Riding a ‘controlled explosion’

Rotary encoders from Renishaw are helping to improve performance of a drag-racing motorcycle

. The KTM Dragster – whose 7,500 rpm engine helps it cover a quarter-mile race track in 6.7 seconds – uses two Renishaw RM22 compact, high-speed rotary magnetic encoders. These help to ensure optimum engagement of the clutch, to squeeze maximum torque from the engine. Salakazi Racing has equipped the dragster with an automatic Prowork three disc, four-stage clutch fitted with a digital controller. This engages the clutch when the rider opens the throttle. This is where the Renishaw RM22 encoders are used – one to monitor the position of the crankshaft in the engine, the other to measure clutch speed. By comparing these values, clutch slippage, traction and road conditions can be determined precisely. Salakazi Racing’s Petri Mäkinen said: “The encoder isn’t interactively controlling the clutch whilst underway, but the data it provides us with beforehand is critically important. We couldn’t obtain it – and couldn’t preset the clutch - any other way.” The RM22 is designed and manufactured by Renishaw’s Slovenia-based partner RLS, and is immune to dirt and debris to iP68. To survive at 125ºC, it is enclosed in a heavy, machined aluminium housing.