ASFT Ford Galaxy Road Surface Friction Tester

ASFT Ford Galaxy Road Surface Friction Tester is operating with fixed longitudinal slip of about 13 % on the test wheel. It is covered in the recent ISO standard for road friction measurement, and the typically measuring tire is either the smooth ASTM 1551, or Trelleborg T49. Correlation with SCRIM and British Pendulum has been found at three different target speeds 30, 60, and 90 km/h.

1. The computer system
The ASFT computer system includes measurement computer, main computer with printer and an operator's panel with only six keys to simplify the handling of the system.

The computer system controls the measuring procedure and presents the results on the computer display and/or on paper printout.

2. The self-watering system
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 custom 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.

3. The measurement computer
This reads signals from the vertical and torque transducers (sensors) which are then converted into digital form and sent to the main computer together with the pulses from the pulse transmitter. The measurement computer also performs automatic tests on the system, which makes any tedious adjustments unnecessary.

4.The relay box
Relays and fuses for the measurement system are centralised to a service box which is very easy to reach. Here you also have the new system usage counter.

5. The torque sensor
When the measuring wheel slips on the runway surface, the friction creates a torque which is transferred to the chain system and measured by a load sensor.

6. The vertical load sensor
This monitors the vertical down pressure created by the hydraulic system, and makes any necessary adjustments to it. It ensures that an absolute constant ground contact pressure is kept.

7. The measuring wheel
A special high pressure tyre, the Friction Tester "Aero" tyre has been developed for operational measurement purposes. Measuring results with this tire have been shown to correlate well with aircraft braking characteristics. For calibration purposes a low pressure tyre can be used.
The slip ratio of the measuring wheel is about 13%, the exact value depending on the wear of the measuring tire and the car tyres.

8. The hydraulic system
This system provides constant pressure for the wheel retraction mechanism and for the vertical load on the measuring wheel.