Under pressure.

While the automotive world debates which tire pressure monitoring system is best, passive or direct measurement, Cycloid Co. (Pittsburgh, PA) has moved beyond simple monitoring to attack the underlying problem--lack of air pressure. "The real problem isn't monitoring tire pressure," says Merv Carse, president and COO of Cycloid, "it's maintaining the proper pressure within the tire." According to Carse, a survey conducted by Ford shows that 60% of drivers will ignore tire deflation alarms, and research from the National Highway Traffic Safety Administration (NHTSA) shows: about 10% of gas station air pumps don't work, less than 50% are equipped with pressure gauges, and 30% overstate tire pressure. "In its survey," he says, "NHTSA discovered that--at an actual 35 psi--10% of the pumps gave a reading at least 6 psi higher than actual." What's a driver to do?

Cycloid's answer to this dilemma is an air pump that monitors and maintains tire pressure. Mounted on the wheel hub behind the center cap, it adds air through a check-valved tube that travels from the wheel hub to the tire cavity. About the diameter and thickness of a hockey puck, the 8-ounce pump--there is one per wheel--uses wheel rotation to drive a reciprocating piston pump that can add up to 2.5 psi per hour to an underinflated or leaking tire. In addition, the pump's self-contained electronics continuously monitor tire pressure, tire temperature (so it won't overpressure the tire), wheel rotations, and will send a signal to an internal receiving antenna if a large pressure loss is detected. The electronics also keep tabs on a tire's location. "The system learns the position of each wheel and tire assembly after the wheels are rotated through proprietary algorithms we've built into the electronics," says Carse.

Mounting the Cycloid Auto Pump takes just 10 seconds per wheel. The pump attaches to the hub via a patented quick-connect fitting and two self-tapping screws that attach to nylon inserts in the wheel. [Most wheels won't require a styling change to fit the unit.) Because the unit sits within the wheel hub, there is no chance of damaging it when mounting or dismounting a tire, a potential problem with wheel-mounted tire pressure monitoring units. Also, since the Auto Pump can be adjusted to maintain different pressure levels, a single pump design covers a large variety of vehicles. "The unit can be adjusted to the correct pressure setting just before the wheel and tire assembly is mounted on the vehicle," says Carse.

The Auto Pump has successfully completed an OEM-approved rough road durability test regimen, and 120,000 miles fitted on Detroit-area limousines. Not unexpectedly, its first application is likely to be on either an SUV or minivan, two vehicle types where offering an extra margin of safety can give an OEM a leg up on its competition.