean the clutch itself is loose. In some cases, it may also mean the actuator is too worn and must be replaced.
What Causes Husqvarna Clutch Failure?
Husqvarna clutches fail for a number of reasons. In some cases, these are fixable. However, if you have symptoms of a bad PTO clutch like very worn actuators, you might not be able to fix it.
Before beginning, follow all safety instructions as detailed in your user’s manual.
- Park the mower on a flat, level surface.
- Turn off the motor and remove the key.
- Unplug the red cable from the battery.
- Unplug the spark plugs.
- Ensure the PTO switch is in the “Disengaged/Disengages” position.
- Turn the ignition to remove any excess electricity from the wires to ensure the blades do not turn.
Improper Belt Installation
If you have a loose pulley belt, the belt is worn, or is burnt or fraying, you might have to replace it. Similarly, you will have issues if the belt is improperly installed or even slipping. Unfortunately, the belt issues might relate to the pulley belt or to the drive belt. Both can have issues, and both might cause the clutch to seize up.
- Follow the instructions in your owner’s manual to remove the cutting deck.
- Slip the belt pulley off the tractor and pull the cutting deck out.
- Check the belts – both the large one connecting the blade drive shaft to the clutch and the small one inside the clutch.
- If you see signs of fraying, burning, or other damage, replace the belt.
If your PTO clutch has been sitting stagnant, especially outdoors, for some time, it may be rusted. To resolve this, take the clutch out of the mower following the instructions in the manual and soak it to clean rusted plates. Do not oil the clutch before putting it back in. While this can reduce instances of recurring rust, it will also decrease friction, which can be problematic for normal clutch functioning. In addition, if your clutch keeps rusting, you’ll have to replace the clutch very quickly. However, you should use grease made specifically for the clutch.
Wires Not Grounded
If your wires are frayed, broken, or touching metal, your clutch won’t work properly. Clutches normally need 12-14 volts of electricity to work properly, which means they need everything the 12v battery on the mower is supplying. It’s always a good idea to double check for connectivity and, if you’re not sure, test the power at the battery, the clutch, and the cables.
Discs Worn Down / Need Adjustment
Most clutches have to be adjusted every 500 hours of use. If the plates are too loose and aren’t connecting properly the clutch won’t disengage or won’t engage. If the clutch plates are too tight, you’ll have other issues. That also holds true if your discs are worn down through normal use. If the discs are too worn, you’ll have to replace them – normally that means replacing the clutch or finding replacement parts.
Pully Seizing Up
If the pully inside the clutch is seizing up, you might have issues with increased clutch friction, the clutch failing to engage, and overheating. Here, problems are normally related to the belt, to the bearings, or to debris in the pulley.
How to Test Your PTO Clutch
The PTO clutch enables normal and safe operation of the lawnmower blades. Without it, your blades either run non-stop or not at all. Clutch issues can damage the clutch, which can cause issues with PTO switches, wires, overheating, and damage to the clutch itself.
1. Use a voltmeter to test the red, positive post on the battery. Place the negative voltmeter lead on the engine. If it reads 12.5 volts or lower, charge the battery. If it reads 10.5 volts or lower, replace the battery.
2. Check the in-line fuse between the switches and the PTO clutch assembly. Make sure that the fuse is not black. Check the filament to ensure it’s in one piece. If it looks blown, replace it with a matching fuse.
3. Start the engine and let it warm up. Engage the PTO. Listen for any rattling, squealing, or other noises on startup and when running. If yes, proceed to step 5.
4. Activate the PTO clutch and listen for a disengagement noise. If the pulley does not start/stop or takeoff, the plates may be galled together, the slip ring jammed, or the adjustment is too tight. If so, move to step 9.
Safety Precautions Before Next Steps: The PTO clutch turns the mower blades. Your head and hands should never be near the mower blades with power to the clutch. Never test your clutch without engaging in basic safety precautions, as listed above.
Access the Clutch:
- Disengage the Cutting Deck: there are instructions in your user’s manual. This normally involves pulling the 4 pins from each corner of the deck, removing the adjustment rod, undoing the pulley belt. However, exact methods vary from mower to mower. Check your manual for the correct instructions.
- Remove the clutch belt
Most Husqvarna riding mowers feature the clutch on top of the mowing deck. Therefore, you won’t have to elevate your mower to access it.
5. Check for branches, grass, or other debris in the pulley belt.
6. Ensure that the pulley belt turns freely.
7. Check for belt tension by engaging the lever and feeling the tension.
8. Make sure the idler pulley moves freely back and forth on its swivel.
Tip: Reconnect and test the clutch at this stage. If it still doesn’t work, disconnect everything again.
9. Take the PTO clutch out and clean it or adjust it. Check for damage. Then put it back in. Exact instructions normally depend on your specific model, but you can check the next section for more details.
With the engine turned off but the battery plugged in, test power to the clutch. Remove the main wire going to the PTO clutch assembly. Turn the wire towards yourself. Stay as far away from the blades as possible. If the PTO clutch engages, this is very dangerous.
Use a test light. Place the negative alligator on a ground source. Connect the positive lead to the PTO clutch lead. If the light fails to turn on, the problem is in the battery, the in-line fuse, or the lever switch. If the first two are fine, check the lever switch.
It’s also possible to test the clutch by taking it out, connecting it to a battery, and checking to see if it clicks in engagement. If not, there could be an electrical circuit issue inside the clutch. This may not be fixable.
How to Replace Your Electric Clutch
- Remove the deck. Follow the instructions in your owner’s manual.
- Unplug the main power.
- Uncouple the pulley belt.
- Remove the middle bolt.
- Pull the clutch out. Put the new clutch in. Use a wrench to hand torque the clutch in place. You’ll have to hold the clutch in place aligned with the key with a notch in the crank shaft. Then insert the center bolt. Hold everything in place and use a thread locker to lock everything back into place.
- Plug the main power back into place.
- Reattach the belt.
- Reattach the deck.
- Test the new PTO clutch. Turn on the motor and engage the PTO. If there are problems, re-assess the installation.
Replacing or repairing the PTO clutch won’t always solve all your mower problems. You may still have other issues. This FAQ should help.
Why is one side of my mower deck lower than the other?
The front of your mower deck should always be ½ to ¾ of an inch lower than the back. However, the sides should be level. If the sides are not level, adjust the mower deck using the adjustment bolt.
Should mower deck wheels touch the ground?
Normally mower deck wheels should not touch the ground. These should be ⅛ to ½ an inch off the ground, depending on cutting height. If not, adjust them.
What are anti-scalping wheels?
Anti-scalp wheels, or the wheels on your deck, are intended to prevent the deck from scraping against the ground when you go over a high spot. The wheels kick in and push the deck up, preventing damage.
We’ve covered most of the things that normally go wrong with an electric PTO clutch. If you still have issues, it’s usually a good idea to either replace the clutch or have an expert look at it. Hopefully, you finish this article with your electric clutch fixed.
It’s also important to keep in mind that your clutch can seize up because of non-clutch issues. For example, seized drive shafts, electric wires, etc. It’s important to inspect the full machine for blockage, bare wires, and rust, before you start taking the machine apart. Hopefully, this guide offers enough pointers that you can determine what’s wrong with your PTO and fix it.
Most importantly, make sure you always practice good safety. Working around powered blades is dangerous. Good luck fixing your PTO clutch. And, if you have other issues, check out one of our other Husqvarna riding lawn mower guides.