The wheelbarrow, a Chinese invention, has evolved over the years from a crude but effective wooden object to a streamlined tool used by construction workers, gardeners and people who generally work outdoors. The materials to make wheelbarrows may have changed, but their usefulness certainly has not.
The modern wheelbarrow generally has one large, air-filled wheel, but newer, heavier-duty wheelbarrows used in construction have two air-filled wheels for greater stability and are especially designed to handle larger loads. As with car tires, wheelbarrow tires are available in different sizes.
A wheelbarrow tray or bin can be made of steel, plastic, wood or even canvas, as in collapsible wheelbarrows that can be folded for ease of storage and maneuverability. The trays come in different sizes from 4 to 12 cubic feet, for example, and can often be replaced without having to buy a completely new wheelbarrow.
Wheelbarrow handles come in pairs and are made either of wood or metal. They vary in length from 36 to 60 inches, depending on the size of the wheelbarrow tray. The handle ends are often covered by fiberglass, vinyl or plastic grips for better handling.
There are a few other, smaller parts for a wheelbarrow as well, such as two bent, metal braces beneath the bottom of the upper portion of the bin. These act as stands or brakes to keep the wheelbarrow in place when not in use. There are also brackets to which the tire is attached.
It's easy to lose control of a wheelbarrow that has been overfilled or is being rolled downhill with a heavy load. To prevent this, the load inside the tray should be centered and balanced over the wheel to maximize control.