I'm planning to build a step stool on casters than can be easily moved around the room. In the past I've seen store-bought step stools where the wheels automatically lock when weight is applied. I don't know if there's a specific name for this type of wheel, but I haven't been able to find them anywhere online.
(I need to build the step stool rather than buy one already made, because it needs to have handrails for the user to hold onto.)
Best Answer
It appears that the product description you seek is called a compression brake caster. The specifications I've found using those terms in a search indicate the mechanism within causes the brake to activate when weight is applied. I recall a library step stool from my early days in which the entire caster was enclosed in a tubular leg. The mount for the caster was on a spring, which was compressed when weight was applied, causing the load to be held on the cylindrical leg. This does not appear to be the method for compression brake casters.
I would offer links, but there are far too many and would represent product recommendation, considering how many different choices are available.