busride maintenance january 2015
DESCRIPTION
The exclusive maintenance resource for the transit and motorcoach industry.TRANSCRIPT
THE EXCLUSIVE MAINTENANCE RESOURCE FOR THE TRANSIT AND MOTORCOACH INDUSTRY
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BUSRIDEMAINTENANCE.COM
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Focus On: Brakes
DPF regen requires TLC p4
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2 BUSRIDE MAINTENANCE | JANUARY.2015 busridemaintenance.com
Publisher Steve Kane
Associate Publisher David Hubbard
Editor in ChiefRichard Tackett
Art DirectorStephen Gamble
Accountant Fred Valdez
VOL. 05 • NO. 1
POSTMASTER: Please send address changes to: BUSRide Maintenance Magazine
4742 North 24th Street, Suite 340Phoenix, Arizona 85016Phone: (602) 265-7600
Fax: (602) 277-7588 busridemaintenance.com
A publication of:
BUS industry SAFETY council
FROM THE EDITOR IN CHIEF
Products and Services
From the Editor in Chief
Departments
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6Focus On: Brakes A cooperative maintenance forum exploring brake design elements
DPF regen may require TLC How to safely regenerate Diesel Particulate Filters (DPF) without disruption to business By Christopher W. Ferrone
4On the cover:
Bendix: Don’t cut corners with rebuilt parts
As part of the Bendix Tech Tips series in 2014, Henry Foxx, director of remanufactured parts for Bendix, Elyria, OH, offered some tips to the public on getting the most value from remanufactured components. It’s a good time to revisit these tips:
“Selecting quality remanufactured parts begins with the right sourcing – knowing what to look for, and knowing what questions to ask the part supplier,” Foxx writes. “And among the first and most crucial things to learn is whether you’re dealing with a true parts remanufacturer or a rebuilder.”
Parts remanufacturers replace or repair the part’s components so that it once again meets OEM standards. Parts rebuilders don’t hold themselves to the same stringent standards, often only cleaning or repainting the components to sub-OEM specs.
Bendix and Foxx offer the following questions to ask of potential remanufacturing partners:• Do they replace non-salvageable or irreparable components with new?• Do they replace wear components 100 percent of the time?• What type of tests do they conduct to validate the performance of their parts?• How do they support the product through warranties and/or service needs?
Maintenance and fleet managers will do well to stay cognizant of these kinds of tips coming from OEMs. Whether they manufacture parts or vehicles, these companies have a keen business interest in educating their customers about smart buying decisions. Advice like this from Bendix and other OEMs can ensure that your garage stays stocked with performance-tested parts backed by reliable OEM post-sale support.
Find out more and read the entirety of the Bendix Tech Tips series at www.Bendix.com.
Richard TackettEditor in ChiefBUSRide Maintenance Magazine
busridemaintenance.com | BUSRIDE MAINTENANCE 3
PRODUCTS & SERVICES
Enhanced 48V Module now features DuraBlue™
Maxwell Technologies, Inc. announced an enhancement to its industry-leading 48V module product, which now includes the benefits of the company’s new DuraBlue™ Advanced Shock and Vibration Cell Technology. It combines Maxwell’s unique dry electrode formation and manufacturing process with a patent-pending cell structure design, resulting in a significant increase in vibration immunity of as much as 300 percent and in shock immunity of as much as 400 percent versus most comparable competitive offerings; exceeding the most demanding testing requirements for mass transportation applications, such as in hybrid buses.
Maxwell TechnologiesSan Diego, CA
Webasto introduces Thermo Pro heating systems
The new Thermo Pro 90 engine-off coolant heater with up to 31,000 Btu/h of heating power offers new features specially designed for specialty commercial vehicles. It features improved fan motor durability and is bio-diesel compatible.
The Thermo Pro 90 offers offer quick warm-up times, low power consumption and high product quality. The Thermo Pro 50 is capable of up to 17,000 Btu/h of heating power and is available as a standard or Heavy Duty kit. Both are available immediately, as compact kits (12V) or with enclosure box (12V and 24V).
Webasto Thermo & Comfort North AmericaFenton, MI
Stertil-Koni unveils Diamond Lift
The Diamond Lift from Stertil-Koni is a state-of-the-art high pressure telescopic piston lift. The company says it provides optimum flexibility, productivity, durability and environmental containment. It’s available in a two- or three-piston configuration, with a total lifting capacity of 32,000 pounds per piston.
The Diamond Lift features hard-chrome plated piston rods for maximum protection against corrosion, wear and debris, and electronically synchronized for maximum safety and convenience. The mechanical locking system utilizes a hardened, nitro carburized locking rod for maximum protection.
Stertil-KoniStevensville, MD
Ursa® Super Plus improves fuel economy
Chevron Products Company introduces Ursa® Super Plus EC SAE 10W-30 motor oil to the United States and Canada. The company says it helps improve fuel economy in heavy-duty diesel fleets now using SAE 15W-40 engine oil at a competitive price point.
Ursa Super Plus meets stringent API CJ-4 service category requirements which provide engine protection and improved emission control system life. Specifically formulated for 2010 compliant low-emission diesel engines with SCR and DPFs, this oil is recommended for select engine types including Cummins, Detroit and Volvo.
Chevron Products CompanySan Ramon, CA
4 BUSRIDE MAINTENANCE | JANUARY.2015 busridemaintenance.com
DPF regen may require TLCHow to safely regenerate Diesel Particulate Filters (DPF) without disruption to businessBy Christopher W. Ferrone
[EDITOR’S NOTE: This encore article originally appeared in BUSRide Maintenance, January 2011.]
Since 2007, when the first of the EPA emission standards went into effect, bus and coach operators have had to learn how to safely regenerate Diesel Particulate Filters (DPF) without disruption to business.
busridemaintenance.com | BUSRIDE MAINTENANCE 5
The process of DPF regeneration collects soot and ash produced by the engine and converts it to carbon dioxide gas. The DPF heats to a temperature in the conversion by introducing or dosing diesel fuel downstream of the turbocharger to create a furnace effect within the DPF that expels the gas out the tailpipe.
At some point a technician may need to remove the DPF and clean out the residual soot and ash using a special machine. The cost for this process can run as much as $400 plus labor.
A motorcoach that typically operates at low average speeds, such as a sightseeing bus or trolley, may not ever achieve the road speed required for automatic regeneration. In spite of the inconvenience of the DPF not regenerating automatically on public streets, the DPF still needs periodic regeneration nonetheless. Operators of any slower moving vehicle need to understand the regen process. They must know what triggers the DPF and how to regenerate it when normal operation does not automatically trigger the process.
Failure to regenerate automatically or manually can become a serious problem if the condition goes uncorrected once the dash light illuminates. The electronic control module (ECM) will kick in and derate the engine power to travel only at very low speeds, regardless of throttle position.
The idea here is to force the operator to regenerate the DPF and not ignore the problem. Left alone, this condition eventually renders the bus unusable. If stopped or slowed in a travel lane, the situation could create the potential for an accident.
Automatic and stationary regeneration
During automatic regen the system takes over and conducts the process, which the operator does not detect with the possible exception of a slightly elevated noise from the turbocharger. This is due to the VGT feature on some engines that elevates exhaust temperatures to complete the process.
The stationary process is simple, but one that requires the correct equipment and a little know-how. OEMs have provided a dash switch that activates the regen process, while the vehicle is stationary with the transmission in neutral and the parking brake applied. If the OEM has not activated the stationary regen capability within the ECM, the technician will need to attach a laptop computer with the appropriate software and manually change the stationary option from disable to enable.
During the regen process the exhaust temperature can reach as high as 1,500 degrees F, well above the auto-ignition temperature of almost all fluids and other combustibles on the vehicle.
Before initiating the process, park the vehicle away from people in a location where the heat will not damage the pavement and the surrounding area is not a fire hazard. Some OEMs have included an additional dash light that will illuminate if the exhaust temperature reaches a critical level. This indicates nothing more than the exhaust temperature and will not derate the engine power or stop the vehicle.
The most practical way to reduce the exhaust temperature is to begin driving. This is as simple as going around the block a few times at a slow rate of speed. This will wash cooler air over the DPF, creating a convective cooling effect on the turbocharger gases to reduce the DPF temperature. In some cases the diagnostic software can initiate and perform the stationary regen process.
A forced duty cycle is a second stationary regen method. This method simply puts the vehicle of slow average speed into a duty cycle that exceeds the threshold required to trigger the regen process.
One way is to drive the vehicles periodically out on the open roadway to force the DPF to regen. Typically, once the DPF light comes on, a 20-minute drive at 55 mph will force the regen process to convert the soot and ash and turn off the dash light.
Some manufacturers cite as many as four stages of DPF blockage. Once the system reaches stage four, no amount of attempts, regardless of method, will clean the DPF and the dash light will remain illuminated. The only way to put the vehicle back into service at this point is to remove the DPF for cleaning with the appropriate machinery.
The dash lights indicate the need for regen cleaning. There are typically two dash lights for the DPF system, but the check engine light doubles as an indicator that the DPF system needs a regen. Even if the DPF system senses the need but the condition is not severe, the DPF dash light will still illuminate.
When it hits severe levels and the system begins to derate the engine, the check engine light will illuminate simultaneously with the DPF light, indicating the DPF needs to regen immediately.
The process of DPF regeneration collects soot and ash produced by the engine and converts it to carbon dioxide gas. Photo courtesy of Demand Detroit.
6 BUSRIDE MAINTENANCE | JANUARY.2015 busridemaintenance.com
What constitutes good brake design?
FOCUS ON: BRAKES
With their basic function of slowing and stopping the vehicle — often in the shortest time and distance possible, who would argue that motorcoach safety begins with a fully-functioning, well-balanced brake system? A malfunctioning foundation brake compromises the vehicle’s entire operation and performance.
The challenge for motorcoach operators is selecting and maintaining braking systems that meet the safety challenges that come both from public demand and stiffening performance regulations. While new federal regulations on reduced stopping distance do not include motorcoaches, whose requirement remains 280 feet at 60 mph, a recent mandate for heavy-duty trucks has led to significant developments in braking technologies that benefit the wider commercial vehicle industry.
While operators expect performance, reliability and durability from the brakes on their coaches, without the expertise and guidance from industry professionals, the steps in achieving these factors can turn into complex equations and overwhelm.
Lessons learned from prior technologies have enabled an evolution to the modern, effective designs that have overcome the shortcomings of both drum brakes and the early offerings of air disc brakes. An advantage of air disc brakes is their passenger car-like feel, which means less fatigue for motorcoach drivers traveling long distances. The stopping distance of air disc brakes over drum brakes increases significantly as speeds surpass 60 mph. Fleets and other end-users are increasingly choosing air disc brakes over the more economical drum brakes, as the technology moves away from specialty and niche applications, emerging as a viable option for everyday use.
For operators, the optimum brake solution comes down to critical choices — foundation drum or air disc brakes — with the decision ultimately based on the unique needs of the operation
and performance. Brake manufacturers and motorcoach OEMs work together endlessly on the design of a brake package that squares those needs.
The optimum package factors in load, wheelbase, center of gravity, maximum speed and mating the correct tires with the brake system. Engineers help to size brakes, chambers and the air system.
One development is larger and more powerful drum brakes, engineered to develop the increased torque necessary for shorter stops. The brakes then sustain that torque, reducing brake fade and stopping distances. However, even with the improvements to drum brake technology, many coach operators maintain that air disc brakes provide the best available performance and safety.
Commercial vehicle brakes do not look much different than they did 30 years ago. Nonetheless, nothing compares to current day braking systems that incorporate advancements in materials, along with 21st century technologies such as Electronic Braking System (EBS) to bring a fully loaded modern motorcoach to a complete stop within the mandated distance.
Brake systems are both mechanical and electronic, with an electronic control unit (ECU) to direct the antilock brake system. Brakes will become more technically advanced as systems continue to evolve to meet increasingly stringent safety requirements.
Because of the reduced stopping distance mandate, the newest generation of brakes is more powerful than its predecessors. The brakes achieve this performance through design advancements and carefully chosen friction material. Incorrect or inferior replacement friction material can reduce performance, wear out sooner and negatively affect vehicle safety.
With this issue, BUSRide Maintenance launches Focus On: Brakes, a cooperative forum series that addresses the critical design and manufacturing elements associated with effective heavy-duty brake systems for buses and motorcoaches.
busridemaintenance.com | BUSRIDE MAINTENANCE 7
Advantages in brake design
FOCUS ON: BRAKES
The philosophy of ProTec Friction Group is that all the elements of a brake system must work together. A braking system is a holistic entity, requiring a combination of research and science with on-the-street experience in order to generate breakthrough safety and lifespan solutions.
Managers and maintenance personnel in the coach bus and municipal transit sector have always been interested in improved safety, extended mileage, and reduced road calls for brake-related service. ProTec is working to redefine “quality” in friction materials. We have recently determined that transit and coach bus friction materials currently on the market generate excessive heat.
Engineers and physicists agree that a moving vehicle requires a certain amount of counter-energy to stop. It has always been assumed that the amount of energy generated was theoretically the same irrespective of brake material.
Recently, however, we have found it is not quite true. There are various other efficiencies to be considered. Different materials follow different energy trajectories. The generation of heat at the friction material / mating member interface depends on the surface conditions of both components. Just running your hand across a piece of paper and then a sheet of sand paper will help you to understand how surface conditions affect a brake system’s useful life.
This has led us to create a new family of friction materials for the bus vehicle market that allow a cooler running brake interface, which in turn lessens lining, drum and rotor wear, while maintaining stopping distance. In addition to using more advanced synthetic and organic fiber combinations for superior reinforcing, insulating and wear life properties, we also utilize high temperature lubricants. Finally, we compression mold at significantly higher pressures than all other brake manufacturers in order to achieve unparalleled friction contact with drums and rotors.
This strengthened hyper-compacted surface structure spreads heat energy/thermal loading more evenly across the lining surface. The result is that the friction runs dramatically cooler. More uniform contact makes both the friction material and the mating member last longer by reducing the tendency of a lining to develop and spread “hot spots” which lead to premature brake wear.
Our tests show that our most advanced friction pads will virtually eliminate brake rotor wear. Field trials are currently underway in order to precisely quantify and document this effect.
The ProTec claims regarding brake rotor life are pretty serious – serious because rotors are both expensive to buy and expensive
to install. It is also serious because a worn and / or grooved rotor negatively affects braking quality and precipitates early pad wear out, noise and caliper damage.
The downside of rotor wear is certainly a reason to evaluate another option and ProTec has that option. We invite you to track rotor wear in your fleet and prove our claim for yourselves. What we do in our test vehicle program is to observe regularly, through the wheel slots, the rotor face condition. The pads keep the rotor at a lightly burnished state free from grooving and scoring. At regular intervals the wheels are removed and the rotors measured.
By cleaning off a spot on the outer edge of the rotor (just beyond the pad contact area) with a scouring pad or crocus cloth, the new rotor thickness is exposed. We measure that
thickness slipping a micrometer or caliper in beside the caliper. By sliding the instrument a little toward the center of the rotor we pick up the wearing surface thickness. The difference, of course, is the wear the rotor has experienced. Using this method ,it is easy also to track a system using conventional components and establish your own baseline. Nothing drives home a product improvement like evaluating it in your own application.
In addition to the harvest of significantly lower lifecycle costs, there exists a positive “green effect” from the reduced consumption of cast iron drums and rotors which waste huge amounts of energy to extract the iron ore, manufacture, transport and replace. Our more advanced pads eliminate brake dust completely and absorbs all noise such that no shim, chamfer or other noise suppression hardware is needed.
If you are still reading this article:A. You probably own, operate or manage a motorcoach fleet or
public transit authority.B. Accordingly, you have an interest in safely and cost-effectively
extending brake system life.C. You’re scratching your head and wondering if the author
is just fantasizing about dramatic improvements in brake performance, or in touch with the future of bus brake systems.
For more information, contact ProTec Friction Group at 914-244-3600 or visit their website: www.protecfriction.com.
Jerry Thompson is the director of Engineering Services at ProTec Friction Group where he oversees the departments responsible for research & development, application engineering and technical consulting. This follows a successful technical career General Motor and Raybestos. Now a member of the exclusive Road Racing Drivers Club and the Corvette Hall of Fame, Jerry is an active racer and avid ambassador for the sport.
By Jerry Thompson
ProTec brakes are constructed with fibrillated aramid fibers in a branched structure that creates millions of microscopic air pockets which absorb significant heat and cool the friction interface.
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