Jaguar Racing advances gearbox test-rig

The variable-speed-drive rig is used to simulate on-track conditions that gearboxes can encounter, including overrun conditions during braking deceleration, when the wheels (and therefore the gearbox) drive the engine, requiring rapid reversal of the direction of torque. The 160kW rig is in regular use throughout the year, ensuring that three fully tested spare gearboxes are available for each race. "The Scada system has improved our data-logging and trending as well as enabling us to check that every aspect of a test has been completed properly", said Jaguar Racing test engineer Rory Oliver Hall.

New gearboxes are subjected to rigorous tests (in both forward and reverse) over about 90 minutes, whereas used gearboxes have a shorter test regime. Tests start with a warm-up period under no load, which enables the test engineers to monitor oil flow rates, temperatures and pressures. Then loading is progressively increased right up the speed range to 16,000rpm. During this run-up period, the facilities built into the test-rig enable the engineers to tune sensors in the gearbox and to calibrate clutch and gear positions. A Pi-Sigma 'driver' control (complete with steering wheel and gearshifter) simulates driving conditions by sending speed reference signals to the input drive and independent torque control or load-sharing signals to the output drives.

The test rig comprises three 160kW motors, each driven by a Unidrive, and a 5.5kW motor driven by an equivalent-sized Unidrive. One 160kW motor, driving at 4300rpm through a step-up gearbox, runs in speed control to mimic the engine output, giving a maximum output through the Jaguar gearbox of 18,000rpm. The two other 160kW motors are in closed-loop torque control, and are coupled to the output shafts of the gearbox to simulate the output loads. The final 5.5kW Unidrive, referenced from the input drive, controls the gearbox oil pump motor.

System control is via Control's high-speed 'CT-Net' network, that provides communications between the Unidrives' onboard UD70 SYPT-programmed application modules and the Pi-Sigma racecar control system. SYPT is Control's Windows-based graphical programming software.

Now equipped with the 'Scada CR32' system, the test engineers are able to monitor and plot more than 40 variables including drive outputs, power, current, torque and speeds, time delays on gearshifting, oil temperature/flow/pressure, and a number of alarm setpoints.