Dump truck – a truck used for transporting loose material (such as sand, gravel, or dirt) for construction. A typical dump truck is equipped with an open-box bed, which is hinged at the rear and equipped with hydraulic pistons to lift the front, allowing the material in the bed to be deposited (“dumped”) on the ground behind the truck at the site of delivery.
The very first version of a dump truck used to haul and dump material was nothing more than a simple dump body style cart drawn by horses. It would have consisted of a two-wheeled cart hinged to the axle with the center of gravity, when loaded, just behind the axle. The loaded front body was hooked, and when unlatched, would dump. These carts were used in open mines and pulled by horses along a railway track. After 1900, a four-wheeled horse-drawn flatbed wagon with a rectangular body lifted with a hand hoist in the front was employed.
Hydraulics were being incorporated into truck mounted dump bodies relatively early on. Records show that one of the first hydraulic dump bodies was the Robertson Steam Wagon with a hydraulic hoist that received power from the truck’s engine or an independent steam engine. Alley & McLellan of Glasgow developed another early hydraulic dump body in 1907 that was power-driven by steam.
What’s the problem?
Dump trucks are handy for moving dirt during construction. During large construction projects, large amounts of dirt must be moved from one place to another, either for removal or to fill in low spots, such as in new road building. This requires a special kind of truck.
- Ask – How much load can be hauled by a regular truck? How will the dirt be placed in the truck? How will the dirt be emptied?
- Imagine – Using some ideas from simple machines and existing truck structures, how can the truck bed be modified to tip to have the load slide out? How would the truck be emptied by hand? Are there motions that the truck can imitate?
- Plan, Create – Starting with a heavy duty basic truck frame, how big can the bed or box part of the truck be? How will it be attached to the truck body? How will the hydraulic arm be placed to lift the front of the bed to tip the bed? Is this enough of an angle so the load will slide out? How will the tail gate swing open? How will the tail gate be secured when the truck is hauling the load?
- Improve – How can the dumping mechanism be improved?
- axle – an important structural component of a wheeled vehicle. The axles maintain the position of the wheels relative to each other and to the vehicle body. Since for most vehicles the wheels are the only part touching the ground, the axles must bear the weight of the vehicle plus any cargo.
- hydraulics – operates by transmitting force via a near compressible fluid, usually oil. When an operator pulls a lever or presses a control button that force is pushed into a cylinder by a piston and creates an action.
- hydraulics, hinge, hydraulic, piston, lift, axle
Challenges for you to work on…
- Build a model dump truck, with a separate lifting mechanism for the bed to tip.