Wheels On Mobile Tables, Etc.


How do the wheels on metal tables and other objects used to transport objects, not break, yet look so flimsy?

In: Physics

Materials are generally subjected to three forces; compression (squeezing), tension, (pulling), and torque (twisting). Different materials have different strengths and weaknesses. Concrete, for example, is very strong in compression but extremely weak in tension and torque.

Casters (wheels) on a moving table are generally just under compression; the weight of the table pushing down and the force of the floor pushing back up. The metal of the table leg is very strong in compression, as is the plastic in the wheels. Due to their high strength you can use minimal and low-quality materials. The case of this table also doesn’t have a lot of other nice to haves, a cheap hard plastic can be used since bounciness isn’t really a concern. Skidding/sliding, etc isn’t a problem because who cares if the table bangs a wall a bit.

Short story – they are cheap because the requirements are extremely easy to meet with cheap materials and there are limited reasons to use more expensive materials. Capitalism 101.