Getting the most out of your brakes
CALGARY, Alta. – They may not be the most glamorous components on your rig, and certainly don’t serve as eye-candy at most show’n’shines. But with RoadCheck just around the corner they’re what all the inspectors will be checking out on your rig: Brakes.
Your braking system requires more maintenance than many of a truck’s components, and given the plethora of braking systems available on the market, a little know-how can go a long way in ensuring your truck can stop on a dime – every time.
There’s no question braking technology has grown in leaps and bounds over the past decade. But while many of the newest systems promise to work better and last longer, don’t be fooled. Ron Bailey, technical sales manager of air disc brakes with Bendix, says although many new products are labeled automatic they still require attention from time to time.
“It doesn’t mean that they’re maintenance-free devices, they still need to be looked at and they do need some periodic lubrication,” says Bailey.
Gary Ganaway is ArvinMeritor’s business unit director for air disc brakes North America, but before taking on that role, he provided customer service support for the company. That position made it clear to him that many fleets neglect the regular maintenance necessary to get the most out of their brakes.
“A lot of customers in the field either take it for granted or don’t understand it,” says Ganaway.
One of the biggest mistakes fleets and owner/operators are guilty of, he insists, is pinching pennies when it comes to buying replacement parts, putting the driver and other motorists at risk.
“There’s a lot of time and effort to make sure that the braking system is optimized for the vehicle and its intended use,” warns Ganaway. “As customers go to re-align or service vehicles, in many cases they’re buying simply on price and they’re buying parts simply because they physically fit … that really degrades the performance of the vehicle.”
Scott Walpole, friction product manager with Haldex, says just because there are more products on the parts store shelves doesn’t mean they’re all created equally.
“There’s a lot of offshore stuff starting to come in that people really don’t know anything about,” says Walpole. He adds there’s very little stopping fly-by-night companies from flooding the market with dangerously inferior products.
“There are no requirements for aftermarket friction materials aside from those which the supplier holds itself to,” says Brent Armentrout, applications engineer for heavy-duty products with Haldex. “In the absence of regulations, your only protection then becomes a reputable supplier.”
With fleets seeking ways of improving the efficiency of their drum brake systems, one popular option has been the use of bigger brakes. But bigger isn’t always better, warns Bailey.
“The biggest problem with putting a bigger drum brake on front axles … is that you can have some instability in the drum brake,” says Bailey.
There can be up to a 30 per cent variation from brake to brake, he notes. “Now the problem is keeping it between the white lines on the road,” Bailey adds.
To meet the growing needs of fleets seeking larger brakes, ArvinMeritor has developed a hybrid line of brakes that offers larger drums without compromising weight. The larger brakes also help dissipate heat, resulting in a longer lining life.
“Customers like the feature of having bigger brakes but they don’t like having the added weight that comes with them,” says Ganaway. ArvinMeritor’s Q Plus brake line features a 16.5×8-inch rear brake and a 15×5-inch front brake.
“It may not seem like a lot, because those sizes are only an inch wider than standard brake sizes, but we’ve seen, typically in a line-haul operation, about a 30 per cent improvement in life,” says Ganaway.
From a driver’s perspective, there are a few things that can be done to make the fleet’s maintenance staff a lot happier. The number one enemy of brake linings is heat, and driving style can greatly affect the amount of heat the linings face.
“You want to make sure the brake is operating at as low an initial braking temperature as possible,” says Ganaway. When descending a hill, Ganaway recommends drivers shift into the highest recommended gear.
Another way to prevent heat build-up is to spec an engine retarder.
“We’ve seen improved lining life by as much as 30 per cent just by having the engine retarder,” says Ganaway.
Haldex says that while heat remains the number one enemy of brake systems, its Cross-Link technology helps fight the problem. Cross-Link, which will be launched this summer, results in better bonding of resin and fibre.
“As you get more and more heat into the product, it tends to retain its structure better than it does without the Cross-Link technology,” explains Dr. Dave Patten, director of research and development for Haldex.
In order to get the most out of their brakes, drivers should also avoid the use of hand brakes when possible, and ensure there’s a good balance between the tractor and trailer brakes.
More and more fleets are making the switch to air disc brakes, and according to the manufacturers, that could be a shop mechanic’s dream.
Bailey explains, “The disc brakes generally have less maintenance, primarily because they are a sealed-for-life mechanism.”
Once installed, performing routine maintenance on air disc brakes can take about one-third of the time.
“We’re seeing dramatic improvements in life versus comparable drum brakes,” says Ganaway. “Not only is the maintenance task itself much simpler, but the frequency goes down.”
Disc brakes improve performance, reward drivers
For many years, air disc brakes have been standard on European rigs. At the same time some North American fleets, mainly specialty applications like hazmat haulers, have used disc technology to improve braking performance. But the majority of North American fleets continue to rely on traditional, low-cost S-cam drum brakes to stop their trucks.
But that’s all about to change according to Jim Clark, chief engineer in charge of foundation brakes at Dana Corp. He insists a major push from the U.S. National Highway Transportation Safety Administration (NHTSA) to improve truck stopping distances, combined with the never-ending need to bolster productivity, will soon make disc brakes a more common component on this side of the pond.
“Government agencies throughout North America are keenly aware of the fact that trucks don’t stop as well as cars do and that something needs to be done to close the gap,” notes Clark. “In the U.S., NHTSA is calling for a 30 per cent reduction in stopping distance in new rulemaking planned to take effect by 2007. They believe that this improvement alone will achieve a 50 per cent reduction in truck-related highway fatalities.”
Clark believes these braking distance changes will be formally defined in about three years and then the rule will take full effect in the U.S. by 2007. He predicts Canada’s governing agencies will follow a similar timetable – perhaps only one year later than the U.S. implementation.
Proactively responding to this emerging opportunity, major brake suppliers have recently introduced new air disc brake systems for Class 7 and 8 trucks. For several years, brake makers have been working to Americanize European disc brakes by making them lighter and easier to both install and maintain.
These systems will still offer a range of benefits over the S-cam option, including reduced stopping distance; increased brake pad life – 30 to 50 per cent better in some cases; car-like braking and steering; as well as overall lower life-cycle costs.
According to Clark, the most likely configuration for disc brakes will be on steer axles, with today’s drum brakes still on the drives and trailers.
Why? The performance level for the vehicle rises significantly when a disc brake is used on the steer axle because this is the axle receiving most of the weight transfer in a braking application.
In addition, disc brakes
reduce the chance of steering pull from brake torque. Clark reports during Dana’s field tests, drivers literally fell in love with disc brakes. One veteran test driver claims he could perform a panic stop from 60 mph without touching the steering wheel. That level of performance can certainly be used by fleets to attract and retain drivers.
“Disc brakes are currently used in motor coaches, fire trucks and city buses but also in tankers,” says Clark. “Now that disc brakes are readily available in the U.S, we are starting to see an increased level of interest from all kinds of fleets during the specification process. And a greater number of owner/operators, who typically keep their vehicles longer, are also exploring both the life-cycle costs and safety benefits of disc brakes.”
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