SPOTLIGHT. Bigger, Stronger Brakes Meet New NHTSA Rules. From the July/August 2011 issue of Equipment & Maintenance Update

Transcription

1 Bigger, Stronger Brakes Meet New NHTSA Rules From the July/August 2011 issue of Equipment & Maintenance Update

2 Bigger, Stronger Brakes Meet New NHTSA Rules Manufacturers Upgrade Drum and Disc Systems By Mindy Long Contributing Writer Brake and truck manufacturers have reconfigured drum and disc brake setups to meet a new federal mandate that shortens the stopping distance requirements for Class 8 trucks, strengthening and enlarging components in the systems to comply with the rules. The extra stopping power built into drum setups that many fleets rely on has placed added pressure on axles, springs, spring hangers and other parts. To withstand that pressure, these and other parts have been beefed up, adding weight and cost to trucks. The engineers have to evaluate the entire system again, said Frank Bio, trucks product manager for Volvo Trucks North America. While air disc brakes have long promised improved stopping performance over drums, their accompanying higher price tags have historically kept fleet buyers at bay. However, the combination of the new rules and re-engineered drum setups has reignited the debate over drum versus disc brakes, with parties on both sides making their case. New stopping-distance standards from the National Highway Traffic Safety Administration that take effect in August require tractor-trailers traveling at 60 miles per hour to be able to come to a complete stop within 250 feet when loaded to the gross vehicle weight rating nearly a 30% improvement over the old standard that required a complete stop within 355 feet. Brake maker Meritor Inc., Troy, Mich., tested more than 100 different materials and has run more than 8 million miles of on-road testing in getting its brakes ready for the new rules. The company is updating its Q Plus drum brake system with new friction materials, and the sizing of the brakes may change as well, said Amanda Phillips, manager of the on-highway brake business for Meritor. Meritor is also increasing the size of brake drum mounting bolts to make them stronger and changing to a different knuckle that will accept the bigger bolt. We ve worked individually with each OEM to learn how they re going to be interpreting the regulations and where their comfort level is to ensure they re meeting the stopping distance requirements, Phillips said. On its drum brakes, Bendix Spicer Foundation Brake, Elyria, Ohio, is using bronze bushings, which offer greater durability compared with plastic bushings, and tightened tolerances within the brake. Bendix has also reconfigured linings and is using materials that are more capable and produce less fade than traditional drum brake linings. We re producing more precise components to reduce variation from brake to brake, said Tom Runels, engineering manager for drum brakes, Bendix Spicer Foundation Brake. Truck makers have also adopted new standards for their drum setups. Volvo Trucks North America, Greensboro, N.C., is going to a inch drum brake from a inch setup. The OEM is also adding heat shields to keep temperatures of brake linings down and changing components on the suspension and axle to meet the higher torques. Daimler Trucks North America, Portland, Ore., is changing the size of its standard drum brakes to from 15 4 on the steer and to /8 from on the rear. To meet the stopping distance, the torque output on the front axle had to go up 51%. We went to a larger brake that was more capable of handling the work, said Thomas Macmenemy, foundation brake manager for DTNA. Macmenemy told Equipment & Maintenance Update that the reduced stopping distance drum brake will stop within a foot of the disc brake, which Daimler first launched in 2 Transport Topics SPOTLIGHT

3 2009. Plus, he said, the linings with the new drum brakes should last longer, noting that the company s goal is to get the brakes to 500,000 miles or more without having to replace the lining. Today, our average lining life is 325,000 miles, he said. However, all of these upgrades carry extra weight. For C.R. England, Salt Lake City, Utah, new brakes are adding about 100 pounds to their tractors. There is no question that is a concern given the fact of the 500 or so pounds we had to take on with the 2010 emission requirements, said Todd England, executive vice president for the refrigerated carrier, referring to new pollution control systems that debuted on new trucks last year. Meritor s Philips said the new Q Plus brakes add around 51 pounds to the front axle, and 100 pounds to a rear tandem-axle setup. Gary Ganaway, director of the foundation drum brake group at Bendix, said his company s new drum setup adds about 70 pounds but was reluctant to get into specifics for each component. As you might imagine, weight is a fairly sensitive competitive issue where our products are concerned, he said. However, he allowed that about 39% of the weight increase is in the brake itself, while 56.5% is in the drum and 4.5% is in the brake chamber. While Volvo and Daimler will continue to offer disc brakes as options, Peterbilt Motors Co., Denton, Texas, is making front-axle disc brakes standard on its entire line of Class 8 trucks. Customers can still order drum brakes on most models, with the exception of Model 587. We ll hit reduced stopping distance with the drum brake, but we still see better feel and performance out of the disc brake, said Mark Green, senior project engineer and supervisor for Peterbilt s air and brake systems group. Green added that disc brakes have more of an automotive feel, reduced Peterbilt is adding front-axle air disc brakes to the list of standard equipment on its Model 587 trucks. pull and reduced exposure to fade. Fade occurs when drum brakes heat up, increasing the size of the drum and making friction material travel farther. Although Peterbilt s air disc brakes already met the stopping requirements, the OEM upgraded the rotors provided with air disc brakes to a newer splined design that will also be standard, he said. The new rotor design is 50 pounds lighter, offers more resistance to high temperatures, and features common parts on the steer and drive axles, a move that the company said will ease the maintenance burden for fleets. Green also stressed that disc brakes require no lubrication and reduce the amount of brake re-linings a tractor needs and the amount of time it takes to do a brake relining. Bill Januszewski, manager of fleet support services for Trimac Transportation, Calgary, Alberta, said disc brakes have saved his fleet time and money on maintenance. Maintenance tasks are much easier with disc brakes and, in most cases, reduced maintenance costs more than offset the higher up-front cost, he said. For example, in higher gross combined weight applications in the United States, Trimac s brake life was extended 2.5 times. What s more, when brake service was required, only the brake pads were replaced and the original rotors were still on the trucks when Trimac took them out of service, he said. Meritor s Phillips said disc brakes cut some maintenance time because mechanics don t have to take the entire wheel end off to replace a pad. When a rotor needs to be changed, that is when you re going to have to take the wheel end off and that particular maintenance would take longer than it will with a drum brake. Beyond maintenance, Januszewski likes air disc brakes because they don t have issues with fade resistance because the brake rotor moves closer to the pads as heat increases, he said. As they get hotter, they do a better job, he said. Schneider National, Green Bay, Wis., is ready to find out what kind of job discs will do on its trucks; the carrier is slated to take delivery of five trucks equipped with disc brakes in the third quarter. We ll run them at least five years, but most of the learning will happen in the first couple of years, said Steve Duley, vice president of purchasing for Schneider. We ll start with a small (Continued on next page) Peterbilt Motors Co. Transport Topics SPOTLIGHT 3

4 (Continued from previous page) quantity, learn from them and see how we want to move forward. Duley said there could be maintenance advantages to the disc brakes because mechanics can replace brakes quickly. However, he added that disc brakes increased the price of the vehicle 1% to 2%. During the cautionary period we ll be looking at what else fails on this brake. It could go from a maintenance advantage to a disadvantage if you start having to replace components, Duley said. Schneider ranks No. 9 on the Transport Topics Top 100 list of the largest for-hire carriers in the United States and Canada. For many fleets, the downside of the disc brakes is the acquisition cost, which Meritor s Phillips said is about $2,500 per truck for all axles. In a typical line-haul application we estimate it takes about 800,000 miles to work that off, she said. The cost for just the front axle is about $750, she said, but noted that pricing will likely vary among truck makers. C.R. England uses drum brakes on all of its tractors and hasn t been able to justify the cost of disc brakes over the life of its vehicles. The company has also been crunching the numbers on the cost of the reconfigured brakes. New Stock on Parts Room Shelves The National Highway Traffic Safety Administration in August will reduce to 250 feet from 355 feet the maximum distance a Class 8 vehicle may use to come to a complete stop from a speed of 60 miles per hour. We ve been going through a whole analysis of the options we have in meeting the new stopping distance requirement. The cost to go to discs is about $2,400more per truck, England said. The cost with the new drum brakes increased $400. C.R. England ranks No. 22 on the Transport Topics Top 100 for-hire list. Aaron Schwass, director for the air disc brake group at Bendix, said the cost differential can range from $1,400 for a single front-axle with two air disc brakes to $3,300 for a tandem axle with four discs. DTNA is the only OEM to offer discs on the drive axles, he said. As a result of the new stopping distance rule and reconfigured brakes, maintenance managers will have to start stocking additional part numbers. In our fleet, we could use the same shoes and pads on our tractors and trailers. That will change now, and we ll have different parts on the tractor and trailer, said Todd England, executive vice president for the refrigerated carrier C.R. England. Brake manufacturers and OEMs alike stressed the importance of replacing like parts for like parts on the reduced stopping distance brakes. All OEMs are using and testing certain brake packages and materials. The aftermarket replacements for those may or may not be as they should be, said Tom Runels, engineering manager for drum brakes, Bendix Spicer Foundation Brake. If they use less viable aftermarket parts, they can change the balance and how the vehicle reacts. Mindy Long AAside from longevity, ensuring that the new braking systems work with older trailers is important to fleets, Phillips said. One of the keys was making sure we maintain tractor-trailer balance so the tractor and trailer maintain equal usage of their brakes, he said. That will ensure a fleet can use an old trailer with a new tractor. To get the compatibility, Meritor used the same 5.5-inch slack adjustor on its new drum brakes as its older ones. Phillips compared slack adjustors to levers the longer the lever, the more pressure you can apply. With a 5.5-inch slack, friction material, not force, creates the additional stopping power. There are some manufacturers that use 6-inch slack that is a short cut to the design to get to the same place, Phillips said. During testing, Daimler did downhill mountain tests to ensure there wasn t a thermal difference between the tractor and the trailer. We look at temperatures at the steer drive and the trailer so no one axle is higher than the other, Macmenemy said. Despite the compatibility challenges and added costs all of the new braking systems may bring, England believes there will be a payback. We think we ll be able to extend our brake life, he said. We ll reduce some accidents, and there will be a safety benefit, he said. l Graphic by Transport Topics 4 Transport Topics SPOTLIGHT

5 Dynamically productize open-source outsourcing after cross-media channels. Competently procrastinate cross