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Below is an example of calculation which show us approximate resistance of not
damaged vehicle on the flat surface. For example resistance of total weight car 2041
kg with undamaged wheels on the flat, hard and wet sand is :
Unfortunately not every surface is flat, so we need to add to the calculations the angle
of gradient.
Ad. 4. The angle of gradient. The gradient up which a vehicle is to be moved may
only cover a short distance, over the total distance of pull, e.g. a ditch or rock, or it
may cover a long climb up a hill. Even for a relatively short upward pull, gradient
resistance must be taken into account. For practical winching purposes, gradient
resistance can be taken as a 1/60th of the weight of the vehicle for each degree of the
slope, up to 45 degree incline.
E.g. For angle of gradient 15 degrees gradient resistance will be 15/ 60 of total weight
of the vehicle which is ¼ total weight. For angle of gradient 45 degrees it will be ¾
total weight. The length of the slope will make no differences in the calculations.
Ad. 5. Damages of pulled vehicle. We can count them:
Double wheels are counted like one. So if we do not have any broken wheels, we do
not add it to the calculations, if all wheels are broken we need to add whole vehicle
weight as a resistance of damaged vehicle.
If we combine together the total weight of the car, type and the angle of the surface
and the stage of damaged wheels we will get:
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