San Antonio A new power steering system developed by River City Products uses "power centering" for keeping trucks on a straight path. Unlike traditional systems that are designed for assisting drivers only when the vehicle is turning, power centering is designed for guiding the vehicle in a straight line when the driver is not turning.
Conventional steering-wheel systems produce destabilizing forces responsible for the lack of directional stability in trucks, according to Howard. "The king pin angle and the caster angle are both measured in degrees of caster angle, so the steer wheel castering is mistakenly assumed to have a stabilizing effect," he says.
The new power centering system uses hydraulics and pneumatics for automatically holding the truck's steering wheels on center. "The vehicle tracks straight even on crowned or rutted roads, unless the driver turns the steering wheel," says Dee Howard, the inventor of the power centering system. He notes that keeping the vehicle on a straight path greatly reduces driver fatigue.
A new CS1573 air regulator from Clippard Instrument (Cincinnati, OH) supplies pressure to a trim cylinder that controls the amount of force applied to the steering system. With a few turns of a knob, the regulators allow adjustment of pressure settings to match road conditions. "The regulator also has a small 1 1/16-inch diameter piston, so it has a fast response time," says Rich Boutell, an engineer with Clippard. "Fast response time is important when drivers are travelling down the road at high speeds," he says.
Additional applications for the power centering system include buses, motor homes, agricultural equipment, and marine craft. Air pressure regulators can also be used in automation equipment, medical devices, material handling conveyers, and packaging equipment.