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Scrub radius and SUV handling Vehicle testing The goal of vehicle testing was to compile a series of fully instrumented events with a stock-configured vehicle and then modify it with the reduced scrub radius CV Hub design. Table 1 summarizes the handling and braking tests completed for both vehicle configurations. Brake lead tests were run to simulate left-to-right front brake-force variances and to measure vehicle drift. A proportioning valve was used to create a 60/40 left-to-right brake line pressure split, and the ABS was disengaged for this event. Starting at 88.5 km/hr (55 mph), a constant 0.5-g deceleration was maintained while stopping on a flat surface with no driver steering input. Steady-state cornering performance was measured via the constant radius method. A 15.2-m (50-ft) radius circle was maneuvered at varying speeds from engine idle up to and including impending skid. Lateral acceleration levels were measured directly, along with steering wheel position. The two variables were then cross-plotted to generate standard understeer plots. Transient cornering behavior was examined through a variety of standard tests. The tests were the single lane change maneuver, two different types of double lane change maneuvers, and a 22.8 m (75 ft) slalom maneuver, all of which were performed at differing speeds. Steering wheel effort (torque) was measured as a comparison for all maneuvers. Thirty five different vehicle performance tests were run for each of the four different scrub radii. All vehicle test events were recorded in real time using a multichannel data-collection system in which data were sampled at 250 Hz. All six degrees of freedom were sampled using accelerometers. Steering wheel position and force, wheel torque, and wheel rpm (front only) were recorded for the brake and acceleration test events. Brake-pedal force was recorded on the brake-lead test.
Table 1
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