Engines built to meet 2002 emission standards produce cleaner exhaust than ever, but technology such as Exhaust Gas Recirculation systems has come at the cost of higher under-hood temperatures that are deforming hoses and cooking components ranging from alternators to belt tensioners.
To make matters worse, the next generation of engines to be introduced in 2007 will include particulate traps that need to run as hot as a whopping 400 Fahrenheit as part of their regeneration process.
The higher temperatures have presented challenges for engineers and fleets alike, speakers said during a recent Technology and Maintenance Council meeting.
Some hoses were never designed to handle the higher heats, says Rod Ward of FlexFab, noting how many spec’s were designed before the latest generation of engines were ever a reality. A typical AC hose can withstand temperatures up to 257 F, but coolant temperatures have been found to exceed 200 F under typical operating conditions.
Firewalls on the turbo side of the engine alone are reaching 250o F.
For now, fleets and owner/operators need to be careful to select replacement hoses that offer added strength, he said. Some high-pressure fuel and AC hoses, for example, are reinforced with wire braid, and hoses of any sort should also be changed if they become soft and gummy or deformed.
“Hoses near hot exhaust pipes must be shielded or insulated and tethered in position,” Ward adds.
Meanwhile, power steering systems can fail if temperatures reach a constant of 106 F, says Richard Petrut of RH Sheppard. “Seals have a tolerance temperature of 235 degrees, and they’re not forgiving.”
If designs are failing from exposure to heat, solutions can involve ordering bigger reservoirs or power steering oil coolers (when there’s room to install them), or lengthening power steering lines. And all 45- and 90-degree bends in the lines should also be removed, he says. “Every time the fluid turns a corner, the temperature goes up.”
Off-the-shelf cooling fan bearings with synthetic grease can withstand temperatures of up to 250 F, but sustained temperatures of up to 270 F are not unheard of, adds Jim Leclaire, manager of field service and warranty for Horton, a maker of front end accessory drives. “We’ve run over 300.
“The bearing is not going to live. The O rings are not going to live,” he says of the excessive temperatures. “What’s been standard components in the past won’t work today.”
Even alternator designs have needed to evolve to handle the higher temperatures, says Randy Andis, director of fleet operations with Remy Inc. (formerly Delco Remy). Bearings are being protected by improved grease and seals, rectifiers have been refined to better dissipate heat, wires are protected by new coatings, and internal insulators have been improved.
Prior to 2002, the temperatures of an alternator’s inlet air exceeded 165F 9% of the time, but since then those temperatures are seen 58% of the time, Andis says of the changing environment. And that means it’s particularly important to ensure aftermarket replacement parts are up for the job. Late-model designs, for example, include additional vents.
To make matters worse, emission-related equipment is taking up valuable space under the hood, limiting the flow of air around the engine.
“Hood designs are valuable for aerodynamics … but not so much for [the supply of] underhood air,” says Vince Ursini, of Behr America, a maker of cooling systems.
“It’s getting crowded in there,” admits Petrut, referring to the 80 cubic feet of space that exists under a typical hood.
Several U.S. fleets have responded with their own makeshift refinements to hood designs. Some have removed spash shields behind the front tire, and others have cut holes into hoods.
“Small changes to panels and body work can reduce heat dramatically,” Leclaire admits. But random holes aren’t going to help, he adds, referring to one fleet that added side vents only to find that they were driving more air under the hood instead of letting heat escape.
“Noise regulations and increased cab noise are concerns as you open up these areas,” Ursini adds.
Some problems can be solved through pre-trip inspections looking for damaged hoses or low fluid levels, and fleets should pay close attention to driver complaints about such things as lost air conditioning, Leclaire says.
“If we don’t fix this, we’re not going to be able to handle ’07.
“But we can be cool again.”
Measuring apples and oranges
Comparing the fuel economy of different engines?
The process may be more involved than you think
Comparisons of the fuel economy enjoyed by different engines can involve more than downloading reports from Electronic Control Modules (ECM), particularly since each manufacturer tracks related figures in a different way, speakers said during a recent Technology and Maintenance Council conference.
Herman Miller, fleet equipment manager for Shopko Stores, refers to his own ECM reports that suggested one truck’s fuel economy was 6.9 per cent better than it was in reality, and another model’s fuel economy was five per cent worse.
“You might not drive the right conclusion because that’s a 10, 11, 12-point spread,” he says of the figures that could encourage a fleet to choose one piece of equipment over another. “And using the ECM gallonage [tends to be] friendly to the engine manufacturer.”
At the very least, fleets need to be consistent in the approaches they use when comparing fuel economy, speakers said. And the work could begin with an understanding of the way each ECM tracks fuel-related figures.
Where one ECM will begin counting idle time after five minutes, another will count idle time after 15 seconds, said Caterpillar’s Bob Wessels. And the idling percentage can be calculated by dividing idle time by the truck’s running time or the engine’s entire running time.
The simple count of consumed fuel can vary five per cent between different engine designs, he adds, noting that numbers can be plus or minus 0.1 kilometres per litre at the best of times.
Even counting the number of tire revolutions per kilometer can lead to a variable of plus or minus two per cent, because the diameter of a tire will wear down with use. (Some fleets set their ECMs to recognize a tire size that’s half way between a new tread depth and the point at which the tire is pulled for re-treading.)
“There are lots of variables to input correctly,” Wessels says, adding that a count of pump strokes and the number of kilometers recorded by a map will offer the best comparison.
“In the good old days, two-truck tests probably got the right answer,” adds Chuck Blake of Detroit Diesel. But that could be a source of trouble with some of today’s designs. Some engines will improve fuel economy when they warm up, while others are better at slower speeds.
He recommends the Technology and Maintenance Council’s Type 4 test (Recommended Practice 1109-7) that requires test trucks to warm up for an hour, travel a minimum of 240 km and consume 114 litres of fuel. To remove the variables that can involve driving habits, two tractor-trailers chase each other until the test route’s half-way point, where trailers are switched and drivers change tractors.
“Repeatability with different vehicles is important,” Blake says. “Your first test is an indicator. Your second test is looking at a trend.”
Cruise controls should also be used to ensure speeds are constant.
“We like to see the same person taking the temperature reading [of fuel] at the same point in the tank,” he adds.
Another important step is to shut off fuel crossover lines when conducting tests, to ensure the supply of diesel is coming from a single source.
In fact, there’s an argument for considering figures from a variety of sources, speakers said.
Shopko, for example, compares driver trip sheets that record fuel purchases and distances against reports generated by fuel island computers.
FedEx drivers enter employee numbers, unit numbers and mileage at fuel islands before every fill up, says Dan Umphress, managing director of maintenance solutions at the LTL operation, which includes 10,000 tractors consuming 442,000 gallons of fuel per day. And that fleet’s system was also programmed to ensure the entered mileage can’t be lower than the last entry for the truck.
The data feeds fuel economy reports that can compare performance on a daily, weekly, monthly and an annual basis, as well as for the life of the vehicle.
“You can reach a point you drive yourself nuts,” Wessels admits, referring to the array of variables outside an operator’s control. “The only approach I know to correct that is to run enough data [at least six months’ worth].
“If you don’t have a lot of information on a lot of routes and a lot of weather conditions, you’re at a real risk.”
The future of fuel pricing remains uncertain: ChevronTexaco president
Are you bemoaning the price of diesel at the pump? Don’t expect much relief in the near future.
Factors ranging from political instability to a high demand for fuel are adding to the pressures that affect diesel prices, ChevronTexaco Global Lubricants president Mark Nelson told members of the Technology and Maintenance Council last month.
“We have been through and maybe endured 2004,” he said during his keynote address. “But the forecast is hazy. “It’s not easy to predict if or when the growth [in demand] and pricing will moderate.”
While the price of fuel at the rack was on the rise last year, it also marked the largest single-year growth in demand since 1978, he said. Initial figures suggest the U.S. required 85 million barrels of oil per day – a decade ahead of levels that were expected in a “doom and gloom” forecast.
Prices will likely remain high in the short term because of a strong demand for diesel, particularly in light of increasing freight volumes, he added.
Still, the good news is that the transition to Ultra Low Sulfur Diesel (ULSD) is going according to plan. About 95 per cent of all on-highway fuel in the U.S. will contain a mere 15 parts per million of sulfur by next June, he said. And that’s seen as a key to the introduction of particulate filters that will come in the next generation of diesel engines.
The move to ULSD is “the most challenging transition for fuel suppliers since unleaded gasoline,” Nelson added, noting that the fuel requires as much attention as aviation fuel. If a supply of traditional diesel enters the system, the benefits are lost.
The high injection pressures and closer tolerances in today’s engines make the fuel systems similar to hydraulic systems, he said. “Fuel cleanliness and filtration is absolutely crucial to moving forward.”
The next generation of oils, known as PC-10, will also be compatible with older engines, he added, noting that the new standards can also be met with mineral base stocks instead of synthetic formulas.
Combined with low-sulfur diesel, he suggested it could actually extend today’s drain intervals.
“[But] it’s less clear what the price on the street will be.”
Research with a bang
Why TMC is blowing up the evidence of zipper failures
Don’t be alarmed if you hear loud bangs ringing from the hills of Pennsylvania this spring.
The Technology and Maintenance Council (TMC) is attempting to determine how tires should be tested for potential “zipper failures” that are typically linked to damage caused by low inflation levels. And the group will be blowing up weak tires at the Alcoa Wheel Service Centre to gather the data needed to set new installation standards.
“It [the sidewall] gets so weak, when the tire is inflated again … it will blow out, and the blow-out looks just like a zipper,” tire expert Peggy Fischer says, explaining the failures.
To ensure under-inflated tires can be put back into service, the Rubber Manufacturers Association and TMC have recommended over-inflating questionable tires by 20 psi and holding the pressures for 20 minutes. After surveying TMC members, however, they found that few fleets actually followed the practice.
“The only use this [Recommended Practice] 232 has is really for lawyers to use in a courtroom when a tire has blown out and somebody has been injured,” Fischer says. “It’s an arbitrary thing. It came out of somebody’s ear… there’s no data to support it.”
Compounding matters is the fact that it isn’t practical to follow the process in a shop that mounts and demounts 100 tires a day.
Keep it between the lines
Early lane departure systems proving their worth
The parting wish of “keep it between the lines” has been shared by generations of truckers, but a new generation of lane departure warning systems could eventually make the saying redundant.
Several U.S. fleets have reported initial success with systems made by companies including California-based Iteris, which use video cameras and software to track the outer edges of a lane.
The systems are able to track solid and dashed lines, as well as the shoulder of the road or tracks in the snow, says Richard Bishop, a consultant who focuses on intelligent vehicle systems.
“It’s essentially what we do with our eyes and our brain when we’re driving … but the driver always keeps control. This is a warning-only system.”
Drivers can be warned with everything from the simulated sound of a rumble strip (the most common) to a beep or vibrating seat.
“They do exactly what they told us they would do,” says John Serich, corporate director of maintenance for Falcon Transport, a flatbed and truckload van carrier in Youngstown, Ohio that is testing the equipment in 13 trucks.
The systems aren’t perfect, but false alarms appear to be few and far between.
“The only issue our test fleet brought forward was audible activity in construction zones and wet weather conditions,” said Mike Jeffress of Arkansas-based Maverick Transportation, which has been testing 200 of the units over the past year. While drivers have the chance to override the systems in these areas, they tend to become accustomed to the warnings.
“It is not all rumble-free, let us say, but we’ve had very little feedback so far,” he says. “It’s pretty much a maintenance-free item the best we can see.”
Tom Rule, vice-president of operations at Logex Transportation, which has systems installed in 117 trucks, says there tend to be no more than one or two false alarms per day. Some of the only changes his fleet has required have involved the addition of resistors that limit the sound of the warning heard by drivers in the bunk, and altered software that can reset systems that have been turned off for 15 minutes at a time.
In general, the systems need to automatically shut off when signals vehicle speeds drop below 55 km-h, because lane markings in parking lots don’t tend to be very clear.
However, fleets involved in the tests complain that the systems could offer better reports about such things as the number of times a truck leaves its lane in a fixed period of time.
Typically, the equipment can be installed in three to five hours, Serich says, but he suggests it also needs to be designed for a quick switch from one truck to another.
Supporters of the systems say the equipment could play a key role in reducing single-truck accidents.
The U.S. records one rollover for every 1.6 million km of truck travel, Rule says. “Fifty-eight per cent of fatal injuries to the truck driver occur in rollover crashes … every accident that I’ve had to investigate, I usually find a driver who has been fatigued.”
Back in 1996, the Federal Motor Carrier Safety Administration announced that it wanted to cut the number of truck related deaths in half within 10 years, although that goal has since been updated to a 41% reduction within 12 years.
Legislators could eventually mandate the equipment, much like the way they forced the industry to use everything from seat belts to collapsible steering wheels, Rule adds.
“For us to get to the point we all want to be, we’re going to have to find out how we can use these technologies to drive down these accidents.”