Should There Be Continuity on the Pto Clutch

The PTO clutch is an essential part for your lawn mower's function. Without the clutch, or with a poorly functioning clutch, your riding mower will be nothing but a slow, one-seater vehicle. While this may be useful for teaching your teenage kid to drive, it will be useless for mowing the lawn. The clutch is needed to transfer power from the motor to the blades, so that you can cut grass! Luckily, it's pretty easy to tell if you have a bad clutch. We will go over some ways to diagnose and fix lawn mower clutch problems here.

How to Spot Common Riding Lawn Mower Clutch Problems:

If you are activating your PTO switch on the mower, and you don't hear it engage or hear the blades start turning, there is probably a problem with either the engagement mechanism or the clutch. The electric solenoid can go bad, the clutch can be worn out and slipping, or the clutch can be fused together by excessive heat. There may also be a safety system malfunction, which may not let the blades engage.

With the first problem, nothing will happen when you activate the switch. This is a telltale sign of an electrical problem. If the clutch is damaged, you may hear it slipping while it tries to engage, or you might hear your PTO engage and then stop right away, as it is designed for the fuse to fail first if it cannot turn the clutch.

Most Common Riding Lawn Mower Clutch Problems:

The Electric PTO is Not Getting the Voltage Needed, or the PTO Solenoid is Toast

If the solenoid switch that controls the electromagnetic clutch engagement is bad, you will not hear anything happen when you activate the switch. There are three common reasons for this: There could be a bad fuse, which is the easiest fix. The solenoid may not be getting enough voltage from the battery to engage, in which case you will want to test the voltage coming from the battery. The other possibility is that the solenoid is bad, and in this case, you will want to head down to your local small engine repair shop to obtain a new one.

The Clutch is Slipping, Damaged, or Fused Together

If you activate your PTO switch and you hear a squealing, screeching sound, disengage the PTO and turn off the mower. You may have something in the blades that is keeping them from turning, your PTO belt may be worn out, or worst-case scenario, you may have a lawn mower clutch problem. Whatever you do, NEVER GO NEAR THE BLADES WHILE THEY ARE SPINNING, OR THE PTO IS ENGAGED. It's best to completely turn off the mower and remove the key before trying to service any part of the PTO system.

A Safety Switch Somewhere Else is Causing the Blades Not to Engage

There is the possibility that another safety mechanism or switch is keeping the PTO from engaging. There are multiple switches in most mowers to ensure that you are safely seated on the mower when the blades start spinning. This may be a safety switch in the seat, or possibly a switch in the emergency brake or transmission. Try shifting your mower into neutral, engaging and disengaging the emergency brake, and make sure your weight is centered on the seat while engaging the PTO switch. Sometimes the switch under the seat may go bad or get dirty, and it will not sense your weight on the seat. The blades won't turn on if that's the case.

Symptoms of a Bad PTO Clutch on Your Lawn Mower (Mechanical):

These symptoms may indicate a mechanical problem with the actual clutch of the mower.

The Clutch Makes Noise When Engaged

If this is happening, your clutch may have a bad bearing, the surface of the flywheel may not be in good condition, or your PTO belt or pulley may need replacement. The belt slipping may cause the noise, so the first thing to check would be that the belt is tight and not damaged.

The Clutch Causes the Engine to Rev Higher

If the engine is revving up higher when you engage the PTO, it becomes evident that the power transfer from the engine to the blades is not working as it should. This may indicate some of the same things mentioned above. Your actual clutch may have a bad bearing and not be spinning smoothly, causing the engine to use more power. The PTO pulley may also have a bad bearing which would cause the engine to supply more power to get it moving.

The PTO Clutch Starts, Then Immediately Stops, and Fuse is Blown

If the fuse to your PTO switch blows right away when you activate it, that could still indicate a mechanical problem. This could mean that the clutch was impossible for the motor to move, and the motor had to try and supply so much power that it blew the fuse. Your clutch may be seized up completely, there may be something stuck in the blades, or your PTO pulley may be seized up. Either way, you won't be mowing until you figure out the problem.

Symptoms of a Bad PTO Clutch (Electrical):

The PTO Switch Makes No Sound When Activated

This can indicate that the actual switch is bad or is not receiving enough power from the battery. You will need to do some electric PTO clutch troubleshooting to fix this problem. Listed below are the possible problems to check for if you experience this. You will likely need a multimeter to check for these.

Check the Fuse – The fuse for the PTO System is the easiest part to check and change. It should not be burnt, and you should be able to see that there is still a solid connection.

Battery Voltage – The battery may not be supplying enough voltage to activate the solenoid. This is a common problem, as lawn mower batteries can lose charge while sitting.

PTO Solenoid – This is the actual electromagnetic switch that controls the clutch, and replacing this part is a little more in-depth. You can check for its function with a multimeter.

How to Test the PTO Clutch on Your Mower

For the purpose of testing the PTO clutch on your mower, you will need to use a multimeter. It doesn't have to be anything fancy, it just needs the ability to check voltage, resistance, and amperage.

Testing the PTO Clutch (Mechanical)

First, perform a mechanical test on the clutch just to rule out any physical problems with the clutch. You will need to turn on your mower. Make sure the mower is in neutral or park, and that the emergency brake is engaged. Some mowers have differing safety features, and you may need to disengage the emergency brake to start the PTO.

With the mower running at full throttle, try engaging the PTO switch or lever. If you hear the blades try to start up, you can rule out the PTO solenoid. If the clutch is squealing or the mower engine starts revving higher, disengage the PTO and turn off the engine. You may have a bad bearing in the clutch, a bad contact surface on the flywheel, or a bad PTO pulley.

Also, check the belt for the PTO and make sure that it is not loose, frayed, cracked, or otherwise worn out. You can find replacement pulleys, belts, and clutch assembly parts at your local small engine repair shop. If you activate the PTO switch and your blades turn on without incident, Congratulations! You have a functional PTO clutch and you can mow away!

Testing the PTO Clutch (Electrical)

If you tried to activate the PTO in the last step and nothing happened, it's time to check some electrical connections.

1) Fuse – First, look for the wire that goes to the PTO mechanism. There should be a small fuse box containing the fuse for the switch. If the fuse is blown, you will be able to see it. The metal connection inside the fuse will be melted, broken, or burnt-looking. This means that the clutch was trying to draw too much amperage for some reason, and it usually points to some sort of mechanical problem (bad bearing, etc.). Replacement fuses are cheap, and you can replace it with the same amperage fuse that was in there. Usually, they are 10 or 15A.

2) Battery – If the fuse is good, the next thing to check would be the battery. You want to make sure the battery is supplying the correct voltage to the parts of the mower. Take your multimeter, switch it to Volts, and place the positive (red) probe on the positive terminal of the mower battery. Take the negative (black) probe and place it on a metal part of the engine. If your battery is putting out the correct voltage, the meter should read about 12.6 volts. Anything under that and your battery will need a charge. If this checks out, all that is left to check is the function of the solenoid.

3) Solenoid Function – You will want to find the clutch assembly under the mower, with the mower turned off, and unplug the wire that comes from the PTO switch. Put the key in the mower and turn it only to the first click. You don't want to start the mower up, you just want the battery turned on. You will need to switch your multimeter to Amperage and connect the black probe to a grounded metal piece. Next, you will need to insert the red probe into the wiring harness coming from the switch. Activate the PTO switch and this should give you a reading of about 4 amps. If there is no reading, it is likely that the switch is bad. You may need to contact the manufacturer to get the part number for that PTO switch.

If you checked for these lawnmower PTO clutch problems and everything worked, your clutch is in working condition and you are ready to mow!

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Source: https://lawnmowerguru.com/lawn-mower-clutch-problems/