ASFT Continuous Friction Measuring Equipment (CFME) is a friction test method operating with fixed longitudinal slip of about 13 % on the test wheel. This is also referred to as skiddometer principle or fixed slip devices. The advantage of a slip measurement is that it can provide a continuous record of the friction.

The rear axle has a third smaller wheel on an arm. This is the measuring wheel. The tyre has a material, a shape and a tread which closely resembles those of a normal tyre. This gives friction readings that closely correlate with true friction values that you get from a vehicle in operation.

The vertical load on the measuring wheel should be 1400N, and to achieve this we use hydraulic pressure to generate the vertical load and through the vertical transducer we can monitor (and calculate with) the actual load on the measuring wheel at any given moment. The measuring wheel is connected to the rear axle with a chain transmission. The gear ratio provides a constant 13 % slip. As the measuring wheel has a smaller diameter than the rear wheel, the chain will be tensioned when the vehicle moves.

This tension is proportional to the friction number. The torque transducer (T-sensor) transforms the tension into analogous signals, which are used in the calculation of the friction values. The friction value is then presented in various ways.

ASFT CFME can also be equipped with a self wetting or water system for simulation of rain on the road infrastructure. The standard tank sizes are 500 and 700 litre, but any size tank can be costumed made. There is no uniformed regulation among the different road administrations for the depth of the water film. Our system is therefore equipped with a water pump, and the operator can electronically adjust the depth of the water film from 0.1 ñ 5.0 mm.