Toro Super Bagger 20192 Transmission Powering Left Wheel Only

[Blaine B.]

Suddenly the transmission on my Toro Super Bagger model 20192 began powering only the left wheel, which of course will create a myriad of issues when trying to cut straight and also traction loss as well. This particular mower does not have the ratcheting gears like some of the older Toro Recycler lawn mowers do. I believe that the older Toro Recycler lawn mowers have a differential in their transmission that acts more like a full time locker, so they rely on the ratcheting star gears to act as the open differential.

The transmission on this Toro Super Bagger 20192 seems to behave more like a true open differential, and the axle shafts are positively connected to the wheels full time. What fails inside of these transmissions that only allows power to be transferred to one wheel only?

 

[Rivets]

Remove the wheel and see if the teeth are in good condition. As the bearing hoc wears the drive gear with loose it’s alignment with the wheel gear, chewing it up.

 

[Blaine B.]

Remove the wheel and see if the teeth are in good condition. As the bearing hoc wears the drive gear with loose it’s alignment with the wheel gear, chewing it up.

I took off the wheels just to double check. These wheels use metal gears. I am all too familiar with the Toro Recycler models post-2009 that used PLASTIC gears in the wheels which were just awful!

This Super Bagger doesn't have any kind of a spring loaded ratcheting for the gears on the end of the axle shafts either. The axle shaft and small pinion gear are fixed. It seems that though something within the differential isn't applying power to the right wheel.

 

[Rivets]

Sounds like the axle is broke inside the tranny. If you have the rear wheels off the ground, can you turn the wheels independently? If yes internal damage and these trannies are not serviceable. I have seen it happen, but can’t remember the last time I replaced one.

 

[StarTech]

Can also an axle flange bearing failure.

 

[Blaine B.]

Can also an axle flange bearing failure.
View attachment 66105

I understand when these fail the axle gears do not mesh with the wheel gears. Not the issue here, yet.

 

[Blaine B.]

Sounds like the axle is broke inside the tranny. If you have the rear wheels off the ground, can you turn the wheels independently? If yes internal damage and these trannies are not serviceable. I have seen it happen, but can’t remember the last time I replaced one.

Yes, the wheels spin independently and also spin equally with their axle shaft half.

Between the last time I mowed the grass up until on Thursday when I mowed last, I did nothing unusual, with the exception of add tension to the Personal Pace cable right before starting the mower up on Thursday, which was the first time I noticed that the mower wasn't tracking straight and was also losing traction on terrain as a result of only having 1 drive wheel receiving power.

I'm familiar with these mowers. I have replaced wheels THREE times and a transmission ONCE on my Father's 2009 Toro Recycler model 20333 (with blade clutch.) After that many replacement parts we sold that mower before anything else had the chance to fail again, I thought that was ludacris. That mower's plastic wheel gears were atrocious. I later found out that an aftermarket wheel with metal gear was available. Also the tire tread on that particular mower seemed to be made of a less durable material that wore out super quickly as well.

I also replaced the transmission and wheels both one time each thus far on my 2007 Toro Recycler model 20073 which I still have, and will begin using once again.

QUESTION TO CONSIDER - If the axle shaft IS broken inside of the Toro Super Bagger's differential housing, wouldn't the mower not move at all? Typically with an automotive differential that is fully OPEN and not locked or with limited slip, if an axle shaft breaks, since that axle shaft will have the least resistance, that is the side that will receive 100% of the power, rather than the opposite wheel. Why in this mower's configuration is the opposite wheel still receiving tractive power??

 

[Rivets]

Since I’m not there to see the unit the only way I see to find the cause of this problem is to open the tranny and take a look inside. This is one of the problems in trying to diagnose problems from a thousand miles away.

 

[Blaine B.]

Since I’m not there to see the unit the only way I see to find the cause of this problem is to open the tranny and take a look inside. This is one of the problems in trying to diagnose problems from a thousand miles away.

I've done that once before with a similar plastic transmission on the Toro Recycler model 20333. These transmissions are a PITA to work on - case halves sealed with silicone/RTV and they also use a viscous gear oil. They do not have a "cover" that can be removed for inspection unlike the older metal transmissions with the 4 bolt cover and grease.

On these plastic transmission, if you remove all of the screws, the two case halves essentially fall off of the axle shafts and the unit cannot be inspected while it is installed in the lawn mower. Ask me how I know!

I also assume this kind of failure isn't discussed. Most people probably just wheel the mower to the Kerb and that is that.