FORGOTTEN MOTOCROSS TECH: OHLINS HYDRAULIC TWO-WHEEL-DRIVE YAMAHA 2-TRAC
The hydraulic hoses run down the front of the fork leg and then back into two fittings on the hub.
Motocross history is filled with examples of creative ideas that were heralded as groundbreaking, but, because of the rapid rate of change in development, sank into the swamp of forgotten technology. MXA loves to reveal motocross’ tech trivia.Do you remember the Ohlines two-wheel Yamaha 20-Trac?
Do you remember Ohlins’ hydraulic two-wheel-drive system. Ohlins dedicated 15 years and a large chunk of its R&D budget from 1992 to 2007 into perfecting two-wheel-drive motorcycles—both off-road, rally and street. Ohlins’ management even convinced Yamaha, who owned Ohlins at the time, to commit to manufacturing a small test run of 445 Yamaha WR450F 2-Tracs for sale in 2004.
Yamaha put the 2-Trac in production in 2004, but it didn’t sell well enough to get a return engagement.
Obviously, the much newer Christini two-wheel-drive bike is still in production, but Ohlins didn’t want to rely on shafts and chains to get power to the front wheel. Instead, Ohlins designed a hydraulic system that forced an incompressible fluid through flexible tubes from a countershaft-driven pump to a small, front hub-mounted hydraulic motor.
The big plus of driving the front wheel with hydraulic pressure was that the system could be fit on a conventional bike without any major redesign, because only the two flexible hydraulic hoses had to be routed from the pump to the front wheel. The front hub had sensors in it that signaled when the rear wheel was spinning freely, and that is when the 2-Trac’s front-wheel drive kicked in.
Because the pump was driven from the gearbox’s countershaft sprocket, the front wheel could never turn faster than the rear, so it wouldn’t spin. But, if the rear tire started to spin, the pump would run faster, which would increase the hydraulic pressure and therefore the amount of power going to the front wheel. It is not, in the truest sense, an all-wheel-drive system.
The hydraulic lines powered the front wheel.
Ohlins used the system in Paris-Dakar-style rallies with some success and even built a Yamaha R1 prototype to test its feasibility on a street bike. Unfortunately, Yamaha lost interest in the concept when the WR450F 2-Trac was a sales failure.
The post FORGOTTEN MOTOCROSS TECH: OHLINS HYDRAULIC TWO-WHEEL-DRIVE YAMAHA 2-TRAC appeared first on Motocross Action Magazine.
