Figure 10. Forces acting on CIV (front wheel drive)

Source :

0125h - r

0125i - l

Snow Density (Mg/m 3) : 0.257

Figure 9. Comparison of values measured by Blaisdell (1987) and those obtained here for

trailing tire resistance behind a driven wheel. Blaisdell's data are shown 1 standard

deviation.

of the sum of the load cell output, reading by

vehicle sinkage was about 28 cm in the deep snow.

reading, and the corresponding velocity. It does

Table 6 is a summary of the forces on the CIV; hard

surface resistance was estimated using equations

not appear that momentum has an effect, since the

velocities are nearly steady, and the small varia-

developed by Shoop (1992) for the left and right

tions in velocity don't necessarily correspond to

front tires of the CIV based on velocity. Since no

changes in the sum of the forces on the vehicle.

data are available on the hard surface resistance of

The force exerted on the undercarriage is esti-

the rear CIV tires, it was assumed to be the same as

mated to be 734 and 770 N for tests 0125h and 0125i

the front. From Figure 10, the sum of the measured

respectively. It can be seen that, without including

forces should equal the force ascribable to the

the effect of the slope, the vehicle would have been

dragging undercarriage, if the momentum effect

immobilized. Using the information from tests

can be assumed to be zero (i.e., the vehicle is not

0215f and 0215g to obtain a value of resistance

accelerating or decelerating). Figure 11 gives plots

+ Forces

Forces

∆ Momentum

R (gravity)

R (undercarriage)

R (terrain, internal)

Net Traction

Snow

Compacted Snow Layer

Figure 10. Forces acting on CIV (front wheel drive). Net traction + R(terrain, internal)

+ R(gravity)* + ∆momentum + R(undercarriage) = 0.

*Horizontal component of gravitational force used when operating on a slope.

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