Oct 28 2013
There are little things in life that we take for granted. These are things that make our lives easier, but we hardly notice them unless they’re gone. Casters are one of those things. Sure, we notice if we have to move something heavy or we’re sliding around in our office chair, but have you ever stopped to consider this simple, yet helpful mobility aid?
First of all, let’s state what a caster is and not. A caster is not a wheel, although a wheel is one of its components. A caster is a small, sometimes complex mechanism that consists of a wheel, a caster bracket, and a mounting plate. A swivel caster also contains bearings to enable the wheel to move in any direction. These are attached to the outside, at the top of the mounting plate. A caster can be affixed to the vehicle object by stem, bolt, or a combination of these. You might think these distinctions are unimportant, until you go to buy a replacement.
There are several different types of caster, and each is convenient to different purposes. A rigid caster is one that is attached directly to a chair, cart, or other item from the mounting plate, making it able to move only forward or backward. A swivel caster is attached to a bearing and tubes, which are in turn attached to the host object, allowing 360-degree mobility. Some objects have a combination of rigid and swivel caster, which comes in handy when an object must traverse a narrow passage and make frequent stops, such as with an airline service cart. A caster can also be fitted with a locking mechanism for objects that need portability, but require stability when in use, such as kitchen work stations.
Wheel size and shape is also a consideration that’s determined by use. Heavy objects obviously require a larger size to support the weight, but if a caster is too high, that creates a stability problem when the base must be raised so the caster can fit beneath the object. One solution to this problem is to offset each caster. Another solution is wider wheels, which have the added advantage of covering gaps in surfaces without getting stuck. Fitting an object with a caster that can handle its weight is important in order to avoid the shimmy effect, a phenomenon that anyone who has pushed a shopping cart is aware of.