Any push mower experts out there?

[tunahead72 2,424]

I have a 2005 Troy-Bilt self-propelled mower that has served us well over the years.  I'd like to hold on to it, but it isn't self-propelling at the moment, and my body is complaining.  With the engine running, if I raise the front of the mower and squeeze the handle, the front wheels will turn and I can adjust how fast they turn with the little knob at the handle, but there's no forward motion when I lower the mower to the ground.  I could use some advice....

 

I think my problem is with the cable, because the gear box isn't rotating forward and tightening the belt like it's supposed to.  Thinking it's probably stretched over the years, I measured it and found that it's about an inch longer than the current Stens replacement.  I was able to adjust the cable a fraction of an inch yesterday, by unthreading the caps at each end, effectively "lengthening" the cable housing and "shortening" the cable itself.  It didn't help, the gear box still isn't rotating forward, and the belt still isn't tightening.  The clutch lever on top of the gear box does move like I think it's supposed to when I pull the handle, but nothing else happens.

 

I cleaned all the grass from the entire mower earlier.  The handle assembly works fine.  The wheel assemblies and spur gears seem okay, a little loose and wobbly, but not bad -- there's very little wear that I can see on the gears or the inside of the wheels.  The belt is only about a year old and looks good.

 

I would just replace the cable, but I wonder if there might be something wrong with the transmission.  The cable slides easily inside its housing, but I did notice today that one end is just starting to fray a tiny bit.

 

I should mention that this self-propelled mechanism has never worked as well as I hoped, even when it was new.  And now it's acting much like nearly dead weight, and practically begging to be removed completely.  I hope it doesn't come to that.

 

Here's some photos, any thoughts?

 

 

 

[SylvanLakeWH 25,731]

Maybe put a spacer on the black plastic doohickey that moves/hits the box? Take up some of that space so it is snug? May do the trick.

 

Just a thought.

[wallfish 17,055]

Verify the gearbox is good and working by spinning that pulley. Maybe by the nut on top of the pulley with a socket and a drill. Try and add some load to the wheels to verify it's not slipping gears and can move the mower. If the gear box doesn't work then belts and cables don't mean a thing.

If the gearbox is good then a shorter belt may be the solve because that bracket can only move so far to tighten the belt. (or at least it appears that way in the pic) If the tab with the spring attached to it is bottoming out where the end of the cable attaches, then it may not be moving enough to fully tighten the long belt.

 

[squonk 41,226]

Belt looks well worn too. 

 

Time to get on the Horse and gain some weight like us other old guys! 

[tunahead72 2,424]

2 hours ago, wallfish said:

Verify the gearbox is good and working by spinning that pulley.... If the gear box doesn't work then belts and cables don't mean a thing...

 

That's really the key, isn't it?  I've been meaning to do just that for a couple of days now, I'll check it out this afternoon and get back to everybody later.

 

Thanks for your replies, guys!

[Stormin 9,981]

6 hours ago, squonk said:

Time to get on the Horse and gain some weight like us other old guys! 

 

Speak for yourself. 

[squonk 41,226]

5 minutes ago, Stormin said:

 

Speak for yourself. 

How many calories in pudding and crackers? 

[tunahead72 2,424]

Just a quick update....

 

I tested the gear box today, by removing the belt and engaging the box by hand (I'd already removed the cable), and then spinning the pulley with my cordless drill.  The box rotated forward easily, and turned the output shaft with no unusual noises or anything.  Both front wheels turned freely, but not as fast as I expected to see.  I forgot to try simulating a load on the wheels, I'll try that tomorrow.  But bottom line, it's possible the gears inside the box aren't meshing completely and are thus slipping.

[tunahead72 2,424]

I tested the gear box again yesterday, both with and without a load.  Same results as before with no load, with both wheels turning freely but not very fast, and any kind of load slowing the wheels down pretty quickly.  That matches what I see when I try to actually use the self-propel system while I'm mowing.

 

This mower has work to do, and it works fine as a basic human-propelled mower with a slightly heavy front end.  I have two Wheel Horses that need attention more immediately, so I'm going to use this one as is for now.  It looks like the two halves of the gear box housing are held together with 8 Torx screws, so I'll open it up at some point soon and see what it needs.  The box assembly isn't available (and I wouldn't want to spend the money on a new one anyway), but some parts are still available, including what looks like a plastic gear that rides on the output shaft -- gee, I wonder if that could be worn.

 

By the way, I don't have a photo, but the underside of a Wheel Horse drawbar works very well as a hold-down device if you need to tip a push mower onto its back wheels and keep it there for a while. 

 

Thanks everybody for your ideas, I'll keep you posted.

[squonk 41,226]

Plastic gear. And some engine companies use these to drive their camshafts now! 

[sjoemie himself 3,068]

I'll one up ya.. Taryl showed lawnmowers with plastic 'transmissiôns'.. load of fecal matter.. 

[sjoemie himself 3,068]

Just now, sjoemie himself said:

I'll one up ya..

I take that back.. plastic to drive a cam is worse now that I think about it

[Handy Don 12,343]

19 hours ago, sjoemie himself said:

I take that back.. plastic to drive a cam is worse now that I think about it

Engineered plastics can be pretty amazing but, I suspect, these components are not expected to be functioning properly in thirty to sixty years.

Edited July 20, 2022 by Handy Don

[sjoemie himself 3,068]

5 hours ago, Handy Don said:

plastics can be pretty amazing

True.. and although not plastic, i've seen carbon fiber driveshafts being used instead of steel or aluminium.

 

About the longevity, I don't think that anything produced today is intended to last 30 to 60 years anyway.

 

[squonk 41,226]

I remember the good old days. The best engine ever built, the small block Chevy with a plastic cam gear! 

[8ntruck 7,052]

Kind of like the 20 np Sears riding mower I had a long time ago with a Pierless 6 speed tranny.  The kids didn't feather the clutch when they mowed.  I replaced the pot metal input bevel gear three times.....

Edited July 20, 2022 by 8ntruck

[The Freightliner Guy 1,327]

What the heck is that front drive system I’ve never seen something like that 

[tunahead72 2,424]

I'm not sure how to answer your question exactly.  It's similar to others I've seen elsewhere, I've just never had to look at one closely enough to try to make it work better.

 

There is a plastic cover that I removed for the photos, maybe that's throwing you off.   That's where the mice like to party, it's a good idea to take that cover off every once in a while and clean up their mess.