Dump trucks are an important part of our mechanized, modern life. From hauling large quantities of material to and from construction sites, road building, food transport, and mining, the dump truck plays an important part in keeping the cogs of our society turning.
Dump trucks come in a range of sizes and dumping mechanisms, depending on the intended purpose of the truck. Some dump trucks are end dump trucks, side dump, and bottom dump trucks. Most dump trucks can travel normal public roads, while others are too large and can only be used onsite.
What Are Dump Trucks Used For?
The dump truck has a surprising history that pre-dates the invention of many other commercial vehicles. The Thornycroft vehicle company developed a steam-driven garbage collection vehicle in 1896, with an effective tipper mechanism to dump the load.
The first motorized dump trucks were developed in the USA in 1910, and shortly after this date, the use of hydraulics saw the expanded use of the dump truck across many industries. The demand for dump trucks exploded during World War I, which accelerated the development of these vehicles to produce high-quality, heavy-haul, automated dump trucks.
By 1920, these trucks were firmly established in the mining industry and road construction. Hydraulics has remained the primary mechanism for lifting the dump box to deposit the truck’s load where required. Modern dump trucks still use this technology, including side dump trucks and belly dump trucks.
1. Standard Dump Trucks
A Ford F750 Dump Truck at a dealership.
The standard dump truck is a versatile vehicle with many industrial uses. They can range in size from a small payload capacity of around 10 tons to a large payload capacity of around 35 tons.
Standard dump trucks use a standard truck chassis but incorporate a dump box mounted in place of a cargo-carrying bay. The dump box is elevated by one of two methods.
The first method is a single hydraulic piston situated under the front of the dump box near the truck cab. This piston uses hydraulics to lift the front of the dump box, lower the rear of the dump box and allow the load to slide out through the tailgate.
The second method of lifting the dump box is with hydraulic pistons mounted on either side of the dump box, raising and lowering the load.
The tailgate on these dump trucks can be top-hinged, bottom-hinged, or have a hydraulic system of its own that lifts the tailgate out of the way when the load is dumped.
Since these dump trucks use standard truck chassis, they are roadworthy and can move around on standard roads and highways in and around our cities.
Standard dump trucks offer good maneuverability but cannot negotiate soft soil and off-road conditions at large construction sites. Consequently, standard dump trucks are mostly used for residential-type construction sites, road building, and agricultural-type applications.
2. Winter Weather Dump Trucks
Locations that experience heavy snowfalls in wither regularly make use of dump trucks as snow-clearing vehicles. These are standard, heavy-duty dump trucks that have been modified for working in this capacity.
A snowplow blade is fitted to the front of the truck to push snow off the roadway. The dump box can carry a load used to balance the truck when it pushes a heavy load of snow at the front.
The dump box can also be used to carry salt, which is spread on the roadways to prevent ice formation on the road surface.
3. Transfer Dump Truck
A transfer dump truck is a standard dump truck with a modified dump box. The transfer dump truck can transfer a load box from a specially designed trailer into its own dump box.
The load box from the trailer rolls forward on its own chassis on rails and into the truck’s dump box. The trailer load bay is secured in the truck’s dump box and transported to the dumpsite by the truck. The trailer can be left in its current location while the truck transfers the load to the new location.
The dump truck can elevate its dump box, with the trailer cargo box secured inside, and dump the contents at the required location. The trailer cargo box can then be returned to the trailer and transferred out of the dump truck back onto the trailer chassis.
A variation of the transfer dump truck is the truck and pup, with the difference being that the trailer, or pup, has its own hydraulic system, allowing the trailer to self-unload if required.
These trucks are all built on standard truck chassis, making them capable of operating on all normal roads and highways around towns and cities.
4. Semi Truck Trailer End Dump Truck
Semi-truck trailer combinations can also be configured to be used as dump trucks. These vehicles have standard semi-trucks as the hauling power, but the trailer is the modified part of the combination with the dumping capability.
The end dump means the cargo is dumped from the trailer’s rear end. The length of these trailers and the massive loads they carry require a very powerful hydraulic piston at the front of the trailer to lift the front end and dump the cargo.
The size of the piston makes for an impressive sight when lifting the dump box to expel the cargo, but its length also means it can easily suffer damage.
Operators of these trucks need to exercise care to not damage the hydraulic piston when offloading. If the dump box is overloaded, has an unevenly distributed load, or is offloaded on uneven ground, the hydraulic piston could bend, damaging the lifting mechanism. If the truck is unbalanced during the offloading process, the entire truck can overturn.
The semi-truck dump truck is useful for the large loads that can be transported and because the truck can navigate normal roads and highways.
These dump trucks are not suitable for rough terrain or soft ground construction sites since the trailers do not have drive wheels to assist the truck in these conditions.
5. Super Dump Truck
A super dump truck is a normal semi-truck trailer dump truck with an added trailing axle at the end of the trailer. The additional axle can be lifted off the road when the truck is empty, lowering the taxes incurred for vehicles with a certain number of axles on the road.
When the truck is fully loaded, the trailing axle is positioned into place by a hydraulic system to extend further to the rear of the trailer and make contact with the road. This spreads the truck’s load over a greater area, increasing the legal carrying capacity of these trucks. This increases their payload capacity per trip and thus profit per load.
The additional carrying capacity of these trucks has led to them being termed super dump trucks.
6. Semi Truck Trailer Bottom Dump Truck
Corn being transferred to a semi truck trailer dump truck.
A semi-truck trailer bottom dump truck has a similar configuration to the semi-truck trailer end dump truck, but the trailer has a different shape and offloading method.
Bottom dump trucks are also called belly dump trucks since the cargo is dumped from the bottom or belly of the dump box.
The shape of the dump box is key to the bottom dump mechanism to ensure the entire load is dumped without any cargo remaining inside the dump box. The sloping sides of the dump box to the central bottom of the dump box is referred to as a clamshell design.
When the bottom of the clamshell is opened, the load is deposited directly under the dump box. This dump method allows the truck to drive forward, depositing the load in a line where it is needed.
These dump trucks are often used to transport cereal grains for agriculture or food production but can also distribute sand for construction.
These trucks can have multiple bottom dump trailers, often 2 trailers, but sometimes 3, especially for long-distance haulage. These trucks with multiple trailers are notoriously difficult to reverse, requiring highly skilled drivers.
Since these trucks can, in some cases, carry up to 52 tons, some locations require this load is spread over multiple trailers to spread the load over a greater area of the road. This minimizes wear and tear on the roadways by these heavy loads.
7. Side Dump Trucks
Side dump trucks provide the option for dumping the load out the side of the dump box. There are various configurations for the dumping mechanism for these trucks.
These trucks are usually semi-truck and trailer combinations, with the dumping mechanism being built into the trailer rather than relying on the truck. Side dump trucks often pull multiple side dump trailers to maximize the amount of cargo hauled in one trip.
Side dump trucks are equipped with a hydraulic mechanism at the front and rear of the dump box, which rotates the dump box on its mid-line axis. This action tilts the dump box to one side, emptying the cargo over the side of the box.
This mechanism can usually swivel the dump box to the left or the right, allowing the dump box to be emptied on either side of the trailer.
This method of offloading the cargo is significantly safer than end dump trucks, which can become unbalanced during offloading and tip over.
Side dump trucks do not have this problem, but a side dump trailer is prone to tipping over if the offloading is halted prematurely. The load must also be deposited at the correct angle to prevent the load from falling around the trailer’s wheels. This can cause the truck to become stuck in its own load.
Side dump trucks can carry heavy loads, and the offloading mechanism is much faster than end dump trucks, allowing for a faster turnaround for these trucks.
Consequently, they are highly favored in the mining industry for hauling ore from the mine to processing plants.
These trucks are based on normal cargo-hauling trucks, enabling them to traverse standard public roads and highways.
8. Haul Dump Truck
A haul dump truck at a mine site.
Haul dump trucks are extremely large, capable of hauling between 40 tons and 400 tons of material per load. The capacity of the load will depend on the size of the truck. Most haul dump trucks are twin axles, but the larger versions can have up to 3 axles.
These heavy-duty haulers are not intended for use on public roads due to their size and are restricted to onsite use only.
Haul dump trucks can have two offloading mechanisms. The first type is the traditional hydraulic front lift of the dump box, tilting the dump box for the load to fall out the back.
The second method is a rear-eject mechanism. This method has a push-plate on the inside front surface of the dump box. When activated by the hydraulics, this plate moves towards the back of the dump box, ejecting the load from the back of the truck.
This is a more stable method to offload the cargo and does not necessitate level ground for the offloading process.
Haul trucks are typically used in heavy mining operations and large construction sites requiring these massive dump trucks to haul material to different job site locations.
9. Articulated Haul Dump Truck
A large articulated dump truck in Oregon.
An articulated haul dump truck has an articulated joint between the truck’s cab and the dump box. The articulated joint is permanent, meaning it is not possible to separate the cab from the dump box trailer.
These vehicles are all-wheel-drive, making them perfect for offroad operations, and the articulated chassis provides greater maneuverability.
The hydraulic steering mechanism, combined with the vehicle’s articulation, means that the rear wheels follow exactly the same track as the front wheels. This is an important offroad operating feature for rough conditions where the vehicle’s rear may get stuck if it does not track on the same path as the front wheels.
Articulated haul dump trucks are generally end-dump trucks with hydraulics to lift the dump box to tip the load out the rear of the box.
Conclusion
Dump trucks hold a fascination for many vehicle enthusiasts due to their sometimes impressive size and versatility in hauling large cargo volumes.
The technology and engineering applied to these vehicles to facilitate the offloading process can be ingenious in itself to create vehicles for task-specific dumping.
Dump trucks are important vehicles that help drive our mining, industrial, and construction sectors. They facilitate efficient and faster movement of materials for use in these crucial sectors supporting our society.
There are many types and varieties of dump trucks, each following a generally similar design but with unique features depending on the type of industry the truck is intended for. The capacity of the loads these trucks can transport and easily offload allows construction, agriculture, and mining to keep up with the ever-increasing demands for faster turnarounds.