Tyre Testing for Power Consumption
Page 45
If you've noticed an error in this article please click here to report it so we can fix it.
THE power absorbed by a vehicle tyre represents a wastage of fuel and is also a measure of the heat build-up in the carcass. A reduction in power losses is therefore important as a means of improving fuel consumption and of reducing the running temperature of the tyre which gives a greater resistance to failure when the vehicle is travelling continuously at high speed.
Demonstrated to the technical Press for the first time last week, the new circulating power laboratory of the Dunlop Rubber Co., Ltd., Fort Dunlop, Birmingham, enables power loss to be measured when either a driving or a braking force is transmitted through the tread. The information obtained is supplementary to that derived' from tests on early types of equipment, which simulate the running coriditions of tyres mounted on the front or non-driving wheels of a vehicle.
The laboratory equipment is of particular interest because it has eliminated the need for a dynamometer to measure the output torque of the tyre. Two similar tyres are tested at the same time and each is in contact with a drum driven by an electric motor, both drums being run at the same speed. The drums are of different diameters, but the wheels on. which the tyres are mounted arc connected by a universally jointed torque shaft and rotate together. The load on each tyre is controlled by an hydraulic ram.
During a test the tread of one tyre is compelled to "gain distance" whilst the opposite tyre is compelled to "lose distance," which is accompanied in each case by distortion of the tread, This simulates conditions in which a braking force is transmitted to one shaft and a driving force to the other. The torque of the electric motor is measured by a load cell, and four torque meters are in use at appropriate points in the circuit to measure the input and output torques of the tyres. All the instruments are housed in a control room located above the test equipment. According to the Dunlop company, proving trials of the equipment are well advanced and interesting results are being obtained.