Smooth operators

by James Menzies

CALGARY, Alta. – The suspension may not be the most glamorous part of your truck, but when you’ve got a bad one under you, you know it.

Spec’ing a good suspension is more than a matter of driver comfort; with the advent of air suspensions, both truckers and shippers have come to expect a smoother ride.

And more shippers are also expecting the best for their precious freight.

As a result, competition among suppliers in the market is intense, with each supplier looking for improvements in handling, durability or serviceability to differentiate its products.

What follows is a look at what some of the biggest names in the heavy-duty truck suspension business have been working on.


ArvinMeritor is promoting an entirely new way of thinking about suspensions.

Rather than viewing a suspension as a collection of components, the company is urging OEMs to consider a complete systems approach.

Such an approach could provide a better ride as well as reduced weight and costs, says Dan Chien, director of the commercial vehicle systems business unit for suspensions.

“Because we supply components on the truck and the trailer, we’re designing future modules and systems that are compatible and designed to work together in an optimized way,” says Chien.

A systems approach would include everything from axles and brakes to steering components and electronics.

While the company says the end-user would benefit from a systems-approach, OEMs would have to re-evaluate the entire manufacturing process, says Bob Zirlin, director of worldwide marketing, suspension systems and trailer products.

“There’s a change in paradigm that’s going to be required,” says Zirlin, who recently published a white paper on the subject.

In the meantime, ArvinMeritor continues to see growth in the air suspension segment of its business. About 60 per cent of new trailers are now equipped with air ride suspensions and that’s expected to continue to grow.

“I think it will level out at less than what Europe has,” says Zirlin, noting about 90 per cent of new European trailers are air suspension-equipped.

ArvinMeritor is also forecasting increased demand for composite mechanical suspensions.

“Composite mechanical suspensions have not been all that they can be because the idea to date has been to fit the composite spring into the envelope provided by the steel mechanical spring,” says Zirlin.

Recently, ArvinMeritor inked a deal with Liteflex Composite Springs that will see the two companies work together to market integrated composite suspension systems.

Hendrickson International

Front air suspensions earned a bad rap their first time around, but Hendrickson International says it has overcome many of the challenges facing them with its AIRTEK front air suspension.

On the market for two years now, the front air suspension has changed the way O/Os and fleet managers perceive air suspensions, says AIRTEK marketing co-ordinator Chad Nibbelink.

“Within five years, I think front air suspensions are going to be standard on the front axle,” predicts Nibbelink.

“We’ve been able to address many of the concerns created by these suspensions.”

The biggest benefit of a front air suspension is improved ride, but since there’s an upcharge to spec’ a front air suspension, Nibbelink says the company has been trying to substantiate the theory that there are other benefits to the system as well.

“It’s tough to get people to buy into it just over the pure ride benefit but there are also some maintenance savings we’re in the process of quantifying,” he says.

“It’s transmitting less vibration up into the frame so not only is your driver getting a smoother ride, but your components are also getting a better ride.”

The AIRTEK is standard on Volvo sleeper cabs, and available for about a US$200 upcharge on Volvo daycabs.

It’s also available on Freightliners, at an upcharge of about US$500.

Studies indicate the AIRTEK delivers about a 21 per cent improvement in ride on Volvos and up to 30 per cent better ride on Freightliners.

This was measured by strain gauges installed on the frame. Nibbelink says even a six per cent improvement is noticeable in the cab.

Chalmers Suspensions International

Chalmers is a Canadian manufacturer that is best known for its rubber spring suspensions which have become popular in the heavy-duty construction market.

Construction applications place unique demands on the suspension, and Chalmers says its high-articulation, low-maintenance rubber spring suspension addresses these challenges.

“The floating walking beam with the rubber spring centered between the two axles carries the weight,” explains Steve Clarke, general manager of Chalmers Suspensions International.

“The spring compresses inside the can and distributes the weight equally to all four corners. The torque rods don’t carry any weight because all of the weight is carried on the rubber springs between the two axles.”

The patented rubber spring technology provides durability, but also improved ride, says Clarke.

“It gives you an excellent ride loaded, but it also gives you a good ride while unloaded, and that’s the hardest thing to accomplish,” he says.

Other benefits of the rubber spring suspension include improved traction and tire wear and less wear and tear on components and equipment, Clarke adds.

Ridewell Corporation

Ridewell Corporation has continued developing its air suspensions to keep up with increased demand in the Class 6-8 markets.

“Companies are finding out more and more that air ride certainly extends the life of the piece of equipment over springs,” says Gary Wasney, Canadian sales manager for Ridewell.

“Certain customers nowadays want a carrier that has air ride or they can’t haul their freight.”

Wasney says mechanical spring suspensions are hard on the driver, equipment and cargo, and more fleets are realizing the benefits of upgrading to air suspensions.

“With the springs you get shock loads and it creates problems throughout the units with wiring, with lighting and with welds,” says Wasney.

“Air ride is the better way to go and I think eventually we’re going to see more and more people going to that.”

Most recently, Ridewell released its Ridelite integrated trailer suspension, which the company says is an easy-to-install suspension designed for platform, dump, tanker, grain and specialized trailers.

For now, Ridewell is sticking to producing mechanical suspensions for the steer axle of trucks, and only utilizing air ride technology on trailer and drive axles.

“I don’t think (air) is as noticeable on the steering axle of a truck as much as it is on the drive axles or the trailer, because of the weight of the engine and so forth sitting right over top of that front axle,” says Wasney.

Tuthill Transport Technologies

Manufacturer of the Reyco/Granning line of suspensions, Tuthill Transport Technologies has also noticed a steady increase in demand for air ride trailer suspensions.

So much so, according to international marketing administrator J.P. Claude Sauriol, the company is considering pruning some spring suspensions from its product line.

Integrated suspensions are also in demand, but the constant push to reduce weight in integrated suspensions is also having somewhat of a negative effect, explains Sauriol.

“Everything from pivot bushings to trailing beams to hangers are being reduced in size to reduce weight, thereby reducing their effectiveness in a heavy-duty application,” he says.

“More than ever, fleets and manufacturers must work together to determine the true application and environment that a trailer will be working in, to ensure that the most suitable equipment is being used which will provide the longest life and least maintenance.”

The latest product to be added to Tuthill’s lineup is the Gen-Tech integrated suspension and axle system, featuring large pivot bushings, short camshafts and improved stability and roll rate. It’s rated at 23,000-
lbs per axle.

Raydan Manufacturing

Another Canadian suspension manufacturer is Edmonton-based Raydan.

The company focuses on air tandem suspensions for vocational applications.

The company’s Air Link rear tandem suspension has been on the market for more than 10 years.

It’s currently available as a factory option on new Macks and Western Stars.

The company also recently launched its Air Link front tandem suspension.

“There’s a lot more concern about roll stability and everyone wants a nicer ride and this is a combination of both of those pursuits,” says Pat Schryver, an engineer with Raydan Manufacturing.

The new offering is currently in use in Northern Alberta oil fields.

It also has other vocational applications.

The Air Link front tandem suspension is currently available as a retrofit component.

Schryver says it may also eventually be a factory option on some heavy-duty trucks.

Dana Spicer

Dana Corporation recently expanded its suspension lineup with the addition of the Dana Spicer RF Series Air Ride Trailer Suspension module.

The latest offering is a lightweight, yet durable trailer suspension that features a 5 3/4″ diameter axle tube for increased strength, says Allen Peacock, chief engineer, trailer suspensions.

While U.S. customers are demanding lighter axles, the focus in Canada has been on durability, says Pat Brandt, general sales manager, trailer division.

“Up in Canada you have people talking a bit about weight but weight doesn’t seem to be a big issue up north,” he says.

Dana has also noticed increased demand for air suspensions and the company is also noticing a shift towards a systems-approach.

“Fleets are looking more and more for a one-stop shop,” says Brandt.

“They would like to have one person to call for that system.”

Link Manufacturing

The economic downturn in the U.S. has kept demand for liftable suspensions in check, but Link is optimistic they will increase in popularity when the economy bounces back, says Fred Krommendyk, liftable suspensions product specialist with Link Manufacturing. But the company hasn’t been sitting back waiting for a market recovery.

It recently introduced two new liftable suspensions at the Mid-America Trucking Show – the Duramax and the DuraLift – which the company says deliver improved performance.

There’s been more demand for self-steer liftable suspensions – such as the recently-debuted DuraLift – since governments in Canada and the U.S. have been implementing legislation enforcing the use of lift axles to protect roadways, Krommendyk says.

Customers are continuing to demand suspensions that are lightweight, yet durable, he adds.

“The drive to make everything lighter weight on the truck certainly extends to lift axles as well.”

Another trend Krommendyk notices is that more liftable suspensions are being factory-installed rather than retrofitted, so spec’ing a liftable suspension has gotten easier.

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