Plastic spherical bearings for electric wheelchairs

Eight thousand kilometers per year

Maintenance, dirt- and corrosion-free polymer spherical bearings
for electric wheelchairs

This electric wheelchair is characterized not only by an extremely all-terrain, transaxial all-wheel steering, but also by sophisticated environment control systems.
Whether iPad and iPhone connector or integrated distress call system: A variety of constructive developments improve the mobility in everyday life and compensate physical deficits. Lubrication- and maintenance-free plastic bearings thereby provide
the required functional reliability. "The clear market for specialty aids demands high quality," reports Niels Richter. He is one of two managing directors of the Richter Reha Technik Richter R. m. S. GmbH in Franconian Thurnau. "And with our special wheelchairs we are moving into an even smaller niche. " The family business, founded in 2001, contributes toward helping people with disabilities to be mobile in their daily lives in different areas. This is ensured by 17 highly specialized employees at the production site and five sales representatives in Germany, Austria and Switzerland. In collaboration with hospitals, medical suppliers and end customers, the company creates customized solutions that are tailored individually to the respective daily requirements.

New electric wheelchair "Tango GT" of the Richter Reha Technik Richter R. m. S. GmbH, Thurnau (Franken). Similar to the car, there are different classes among the electric wheelchairs - compact, middle and (here) upper class. The transaxial all-wheel steering makes driving stable in the tightest bends. Even steep climbs are possible.

Adaptation to the disease

The manufacturing penetration of the specialist provider is relatively low. The component assemblies, which mainly concern the chassis, are outsourced. Only the final assembly takes place on site. "We know the requirements of the rehabilitation market. Our special expertise lies in the special structure that is adapted to the particular disease," clarifies Niels Richter. "For this, we analyze the specific application areas on site − from the school through the home environment up to the workplace − and adapt them according to the special features. "This can be for a special control system such as controls by the chin, suction/blowing or occipital movements. Second, even heavy-duty functions up to 350 kg are possible. The latest development of the company is the electric wheelchair "Tango GT". Similar to the car, there are also different classifications for electric wheelchairs: compact, middle and upper classes. With their new electric wheelchair, the company Richter has deliberately positioned itself in the upper class. The aid can be used mainly outdoors, and also indoors. The transaxial all-wheel steering makes driving stable in the tightest bends. The wheelchair is maneuverable in tight spaces. It offers a special off-road capability and manages even steep climbs thanks to the extra powerful engine without sacrificing performance.

The lubrication- and maintenance-free "igubal®" spherical bearings of the series "KGLM" are used at the pivot points of the triangular steering. Two bearings each are installed in the upper and lower swing arm. They are easy to install, adjust to any angle deviations, are insensitive to dirt and corrosion-free.

The "igubal®" flange bearings made of "iglidur® G" material are fitted in all standing devices with a 45° shift in the center of gravity.

The "igubal®" flange bearings made of "iglidur® G" material are fitted with two and four (picture) mounting holes in all standing devices with a 45° shift in the center of gravity. These are used for rotating and pivoting movements.

Plastic bearings for everyday use

Niels Richter: "This wheelchair is currently the only one on the market with a so-called triangular steering system. " The special feature is that the steering is not merely spring loaded, as is usually the case with wheelchairs, but can move in all directions. "So from a two-dimensional motion we have created a three-dimensional motion. " Lubrication-free and maintenance-free igubal® spherical bearings of the KGLM series are used at the pivot point of the triangle steering. Two bearings each are installed in the upper and lower swing arm, so that a total of eight spherical plain bearings on the wheels of the front and rear axis prove their suitability for everyday use.

Balances misalignments and edge loads

Besides the high dampening ability, the "KGLM" type series distinguishes itself in the high-tech electric wheelchair "Tango GT" mainly by the vibration dampening. In addition there is the compensation of misalignment and edge loads. The lightweight and rugged spherical bearings have proven themselves from day one in the steering of the special wheelchairs. "They are easy to install and can be adjusted very well," says Niels Richter. "Also remarkable are the small clearance, the mobility and, of course, the inevitable freedom from lubrication and maintenance. “

Lubricating grease is a taboo

Wheelchairs are usually used indoors and outdoors. "We have for example a customer who drives around 8,000 km a year", the CEO reports from experience. Especially in outdoor use, the chairs must withstand all weather conditions. Lubrication points are off limits on these aids. Because grease attracts dirt and dust that inevitably falls down indoors on the floor. "This meant it had to be avoided at all costs," says Richter. "So only polymer bearings are basically used in our product range. " In addition, high forces act on the built-in bearings when driving over curbs. The shock/impact force at the moment of driving over is extremely high.

In the "Tango GT" it is mitigated by a mountain bike suspension system and large-volume tyres to prevent excessive stress. "The plastic bearings are our first choice in the triangular steering system," says Niels Richter.
For many years now, the rehabilitation technology company has been relying on the polymer bearing range in its aids. "We maintain close relations with our contact person in the field, who regularly draws our attention to new products and provides us with appropriate samples," Richter reports. "These are placed in a kind of evidence room on demand. For new or further developments, we first check what we already have in stock and test the polymer components for their suitability for everyday use. In this way, we immediately recognised the technical advantages of spherical plain bearings in all-wheel steering. “

Also polymer plain bearings and profile guides

In addition to the spherical bearings, various flange bearings made of the material iglidur® G, for example, are installed in all upright devices with a 45° centre of gravity shift. The versatile all-round bearing is used for simple rotary and pivoting movements, among other things. It is built into the calf plates and provides appropriate support and thus safety when standing. In addition, particularly flat drylin® profile guides prove their versatility in the foot and leg adjustments of all electric wheelchairs. They are easy to install. The tribologically optimised polymer liner ensures very good friction and wear results. Here too, the absence of lubrication makes the entire system extremely insensitive to dirt.

The company Richter is currently revising part of its product range. The triangular steering system is planned to be adopted in all electric wheelchairs, as there is great interest from our customers. The individual assemblies are constantly put to the test. This ranges from electrical adjustment of height and length of the seat, electrical adjustment of pressure to relieve it on individual parts of the body, up to electrical leg adjustment and all-wheel steering. The company is consistently dedicated to the task of compensating for physical deficits better and more effectively.

In the floor assembly drylin® profile guides are used for foot and leg adjustments. They are also smooth-running and insensitive to dirt. The tribologically optimized polymer liner provides for very good results in friction and wear.

The shock/impact at the moment of driving over is very high. It is mitigated by a mountain bike spring system (picture) and large tires. Then there are the good dampening properties of polymer bearings that – unlike steel – can absorb vibrations.

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