The good thing about self-propelled lawn mowers is that they take a lot of the effort out of mowing. But this is only true when your lawn mower’s drive system is working. If you are dealing with issues such as your lawn mower wheels not turning or rear wheels locking up, then you’ll need to inspect your mower’s drive system. So, let’s take a look at how to diagnose why your lawn mower wheels are not turning and see what can be done.
Lawn Mower Wheels Lock Up (The Short Explanation)
Several parts work together to turn the lawn mower wheels. This process works by engaging and disengaging each part within the drive system. Therefore if one part fails and doesn’t work properly, the entire drive system fails. So, to diagnose why your lawn mower wheels are not turning, you’ll need to inspect the following items:
- Drive Belt
- Drive Cable Adjustment
- Transaxel Adjustment
- Drive Engagement Lever
- Wheel Gears
- Wheel Drive Pinion Gear
- Your Lawn Mower’s Cleanliness
8 Possible Reasons Why Your Lawn Mower Wheels Are Not Turning
As you can see, there are many different reasons why your lawn mower wheels are not turning, and you’ll need to inspect each closely. Here are eight different steps you can take to figure out why your mower wheels are locked. Let’s take a look.
Drive Belt Damage
The first place I would check if my wheels won’t turn is the drive belt. The drive belt is the component that transfers the motion of the engine to the wheels, so this is a pretty good place to start. When checking the drive belt, make sure that it isn’t damaged or stretched, as this could cause an issue and prevent the belt from transferring power from the drive shaft pulley and the transaxle.
To start, tilt your lawn mower the right way, then engage the drive. If the belt is slack, you’ll have discovered that the belt is likely unable to transfer the engine power to the wheels as needed.
Drive Cable Adjustment
Most lawn mowers will have some type of drive cable adjustment that allows you to tighten the drive belt as it becomes worn and stretches out. The best benefit of this function is that it gives the drive belt an extra few months or years of life.
First, you’ll need to locate the drive cable adjuster and figure out if it has any further adjustments available. Now if you have already used all of the adjustments, you’ll either need to replace the drive belt or check if your lawn mower has transaxle adjustment.
The transaxle is a small gearbox that converts the motion of the drive belt to the rotation of the wheel axle. Now, the transaxle usually rotates on its mount to take the slack out of the belt and engage the drive. Therefore as the belt stretches out with age, you can make small adjustments to compensate by adjusting the transaxle adjustment screw.
So, take a look under your lawn mower and check the transaxle. First, check if you have an adjustment screw, then check if any adjustments are available.
Drive Engagement Lever
The drive engagement lever is the device you use to engage the drive, which is located on the lawn mower’s handlebars. Now, if the drive lever is damaged or corroded, then it may not be able to travel the full distance required to engage the drive.
To test the lever, try pulling it and ensure it is operating correctly and travels the full distance required. If you find that it isn’t, then you’ll need to repair it. This is because the limited travel of the lever won’t pull the drive cable far enough to engage the transaxle and take the slack out of the belt.
You’ll find a gear inside your lawn mower’s wheels. This gear is usually a series of teeth molded into the plastic of the wheel, which connects to the pinion gear connected to the driveshaft. Now as these teeth are usually only made of plastic, they can easily wear down over time or become damaged with misuse.
Also, as each wheel is independent, you may find that only one wheel has an issue and can result in a self-propelled lawn mower with only one wheel that turns. So to diagnose a problem with the wheel gear, remove the covers from your lawn mower’s wheels to gain access to the gear and inspect it for any wear or damage.
Wheel Drive Pinion Gear
Once you remove the cover from the drive wheels when inspecting the wheel gears, you’ll also be accessing the pinion gear. Now, these small pinion gears are used on a lawn mower so that the lawn mower can be pushed around without engaging your lawn mower’s drive.
Unfortunately, the pinion gear can go wrong in a few different ways, which can result in push mower wheels being locked, lawn mower wheels not turning, and even one wheel doing one thing and the other wheel doing something else.
To inspect the pinion gear, first, remove the drive wheels from your lawn mower. Now you’ll be able to turn the pinion gear by hand to make your diagnosis. Now, the pinion gear should turn freely in one direction and not turn in the opposite direction. If you find that the pinion gear turns in both directions or doesn’t turn in either direction, you’ll need to install a replacement.
As I mentioned before, the transaxle is a small gearbox that converts the motion of the drive belt to the rotation of the wheel axle. Now inside the transaxle, there are several gears used to complete this process. Unfortunately, each gear can fail and prevent this operation from happening.
To diagnose your mower’s transaxle, turn the pulley on top of the transaxle by hand. The wheels should turn. If they don’t, then you’ll have discovered that your mower’s transaxle is broken, and you’ll need to install a replacement.
Cleanliness of Your Lawn Mower
Whenever I have an issue with my lawn mower wheels not turning, I’m always aware that dirt and grass clippings could be the cause. How? Well, dirt and grass clippings can stop a drive system from engaging and can prevent the proper operation of the various components of the drive system. Here are a few examples:
- Grass build-up prevents the required rotation of the transaxles.
- Dirt inside the drive cable prevents required cable movement.
- Debris in the gears prevents the gears from locking together.
- Dirt in the pinion gear causes the ratchet key to become jammed.
So, it may not be the case that anything is actually damaged or broken with your lawn mower. Instead, it could be something as simple as dirt causing the wheel issue. So when diagnosing each component, be on the lookout for dirt and debris getting in the way.
How to Fix Lawn Mower Wheels That Lock Up (8 Possible Solutions)
Now you know how to diagnose why your lawn mower wheels lock up. So next, let’s take a look at the various repairs. Here are eight fixes you can use to restore the drive on your lawn mower and get the wheels working how they should.
- Cleaning Down Your Lawn Mower
- Adjusting the Drive Cable
- Adjusting the Transaxle
- Replacing the Drive Belt
- Repairing the Engagement Lever
- Replacing the Wheels
- Replacing the Pinion Gear
- Replacing the Transaxle
Cleaning Down Your Lawn Mower
If you skip cleaning your mower on a regular basis, then you likely face issues with how your lawn mower performs. So, to avoid issues such as lawn mower rear wheels locked up or your wheels not working at all, you’ll want to gather a few tools and give your lawn mower a good cleaning. This will remove any debris or dirt that could be causing any issues.
When I clean my lawn mower, I use tools like a garden hose, an air compressor, a leaf blower, and things like scrapers and screwdrivers. Then, it’s just a case of getting all the dirt out of the components and cleaning them.
First, I wash down my lawn mower, use the hand tools to break off any stubborn dirt, and use an air gun on my compressor to blast dirt out of the hard-to-reach places.
Next, I use my leaf blower to dry off any water and blow off any remaining dirt.
Finally, I go around my lawn mower with a can of WD-40 to lubricate all the moving parts to prevent corrosion. You would be surprised how effective a thorough cleaning is to not only prolong the life of your lawn mower but also to avoid mechanical issues.
Tools Required to Clean a Lawn Mower
- Small Hand Tools
- Air Gun & Compressor
- Garden Hose
- Leaf Blower
Adjusting the Drive Cable
To adjust the drive cable on your lawn mower, you can usually turn the cable adjustment nut by hand, or if it’s stiff, you can use a pair of pliers. Now all you need to do is turn the adjustment nut on the end of the cable to push it further away from its mount. This basically extends the length of the cable sleeve and tightens the cable.
So turn the adjustment nut until the adjustment lever correctly engages and disengages the transaxle. Just be careful not to tighten the cable too much because this will permanently engage the drive, and you won’t be able to stop your lawn mower from moving.
Tools Required to Adjust the Drive Cable
Adjusting the Transaxle
To adjust the transaxle movement, you’ll need to adjust the adjustment bolt to allow the transaxle to rotate more so that it can remove more slack from the drive belt. To do this, you can use a wrench to adjust the bolt.
Once you have done this, you may need to use the steps from above to adjust the drive cable to fine-tune the drive system. This does take a little time and requires some back and forth, but with a little patience, you should be able to dial it in so that it’s just right.
Tools to Adjust the Transaxle
- Wrench Set
Replacing the Drive Belt
There are several steps you’ll need to follow to replace the drive belt. To make things a little easier, I have listed the steps 1-15. Not all lawn mowers are the same, so the steps will vary, but this will give you a good idea of what you need to do.
- Remove the spark plug cable
- Remove the cutting blade
- Remove the belt guard from the underside of the lawn mower
- Remove the transaxle guard from the rear of the lawn mower
- Remove the belt guide from the transaxle
- Remove the belt guard from the cutting blade pulley
- Lift the drive belt off of the transaxle pulley
- Lift the drive belt off of the cutting blade pulley
- Install the new belt onto both the cutting blade pulley and the transaxle pulley
- Install the belt guard onto the cutting blade pulley
- Install the belt guide onto the transaxle
- Install the transaxle guard onto the rear of the lawn mower
- Install the belt guard onto the underside of the lawn mower
- Install the cutting blade
- Reconnect the spark plug
Tools & Parts to Replace a Drive Belt
- Socket Wrench Set
- Screwdriver Set
- Replacement Drive Belt (Mower Specific)
Repairing the Engagement Lever
Usually, the main issue with the drive engagement lever is that it is either bent or it is rusted up. So, if your lever is bent, you’ll need to use a bit of muscle to try to straighten it out. Typically it is made of pretty flexible metal, so you should be able to bend the lever back into shape.
However, if your lever is rusted, then spray some WD-40 on the rust and repeatedly move the lever from engage to disengage. I find that doing this for a few minutes is enough to get the lever working freely again.
Tools Required to Repair a Corroded Drive Lever
Replacing the Wheels
If you have a lawn mower like a Troy Bilt or a Toro and need to replace the drive wheels, this is the repair you need. All you need to do is remove the wheel cover, remove the center nut, then lift off the old wheel.
Then, attach the new wheel, secure the wheel nut, then reattach the wheel cover. That’s all there is to it. Five minutes and you’re done. So here are the tools and parts you’ll need for this repair.
Tools & Parts to Replace a Lawn Mower Drive Wheel
- Socket Set
- Replacement Drive Wheels (Mower Specific)
Replacing the Pinion Gear
Now let’s take a look at what you’ll need to do to replace a lawn mower pinion gear. There are plenty of steps to follow, so let’s dig in.
- Remove the spark plug
- Raise the lawn mower
- Remove the wheel cover
- Remove the wheel nut
- Remove the wheel
- Remove the snap ring from the pinion gear
- Remove the washer from the axle
- Remove the old pinion gear
- Grease the new pinion gear
- Confirm the ratchet key is in place
- Install the new pinion gear onto the drive axle
- Install the washer onto the axle
- Install the snap ring
- Install the wheel
- Install the wheel center nut
- Install the wheel cover
- Lower the lawn mower
- Reattach the spark plug
Tools & Parts to Replace a Lawn Mower Pinion Gear
- Socket Wrench
- Snap Ring Pliers
- General Purpose Grease
- Replacement Pinion Gear (Mower Specific)
Replacing the Transaxle
Transaxles come in all shapes and sizes, with some on the rear of a lawn mower and some on the front. Here is an example of how to replace a Craftsman front-wheel-drive transaxle.
Lawn Mower Transaxle Removal
- Remove the spark plug
- Remove the lower drive axle cover
- Remove the upper drive axle cover
- Remove the belt guide from the axle drive pulley
- Remove the drive cable from the transaxle
- Remove the wheel covers
- Remove the center wheel nuts
- Remove the wheels
- Remove the wheel dust covers
- Remove the snap ring from the pinion gears
- Remove the pinion gear and washer
- Remove the axle tension spring
- Remove the axle mounting clips
- Lift the axle from the lawn mower
Lawn Mower Transaxle Installation
- Position the transaxle onto the lawn mower
- Secure the axle to the lawn mower
- Connect the tension spring
- Install the pinion gear, washer, and the snap ring
- Install the wheel dust covers, wheels, wheel nets, and the wheel covers
- Connect the drive cable
- Attach the belt
- Install the belt guide
- Install the drive axle covers
- Connect the spark plug
Tools & Parts to Replace a Transaxle
- Socket Wrench
- Snap Ring Pliers
- Replacement Transaxle (Mower Specific)
Riding Lawn Mower Wheels Won’t Turn: Are the Causes/Solutions Any Different?
Now if you have read this blog and are wondering if these diagnoses and repairs apply to why your riding lawn mower wheels won’t turn, well, some will and some won’t. When it comes to riding lawn mowers, there are several differences, and there are different issues you’ll need to look into. So here are a few examples of where you would need to start your investigation.
- Damaged Accelerator Pedal
- Broken Accelerator Cable
- Loose Transaxle Connection
- Poor Transaxle Operation
- Hydrostatic Motor Failure
- Hydrostatic Pump Air Blockage
- Control Levers Adjustment
- Missing Wheel Keys
- Slack Drive Belt