Lawn Mower Hard To Push
Poor cable tension
How a mower drive system works
Four components make your mower move:
- Crank pulley
- Drive belt
- Trans-axle assembly (incl. wheels)
- Drive cable
1 Crankshaft pulley
The crankshaft pulley is dedicated to sending power to the trans-axle. It’s fitted right under your mower engine, fixed to the crankshaft, so when the engine is running the drive pulley is working.
Pulley’s usually have a plastic or metal shroud to help protect them from flying debris. Often the shroud comes loose, which allows grit and stones hit the pulley causing damage.
Your pulley may or may not be visible when you turn your mower over. (always turn your mower over with carburetor side facing up – prevents gas spill and flooding)
Crank pulleys become brittle over time and a direct hit can cause them to break.
This mower has lost its protective shroud.
2 Drive Belt
The right belt is mission critical, getting this wrong can cause even more problems.
The missing shroud on this mower will cause debris to impact the belt and will shorten its life.
Trans……what? Is that even a real word? Mmm, I think so. A trans-axle is the name given to the complete assembly. That’s the transmission, differential and the axle combined into one compact unit.
If you want to read more about lawn mower trans-axles, you can check out this post “What’s a lawnmower trans-axle?”
The trans-axle is the business end of making your mower actually move. It has a pulley fixed to the top of the assembly to receive the drive belt. These pulley’s are pretty durable but on some axles are made of plastic, you can guess what happens to them over time.
Anyway the transmission component of the trans-axles unfortunately does usually wear out before the engine. Especially mowers that spent their working life laboring on a hilly yard.
And the worse news is mower manufacturers don’t usually supply internal parts for the transmissions. However they will sell complete transmissions. For some mowers paying for a new tranny and the labor to fit may not make economic sense.
Other common trans-axle problems include axle-pins and wheel drive gears, these guy’s simply wear out, and again may not be economically viable to repair.
Trans-axle or transmission, both words are used to describe this component. But trans-axles is a more accurate description of this type transmission.
A lawn mower trans-axle may be fitted to the front or the rear of the mower, making the mower either front or rear wheel drive.
Trans-axles are commonly lubricated at factory for life.
Other common axle issues
4 Drive Cable
A good drive system requires control, you need the ability to progressively apply power. This is usually done by way of control lever and braided cable. Same type cable used on bicycle brakes.
The cable pulls on a lever mounted on the transmission. The lever locks the transmission progressively, which causes the mower wheels to move.
As you can imagine, any thing that prevents this lever from being fully applied will cause the mower to feel slow. This is the most common cause of a slow transmission and can fixed in a snap.
Adjusting the drive system
And finally adjusting the drive system. This isn’t a difficult process, but there’s a few tips you’ll need in order to get it right. It covered in the pictures below.
Your mower drive adjuster may not be identical to the one’s shown here, but that’s OK, because the principle is the same.
Some mowers will have a tool-less adjuster, nice!, makes life a ton easier. However most mowers will require tools, but not many, two vice grips or adjustable wrenches is all you need.
If you’ve got some WD40, shoot it down the cable inner, you might need some eye protection, tends to splash back, Awkward? Yes, but worth the effort.
Locate the cable
Now go ahead and locate the cable adjuster.
Two types are common:
- An adjuster at the drive control lever bracket
- In line cable adjuster
Both types will have a lock nut, it prevents the adjuster from backing out.
Simply open the lock nut by holding one nut and opening the other. Back off the lock nut so as to allow plenty of room for adjustment.
Take up slack
Adjustment is easy, our goal is to adjust the cable so that it moves further away from the drive control lever.
Run it out a few turns, but don't tighten up the lock-nut just yet.
This is an important step, if you over adjust the cable, you'll find the mower difficult (stiff) to reverse. If you have over-adjusted, not a problem, just back it off a few turns.
I like to over adjust and then back it off until I find the sweet spot, then I know I have reached max adjustment - make sense?
Self propelled lawn mower hard to push? The most common cause of a hard to push self propelled lawn mower is poor drive cable adjustment.