Locking gas springs for standing wheelchairs
Wheelchair manufacturer Levo is employing lockable gas springs on its standing wheelchairs, bringing even greater reliability and making them easier to control.
Standing wheelchairs hugely improve their users’ quality of life and independence. In an upright position, wheelchair users can reach things that are higher up and carry out activities that are not possible sitting down. For more than 40 years, the Swiss manufacturer Levo has been adapting its standing wheelchairs to target the needs of people with all kinds of physical disabilities. For the kinematics of its customised wheelchairs, Levo relies on gas springs, which are adapted to fit each specific application.
The company’s gas spring supplier of choice is Suspa, whose application engineer Stefan Richter explains: “Power assistance is one of the most important aspects of construction, as it means that the user is able to easily switch between a standing and a sitting position.”
Levo’s standing wheelchairs are custom developed and demonstrate a high degree of variability. The way a wheelchair is customised – for both children and adults – is dependent on the user’s body weight, for example. For this reason, Suspa provides gas springs for different loads of between 250 and 750 newtons for people who weigh between 30 and 110 kilograms. There is also a selection of different locking characteristics. Non-locking gas springs are used in standing wheelchair variants with integrated electrical standing functions that can be selected by pushing a button. They assist the motor by bracing the wheelchair user’s weight during lifting and lowering. This makes it possible to use a compact motor that only requires little construction space. Locking gas springs with light absorption are used in wheelchairs in which users apply pressure to the armrests in order to mechanically operate the grab rails. This means that upwards and downwards motions can be locked in gently over a number of levels.
“Speed, absorption and holding power are always different depending on requirements and are adjusted in the gas springs at the factory accordingly,” says Richter. In the case of wheelchairs in particular, it is about maximising power assistance to a point where the user can stand up using as little physical exertion as possible. This also means adjusting the gas spring’s progression when retracting the piston rod in such a way that the user can get back into a sitting position effortlessly using their body weight alone. Moreover, the gas springs have been conceptualised in such a way that dirt and UV rays do not impair the wheelchair’s lifespan. The hoses and Bowden cables necessary for operating wheelchairs are installed safely and in a user-friendly way.
Suspa’s gas springs are not just installed in wheelchairs in order to enable the user to stand up; they can also be used as undercarriage absorbers or for adjusting backrests or seat inclination. “We have been continuously working with Levo on face lifts and materials for years, which means that it is becoming easier and easier to operate the wheelchairs,” Richter adds.
The medical industry does not just use the gas springs, dampers and adjustment systems in wheelchairs, but also in hospital beds, side tables and treatment tables.
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