Cup rollers made from different material combinations are lighter and more resilient than solutions made from solid steel housings. (Image: Dr. Tretter)

If the user requires lightweight ball transfer units with good running behavior at low cost, standard versions made of sheet steel are a suitable solution. Thanks to their pot shape, they are quick and easy to fit: They are inserted into a hole without any additional fastening elements. They are typically used in assembly stations and in storage technology.

The more robust cup rollers are similar to the standard ball transfer units. However, they are made of solid steel and therefore achieve higher load ratings and are more robust under impact loads. From size 15 upwards, the cover is also made of solid steel, preventing the ball from flanging when the load starts at an angle. On the installation side, the castors are available with or without a collar. For corrosive environments, they can be made entirely of stainless steel. Depending on the application, Dr. Tretter supplies them with different ball variants. They are used, for example, in feeders, in punching operations, in sheet metal and metal processing or as airport rollers.

Heavy-duty ball transfer units in compact design are suitable for high impact loads and load capacities. (Image: Dr. Tretter)

The shell of the heavy-duty ball transfer units is a hardened and polished saucer-shaped steel table. This means that neither the load rating nor the rolling resistance of the ball changes. This feature makes the design suitable for heavy loads and overhead mounting. The design is characterized by higher load ratings and impact loads with a compact design. The principle also enables smooth and even running behavior. Designers install them in classic machine and plant construction.

Cup and heavy-duty ball transfer units can also be mounted on disk springs - as so-called sprung ball transfer units. Because these variants drop when overloaded or when the preload force is exceeded, several ball transfer units come into play and the load is distributed evenly. This results in even smoother running behavior. The preload force can be specifically designed for this purpose. The spring-loaded ball transfer units are ideal for dies, press tables and tool tables. On request, the company can supply the elements galvanized, in stainless steel or in special sizes. "In addition to standard ball transfer units, we also manufacture special ball transfer units according to customer specifications from medium quantities," says Alexander Rubin. "These include ball transfer units with an external thread on the housing and a square flange to level the height, as well as with threaded pins or with fastening holes in the collar or with a recess."

Light and resilient: Air Cargo

Dr. Tretter has added Air Cargo ball transfer units to its range. These are particularly lightweight ball transfer units with an increased load capacity. Users can obtain them as Saturn ball castors and cup castors. Both types are resistant to dirt and corrosion, particularly smooth-running and durable. Designed as cup rollers, the Air Cargo versions with their additionally integrated stainless steel support shells have a higher load capacity of up to 35 percent compared to types with a conventional solid steel housing. "And that with a tare weight reduction of up to 42 percent, which we make possible thanks to various material combinations," says Alexander Rubin. To save a further 30 percent in weight, the user can choose a hollow running ball. The ball transfer units are installed in airport decks and conveyor belts, for example. They are also increasingly being used in feed tables and equipment for machines. All types are available in a corrosion-resistant design. as