Nice to hear so many of you are worried about me becoming brainwashed (or perhaps are just generally uncertain about my mental stability...).
Let's bone out some of the issues on 2+2 shall we:
Turnincirkle on the 2+2 is very good. We use duals on ours (not really recomended by IH at the time) and the outer wheels will just barely touch when turning fully if one is not carefull. According to "Traktorkalendern #2" by LRF media (excellent series of books including testresults of every tractor sold in Sweden since, well, since forever!) turningradius of 3588 2+2 is 5,8m.
Results for other tractors at the time (no breaks) IH1486 5.2 m, JD 4640 4m, MF 2640 6,65m.
View over the implement is excellent as the cab is close to the rear and the huge bonnet is slightly bent so it blocks front visiblility less than one might think.
The pivot point is just in front of the cab.
The 2+2 series was launched in 1982(?), at the time IH stated that a conventional tractor would be unable to handle that much hp due to wheelslip and stability. Steiger-type tractors would be much more expensive (interesting since today a JD8520 is cheaper than 9120!) so IH invented the 2+2 concept.
They used the rear half of the US-built -86 series tractor (cab,transmission, axles etc) and built a new front section. To handle the power they used equal size wheels all around and put the engine in front of the front axle for ballance. To avoid huge turningradius, a problem on Muir-hill, Dutra, County and other front-wheel-steer-equal-wheel tractors at the time, they incorperated articulated steering and could use a ridgid axle already in production in front. Using standard components helped keep the price down.
So far, in my mind, the thinking is excellent.
However: By using a standard rear end, power had to be transfered by a shaft first from the engine and through the pivot area to the clutch and transmission. This meant a jointed shaft was turning at engine speed at al times and required plenty of maintenace (this is my own opioion as it is a pain to grease). From the transmisson power went to the rear axle and from the tap supposed to provide power to a mfd-axle the power was then again transfered through the pivot area to the front axle.
Problems with the tractor were often related to lack of maintance and using it to pull to heavy implements, and perhaps IH not using strong enough components. The transmission, pivot area and axles are known weakspots today. The 7X88 series of 2+2 tractors (see prototype section of this website) was supposed to have those problems fixed (using components originally designed for the concept) but was cancelled at the CaseIH merger.
Today the 2+2 is neaking back upon us:
Case and JD are mounting the engine further and further infront of the front axle. Front wheels keep getting bigger. Valtra has introduced their X-series with articulation in front of the cab...
Perhaps we will see CNH bring back the 2+2 soon. The TV-140 is pretty close. Also a 2+2 Magnum called MUT is supposed to be out there somewhere...
As far as Quadtracs, I think that kind of traction reqires a machine built for that purpose. 3588's have been tearing axles using just single wheels.
More info on IH 2+2 at
www.bigtractorpower.com and
www.toytractorshow.comTurned out to be quite a lenghty post, hope it made some sense. Feel free to ask if you got any more questions.
