Mobility thanks to plastic plain bearings

Profile

• What was needed: igubal spherical bearings and flange bearings, drylin profile guides
• Requirements: The wheelchairs and bearing components must withstand all weather conditions. They must be free of lubrication in the triangular steering system to avoid dirt and dust accumulation. Driving over kerbs also exerts high forces on the installed bearings, so they must be sufficiently shock-resistant.
• Industry: medical equipment
• Success for the customer: The various bearing components are lightweight, robust, are simple to assemble, low clearance, high mobility, high damping capacity and offer good friction and wear results. For many years now, the rehab technology company has relied on the polymer bearing range in its assistive devices.

New "Tango GT" electric wheelchair from Richter Reha Technik Richter R.M.S. GmbH, Thurnau (Franconia). The transaxial all-wheel steering allows stable driving in the tightest of curves. Even steep inclines are possible.

Problem

Richter Reha Technik Richter R.M.S. GmbH in Thurnau, Franconia, manufactures special wheelchairs providing people with disabilities mobility. The company produces customised solutions that are individually adapted to the everyday requirements of each user.
The manufacturer's "Tango GT" electric wheelchair not only features extremely flexible transaxial all-wheel steering, but also sophisticated environment control systems. 
The assistive device is primarily for outdoor use but can also be used indoors. When the wheelchairs are used outdoors, it is especially important that they withstand all weather conditions. The transaxial all-wheel steering allows stable driving in the tightest of curves. The wheelchair features special off-road mobility and manages even steep inclines without losing power due to extra-strong motors. The triangular steering is also special: it not only has a shock-absorbing function but can also move in all directions.
There must be no lubrication points in the assistive devices. This is because the dirt and dust collects on grease. Therefore, only polymer bearings are used in the manufacturer's product range. In addition, high forces act on the installed bearings when the wheelchair is driven over kerbs. The shock/impact effect is exceptionally high at the moment the chair moves over the kerb.

Solution

igubal spherical bearings of the KGLM series, which require no lubrication or maintenance, are used at the triangle steering's pivot point. Two bearings are installed in the upper and lower swing arm, so a total of eight spherical plain bearings on the front and rear axis wheels prove their suitability for everyday use.
Another main feature of the "KGLM" series in the high-tech "Tango GT" electric wheelchair, besides high damping capacity, is its vibration damping. In addition, there is the compensation of misalignments and edge loads. The lightweight, robust spherical plain bearings have proven themselves in special wheelchair steering systems from the very beginning. They are easy to mount and very easy to adjust. They have mobility and low play, and of course require no lubrication or maintenance.
The "Tango GT" uses a mountain bike suspension system and large-volume tyres to mitigate impacts and prevent excessive stress. The plastic bearings were the first choice for the triangular steering system specialist.
In addition to the spherical bearings, various flange bearings made of iglidur G are installed in all upright devices with a 45° centre of gravity shift. The versatile all-round bearing is used for such applications as simple rotary and swivel movements. It is built into the calf plates and provides appropriate support and thus safety when the rider stands. Flat drylin profile guides also prove their versatility in the foot and leg adjustments of all electric wheelchairs. The tribologically optimised polymer liner ensures very good friction and wear results.
The rehab technology company has now been using the polymer bearing range in its assistive devices for many years.

The shock/impact effect is exceptionally high at the moment the chair moves over the kerb. It is mitigated by a mountain bike suspension system and large-volume tyres. Unlike steel, the polymer bearings have good dampening properties that can absorb vibrations.

The floor assembly uses drylin profile guides in the foot and leg adjustment mechanisms. The guides also run smoothly and are insensitive to dirt. The tribologically optimised polymer liner ensures very good friction and wear results.

igubal spherical bearings of the KGLM series requiring no lubrication or maintenance are used at the triangle steering pivot point. igubal flange bearings made of iglidur G (left picture) are installed in all upright devices with 45° centre of gravity shift (right picture).