While buying or renting the earthmoving equipment like loaders and excavators, which are available in various sizes and configurations, one of the most important choices need to be made is between wheels and tracks. The choice between tracks and wheels will not only depend on the application for which the equipment is required but there are many other factors that have to be considered.
Job site conditions have the most significant influence over the choice for using a tracked machine or wheeled equipment. Rubber tires are easily worn or punctured when operated on abrasive surfaces like crushed rock and demolition debris. Tracks, on the other hand, stand up well to rough and loose surfaces. However, tracks suffer premature wear when shifting about on solid ground that restricts slippage.
The difference between a tracked equipment and a wheeled equipment lies in weight distribution. Tracks, by nature of their design, distribute machine's weight over a larger area far more efficiently than a similar piece of equipment with wheels. Wheels have small areas that contact the ground during their revolutions while the length and width of tracks cover a larger area than the wheels do. Tracks actually work to float the machine over the ground rather than cut into it.
Traction force and Maneuverability
Being able to maneuver well is critical to perform tasks with precision. Greater maneuverability typically translates into improved productivity and efficiency. A key component of maneuverability is traction, and tracks and wheels provide significantly different levels of traction across many surface types.
Wheeled equipment gives superior performance on flat and relatively smooth surfaces that are solid enough to support the sharper weight distribution. On really hard surfaces like concrete and asphalt, wheel appear to have the better traction due to rubber's grip compared to the limited friction offered by steel tracks.
But in adverse or poor ground conditions, tracked machines almost always offer much better traction due to their increased surface area and contact with the ground. In fact, tracks offer superior traction in almost every type of ground condition, from wet mud to soft dirt and loose soil or snow condition. Tracks also out-perform wheels on uneven terrain and sloped sites.
An excellent example of traction is comparing tracks vs. wheels in skid steers. Tracks give these highly versatile machines excellent traction in mud and loose sand in comparison to skid steers with wheels, which tend to sink and get stuck in loose surfaces. In general, tracks offer superior traction and improved functionality across a wide range of surfaces when compared to wheels and this improved traction directly typically translates to better maneuverability.
Rubber tired machines have a big advantage over track machines when it comes to speed. Most pieces of track machinery can only crawl along at a few miles per hour, but those on tires zip along faster than a person can run. Speed is important when the machine is required to make multiple trips over long distances, this is the reason why wheel loaders are the choice in gravel pits and skid steers with wheels at landscape jobs.
Construction machines with tracks are slower by intentional design. That's not to say that track machines can't move fast like army tanks or personnel carriers. It's that construction sites usually don't require traveling speed from equipment unless there's a specialized need for it. Then most machines can be equipped with wheels to fulfill it.
Mobility is more than just speed. Mobility includes the ability to maneuver in tight places. This often puts rubber-tired machines at a disadvantage as they need room to turn about. Track machines are designed to turn within their own footprint or radius. They can swing in a circle without forward or backward motion by braking one track and accelerating the other. Machines with tracks can also shuffle side to side which is impossible for those mounted on wheels.
Tracked machines have a wider footprint with considerably more ground contact than wheeled equipment. Because of the heavy undercarriage built into track machines, they have a lower center of gravity than higher and more unstable rubber-tired machines.
Stability is crucial when working on unstable ground and slopes. The massive ground contact given by tracks creates significant friction that stabilizes machinery when forces of gravity pull them sideways and downward. Wheeled machines don't have this quality, they easily slide and slip on slopes and sink into loose soil and wet ground.
Smoother rides are experienced with track machines. Their long bases and massive footprints let energy absorb better than wheeled equipment. Operators benefit from ride comfort as they're less likely to be jostled by bumps, dips and hollows.
Wheeled machines experience “power hop”, which happens when one or more tires lose traction and break free. This problem interrupts work and can also be dangerous in losing control. Power hop doesn't happen in tracked machines. They remain consistent in delivering power to the earth and remain in control.
Most wheeled machines are versatile as they can be fitted with a variety of attachments. This attribute makes them useful for a range of applications from digging and trenching to material spreading and snow plowing. Wheeled machines can be even equipped with slip over tracks, converting them to versatile track machines where the situation is right.
Capital costs of purchasing and renting wheeled machinery are lower than acquiring equivalent equipment with tracks, due to the expensive undercarriage that track machinery requires. Wheeled machines only have tires, hubs and brakes to absorb, not the mass of support that track equipment needs.
Maintenance is less with rubber-tired equipment. There are fewer moving parts, which translates to less wear and tear, which means there's less to repair. Maintenance on drive systems that rotate rather than slide is faster and cheaper. That discount equates to less operating overhead, which reflects on the bottom line.
Transportation is simpler with machinery on wheels. Rubber-tired equipment can often be driven from site to site rather than be transported on a trailer pulled by an additional truck. This factor saves money and the time required tao call in a truck and trailer then load, ship and unload it.