What we have here, is not just about technical history, also a political piece of history.
Zetor always had trouble with the Communist Central governments. In 1949, Zetor developed one of the first direct injected tractor diesel engines, based on their first model, the 25 A. It was a world novelty, which Zetor planned to put into serial production within a short time.
The communist central office had a different plan, they wanted something bigger. So Zetor developed the Super 35, with a big 4.1 liter engine (an indirect injected version of the Forterra's engine) that put out 42 hp at 1500 rpm, and had a 5 speed transmission which was quickly outdated.
It's weight of 2550 kg gave it a very good traction for those days, and the big engine made it a real puller. However it was not a technical miracle, unlike that direct injected engine.
In 1960 they were successed by the unified range 1, the archfather of the Super and Proxima series.
In 1964, Zetor started the development of the second unifed range, also known as Zetor Crystal. The dommunist Central office would only approve for this project that would make it the world leader in technology, if Ursus of Poland, would join the project. So a small team of Polish engineers went to Czechia to
help with the project. Zetor built the engines and the first transmission compartment, the main gear housing was contract built by a Slovak company, and Ursus also built some gears. In 1968, the first model, the 8011, was completed. Ursus also assembled this tractor in Poland, and sold it as C-385. They were identical, only Ursus used yellow where Zetor used red paint, and the cab doors had their hinges on the back of the door instead of the front.
Zetor updated their first unified range every 5 to 7 years. But the URII Crystal range was depending of some parts from the Ursus factory, Ursus went for sales volumes where Zetor focused on technical advantage. So the Zetor Crystal range, built in one single edition from 1968 to 1989, is one of the longest tractor series built.
Someone told me that Zetor had, in the end of the seventies, several prototypes of long stroke UR2 engines, with a longer stroke, a totally renewed transmission and lots of improvements. It was actually a new unified range.
Ursus didn't want to change anything.
In 1981, another decision was made by the communist planners, Zetor should put away the production of the UR2 to ZTS, a manufacturer of heavy machinery in Slovak, they built railway machines and earth moving equipment under Hanomag license.
When Czecho-slovakia split up in separate countries, ZTS ended the contracts with the Czech state organisation Motokov, which was the monoply distributor.
ZTS stopped the production of tractors two years ago, but keeps supplying engines to Ursus.
the Crystal tractors from Poland is a totally different story, that's just badge engineering. They change the badge, cab and sheetmetal on an Ursus, and sell it as Crystal. They also have an assembly plant for Deutz Agrotron assembly kits, from Deutz (engines) and ZF (gearbox and rear bridge)
If the communist politicians didn't get involved into things they couldn't understand, and leave it to the free market, Zetor would have been one of the strongest players in the tractor market.
