Tracks vs. Tires: A Technical Analysis of Excavator Mobility Across Diverse Terrains

Excavators are indispensable workhorses in construction, mining, and landscaping, tasked with moving significant volumes of earth and materials. Their mobility, a critical factor in productivity, hinges on the choice between tracks and tires. This article delves into the technical nuances of these two locomotion systems, comparing their performance across various terrains and highlighting their respective advantages and disadvantages.

Fundamentals of Tracks and Tires

Tracks:

Tracked excavators employ a continuous loop of interconnected metal or rubber segments, known as track shoes or pads. These shoes distribute the machine's weight over a large contact area, minimizing ground pressure. The track system is driven by a series of rollers and sprockets, providing a robust and stable platform.

Tires:

Tired excavators utilize pneumatic or solid rubber tires, similar to those found on trucks and other heavy machinery. These tires offer a more agile and faster mode of transportation, particularly on paved or relatively smooth surfaces.

Ground Pressure and Traction

Tracks:

The primary advantage of tracks lies in their low ground pressure. Ground pressure (P) is defined as the force exerted by the machine on the ground per unit area:

P=AF

Where:

F is the force (weight of the excavator)

A is the contact area of the tracks

The large contact area of tracks significantly reduces ground pressure, enabling operation on soft or unstable terrains like mud, sand, and loose soil. This low ground pressure minimizes soil compaction and prevents the excavator from sinking.

Traction, the force resisting slippage, is also enhanced by tracks. The interconnected track shoes provide a high coefficient of friction, maximizing grip and enabling efficient power transfer.

Tires:

Tired excavators, with their smaller contact area, exert higher ground pressure. This limits their application on soft or delicate terrains. While tire pressure can be adjusted to some extent, achieving the low ground pressure of tracks is generally not possible.

Tire traction is reliant on the tire's tread pattern and the ground surface. On hard surfaces, tires offer good traction. However, on soft or slippery surfaces, they can experience slippage, reducing efficiency and posing a risk of becoming bogged down.

Terrain-Specific Performance

Soft and Unstable Terrains (Mud, Sand, Wetlands):

Tracks: Excel in these environments. Their low ground pressure prevents sinking, and their high traction ensures effective movement. Tracks offer significantly better stability and maneuverability compared to tires.

Tires: Struggle significantly. They are prone to sinking and slippage, requiring specialized tires (e.g., flotation tires) or auxiliary equipment (e.g., mats) to improve performance. However, they are generally not well suited for this type of work.

Rough and Uneven Terrains (Rocks, Steep Slopes):

Tracks: Offer superior stability and traction on rough terrain. The interconnected track shoes conform to uneven surfaces, maintaining consistent contact and grip. The ability to climb steep slopes is a significant benefit to tracked machines.

Tires: Can operate on moderately rough terrain, but their stability is compromised on steep slopes. The risk of tire damage is also higher due to rocks and sharp objects.

In very severe rocky conditions, tracks are more resilient. Damage to rubber tires is a much more probable factor, than damage to a track system.

Hard and Paved Surfaces:

Tracks: Can operate on paved surfaces, but they can cause damage. Metal tracks can scratch or damage asphalt or concrete, and rubber tracks, while less damaging, still produce wear. Wear is a larger factor for tracks on hard surfaces.

Tires: Are ideally suited for paved surfaces. They offer a smooth and efficient ride, enabling faster travel between work sites.

Travel distance on road ways is a large determining factor. Wheeled machines are substantially faster at travelling longer distances on roadways, than tracked machines.

Confined Spaces:

Tracks: Offer excellent maneuverability in confined spaces due to their ability to pivot on the spot (counter-rotation). This feature is invaluable in urban construction and other tight work areas.

Tires: Offer good maneuverability, but their turning radius is typically larger than that of tracked excavators.

Wheeled excavators due to there use of a steering axle, provide a larger turn radious compared to the zero turn capabilities of a tracked machine.

Maintenance and Operating Costs

Tracks:

Require more frequent maintenance due to wear and tear on track shoes, rollers, and sprockets.

Track replacement is a significant expense.

Travel speeds are lower, requiring more time for transport between work sites.

Tires:

Generally require less maintenance than tracks.

Tire replacement is less expensive than track replacement.

Higher travel speeds reduce transportation time.

Tires can be punctured requiring repair or replacement.

Operational Considerations

Travel Speed:

Tired excavators offer significantly higher travel speeds, making them ideal for work sites that require frequent relocation.

Tracked excavators are slower, limiting their efficiency for long-distance travel.

Transportability:

Tired excavators can be driven on public roads, simplifying transportation between work sites.

Tracked excavators most often require transportation by a trailer, due to concerns relating to road damage.

Stability:

Tracked excavators due to their large footprint, offer a more stable platform. This is highly important in lifting heavy loads, or when working on uneven surfaces.

Wheeled excavators have the possibility of outriggers, that increase stability, when that ability is needed.

6Technological Advancements

Modern excavators, both tracked and tired, incorporate advanced technologies to enhance performance and efficiency. These include:

GPS and telematics: For real-time monitoring and data collection.

Hydraulic systems: For precise and powerful movements.

Operator assistance systems: For improved safety and efficiency.

Advances in rubber track technology, is reducing the amount of damage that tracks do on paved surfaces.

Advances in tire technology, provide greater protection against punctures, and improve grip in adverse conditions.

Conclusion

The choice between tracks and tires depends on the specific requirements of the application.

Tracked excavators excel in soft, unstable, and rough terrains, offering superior traction and stability. They are the preferred choice for heavy-duty earthmoving and construction projects in challenging environments.

Tired excavators offer faster travel speeds and lower maintenance costs, making them ideal for work sites that require frequent relocation and operation on paved surfaces.

A proper analysis of the job site conditions, transport distances, and economic factors will provide for a better understanding of which machine best fits the job requirements. As technology continues to improve both track and tire systems, the advantages of both platforms will continue to advance.