SUVs Spur Market For ArvinMeritor Springs

The popularity of SUVs has opened the door — literally — to new opportunities for ArvinMeritor Inc.

The small town of Marion near Myrtle Beach, SC, is home to ArvinMeritor's sole North American plant for producing gas springs, which provide the familiar “whooshing” sound each time a lift gate opens on an SUV or minivan.

The supplier's research indicates that 85% of new light vehicles have at least two gas springs, and many SUVs have six — two for the hood, two for the lift gate and two for the “flipper glass.”

Gas springs have gotten a huge boost in the market because tailgates on big SUVs are so heavy. Gas springs are charged with compressed nitrogen to provide considerable assistance in raising and lowering the gates.

The Marion plant produced some 2 million gas springs in 1985; this year it will manufacture more than 12.5 million. The arrival of power lift gates will help the growth prospects even more.

Its biggest customer was the Chrysler Group, but the supplier has since diversified its customer base to include General Motors Corp. and Ford Motor Co., and it has a contract with Toyota Motor Corp.

The plant supplies springs for significant new vehicles such as midsize GM SUVs (flipper glass), Saturn Vue (tail gate), Cadillac CTS (deck lid) and '03 Lincoln Navigator (tail gate).

ArvinMeritor says it is the No.2 player, with about 27% of the OEM market for automotive gas springs in North America. No.1 is Germany's Stabilus GmbH, with 66% of the North American market.

ArvinMeritor attributes its growth to a patented technology it developed to make the springs more resilient in cold temperatures. Any long-time customer of minivans knows that freezing temperatures can render conventional gas springs useless, forcing a disgruntled motorist to prop open the heavy gate with one hand while fishing out groceries or packages with the other.

ArvinMeritor's solution is the temperature compensation module (TCM). A conventional gas spring fails in cold temperatures because the nitrogen contracts and loses its force. With TCM, when temperatures dip below 40ÞF (18ÞC), a bi-metal valve allows more nitrogen gas into a second chamber inside the spring, providing the extra boost needed to keep the spring fully functional.

On hot days, the nitrogen expands, making it harder to close the gate with conventional gas springs. With TCM, the spring has less nitrogen to begin with; the gas expands, but it does not make it more difficult to close the tailgate.

In normal conditions, ArvinMeritor engineers say a lift gate with TCM springs requires 15 lbs. (6.8 kg) of closing force, compared to 21 lbs. (9.5 kg) for a conventional gas spring.

ArvinMeritor says about 15% of the gas springs produced in South Carolina are of the TCM variety, and the company says that percentage is on the rise. The OEM cost for a conventional spring is about $5; a TCM spring costs about $6.25.