parallel to the direction of travel. This can be seen on a shopping cart when the front casters align parallel to the rear casters when traveling down an aisle. A consequence of this is that the vehicle naturally tends to travel in a straight direction. Precise steering is not required because the casters tend to maintain straight motion. This is also true during vehicle turns. The caster rotates perpendicular to the turning radius and provides a smooth turn. This can be seen on a shopping cart as the front wheels rotate at different velocities, with different turning radius depending on how tight a turn is made. The angle of, and distance between the wheel axles and swivel joint can be adjusted for different types of caster performance. Industrial casters Industrial casters are heavy duty casters that are designed to carry heavy loads, in some cases up to thirty thousand pounds. An Industrial caster may have either a swivel or rigid caster design. Industrial casters typically have a flat top plate that has four bolt holes to ensure a sturdy connection between the top plate and the load. They are used in a variety of applications including dolly carts, assembly turntables, heavy duty storage racks, holding bins, tow lines, maintenance equipment, and material handling mechanisms. In early manufacturing, industrial caster bodies were typically fabricated from three separate, stamped metal parts, which were welded to the top plate. Today, many industrial caster bodies are made by laser cutting the body from a single metal blank and then using a press brake to shape the legs to the required ninety degree angle, thus producing a mechanically stronger device. Various factors affect industrial caster performance. For example, larger wheel diameters and widths provide higher weight capacity by distributing the load's weight across a larger wheel surface area. Also, harder wheel materials (e.g., cast iron, high profile polyurethane) are less sensitive to and tend to not track dirt and debris on floors. Braking and locking casters Common inexpensive casters may include a brake feature, which prevents the wheel from turning. This is commonly achieved using a lever that presses a brake cam against the wheel. However a swivel caster is still able to move around slightly, in a small circle rotating around offset distance between the vertical shaft and the center of the locked wheel. A more complex type of swivel caster, sometimes called a