TRUCK TRACKS

By: Ken Kelley

Improved working ability is now a clear trend in modifications of axles and other components at the bottoms of trucks and trailers. Among all parts studied, introduction of new air suspensions was the most frequent move.

While air springs are often seen as parts that protect fragile loads, they can be helpful in hauling the less-than-fragile loads. The trailer people at Landoll echoed this view in the announcement of a Neway air suspension (Circle 914) that was being added to two of the firm’s bottom-dump trailers.

The air rides were said "to provide comfort for the driver and decrease the amount of ‘stress’ maintenance necessitated by running empty during return trips."

While offsetting empty-return-repairs is used to justify use of air springs, increased driver comfort is probably listed more frequently.

Driver comfort was noted in recent announcements of air suspension systems on Peterbilt and Western Star trucks and is a plus on products of suppliers including ArvinMeritor, Dana and Hendrickson.

At the heavy-duty end of the work done by products in the suspension field, manufacturers are satisfying demand for stronger components. Recent additions to available tandem rear axles have marched up through the 40, 44 and 46,000-lb levels.

ArvinMeritor is offering variety. The firm just added a unitized wheel end for drive axles in the 23,000- to 40,000-lb capacity range. The units contain seals, bearings and a specially formulated synthetic grease in a single unitized assembly.

The producer said the unit, which utilizes SKF bearing and seal technology, is preassembled, preset for preload, permanently lubricated and sealed for the life of the component.

Another ArvinMeritor offering is a low-maintenance front axle. The unitized hub, seal and bearing assembly is presealed, permanently lubricated with the end play permanently set during manufacture.

Peterbilt’s new entry among air suspensions is the Flex Air Tandem (Circle 915) which the producer said features the lowest installed weight of any comparable system. Capacity of the device is 38,000 lb. The company said it is 400 lb lighter than the firm’s other leading weight-saving air system. The manufacturer explained that the Flex system uses a weight-efficient structure consisting of a very stiff aluminum beam with a small semi-elliptic taper-leaf spring mounted at one end and an air spring at the other.

Hendrickson International is close to leading the industry in variety of suspension systems offered.

The producer is particularly proud of its Airtek integrated front air suspension and steer axle (Circle 916). The device received the prestigious 2001 PACE (Premier Automotive Suppliers’ Contributions to Excellence) award in innovation.

Hendrickson said the novel product delivers a combination of weight reduction and increased stability while lowering maintenance requirements. The firm said Airtek "represents a quantum leap in technology for the company and the industry."

Hendrickson also has announced improvements in trailer suspension systems and those for extreme-duty applications.

A combination of the Dana and Eaton component supplier firms has announced completion of a new Roadranger drive train package (Circle 917) that is said to be designed to reduce damage that often results from destructive torsional vibrations, one of the fastest growing maintenance concerns in truck operation today.

An integral component of the package is the new Dana Spicer 40,000-lb tandem drive axle. This latest addition to the Roadranger system, the Torsionally-Tuned 40 (model DST 40) is said to significantly reduce excessive inter-axle drive-line angles and improve overall drive-train durability and performance, while minimizing size, cost and weight concerns.

"This translates into lower maintenance, a better ride, improved satisfaction and more quality time on the road," said Steve Slesinski, program manager, Spicer Heavy Axle and Brake Division.

A number of variables such as suspension type, ride height setting, axle torque, braking, gross loaded axle weight, fifth wheel location, axle installation angles and axle spacing were listed among other potential causes of damaging drivetrain vibrations.

The Torsionally Tuned 40 tandem can be set up to provide a five-year, 750,000-mile warranty.