Design Considerations
Five Wheel vs. Four Wheel
Wheel location, in respect to the center of gravity, affects the chance of tipping. For example, medical carts with a five star-wheel base should approach a threshold with one wheel leading in front. However, if the medical cart has a four-wheel base, then the two front wheels need to simultaneously approach and make contact with the threshold. The farther forward the front wheel or wheels is from the center of gravity, the better.
Center of Gravity and Caster Size
The center of gravity and weight of your cart affect the probability of tipping while going over a threshold. Heavier medical carts with a low center of gravity are less likely to have these issues. If there are two identical medical carts except one weighs more, the one with more weight will have an easier time broaching a threshold than the lighter one. Caster size also makes a difference. Having larger wheels will make it easier to get over a threshold, enabling medical carts that are prone to slow mobility.
Speed
Walking pace is generally assumed at 0.8 meters per second, a pace at which most medical carts would be maneuvered. However, when it comes getting over a threshold, a faster pace eases the ability to overcome an obstacle. Take this pole vaulting analogy for example.
Let’s imagine that you and the medical cart are the pole vaulter. The bar is the threshold. The size of pole is the radius of the wheels, and the speed at which you run towards the bar is the velocity of the cart. Having a bigger pole radius, within reason, will make it easier to get over the bar, just like caster size in relation to a threshold. If a pole vaulter is only allowed two steps to get over the bar, he or she probably won’t succeed. Similarly, if you try to get up and over a threshold without sufficient velocity to back you up, you’ll struggle because all your kinetic energy is changing to potential energy. So, the more forward momentum you have, the more opportunity you have to change your potential energy.
Not every solution is guaranteed to work 100 percent of the time, which is why we’ve included alternative actions or ideas customers can consider.
Alternate Options
In an event where your medical cart doesn’t make it over a threshold on the first try, or in the absence of speed, the addition of a kick plate offers a safe back-up plan for getting up and over a threshold. Instead of continuing to force the medical cart over the threshold, thus increasing the risk of damaging equipment or tipping, a person can apply pressure to the kick plate with his or her foot while pulling down on the handle to lift the front part of the cart over the threshold. The rest will follow.
Designing your medical cart so that a person has the option to pull it over a threshold also serves as an efficient method. By pulling your device, you effectively eliminate tipping issues because the center of gravity is already ahead of the wheel.
For carts or devices that are suited for outdoor or unpredictable environments, we suggest implementing directional casters to save your product from veering off-course or tipping.
It’s crucial to establish the best options for getting your custom medical cart up and over a threshold. Contact us today if you have any questions regarding optimal custom medical cart design. 
