As well as enabling simple outdoor activities like walking a dog, Molten Rock’s Boma7 electric wheelchair is an all-terrain vehicle capable of operating in more challenging landscapes. However, harsh weather environments and steep gradients with mud, rain and ice mean that the chassis, suspension and especially the steering mechanism are subjected to high levels of shock and vibration.
To meet such demands, the engineers chose Variohm’s ELPM linear position sensor to match the high demands of the steering system specification, which includes a robust Linak linear actuator and a Dynamic Controls joystick control system.
Molten Rock company director, Chris Swift, explains: “We have been producing the joystick version of the Boma7 since 2010, and from development through to full field use the sensor has been thoroughly tested on the wheelchair and has performed very well under a range of conditions.”
The compact motorsports position sensor is available in measurement ranges from 12.5mm to 150mm with independent linearity to ±0.5%.
According to the company, the ELP potentiometric series sensors feature a conductive plastic resistance element built up by the application of several layers of specialised printed inks combined with a wiper assembly with an elastomer damped multi-fingered precious metal brush arrangement. This patented measurement technology ensures smooth and uninterrupted contact with low electrical noise under the most demanding physical and environmental conditions.
Additional features of the sensors include an improved felt seal and O-ring sealing arrangement which provide IP67 protection, a 150°C upper temperature rating (175°C short term), and a serviceable rated life of more than 25 million operations.
These also have self-aligning spherical bearing mounts and a compact retracted mounting distance for straightforward installation. An optional quick release version (ELPM-Pop) includes snap on fittings for very fast replacement.