Archive through September 02, 2009

[jmuncie]

Drag racers and pullers do need a bigger contact patch, but for different reasons.

For starters, frictional force between two surfaces is equal to the coefficient of friction multiplied by the normal force (force pushing the two surfaces together). Most of the time, the coefficient of friction is a constant for the pair of surfaces, so the frictional force is independent of contact area and increases proportionally to the normal force. Double the normal force and the frictional force doubles.

Rubber on asphalt is an odd case. As contact pressure goes up, the coefficient of friction decreases. Double the normal force and the frictional force doesn't quite double. Therefore, you can increase traction of tires on asphalt by increasing the contact area.

For pullers, it's an issue of shear strength of the soil they're pulling on. There's a limit to how much force the tire can exert on a square inch of the track before the upper layer of soil shears away from the track. In order to increase the pulling force, increase the square inches of soil being sheared away from the track.

 

[rpalmer]

So for me.. "Joe ol man" pushing snow with my Cubs, do I want a narrower or wider foot print? I just want to maximize my tractors power.

 

[jmuncie]

Oh yeah, this started with snow. Snow is similar to dirt in that you're limited by the shear strength of the snow. You can also greatly improve the shear strength of snow by packing it. If I had to plow snow (and I don't) I'd go wide to get the surface area and add a bunch of weight. Back when we got enough snow to mess with in central Indiana, we ran 23-10.50 turf tires with chains and 40 lb wheel weights (per wheel) with pretty good luck. That combination worked much better than the 23-8.50 Carlisle ags with old style CC weights on my 126 used to pull my daughter on a sled. They tended to float on top of the snow until the going got tough. Then they'd dig a hole that they couldn't climb out of.

 

[kredlinger]

Lookin to change the carb out for a pro from the recast type that seems "sluggish". Been told that there are a few very good reworked carbs out there that have an extremely good pick up signal & have good velocity/flow. What have a few of you used or are using that have proven themselves for better or worse?

 

[drohacek]

My information shows that the Winter Nationals from the Hillard Ohio club will be held Jan 8-9th. Is this correct? It used to be much later in the month. Is it still at the same location in Columbus as well? Same building?

 

[ewank]

It has been that early and in the bigger building for a few years now. Still on the state fairgrounds. Heated pits now.

 

[gfedwards]

---Evan, we use the Vogel 1.2 "boat carb". They have been flawless for us for several years. I have tried other people's "recast" carbs and they are not very good. We have been very pleased with our Vogel 1.2's.

 

[gfedwards]

Sorry!!! My last post was supposed to be addressed to Kyle.

 

[kredlinger]

Thanks Greg, I had 2 others say Vogel & Kerbers name came up too. The 2 recasts I have(different makers)have not made me happy.
Thanks for the input.

 

[rbernard]

Hi everyone,I'm trying to build a hydro pulling tractor.The standard rotation for the hydro pump on a 782 is in a ccw rotation,does anyone know that if by turning the plate on the charge pump 180 degrees the pump will work in a cw rotation?

 

[drohacek]

Ron,
You can turn the charge pump 180 degrees and it will work. It won't work flawlessly but it will work. Reader's digest version explanation is that there is a plate inside that has a beveled edge that allows the fluid to start to flow smoothly. If you turn this backwards there is no bevel on the opposite side. Hence it will be a little jerky when you start off. Probably not a problem in a pulling tractor. Just so you know, turning the pump over 4,000 rpm will not improve your pulling capability so your pulling motor will do you no good unless it's making power at 3,500-4000 rpm. Anything after that is just spinning the pump for nothing and also will shorten the life of the pump. Also you can turn the carrier over to reverse the direction on the rear but driving the ring gear from the back side of the tooth is not recommended and will not hold up. There are reverse cut ring and pinions available if you need to reverse the carrier.

 

[rbernard]

Dave,thanks for the info on the pump,thats what i needed to know,I'm using an older harley 74 ci v twin which makes the most power around 3500 to 4000 rpms.I'll have to get the reverse ring and pinion.

 

[jmuncie]

Dave,

Correct me if I'm either a) wrong about Cub Cadet rear ends or b) you're discussing a tractor that has had a different differential swapped in, but I believe the Cub gears are straight cut bevel gears which is the only reason you're able to flip the carrier to begin with. That's the way they were installed in the Farmall Cub to get the wheel rotation right with the drop boxes. The have the same strenght no matter which way you drive them.

With hypoid gears, they are weaker when driven one direction vs. the other. The gear axes do not intersect with hypoid gears and if you flip the carrier the teeth would cross each other instead of meshing. Reverse cut gears are basically mirror images of the standard gears.

Jerry

 

[drohacek]

Jerry,
You may be right. I may be having a brain cramp here and just generalizing about driving from the back side. Typically you would not want to do that but if they are straight cut gears it would not make a difference. I was thinking they were hypoid gears. If there is no curve it can't be a big deal to drive either side then. Been a while since I have had to work on the carrier.

 

[jdiederichs]

We've flipped the carrier on several cast iron rearends with great results. Ran for 9 years of pulling with our Super Stock turbo diesel Cubs. It'll take the power w/o any problems if the backlash etc is verified. Works great. If you have the staright cut ring and pinion from the aluminum rearend the same applies, works well!
Hmm, Milwaukee iron in a Cub, I like it.
Note that the stock carrier (if cast iron ) will likely not hold up to any serious loads, you should use a 2 piece carrier from the later X82> Cubs with the aluminum rearends, they are nearly bullet proof.

 

[bbrigham]

Now I'm not a big HD fan, but.....a Cub with a HD V-twin and duel stacks coming up one side........

 

[rbernard]

Hi again,I really appreciate the information,I'm using the transaxle from a 782,it has the hypoid gears and fine spline axles.Getting everything turning in the right direction was the biggest challange,the rest shouldnt be to bad,thanks again

 

[jdiederichs]

Ron,

Not all fine spline units were the strong two piece carrier! If it is the IH cast carrier it will have red (maroon) epoxy paint on it's exterior. Only the side gears were changes to allow the fine splines as an interim solution; the 2 piece carrier us unpainted and has multiple capscrews bolting the carrier assembly together.

Now the ring gear will bolt up to either style, so you can swap if needed. The 2 piece is a much stronger unit, stock pulling tractors with 12 HP could bust the cast iron carrier. BTDT years ago.

 

[gfedwards]

Ron,
There is not an issue running your carrier flipped over. We have done it for years in our Open Super Stock vtwin tractor. We have other pullers that we know that run them like this, too. Don't let people tell you that you can't do this. They are usually people that have never done it or seen it done and are going on what they have heard from either a book or someone else. Take it from someone who has done it. Jim Diederichs will back me up. Good luck on your project.

 

[jmuncie]

Ron,

Do I understand correctly that you have hypoid Cub Cadet gears? I didn't know there were any.

Jerry