Wheels and casters: Flexibility and mobility for every application

Wheels and casters are indispensable standard parts in many areas of daily life and in industry. From workshops to offices and warehouses, they provide mobility and make it easier to move goods and equipment around.

Wheels and casters – differences and similarities

A wheel consists of the components contact surface, wheel tread, wheel core, bearing and hub. The properties and functions of these components are explained below.

The contact surface is the part of the wheel that touches the floor. It is also referred to as the profile. The contact surface may be smooth or textured to increase traction.
The wheel tread is the tire of the wheel. Its outer surface forms the contact surface. It can be made of various materials, and the associated material properties determine the potential areas of application for the wheel. It can be glued, vulcanized, cast or injection molded and is always firmly connected to the wheel body.
The wheel core is the main structural component of the wheel and serves as the rim, forming the connection between the wheel tread and the bearing. Various designs are possible, such as versions with or without spokes, as well as a variety of materials. It can consist of a single part or multiple connected parts.
The bearing and the hub form the interface between the fixed axle and the wheel, which rotates around the axle. The selected bearing type has a direct influence on the running properties. A variety of wheel bearing types are used, such as ball bearings, roller bearings or friction bearings that run directly in the hub bore.

When a wheel is combined with a bracket, this is referred to as a caster, or more specifically as a swivel caster or ridig caster, depending on the bracket type. The bracket is the connecting element between the wheel and the cart. The various types are turning brackets, turning brackets with total lock brakes and fixed brackets.
The sviwel bracket rotates around its vertical axis when the pushing direction changes. The wheel axle is offset from the bracket axis to provide for good maneuverability of the cart. Maneuverability refers to both the ability to steer the cart and to move in a straight line.
The rigid bracket consists of die-cut sheet steel and holds the wheel via the wheel hub. This combination is also called a rigid caster and helps keep the cart moving in a straight line.

Wide range of uses for wheels and casters

Wheels and casters are used in many different applications. Here are a few of the most important uses:

Industry and logistics: Heavy duty casters simplify the transport of pallets, machines and other heavy goods. They are robust and can bear heavy loads without restrictions on mobility.

Office furniture: Swivel chairs and rolling containers would be hard to imagine without smoothly rolling casters. They ensure freedom of movement and support good ergonomics.

Furniture casters: Cabinet or table casters make furniture mobile and enable flexible room layouts.

Choosing the right wheels and casters

A number of different criteria play a role in selecting wheels and casters:

Load capacity: The load capacity of the casters varies depending on the intended area of application. Heavy duty casters are designed for heavy weights, while smaller light duty casters are suited for lighter loads.

Floor characteristics: The type of the floor and the possible obstacles are factors that influence the amount of force required to move the cart as well as the transmission of vibrations and the wear on the wheel. Based on the characteristics of the floor, the following guidelines apply to selecting the right wheel: For irregular floors and in the case of obstacles, the wheels should have soft and thick tread and large diameter. For smooth floors and heavy loads, the wheels should have hard tread.

Maneuverability: Swivel casters offer maximum flexibility since they can rotate in all directions. Fixed casters, on the other hand, do not turn and only permit movements in one direction. Optimal control can be achieved by using both types together.

Brake systems: For additional safety, many casters are equipped with locking brakes to prevent accidental rolling. This is particularly important with heavy loads or in areas where precision is called for.

Calculation of the load capacity per wheel

To determine the required load capacity of a wheel or caster, the maximum applied load must be added to the empty weight of the cart, then this sum is divided by the number of wheels. For a cart with 4 wheels, however, the total load capacity should generally be divided by 3, as not all wheels will carry the load equally, e.g. due to uneven floors or uneven load distribution.

The formula for calculating the required load capacity is as follows:W = (G+Z) / n

W = Required load capacity per wheel or caster
G = Empty weight of the cart
Z = Maximum applied load
n = Number of supporting wheels or casters