8.4. Components of Rolling Resistance

Rolling resistance is nothing but what is the resistance offered by the hauled route to the wheel which is rolling over the particular surface. So, what is the resistance offered by the hauled route to the wheel which is rolling over the particular surface, so that is what is your rolling resistance. So, resistance to the motion of equipment on a level surface is called as rolling resistance.

Rolling resistance is the force that must be overcome to keep a wheel rolling on a surface. This resistance is encountered by the wheels of vehicles or equipment as they move. It arises from the interaction between the wheels and the surface beneath them. On level surfaces, this force is known as rolling resistance.

Imagine riding a bicycle on different surfaces. On a smooth asphalt road, you can ride easily and quickly, but if you switch to a gravel path, you feel a noticeable drag. This is similar to rolling resistance; the rougher the surface, the more energy you need to expend to keep moving.

So, what is the resistance encountered by the wheel, when it is moving on a particular hauled route. That depends upon the type of the hauled route; it may be different for different haul route surfaces. Say for example, for a concrete road the rolling resistance maybe different, for an asphalt road, it may be different, for the earthen roads it may be different.

The rolling resistance experienced by a wheel can change based on the type of surface it's rolling over. Concrete surfaces typically provide less resistance compared to soft or uneven surfaces like earth or gravel. This means that the smoother the surface, the less force is needed to maintain movement.

Think about how a car drives on a highway versus on a dirt road. On the highway, the smooth pavement allows for easier travel, while the uneven dirt road requires more effort to drive through. This change in ease of movement illustrates how different surfaces affect rolling resistance.

If you are properly compacting the earthen roads maintaining the optimum moisture content in the earthen roads, it can even give you a better performance equivalent to hard roads.

Proper maintenance of roads can significantly reduce rolling resistance. By ensuring that earthen roads are compacted and have the right moisture levels, they can perform similarly to hard, paved surfaces. This maintenance reduces the resistance encountered, which can lead to more efficient operation and lower power requirements.

Consider a well-kept garden path versus a neglected muddy trail. The garden path is easy and pleasant to walk on, while the muddy trail requires more effort to navigate. Just like the garden path is maintained for easy access, proper upkeep of earthen roads makes them easier for heavy machinery to traverse.

This rolling resistance you can even call it as wheel resistance or track resistance depending upon what type of mounting your machine is going to have. So, it may be a wheel mounted machine or it can be a crawler or track-mounted machine.

Rolling resistance can vary based on whether the vehicle is wheel-mounted or track-mounted. Each type of mounting affects how the vehicle interacts with the ground surface. For wheel-mounted vehicles, the resistance is often referred to as wheel resistance, while for track-mounted vehicles, it is known as track resistance.

Think of a farm tractor versus a bulldozer. The tractor has wheels, making it easier to maneuver on flat, hard surfaces. Meanwhile, the bulldozer uses tracks that distribute weight more evenly over soft ground but experiences different types of rolling resistance due to its design. Both machines have rolling resistance, but the type of resistance differs based on their configuration.

This rolling resistance is expressed in kilograms of tractive effort. So, rolling resistance is expressed in kilograms of tractive effort or pounds of resistance, these are just different types of units.

Rolling resistance is quantified in terms of tractive effort, which can be measured in kilograms per ton. This allows engineers to assess how much effort is needed to move machinery over specific surfaces. It's essential to have this measurement to ensure that selected machinery can operate effectively under given conditions.

When you push a heavy box across a floor, you can feel how much effort is needed depending on the floor type. Similarly, engineers calculate the 'effort' required to move heavy construction machines, ensuring they choose the right equipment for the job.

Now let us see how to estimate the penetration resistance. Say when a tire penetrates into a surface, so the resistance, the rolling resistance increases.

When a tire sinks into a surface, it requires additional force to pull it back out. This increased need for effort is described as penetration resistance. Therefore, when calculating rolling resistance, it's important to also consider how deeply tires may sink into the ground, as this increases the overall resistance that must be overcome.

Imagine walking in soft sand. The more you sink into the sand, the more difficult it becomes to walk. Similarly, when a vehicle’s tires sink into the ground, it requires more force to move forward, highlighting the effects of penetration resistance.

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