Why the positive camber on the front wheels?

[Hugo Habicht]

Hello,

the camber on the front wheels of the G1900 is positive, about 3 degrees although it looks more.

I would like to change that but not before understanding why it was done this way. As opposed to a pretty ignorant member of this forum I do consider Japanese engineering top class in general and Kubota engineering in particular. So the engineers had a technical reason to do it this way.

Does anybody know why the positive camber?

 

[GreensvilleJay]

easier for tractor to drive in straight line.

 

[Hugo Habicht]

easier for tractor to drive in straight line.

I thought toe or more so caster angle would contribute to that, yet Kubota decided to make both zero.

 

[GeoHorn]

Positive camber accomplishes a couple of things: It allows for higher gross-weight (even with rigid suspensions). It facilitates turning-traction. It favors turn-radius.

 

[ruger1980]

In theory the camber or the vertical center axis of the front tire and the King pin axis should intersect near the center of the tire. This makes steering easier and correctly distributes the load on both items.

 

[NorthwoodsLife]

With all respect:

It is a lawn tractor. Not a race car.

Top speed might be 10 mph. Camber and castor and toe in, is set to help you drive it easily and mow grass.

That is what it does best.

I wouldn't mess with factory settings unless there is a problem with the front wheels tearing up grass, etc.

I will admit, I have a cheap Craftsman lawn tractor for finish mowing and I never checked the camber, castor, or toe in. Nor ever did I have reason to do so.

Good luck Sir.

 

[Hugo Habicht]

Positive camber accomplishes a couple of things: It allows for higher gross-weight (even with rigid suspensions).

How is that?

It favors turn-radius.

You mean tighter turning radius is possible? Have to check that.

In theory the camber or the vertical center axis of the front tire and the King pin axis should intersect near the center of the tire. This makes steering easier and correctly distributes the load on both items.

Yes, I agree. But the design does not achieve this. And the positive camber seem to move the centre of the tyre force (red) rather away from the king pin pivot point it seems (perspective a bit misleading, but picture basically correct).

 

[Hugo Habicht]

With all respect:

It is a lawn tractor. Not a race car.

You are 100% correct there

But then again, we don't know how fast we can get this machine to run and where it will be driven then But this is not my reason for asking.

I will admit, I have a cheap Craftsman lawn tractor for finish mowing and I never checked the camber, castor, or toe in. Nor ever did I have reason to do so.

Well, not much to check, it is clearly visible and I find it looks stupid. That is what is bugging me. The rear wheels (that steer as well) do not have that, their camber is zero.

 

[NorthwoodsLife]

You are 100% correct there

But then again, we don't know how fast we can get this machine to run and where it will be driven then But this is not my reason for asking.



Well, not much to check, it is clearly visible and I find it looks stupid. That is what is bugging me. The rear wheels (that steer as well) do not have that, their camber is zero.

Rear stear is cool!!!

Learn something new every day.

 

[Hugo Habicht]

Rear stear is cool!!!

Learn something new every day.

Yes, it has four wheel steering allowing for a very tight turning radius. With a 48" cutting deck it only leaves about a 20" circle uncut, very handy when cutting around trees.

I bought a 54" deck that will even make that a bit smaller again.

We agree it is not a race car, but with that steering the seat safety switch (that I joked about initially) does make sense. When going "full speed" and turning the steering wheel quickly it would throw you off the seat easily.

 

[Hugo Habicht]

Here you can see the rear wheel steering mechanism.

 

[NorthwoodsLife]

Here you can see the rear wheel steering mechanism.

That is awesome. Sorry that I called it just a lawn tractor.

A great idea but I am guessing it was destroyed by the zero turn mowers... which are just goofy.

I was in town the other day gassing up my truck at KwikTrip. A guy drives in on a zero turn mower. Goofy looking thing. He puts gas in it and then spins a 180, on a dime style, and drives to the church right next to the gas station to continue mowing.

Something inside me didn't like it. The same feeling I felt when I saw a Bobcat skid steer work for the first time, 40+ years ago. Putting me and my Kubota B7100 out of business. It was a better small space machine.

I guess, and know, that I am getting old.

Your G1900 will be a collectable. Keep it going.

 

[Hugo Habicht]

That is awesome. Sorry that I called it just a lawn tractor.

No reason to be sorry, Sir, it is a lawn tractor, not more, not less.

And I agree with the zero turn mowers. I do not like them either, despite their technical advantages. I do not even need four wheel steering, I had planned the shape of the lawn with no corners, no trees, so I have a simple straightforward cutting path.

I guess, and know, that I am getting old.

Yes, I am too, and thinking about it, everybody is, no exceptions.

Your G1900 will be a collectable. Keep it going.

Yes, that is the plan. Still doing up the tractor, cosmetics is next. Good thing is that it's design allows it to repair it yourself.

I think the older the tractor, the longer they can be used. When I looked at my friends L1421 recently (that he plans to use for the rest of his life) with a graphics LC display, CAN bus, fairly complex electronic engine and tractor controllers, I had serious doubts if he will be able to keep it running long term.

Same as with cars, it is often not the mechanics any more that ends it's useful life but the electronics. I think my friends 1960s Massey Ferguson will still be running when his 2019 Kubota is long gone.

 

[PaulL]

I guess, and know, that I am getting old.

Yes, I am too, and thinking about it, everybody is, no exceptions.

The old fella down the road always says to me "getting old really sucks." My stock answer is "it's better than the alternative."

 

[GeoHorn]

….
Your G1900 will be a collectable. Keep it going.

If it remains original.

 

[Hugo Habicht]

If it remains original.

It is and it isn't. I am not making a museum piece out of it, I want it fully functional, paintwork flawless but it has to do work. And every tractor here in the forum I have seen has been modified as per requirements of the owner. Are they original?

Also when I did repairs and noted weaknesses of the original design (weaknesses that showed after over 30 years of hard work) or flaws in the original design I modified it. For example:

- combination box is now contactless, shows error codes, has status LEDs for quick fault finding and an override function that allows the tractor to be started despite faulty safety switches

- instrument cluster now has proper dials for temperature and tank and added instruments for engine oil pressure and an engine rev counter that can be switched to hydraulic pressure and driving speed

- extra seals on the front wheels that prevent corrosion

- front axle modified to remove steering play

- steering box modified to achieve play free steering

- radiator plug that does not brake off any more

- coolant drain valve that does not brake off when you touch it

and plenty more. The work I did so far is described in Reviving a G1900

Decide for yourself if original or not. Every modification I did can be easily brought back to factory condition. So if you want back 2 inches play in the steering, no problem.