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So... for every turn of the crank shaft the wheel moves 1/29th or, put another way, for every 29 turns of the crank shaft the wheel turns once. 
This means for every 29 turns of the engine the truck wheels will complete 1 revolution and hence the truck will move 1.26 metres. If we assume they take 5 seconds to do one crank how many cranks will this be in one hour? (Assuming of course they don’t take a break.) 3600/5 = 720 turns of the crank. That sounds like hard sweaty work! How many turns of the truck's wheels will this be?
720/29 = 24.8 turns of the wheel. So how far have they traveled in an hour? The number of turns times the distance the wheel moves in one turn: 
So our truck is travelling at 0.031 km/h - a break neck speed! To get to the top of the sand dune it looks like they have about 80 metres to travel so this will take them
80/31 = 2.5 about two and a half hours to do.
Sounds plausible, but would they have the energy for this kind of exercise, it’s darn hot out in the desert?
So let’s see if we can work out how much energy our ambulance crew would expend to get that truck up the slope. One way of doing this is to use trigonometry. What the crew are effectively doing is lifting the truck up vertically from the bottom of the slope to the top. We know that they have a distance on a slope of about 80 metres, and that sand dunes (due to the fact that sand granules slide) have an incline of about 32 degrees. You can measure this angle yourself using a pile of salt and a protractor. Can we work out how far vertically the truck goes up, and hence how much energy needed to raise it? You bet an ice cold beer we can! As we all remember from our high school maths:
therefore:
height of triangle = sin(32) x sloping side of triangle
sin32 x 80 = 42.4metres The truck is 4 tonnes (4000kg) so how much energy would be required to lift the truck 42.4m?
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