7 minute read
Disc Decisions
Disc brakes will shorten stopping distances, but they still have maintenance needs
There seems to be no stopping the rollout of disc brakes. The stopping systems that emerged as an option for most OEMs around 2008 had become standard on steer axles by 2012, says Freightliner on-highway product manager Kenton Mitchell. Their use continued to expand as collision mitigation systems were introduced, and by 2018 four OEMs offered air disc brakes on steer and drive axles.
While 5% of trucks were equipped with these brakes in 2010, the take rates on new Class 8 trucks are now closer to 25%. He expects the share to exceed 50% by 2025.
“It’s more, ‘How fast is it going to increase and how high is it going to go?’” he told an audience at the annual meeting of the American Trucking Associations’ Technology and Maintenance Council (TMC).
That could be a good thing. The brakes are more responsive, will reduce brake wear, and shorten stopping distances. Drum brakes on the steer and drive axles will meet the Federal Motor Carrier Safety Administration’s requirement to stop within 250 feet at 60 mph. Put air disc brakes on the steer axle alone, and the stopping distance improves by five feet. When put across the steer and drive axles, about 15 feet will be saved. When they’re combined across the entire tractor-trailer, the stopping distance is down 20 feet.
Still, there are challenges. The brakes are heavier than drums, and they have a higher initial purchase price. Users BY JOHN G. SMITH
need to understand the total cost of ownership for their specific applications, Mitchell said. He also referred to the natural resistance to change, and the fact that users are simply more familiar with drum designs.
At a shop level, one of the most important factors to consider is that air disc brakes still require ongoing maintenance. “Disc brakes are not maintenance-free any more than your drum brakes were,” said Jim Boyd, manager of fleet technical services at Southeastern Freight Lines, which now has discs on 30% of its tractors and 11% of van trailers.
Inspections are required just as often, he said, stressing the importance of monitoring rotors and pads, to ensure there’s always enough friction material to protect the rotor.
“Pay close attention to the pads and pad life. A pad that gets into the rotor is a very expensive proposition – not just from a parts perspective, but from labor, wheel seal, and potential bearing cost,” he said.
“Some manufacturers offer tooling that is used to do wheel-on inspections,” Boyd added, noting that they may display measurements such as remaining rotor thickness and a percentage of the remaining brake pad. Other systems incorporate visual keys for the carrier and rotor.
“The measurement process of the components is more precise for disc brakes compared to drums,” he said. Boyd lists several factors that need to be considered when working on disc brakes. Caliper adjustment testing; guide pins and boots; tappets and boots; pad
thickness from one end of the pad to the other; the condition of the inside pad compared to the outside pad; and the condition and thickness of the rotor. Like any maintenance work, it will also require a particular set of tools. Much can be accomplished with normal hand tools and leather gloves, a wheel-on inspection tool, caging tool, and torque wrench. Feeler gauges, a dial indicator and base, small inspection mirror and light, and a digital slide caliper for measuring the thickness of the rotors and pads will round out the kit. T T
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Task planning is at the forefront of success
The best garages know how to identify the workload. This practice encourages priorities, planning and the sound organization of resources, in addition to managing urgent and spontaneous breakdowns.
Identifying the workload In this garage, the foreman has an accurate picture of the tasks at hand. He knows what work is required on each truck, its complexity, the parts required and the estimated time for each of the tasks. It also makes use of a maintenance schedule with automated follow-ups.
Order by Priority When the foreman knows the workload, the next step is to organize by priority. In other words, the foreman must take the time to determine the tasks, critical as well as non-critical; all while taking into account the availability of the units, mechanics and equipment.
Estimation and Performance Once determined, set objectives and estimate the time required for each task. This identifies the requirements within the established time frame. Evidently, preparation applies to more than just jobs. It applies to mechanic availability and material resources. Preparing the required parts (“kitting”), organizing the shop and equipment, making technical references available and scheduling workers are all ways to improve shop performance.
Timely Assignment Under these conditions, the last step is to assign the work in advance to the right people and location. The mechanic(s) will have time to prepare their environment, retrieve the required parts and inform themselves about the tasks at hand.
What about you? Before you purchase a maintenance management software, it is to your advantage to understand the gains you will make by doing so. Among these gains are: the possibility of short-, medium- and long-term planning for maintenance and repairs; the ability to verify the availability of parts in addition to reserving them and the flexibility to adjust mechanics’ schedules and tasks. Lastly, your software must show you an overview of the workload and capacity of your resources for a given period of time in order to distribute tasks uniformly to avoid overload or low periods throughout the year.
Fleet maintenance management software
Work orders
Mechanic's mode
Inventory
Units
Tire management Dashboard
Warranties and claims
Planning
History
Fuel management
Wabco’s World
Supplier takes over aftermarket destiny, prepares for future
BY JOHN G. SMITH
Come discover TOTAL Heavy-Duty Rubia Optima Range
Aftermarket suppliers who wanted Wabco products have long turned to Meritor for the orders. But no longer.
As members of the industry gathered during Heavy Duty Aftermarket Week, Wabco was standing on its own, having officially ended the distribution agreement for a portfolio that included ABS technologies, stability control, advanced driver assistance systems (ADAS), air systems, and other related products. By March, the company expected to be fully responsible for distributing the products including stability control systems, hydraulic and pneumatic ABS components, OnGuard and OnLane ADAS, electronically controlled air suspension systems, air dryers and cartridges, and air compressors.
But another pending deal will transform the supplier in other ways.
A proposed merger between Wabco and ZF Friedrichshafen AG is expected to close within months. As part of that, Wabco has also entered into an agreement to sell RH Sheppard to Bendix Commercial Vehicle Systems for US $149.5 million. The decision to divest that business, which develops steering systems, comes in the wake of a U.S. Justice Department’s anti-trust review of the proposed Wabco and ZF merger, and a related settlement order approved by the U.S. District Court for the District of Columbia.
“By combining the two companies, we really bring a very, very strong potential to the industry in terms of transmission, powertrain, as well as brake systems and steering and the complete vehicle control chassis combination,” said Wabco Americas president Jon Morrison.
Other potential benefits could come in leveraging the strengths of the two global manufacturers and their respective technologies. With Wabco, for example, ZF picks up a strong presence in the trailer segment. And there’s no mistaking a commitment to maintain and grow the Wabco brand itself. “We’re able to bring the complete Wabco proposition to the market.” Morrison said. T T
TRUCK WORLD Booth # 5417
