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The load on the road from one axle (2 wheels) is 10 times greater for a truck than for a car. However, the fourth power law says that the stress on (damage to) the road is this ratio raised to the fourth power. The road stress ratio of truck to car is 10,000 to 1.
The axle load of a wheeled vehicle is the total weight bearing on the roadway for all wheels connected to a given axle.Axle load is an important design consideration in the engineering of roadways and railways, as both are designed to tolerate a maximum weight-per-axle (axle load); exceeding the maximum rated axle load will cause damage to the roadway or railway tracks.
where is the force on the front tires, is the force on the rear tires, is the wheelbase, is the distance from the center of mass (CM) to the rear wheels, is the distance from the center of mass to the front wheels (+ = ), is the mass of the vehicle, and is the gravity constant. So, for example, when a truck is loaded, its center of gravity ...
If the load is compression on the bar, rather than stretching it, the analysis is the same except that the force F and the stress change sign, and the stress is called compressive stress. The ratio σ = F / A {\displaystyle \sigma =F/A} may be only an average stress.
For instance in a 0.9g turn, a car with a track of 1650 mm and a CoM height of 550 mm will see a load transfer of 30% of the vehicle weight, that is the outer wheels will see 60% more load than before, and the inners 60% less. Total available grip will drop by around 6% as a result of this load transfer.
For this reason weight distribution varies with the vehicle's intended usage. For example, a drag car maximizes traction at the rear axle while countering the reactionary pitch-up torque. It generates this counter-torque by placing a small amount of counterweight at a great distance forward of the rear axle.
Strength depends upon material properties. The strength of a material depends on its capacity to withstand axial stress, shear stress, bending, and torsion.The strength of a material is measured in force per unit area (newtons per square millimetre or N/mm², or the equivalent megapascals or MPa in the SI system and often pounds per square inch psi in the United States Customary Units system).
The load can often be expressed as a curve of force versus speed. For instance, a given car traveling on a road of a given slope presents a load which the engine must act against. Because air resistance increases with speed, the motor must put out more torque at a higher speed in order to maintain the speed. By shifting to a higher gear, one ...