If you've ever been in a play or have seen one one stage, then you probably know that the items in the scenes don't get moved on their own. They don't stay on the stage through the production, either. There are usually people behind the scenes who will work to change the sets, but it's often easier with theater casters that are placed on large pieces. These are small wheels that can help to quickly transport sets when the curtain is down. They are also used when the actors and crew are taking items into and out of the theater.
One of the types of casters looks like a turntable. It makes it easy for items to be turned around a corner and to possibly shift to another direction while they are still on the stage to create a different look. There are two plates on top of each other with a swivel between them. They are often used with welding tables and other workstations when sets are made before they are assembled.
Swivel casters come in various sizes. Most can hold up to 200 pounds each, making them ideal for moving heavy items as long as the weight is evenly distributed. Each piece is about four inches in height. There is a soft rubber on the wheel to allow the caster to roll of various surfaces. Since more weight can be moved, they are often used to transport items over a larger surface. The wheels can swivel in order to move items up and down ramps or through hallways that might not have a lot of room. Smaller casters are two inches in height. There is a braking system on each wheel so that the item can be stopped or left in one place without being moved as easily.
A triple wheel caster dolly holds more weight and can be used for sound systems and the electrical items that sometimes weight more than the typical set pieces that are used. A larger clearance area needs to be available as the caster is larger. The weight capacity for the dolly is up to 600 pounds.