When choosing a wheel one should take into account the following:
- operating (maximum) load per wheel;
- type of surface where the product is intended to move;
- environmental effects (low and high temperatures, hostile environment, high or low humidity, influence of water, dirt, and so on);
- product’s speed of movement.
One of the most important factors that should be taken into account when choosing a wheel is load. In specifications we indicate maximum load per one wheel, on condition that it moves on an even surface at a speed up to 5 km/h, at a temperature from 1°C to 3 °C. In case of any deviation, maximum load should be reduced.
How to estimate load capacity correctly?
Under ideal operating conditions the load is evenly distributed to all the wheels of a structure, but in reality, unfortunately, everything goes in another way: uneven surface results in periodic ‘hanging’ of one of the wheels. That is why the load capacity is estimated on the assumption of the total number of wheels in the structure minus one.
Maximum load capacity of a platform trolley m1 is 400 kg.
The weight of a trolley (without wheels) m2 - 20 kg.
The number of wheels k - 4
The formula to calculate load capacity of one wheel:
(m1+m2)/(k-1)= (400+20)/(4-1)=420/3=140 kg, i.e. it is possible to use any wheel with the maximum load capacity not less than 140 kg.
Now let’s consider such an important topic as choosing the type of a wheel.
See section ‘Main types of wheels’.
We will analyze the types of wheels in details according to its material.
Main materials used for it:
- Hard rubber
- Semi-elastic rubber
- Elastic rubber
- Thermoelastic rubber
- Metal (molded wheel)
Below is given a table of wheels physical properties according to the material:
Let’s consider such an important characteristic as rolling resistance. As a rule, all equipment with wheels is put in motion by a human being; and high rolling resistance results in excessive loss of time and power. Choosing a right wheel can solve this problem. The choice should be made according to the main criteria:
- Wheel material
Below is given a diagram showing dependency of the initial effort required to move a structure on some materials of a wheel:
2. Type of a wheel spindle bearing
The best thing is to use wheels with ball bearings (minimal rolling resistance), roller bearings are a little bit worse, and sleeve bearings have the highest rolling resistance.
3. Wheels diameter
The larger the wheel diameter is (on condition that the wheel material and wheel spindle bearings are the same), the lower rolling resistance is. Sometimes people deliberately choose wheels of larger diameter than it is required for load capacity in order to reduce rolling resistance, i.e. to provide smooth movement of a structure.
4. Number, location and type of casters (swivel and non-swivel) to a large extent influence on steering capabilities and flexibility of a structure).
Three swivel wheels
Good control when moved
in a closed space and with
Four swivel wheels
Perfect flexibility, but bad
control when moving
for a long distance
Two swivel and
two fixed wheels
Good control when
moving in a straightdirection
Two swivel and two fixed wheels
Very good control
and two fixed wheels
Good control when movement
direction is frequently changed,
load is evenly distributed
on the structure
5. One should take into account such an important factor as influence of chemically hostile and not hostile environment. Below is given a table of preferable (or undesirable) use of these or those wheels in certain conditions:
- very bad
- not recommended
We hope that our advice will help you to choose right wheels for your products.