Technology Focus: Materials and Assembly

摘要

Tires for hand trucks, wheelbarrows, and beach carts are soft and fat, giving them the flexibility to negotiate soft sand, muddy turf, and uneven terrain. Roleez Wheels Inc. of Benicia, Calif., used to make those kinds of inflatable balloon-type tires of polyvinyl chloride, but then decided it needed something tougher, according to the company's president, Peter Reich. Sharp objects such as sand burrs and broken shells punctured the material too easily. And the PVC did not have adequate memory to return the wheels to their original size if they had expanded from the heat, he said.