The technology behind the wheel

| Competence | Comfort | Security |



Wheel definitions (see 2D wheel definitions)

Wheel diameter (diamètre, diameter, Durchmesser): Outer diameter of the wheel.

Wheel width (largeur, breedte, Breite): Width of the wheel, measured on the rim*.

Hub diameter (diamètre du moyeu, naafdiameter, Nabendurchmesser): Outer diameter of the hub**.

Hub width (longueur noyeu, naaflengte, Nabenlänge): Length of the hub**. The length can be larger, smaller, equal or asymmetrical to the wheel width.

Bearing seat (logement de roulement, lagerzitting, Lagersitz): Space in which the bearing** is mounted.

   -> Bore diameter (diamètre de l’alésage, boring diameter, Achslochdurchmesser): Diameter of the bore through the hub or inner diameter of the bearing. Determines which axle or bearing fits in the bore of the wheel.

   -> Bearing seat dimensions (profondeur de logement, kamerdiepte, Lagersitzabmessungen): Depth of the bearing seat.

   -> Fixing lenght (longueur de serrage, inspanlengte, Einspannlänge): Width of the bearing assembly, including bearing and flange joints.


Bore hole diameter (alésage, asgat, Achsloch): dimensions in which the axle fits (in the bore of the wheel or in a bearing**)

Flange width (distance de la flasque, Steglänge): Length between the hub** and the rim*.

Wheel centre (corps de roue, Radkörper): Part of the wheel, consisting of hub**flange*** and rim*. The coating is applied to this.

Load capacity (capacité de charge, Tragfähigkeit): Maximum load that can be carried by the wheel.


Wheel (roue, wiel, Rad)

A wheel is made of a tread/tyre, rim and hub.

A wheel can be mounted in a housing.
Depending on the type of housing, the result is a swivel or fixed wheel.

– The castors can swivel 360° around a vertical axis.

– The fixed wheels, on the other hand, are fixed and ensure good directional stability.

In most cases, 2 castors and 2 fixed castors are fitted.

A. Tread/Tyre (bandage, band, Bereifung)

The outer part of the wheel that is in contact with the ground or roadway.

Solid rubber rolls smoothly and silently. However, stiffness and load capacity are limited.
Polyamide is shock and impact resistant, chemically resistant and wear-resistant. On the other hand, this is a non-elastic material.
Polyurethane is extremely wear-resistant, sound-absorbing and has excellent rolling properties.

B. *Rim (jante, velg, Felge)

A rim is the outer edge of a wheel on which the upholstery lies.

C. **Hub (moyeu, naaf, Nabe)

A hub is the central part of the wheel, for the attachment of a (drive) axle. A hub consists of a drilled workpiece in which, depending on the application, the hub is connected to the corresponding shaft via a bearing, a keyway, a clamping bushing or a fixed connection.

1. Bearing (see wheel definitions in the picture)

A bearing is a machine part that allows the movement of the wheel around its axle and reduces friction between the moving parts.

Plain bearing (roulement lisse, glijlager, Gleitlager)

Simple, largely maintenance-free bearing. Shock and impact resistant. Suitable for use in humid environments. For devices with low speed (max. 4 km/h) and for short distances. There is a sliding contact in the bearing.

Ball bearing (roulement à billes, kogellager, Kugellager)

Sturdy, wear-resistant, largely maintenance-free bearings. Low bearing friction. Shock and impact resistant. Permanent lubrication. The most commonly used bearings for low speed devices (max. 4 km/h). Rolls smoother compared to plain bearings. Due to the roll contact, a ball bearing has a smoother ride.

Precision ball bearing (roulement conique, precisiekogellager, Konuskugellager)

For speeds up to 20 km/h and heavier loads. Low rolling resistance when used.

2. Keyway (see wheel definitions in the picture)

A keyway is a machined groove along the length of the bore, which transfers the engine power to the wheel. Via the bore and the axle, the engine force is transferred to the wheel by means of the keyway. No axial securing on the shaft!

3. Clamping bushing (see wheel definitions in the picture)

A clamping bushing is a machine part that transfers the engine power to the wheel without the use of a press. By means of a conical bushing, the shaft and the bore are clamped together so that force can be transferred. Easy to assemble and disassemble. Also provides axial locking on the shaft.

D. ***Flange (voile, flens, Steg)

The flange connects the hub and the rim. This is a disc where bolt holes may or may not have been fitted. The spokes can be weighted with reinforcement ribs for better stability and strength. Steel welded wheels can be fitted with 2 flanges for more strength and weight reduction.

A flange wheel is a wheel with a flange where attachment to a hub is possible.


The choice of wheel and castor primarily depends on:

1. The loadbearing capacity required

What does a wheel/castor has to carry?
– The load of a castor can be calculated using the following rule of thumb:  load = (inherent weight + max. load)/3
– It is divided by 3 because on uneven flooring, even an item of equipment with 4 castors will only have 3 castors in contact with the floor, and these 3 then carry the full weight.
– This is a very general way to determine the loadbearing capacity. Ask your supplier for a detailed calculation.
The load capacities specified in our product range for wheels and castors apply for speeds of up to 4 km/h and an ambient temperature of 10°C to 60°C.

2. The floor conditions

Is the floor rough or smooth? Is the floor covered in tiles, concrete, or is it heavy-duty industrial flooring? In general, on smooth industry floors, you can use harder wheels (thin tread) while, on rough industry floors, soft wheels (thick tread) are better performing. Choose non-marking castors if you wish to avoid leaving rubber tread marks. If there are ground sills, extra loadbearing capacity must be factored in. Choose wheels with plain bearings and a stainless steel housing in food production areas or on wet surfaces.

3. The frequency of use

Is the equipment moved only on occasion, or all the time?

4. Environmental factors (temperature, including
temperature fluctuations, chemicals, moisture and
hygiene requirements)

Every site of use involves specific requirements. Moisture, cold, heat, temperature fluctuations, electrical conductivity and chemicals all affect the durability, rolling properties or the smoothness of motion.

5. Comfort

You can also choose the required level of comfort and smoothness. The material of the wheels determines the rolling properties and ride comfort.
– Solid rubber rolls smoothly and silently. The strength and load capacity are limited however.
– Polyamide is shock- and impact resistant, chemically resistant and hard-wearing. On the other hand it is a non-elastic material.
– Polyurethane is extremely wear resistant, noise absorbing and has excellent rolling properties thanks to its elasticity.

6. Specific dimensions such as wheel diameter,
overall height and hub length, or plate sizes and
assembly hole spacing for castors.

7. Quality of the used materials

VULKOLLAN® is one of the most powerful elastomers in the market. The excellent mechanical properties ensure a wheel with maximum dynamic load capacity and a long service life, even in difficult and demanding conditions. 
PRINTHANE™ is the generic name for all Vulkoprin PU-elastomers developed specifically for extreme fields of application.
Read more on high end materials used by Vulkoprin: click here
Read more on our private label Printhaneclick here