Fixed bracket with wheel brake, PP hub and TPE tread, mounted with top plate, 400 kg

Caster in a fixed bracket with TPE tread and PP hub, top plate, plain bearing

This is a caster in a fixed bracket with a running surface in TPE and a hub in polypropylene, mounted with a top plate and fitted with a plain bearing. It is a simple and maintenance-free caster for a straight direction of travel indoors, built to take some dust and moisture without needing supervision. The bracket is fixed, so the caster rolls straight ahead and does not swivel, which gives a stable run along a defined transport route.

The tread in TPE has a hardness of 85 degrees Shore A. It is a semi-soft thermoplastic elastomer that gives a quiet run and damps the small knocks that arise when the caster rolls over joints and seams. TPE is usually light gray and leaves no marks, an advantage where the floor is to be kept clean. The damping tread in combination with the fixed bracket gives a calm and predictable run that suits premises where the noise level matters.

This caster is built on a plain bearing rather than a ball bearing, and the difference is worth understanding. A plain bearing consists of a smooth bearing surface without balls; it is simple, cheap and takes dirt and wet well, but gives a somewhat higher rolling resistance. That means the caster needs a little more force to start and to roll than a ball bearing caster. In return there are no balls that can be damaged by dirt, which makes the plain bearing a hard-wearing choice in dirty or damp environments and for casters that mostly stand still and are rolled seldom. If the caster has to be rolled often and easily a ball bearing is better; if it has to stand steady and take debris the plain bearing is a reasonable choice.

About the tread: compared with a hard tread in nylon, TPE rolls somewhat heavier but makes less noise and is gentler on painted floors. The semi-soft tread settles a little against the surface and builds a contact area that gives good grip, something that shows as steadiness rather than easy rolling.

The hub in polypropylene is light and corrosion-free and carries the load without rusting. This family has a diameter of 50 mm and, despite its neat size, handles a load capacity of up to 100 kg per caster, thanks to the fixed bracket and the stable hub. The small diameter keeps the overall height down where the space under the cart or the machine is limited.

Where does the caster fit? The low overall height and the high load capacity make it suitable under low carts, machine underframes, fixed installations and equipment that has to stand steady close to the floor. As a fixed caster it is placed at the steering end and holds the course straight ahead, preferably paired with two swivel casters at the other end. The non-marking tread makes it useful in workshops, warehouses and premises where clean floors are wanted.

A word about the relationship between diameter and load capacity. That such a small caster still carries up to 100 kg comes from the fixed bracket and the stable hub taking up the load together, and from the caster not needing the moving swivel bearing that a swivel caster has. A fixed caster can therefore often carry more than a swivel caster of the same size. The small diameter does mean that the whole load rests on a small contact area, which makes the caster need more force to get rolling and more sensitive to thresholds and debris on the floor. On a smooth and level surface this is no problem; on an uneven floor you gain by going up in diameter.

Think about the operating environment. TPE is happiest at normal indoor temperature and in dry to slightly damp spaces, and the material does not take high temperatures. The small diameter rolls more heavily over thresholds and seams than a larger wheel, so on an uneven surface a larger diameter can be preferable. Do you want help weighing overall height against rolling resistance for your particular installation? Get in touch and we will go through it together.