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Ballast tractor
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Ballast tractor
A ballast tractor is a specially weighted tractor unit of a heavy hauler combination. It is designed to utilize a drawbar to pull or push heavy or exceptionally large trailer loads which are loaded in a hydraulic modular trailer. When feasible, lowboy-style semi-trailers are used to minimize the height of a load's center of mass. Typical drivetrains are 6×4 and 6×6, but 8×6 and 8×8 are also available. Typical ballast tractor loads include oil rig modules, bridge sections, buildings, ship sections, and industrial machinery such as generators and turbines.
Only a handful of manufacturers produce dedicated ballast tractors. Extra-heavy-duty chassis versions of mass-production tractor units are fitted with drawbar hitches and a separate ballast box as an alternative. These units are classified as N3 Category of large goods vehicle. Ballast tractors can be traced back to the 1940s when heavy haulers from the UK started employing purpose-built Scammell Showtracs, a short wheelbase 4×2 ballast tractor.
Increasingly, remote-controlled, self-propelled modular transporters (SPMT) are being employed in traditional ballast tractor/trailer roles.
The ballast tractor's name derives from the nautical term “sailing ballast” describing heavy material added to a vessel to improve stability. For a ballast tractor, ballast is added over the driving wheels to maximize traction. The additional weight increases the friction between the tyres and the road surface, allowing the tractor to overcome the inertia and friction of moving a heavy trailed load. Without it, there would be unproductive wheelspin.[citation needed]
With a semi-trailer, ballast is added in the form of the weight of the attached trailer pressing down upon the tractor's fifth wheel. Since the load is separate from a ballast tractor, it provides no ballast: the drawbar only transmits a horizontal force.[citation needed]
High inertia is encountered when starting to move a heavy load. To overcome this, ballast tractors tend to have high-powered, low geared engines that provide substantial torque, especially at low speeds. Additionally, ballast tractors are often fitted with heavy-duty hub reduction axles, a combination resulting in exceptionally low maximum speeds.[citation needed]
A strong chassis is required to both support the extra ballast weight and pulling forces transmitted by the drawbar. A reinforced chassis also allows multiple tractors to be coupled together to maximize power and traction. Heavy-duty versions of commercial tractor units may be fitted with a ballast box and suitable draw gear, or a ballast tractor may be purpose-built. Ballast is placed above the driving axle, or spread out over multiple driving axles to maximize traction on each and evenly distribute its load. Conversion from a regular tractor to a ballast tractor may require some modifications like chassis alteration, extra axle, larger tires, ballast box, and a heavy-duty gearbox so that it can handle the extra weight. The heavy-duty tractors which are usually converted into ballast tractors have 6x4, 8x6 axle configuration, hub reduction, better suspension and a powerful engine ranging from 300 to 1000 hp.[citation needed]
A purpose built ballast tractor tends to be the heaviest class of on-road trucks. In some cases, its kerb weight can be greater than their axle configuration's legal Gross Vehicle Weight (GVW) permits, requiring special permission to use public roads. Some nations have categorized these tractors in a different category than conventional tractors because of higher GVW permits and HMT configuration.[citation needed]
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Ballast tractor AI simulator
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Ballast tractor
A ballast tractor is a specially weighted tractor unit of a heavy hauler combination. It is designed to utilize a drawbar to pull or push heavy or exceptionally large trailer loads which are loaded in a hydraulic modular trailer. When feasible, lowboy-style semi-trailers are used to minimize the height of a load's center of mass. Typical drivetrains are 6×4 and 6×6, but 8×6 and 8×8 are also available. Typical ballast tractor loads include oil rig modules, bridge sections, buildings, ship sections, and industrial machinery such as generators and turbines.
Only a handful of manufacturers produce dedicated ballast tractors. Extra-heavy-duty chassis versions of mass-production tractor units are fitted with drawbar hitches and a separate ballast box as an alternative. These units are classified as N3 Category of large goods vehicle. Ballast tractors can be traced back to the 1940s when heavy haulers from the UK started employing purpose-built Scammell Showtracs, a short wheelbase 4×2 ballast tractor.
Increasingly, remote-controlled, self-propelled modular transporters (SPMT) are being employed in traditional ballast tractor/trailer roles.
The ballast tractor's name derives from the nautical term “sailing ballast” describing heavy material added to a vessel to improve stability. For a ballast tractor, ballast is added over the driving wheels to maximize traction. The additional weight increases the friction between the tyres and the road surface, allowing the tractor to overcome the inertia and friction of moving a heavy trailed load. Without it, there would be unproductive wheelspin.[citation needed]
With a semi-trailer, ballast is added in the form of the weight of the attached trailer pressing down upon the tractor's fifth wheel. Since the load is separate from a ballast tractor, it provides no ballast: the drawbar only transmits a horizontal force.[citation needed]
High inertia is encountered when starting to move a heavy load. To overcome this, ballast tractors tend to have high-powered, low geared engines that provide substantial torque, especially at low speeds. Additionally, ballast tractors are often fitted with heavy-duty hub reduction axles, a combination resulting in exceptionally low maximum speeds.[citation needed]
A strong chassis is required to both support the extra ballast weight and pulling forces transmitted by the drawbar. A reinforced chassis also allows multiple tractors to be coupled together to maximize power and traction. Heavy-duty versions of commercial tractor units may be fitted with a ballast box and suitable draw gear, or a ballast tractor may be purpose-built. Ballast is placed above the driving axle, or spread out over multiple driving axles to maximize traction on each and evenly distribute its load. Conversion from a regular tractor to a ballast tractor may require some modifications like chassis alteration, extra axle, larger tires, ballast box, and a heavy-duty gearbox so that it can handle the extra weight. The heavy-duty tractors which are usually converted into ballast tractors have 6x4, 8x6 axle configuration, hub reduction, better suspension and a powerful engine ranging from 300 to 1000 hp.[citation needed]
A purpose built ballast tractor tends to be the heaviest class of on-road trucks. In some cases, its kerb weight can be greater than their axle configuration's legal Gross Vehicle Weight (GVW) permits, requiring special permission to use public roads. Some nations have categorized these tractors in a different category than conventional tractors because of higher GVW permits and HMT configuration.[citation needed]
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