28 ver's 38 why did Allis disadvantage the selves

My question is not a BRAND comparison.

This is an Allis engineering "why" question.

Yep i agree. Tracton Boost is awesome !

In early 1970's, We sold our MD and MTA Diesel and bought a D17 with Tracton Boost, we were never disapointed in its plowing performance. Or its Power director advantage in baling.

Nice Story about your CA.

Brian, My D-17 IV has standard front spindles and sits a little low on the front. Front tires are 7.50 x 16". The weight of the rotary hoe makes it look level in the picture. When they came from the factory with 13.6 x 38"'s and the tall front axle spindles, it sat low on the rear. Would like to find a long spindle front axle. I think it might be very close to level with the 14.9 rears. I changed to 38's more than 20 years ago for row cultivating kidney beans. Have a 16" single front that I'm thinking of putting in and I think it just might sit level. At one time there was a D-17 III that was a factory 38" option with the tall front end in the area.

Edited by Calvin Schmidt - 11 Jun 2018 at 8:44pm

WF owner wrote: 38's were an option on many tractors, but I suspect the dealers didn't order them since so many tractors were sold by price. $$$

Story that I've been told, back when our WD 45 was new, my grandpa was in a field with a 8 ft cobbled together horse drawn disk and neighbor comes down with his JD A and 8 ftJD disk to help. After a couple rounds granpa laps him , so he stops and says our disk pulls easier and they switch disks. After another couple rounds grandpa laps him again. He stops again, gets his disc back on and tells granpa that it looks like he didnt need any help.

I'm an AC fan and we had a WD45,CA and an Oliver 77 when I was growing up.Although the 77 had less HP than the WD 45 it had 38" rear tires  on a dead pull if it was geared down the 77 would would pull more than the WD45 every time.You always see tractor pullers put on larger diameter tires you never see them drop diameter taller tires just out pull shorter tires in almost all situations.I used to pull a WC with 36" tires way better puller than using 28" on the same tractor.

Gary Burnett wrote: I'm an AC fan and we had a WD45,CA and an Oliver 77 when I was growing up.Although the 77 had less HP than the WD 45 it had 38" rear tires  on a dead pull if it was geared down the 77 would would pull more than the WD45 every time.You always see tractor pullers put on larger diameter tires you never see them drop diameter taller tires just out pull shorter tires in almost all situations.I used to pull a WC with 36" tires way better puller than using 28" on the same tractor.

Was the 77 upgraded with wider than stock tires? Many were a long time ago. Was the 77 engine upgraded to 88 or super 77 overhaul? Some had the entire block replaced with a newer, bigger cubic inch block from another tractor. Besides that, a 77 IS a good puller even in stock form and was very easy to boost rpm a little.

*NATPA TIRE CHART:  

Smaller tires can be just as efficient as the bigger tires as long as your horsepower is getting to the ground. Allis wanted to pull your same size Impliment faster, not a bigger impliment the same speed as the competitor. It doesn’t take more tire to pull the same impliment one mph faster and get the same area covered.

DougG wrote: Lonn wrote: Pulls are one thing, suped-up tractors in most cases, with modified drawbars and non stock wheels and aluminum parts pulling on gravel tracks. I haven't pulled in almost 20 years and don't look to do so again for a very long time, if ever. Field performance is what I like and I like my 200 and 7050 best for that. My days of doing serious field work with a WD or D17 were done back in the early 1990's. I suppose if I was running a new Magnum I'd say the same about running the 200 and 7050. How could Allis ever have put those tractors out with the lack of features that I need today? Right? UUUUMMMM, so Allis was ahead of the class in the 8000 series back in the day, that was back in the 19 Eighties, tractor engineering had new stuff ready to keep them in front and good for farming,, don't quite understand your sentence on what you need today ?

That was sarcasm and a bit of truth. The truth part is if you put me in a brand new tractor, I'll probably never want to go back to a 45 year old tractor.

I'll add some notes here:

First... TRACTIVE EFFORT in agricultural application, is very, very, very well documented by the white paper published by Wismer-Luth many decades ago.  The results of empirical data are very clear-  larger diameter produces greater tractive effort than smaller diameter, and greatest draft capacity appears with least amount of undriven wheels... and greatest ratio of weight on driven wheels... finally, the amount of lowest drag.

Harold Luth just happens to be a family boating friend of many generations.  On many occasions, I've chatted with him about rolling dynamics and his tractive effort prediction calculations, and the reality is, that a larger diameter, but narrower tire will provide greater agricultural tractive effort than a smaller diameter, wider tire, because the rolling resistance drops faster with diameter, while greater width INCREASES rolling resistance.

The suggestion that it takes 'more power' to turn a larger tire is inaccurate.  It takes more torque, which as noted by others above, is corrected for by gearing.

One of the really big reasons for smaller drive tires has nothing to do with traction... it has to do with implements... and forklift trucks ESPECIALLY have to contend with this issue-  LOAD CENTER.    Remember- these tractors have lift arms... when you lift from the back of a tractor, the implement is back there somewhere... and if it's far, far, far back from the tractor, you'll have front wheels in the air pronto.  Just as important, a rigidly-mounted ground-engaging implement behind, will 'force' the machine to steer straight, or if one wheel slips, pull to the side.  The solution, is to keep the overhanging load very short, and keep the ground engagement point as close to the center of the rear tires' contact points as possible.

IF the implement is wide, it'll strike the tires sooner when the tires have larger diameter.

On a forklift, the greatest lifting capacity occurs when the load's center of gravity is directly above the drive axle centerline... but in most circumstances, the forklift can't be designed to 'straddle' a load this way... the mast must be offset forward of the axle.  When you look at extreme-capacity machinery moving forklifts, you'll see they use small diameter wheels, because the offset between load center and axle is very small... hence, the amount of counterweight is much less, and the length of that counterweight's distance away (because that's counterweight leverage) is much smaller, providing tighter turning circle (shorter wheelbase, less overhang of counterweight)

Same goes for tractors.  Snap-coupler impements needed to stay close to the axle centerline in order to work best.  Smaller tires allowed that.

Oh, and look at the first pneumatic tractor tires... notice what size they used?  It was basically same carcass as used in other existing applications...