Why is Weight The Only Solution Being Offered To The Problem Of Traction?

[Jstpssng]

Exactly. However, steel chains actually reduce traction on pavement. They are best at improving traction on ice. Not sure what they do on mud.

They are very good at digging a hole.

 

[Cahaba Valley Farm]

I own three RTVs with tweels on them. We have had them two years. They perform better in virtually all conditions than tires and we operate in all conditions. I have had them in about seven states and conditions from swampy to rocky hills.

We primarily use them because they don’t get sidewalk cuts and go flat but they do have a larger ground contact patch and thus less ground pressure per square inch. We get stuck less.

All that being said when it comes to work and pushing a blade or dragging an implement weight is your friend. Even my dozer with steel tracks will spin out before it loses power when trying to push too hard. My first dozer weighed 20,000 lb and it was about useless for pushing brush. Trees no bigger around than my leg it would struggle with. I would have to dig around them. My new dozer weighs 40,000 lbs and takes these trees out no problem. Yes it has more HP but being able to get that HP to the ground due to weight is the big difference.

So then what you're saying is it's not just about contact area it's also about weight. A lot of contact area with not much weight is still not a perfect recipe for traction.

 

[Cahaba Valley Farm]

So it's a combination of weight and penetration/contact area to achieve traction.

 

[LouNY]

So it's a combination of weight and penetration/contact area to achieve traction.

That was a very specific application being on frozen ground with a thawed surface which gets very slippery and slimey.
The second was some very sticky gumbo clay type soil.

 

[coast40]

I own three RTVs with tweels on them. We have had them two years. They perform better in virtually all conditions than tires and we operate in all conditions. I have had them in about seven states and conditions from swampy to rocky hills.

We primarily use them because they don’t get sidewalk cuts and go flat but they do have a larger ground contact patch and thus less ground pressure per square inch. We get stuck less.

All that being said when it comes to work and pushing a blade or dragging an implement weight is your friend. Even my dozer with steel tracks will spin out before it loses power when trying to push too hard. My first dozer weighed 20,000 lb and it was about useless for pushing brush. Trees no bigger around than my leg it would struggle with. I would have to dig around them. My new dozer weighs 40,000 lbs and takes these trees out no problem. Yes it has more HP but being able to get that HP to the ground due to weight is the big difference.

My small Mitsubishi dozer won't push like the old TD9 or HD7 would, but it's better than the Oliver OC4 was.

 

[ROUSTABOUT]

Because weight is the no traction solution. Maybe you can spray some 3M weatherstrip adhesive on your tires. Duals help you stay up in mud. If it does seem to pull more, just figure the weight of the extra tires, and that is the reason why. All tires on all tractors here are water and anti freezed to the hilt. I've drove around in mess up to my belt. Nowadays I'm not quite so eager when somebody gets stuck.

 

[Cahaba Valley Farm]

Since we have delved down into the physics of how tires work I would like to ask why the front tires are usually so small? I'm thinking the reason being for steering purposes? If it's a silly question forgive me but I figure lets not leave any stone unturned at this point.

 

[npalen]

When I was learning to drive standard shift cars in slippery conditions around 55 years ago, I was taught to start off slowly in the highest gear that wouldn’t stall the engine. The theory being the piston stroke would be longer and smoother at the drive wheels, it usually proved true for me and I think the hst drive helps to provide the same effect.

Yep, let out easy on the clutch! Never thought about it in terms of " piston stroke longer and smoother" and , although the piston stroke length doesn't change, it is slower and smoother. I think you are correct on the hydrostat keeping the tires engaged.

 

[LD1]

Since we have delved down into the physics of how tires work I would like to ask why the front tires are usually so small? I'm thinking the reason being for steering purposes? If it's a silly question forgive me but I figure lets not leave any stone unturned at this point.

It's not a single reason really. Rather a number of factors.

Under most farming conditions....the rear tires do 90% of the tractive work....and carry more load (or capable of) than the front

So everything is made bigger.

And since they are fixed....clearance isn't a problem.

To have an equal sized front tire, the front axle would have to be considerably wider to clear the tire when turning ...so it doesn't come in contact with the engine or frame.

It would also be an obstacle to clear in front loader design

The other option is articulating machines.

But both larger/heavier front tires, axles, and steering setup as well as articulating would add significant cost for little gain for the average person.

They do make machines with equal size tires. Being the really large farm tractors. And some things like JCB TLBs. But if you look at the jcbs....they really didn't oversize the front tires to match the back. Rather comparing to an equivalent sized tractor....it looks as much like the rears we're downsized to match.

And back in the days of rowcrop farming and cultivating....smaller front tires was as much about visibility as anything

 

[npalen]

What type of conditions would mechanically lock a tread with the surface? In that case the cf would be 1. Rubber on dry asphalt is around 1. Rubber on wet smooth concrete in the cow yard is near zero it seems.

What type of conditions would mechanically lock a tread with the surface?
Picture driving across newly poured concrete that is just firm enough to support the load but let the tire lugs sink into the concrete. Then come back next day and drive thru the same tracks. Probably would give a pretty good "bite".

 

[npalen]

So then what you're saying is it's not just about contact area it's also about weight. A lot of contact area with not much weight is still not a perfect recipe for traction.

My college physics teacher posed this question to the class: If traction consists only of weight times friction coefficient and not contact area, why do racing slicks offer more traction? I don't recall anyone with an answer at the time but I think I know the answer after thinking about it for 50+ years now.

 

[Blue hood]

Old tractors used to have some kind of rims add-ons to help rear tires traction, besides the added weight it had an on/off manual spikes system. Who knows why this idea disappeared or has been replaced all together by other more heavy and expensive track systems.

Just thinking, if liquid filling it's not enough to improve traction, what about adding narrow solid rubber wheels without doubling the tractor's rear tires width.

 

[Blue hood]

Here is the old footage a was looking for. Brand name Dinabite

 

[Cahaba Valley Farm]

It's not a single reason really. Rather a number of factors.

Under most farming conditions....the rear tires do 90% of the tractive work....and carry more load (or capable of) than the front

So everything is made bigger.

And since they are fixed....clearance isn't a problem.

To have an equal sized front tire, the front axle would have to be considerably wider to clear the tire when turning ...so it doesn't come in contact with the engine or frame.

It would also be an obstacle to clear in front loader design

The other option is articulating machines.

But both larger/heavier front tires, axles, and steering setup as well as articulating would add significant cost for little gain for the average person.

They do make machines with equal size tires. Being the really large farm tractors. And some things like JCB TLBs. But if you look at the jcbs....they really didn't oversize the front tires to match the back. Rather comparing to an equivalent sized tractor....it looks as much like the rears we're downsized to match.

And back in the days of rowcrop farming and cultivating....smaller front tires was as much about visibility as anything

All that makes perfect sense.

 

[airbiscuit]

 

[airbiscuit]

 

[BnRidge]

IH634 and IH4166 had equal sized front and rear yet still able to steer and clear. It didn't seem to catch on though for some reason. The neighbors had an IH3588, which I always thought looked a little strange. But now that I see it again notice it was articulated and not mfwd. Seems like designs needed to evolve some.

 

[LouNY]

The IH 634 was very similar to the County series of tractors which were Ford based.
County 6;TractorData.com County Super 6 tractor information
They are a very clumsy tractor, not very maneuverable at all. Hard to get on unless the front wheels are turned.

 

[Cahaba Valley Farm]

View attachment 732394

You know I totally forgot about fruit tractors. I have seen them before under specialty tractors but forget about that design so thanks for sharing.

When I look at your tractor picture in your avatar it seems to me that the design is replicating gears in a gear box thus creating a lever of force against the ground. The big wheels in the back moving and rotating against the small wheels in the front. Is this observation correct?

 

[LD1]

View attachment 732393

When you look at these pictures, it's easy to see some of the issues I referred to.

Can you see the issues trying to put a loader on that tractor? Or the visibility issues up front when trying to do roe crop work or something.

And the limited benefit that those higher tires give over smaller ones isn't significant enough to justify the cost, especially given the downsides that go with it.

If you need more traction ...it made more sense and was more cost effective to just move up a size or two to a bigger machine