Sensor Use Rising in Off-Highway Applications

The off highway market’s growing adoption of electronic technologies is opening up a strong market for sensor makers. Solid state sensors are seeing substantial growth in many different aspects of the construction and agricultural markets.

Electronic controls are taking over in a number of areas in off highway applications, from engines to cabs to hydraulics, much like they have replaced mechanical systems in autos. The adoption of these microprocessor-based systems opens the market for sensors, which provide real-world information to the digital controllers.

Subsystem designers are devising techniques for steering by wire, using network connections to replace hydraulics and mechanical steering systems. As the technology moves closer to production in the conservative off-highway market, engineers are changing technologies to improve performance. SKF USA Inc. recently switched from Hall Effect sensors. “We’re using absolute position sensors that have high resolution, 12 bits, that are non-contact so there’s no wear and tear on the components,” says Tim Ruiz, applications engineer at SKF of Kulpsville, PA.

Eaton Corp. Hydraulic Operations in Eden Prairie, MN (www.eaton.com), is employing sensors in its VersaSteer electrohydraulic technology, which includes programmable valves. Sensors make it possible to adjust steering sensitivity so operators driving down the road at high speed and those doing fine moves in tight areas move the wheel in increments tied to those tasks.

Though sensors are seeing far more acceptance in off-highway products, designers note that the harsh environment requires special packaging. For example, tire pressure monitoring sensors are being put inside a number of tires for autos.

But in off-highway markets, the programs are still in development. “The difference from cars is mostly to scale for off-road applications. Size is one factor, but mainly mining and other off highway applications have shock and vibration requirements that are a lot more dramatic,” says Barry Rexroad, senior engineering manager at Bridgestone/Firestone’s Off Road Tire Group in Nashville, TN (www.bfor.com).