Fixed pneumatic caster with PP hub and PUR-foam tread

Pneumatic caster in a fixed bracket with PUR foam and PP hub

This is a pneumatic caster in a fixed bracket with a tread in PUR foam and a hub in PP, built for transport on uneven ground where you want the soft run of a pneumatic tire without the risk of having to pump or repair a puncture. The tread is a cellular polyurethane with a hardness around 65 degrees Shore A. The PUR foam is filled right through instead of with air, so it is springy and damping but cannot be punctured or lose pressure.

This is the big point of the tread in operation. An ordinary pneumatic tire rolls softly but has to be kept at the right pressure and can be ruined by a nail; the PUR foam gives a similar springy run but skips that maintenance. It forms itself to smaller unevenness and damps shocks, while the rolling resistance on a smooth floor is lower than on an air filled tire since the foam does not deform as much with every revolution. On really rough terrain a soft pneumatic tire does swallow large bumps even better, but for normally uneven surfaces the foam is a comfortable middle setting.

A comparison helps the choice. A hard solid wheel in nylon rolls most easily on a level floor and takes a high load, but it damps nothing and is noisy on uneven ground. An air filled tire damps the most but needs pressure checks. The PUR foam places itself between these: a softer run than the hard wheel, less maintenance than the pneumatic tire.

The hub in PP is light and corrosion free and holds the tread in place. The series comes with double ball bearings, a plain bearing or a ball bearing. A plain bearing is simple and maintenance free and takes dirt and wet but gives slightly higher rolling resistance, a ball bearing rolls more easily with an even run, and double ball bearings spread the load over two rows of balls for a stable run. The load capacity reaches up to 100 kg per wheel, right for lighter carts and trolleys.

The wheels come in diameters from 200 to 300 mm. A larger diameter rolls more easily over thresholds and unevenness and lowers the rolling resistance, while a smaller one keeps the overall height down where space is tight. The wheel sits in a fixed bracket and rolls straight ahead, which gives directional stability in fixed positions on an underframe or at the front of a cart.

Where does it fit? Pneumatic casters with PUR foam and a PP hub sit under hand carts, transport trolleys, garden carts and lighter material carts that are run both inside and out. The puncture free foam suits well where the wheel is exposed to spill, chips or sharp remains and where you do not want to stand and check air pressure.

Think about the operating environment. PUR foam is happiest at normal temperature and takes dry to slightly damp environments and most workshop oils and greases. It needs no pressure and cannot be punctured, but a soft cellular material wears faster than a hard wheel if it is run far on coarse asphalt. Choose the diameter to match the surface and the tread lasts longer and the rolling resistance stays down.

Do you want to know which diameter and which bearing suits your cart and your surface? Get in touch and we will go through the load and the environment together.