A British-designed and engineered stepless transmission to rival CVT drives will become a commercial product this year and could soon be at work in farm tractors.
Like other stepless drive systems, Torotrak transmission provides infinitely variable speed control and can be operated to give constant ground speed or to run the engine at speeds giving maximum power, torque or economy. However, instead of using hydraulic motors, the position and angle of steel traction rollers in a mechanical variator unit are changed to alter ground speed.
“Apart from making the unit very quiet, this arrangement involves few moving parts and no wearing surfaces in the variator,” says Torotrak hydraulics group leader John Fuller. “The components are separated by a thin layer of traction oil, so there is no metal-to-metal contact.”
Mr Fuller says the design has greater mechanical efficiency than competing variable drive technologies and, with fewer parts involved, will cost less to produce. Another attraction for manufacturers, he adds, is that the technology is scaleable it can be applied economically to tractors of different sizes.
One of Europe’s biggest suppliers of off-highway transmissions has taken out a licence and is understood to have two tractor makers interested in using the drive system.
Turkey’s biggest tractor maker, Uzel, makes Massey Ferguson-licensed tractors and has acquired rights to develop the technology for agricultural applications with an option to manufacture transmissions in the 30hp to 150hp range.
Torotrak’s novel patented transmission has been a long time coming it was first designed by government engineers in the 1960s. Torotrak, based in Lancashire, was set up in 1988 to exploit the technology and has earned licence and engineering development fees while working towards the novel transmission’s commercial introduction.