For its 2019 car for the Formula Student Competition, Team Bath Racing (TBR) developed a new hydraulic clutch that included precision position feedback as part of its closed-loop hydraulic system. To meet the requirements, the team chose Positek’s P118 series pushrod style linear position sensors which are suited to precision measurement tasks where space is at a premium and where durability, reliability and affordability are key factors. These measure just 19mm in diameter, and offer a customised stroke range from 2mm to 50mm and linearity to ±0.25%.

The clutch needs to withstand the extreme shock and vibration loads associated with motorsports as well as race track temperature, humidity and weather extremes. In both performance and track test modes complete reliability is essential. Its design, however, also required that the measurement sensor be installed in the smallest possible envelope with minimal weight an important factor. TBR developed a design that effectively isolated the P118 from the extreme temperature levels inherent with dynamic clutch operation but still required a generous working temperature range and IP67 sealing as a minimum for dependable operation.

TBR specified the flange mounted version of Positek’s P118 with the 4…20 mA output option managed within the race car’s control system – converting the linear position of the LVDT to a linear output proportional to the clutch displacement. With housing and connected parts in stainless steel as standard, the sensors performance met and exceeded all of the performance specifications required.

Other mechanical options available for the P118 series include body clamp mounting and spring loaded pushrod with a wider operating temperature range of -40 to +125°C for the 5V input version. 24V DC nominal input versions are also available with output options including 4-20mA and 0.5 -9.5 V DC.