Justification of requirements for air pressure in car tires during tests on roller stands

Introduction. Traction and power parameter’s monitoring of wheeled vehicles are often performed on roller stands. The accuracy of determining the traction force in the contact patch of the elastic tire of an automobile wheel with the cylindrical surface of the rollers depends on many factors. With the specified characteristics of the stands, the working air pressure in the tires, the load applied on the wheels and the residual tread height of the tires most significantly affect the results of measuring forces. These parameters have a considerable impact on the speed and force losses of power in tires.

To take into account the force and speed components of power losses in wheel tires while testing cars, a technique was proposed that allows to reduce their impact on test results considerably, and measurement results obtained by testing cars on the roller stand and in road conditions were presented.

Materials and methods. To determine the force component of losses in a tire, the experimental studies were conducted to define the rolling resistance coefficient of tires on two kinematically unrelated rollers of the power stand. The role of the speed component of losses was specified by determining the rolling radius of the wheel on the running drums of the stand and evaluating its effect on the measurement results of traction and power parameters of the car.

Results and discussion. The result of the conducted research is the development of a new methodology for testing traction and power parameters of vehicles with all-wheel drive and single-axle drive, which allows to take into account the influence of air pressure and the residual height of the tire tread on the measured values of traction force on the wheels.

Conclusion. According to the proposed method for measuring traction forces on the driving wheels of M1 category cars on roller stands, the optimal value in terms of the effect of force and speed losses on the results of measuring traction parameters is the air pressure in tire that is not least then 150% of the values set by the manufacturer.

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