These calculations assume that any brakes that are not working properly are not working at all.
If the deceleration rate of the vehicle is measured by means of an electronic decelerometer, the result of that measurement will already be correct and these calculations are not needed.
By checking all four boxes, the effect of a gradient can be calculated for a vehicle with all brakes working.
The diagram below illustrates which brakes are working or non-working on the vehicle. The front of the vehicle faces to the right.
For any brakes that are NOT working, uncheck the corresponding checkbox on the diagram below. Keep the checkbox checked for any brakes that ARE working. Any brakes that are unchecked below will be assumed to be inoperatve for the purposes of the effective coefficient of friction calculation.
Now fill in the values below...
h/L = Where h is the height of the centre of gravity and L is the length of the wheel base. The resulting value should be between 0.20 and 0.25 for cars.
True coefficient of friction:
Proprtion of static vehicle weight on front axle (e.g. 0.6):
Gradient (degrees): Uphill is positive, downhill is negative, level is 0.
Effective coefficient of friction =
For more detailed information refer to R.Smith, Partial Braking, Impact, 4, 1, 1994.
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