Merriam-Webster defines a caster as “…any of a set of wheels mounted in a swivel frame and used for the support and movement of furniture, trucks, and portable equipment”. Sounds pretty straightforward, right? In the world of medical cart design, it’s not that simple. Several factors play a role in determining which caster is right for each application: environment of use, weight of the cart and equipment, and IEC 60601 testing requirements to name a few.
What Size Caster do I need?
When it comes to casters, one of the most basic and important characteristics is wheel diameter. Ranging from 3-6 inches in diameter, the size of the casters needed is often determined by the weight requirements for the application. Three inch wheels are suitable for low profiles carts, whereas wheels larger in diameter are suited for medical carts that require more maneuverability and need to pass IEC 60601 regulatory requirements. Medical carts are commonly fit with 5 inch casters so they can more easily traverse thresholds.
Single wheel or dual wheel?
A single wheel caster is primarily used on carts that are less dense. Dual wheel casters have two wheels per caster and offer the advantage of distributing heavier weights more effectively. They are also more durable and allow the medical cart to be moved with less effort on any floor surface.
Fixed or Swivel?
Depending on the desired type of movement, a medical cart can have swivel or fixed wheels. Swivel casters allow for frequent direction changes and ensures maneuverability even in tight spaces. This mobility makes the swivel caster unsuitable for traveling long distances in a straight line. For this reason, it is often used in combination with fixed casters.
In contrast to swivel casters that can turn in all directions, the fixed caster is significantly better at traveling in straight lines, as it is fixed in relation to the cart. The fixed caster is used whenever long distances need to be covered in one direction. It provides the necessary directional stability for maneuvering trolleys along straight corridors, for instance.
The goal of the IEC 60601 tests is to ensure that, under all conditions and circumstances, your medical cart operates safely. Casters play and important role in assuring that your medical cart conforms to those regulations. One example is the IEC 60601 instability tests. They mandate that your cart cannot overbalance on a 5 degree incline when put in the worst case position. When using only two locking casters the cart may slide to adjust its balance. This would fail the test. As a result of this requirement, most custom medical carts are now using four locking casters.
There are many other factors that also play into the decision of “What caster is right for my custom medical cart.” If you have any further questions regarding caster selection for you custom medical cart or are looking for a design and manufacturing partner, please contact MPE for more information.