Leave it to a discount retailer to focus on saving money. Wal-Mart recently announced that, within a decade, it wants its trucks to average 13 mpg (5.53 km/l) rather than the current 6.5 mpg (2.76 km/...
Leave it to a discount retailer to focus on saving money. Wal-Mart recently announced that, within a decade, it wants its trucks to average 13 mpg (5.53 km/l) rather than the current 6.5 mpg (2.76 km/l).
The goal may be more attainable than it appears, suggests Robert Braswell of the Technology and Maintenance Council (TMC). After all, his group announced in 1993 that it wanted to see the industry’s average fuel economy doubled to 10 mpg (4.25 km/l) by 2003.
Engine manufacturers suggest that equipment built to meet 2007 standards will match today’s fuel use, but how can fleets improve upon these results?
A panel of experts at TMC’s recent Toronto meeting offered the following advice:
LOWER THE SPEEDS: As a general rule of thumb, each mile-per-hour (1.6 km-h) increase in highway speed will lead to a 2.2% drop in fuel economy – an average loss of 0.14 mpg (.06 km/l) on a tandem-tandem configuration.
“This still holds true, even with the newer engines,” Braswell says. “The driver is probably the biggest investment you can make to improve fuel economy.”
Indeed, good drivers can be up to 35% more fuel efficient than their untrained counterparts, according to TMC studies.
But speeds limited with electronic control modules also need to be properly programmed, Caterpillar’s Derec Yakel says, referring to how the Ontario Provincial Police once complained about speeding buses that were equipped with programmed engines.
Drivers were simply dropping back a gear for the added pedal power.
SUPPORT INCENTIVES: Any incentive will fail without management support, Braswell says, adding that monthly payouts tend to be the “tipping point” between successful programs and those that fail.
Benchmarks also need to be reasonable, so drivers feel they can be attained.
LIGHTEN THE LOADS: There are several spec’ing decisions that can shed weight from a commercial truck. A TMC study found that composite springs could save up to 800 lb., the use of under-frame exhausts could shed 90 lb., and up to 400 lb. could be saved by choosing lighter wheels.
CONTROL THE FLOW: Aerodynamic devices can have wide-ranging effects on fuel economy. An air dam front bumper can improve mileage by up to three per cent, side skirts can save another three per cent, and reducing a trailer gap to 25 inches from 45 inches can improve fuel economy by two per cent.
Still, these devices can come at a cost. Skirts and air dams may restrict the flow of air that will cool transmissions and brakes, while reefers may need to work hard to compensate for warm air that’s trapped in a narrow trailer gap, Braswell says.
Technicians often fail to replace splashguards that are removed during engine maintenance, adds Volvo Trucks Canada’s service marketing manager Donald Coldwell.
“But they’re in place for a reason.”
USE THE CRUISE: The regular use of cruise control can improve fuel economy by up to six per cent – but drivers still need to be encouraged to use it. The secret, says Coldwell, is to set an engine’s road speed about 3 mph (4.8 km-h) faster than the top speed that can be accessed with the cruise control.
Any faster, and drivers will choose to stick with the pedal, he adds.
REST THE FAN: Many drivers are switching on their manual fan switches too early when operating the post-2002 engines that run naturally hotter than their counterparts, says Lucas Redpath of Cummins.
That will sap fuel economy in the process.
LUG IT LOWER: Drivers also need to understand that newer engines don’t need to be revved as high as they were in the past.
“You can lug them down to 1,000 rpm,” Yakel says, referring to advancements involving series turbochargers, variable valve actuation and advanced timing.
And don’t forget progressive shifting. The engine shouldn’t be spinning at 1,800 rpm when the truck is in 18th gear.
Train drivers to complete shifts as soon as they have just enough engine speed to reach the next available gear.
PUMP IT UP: Ribbed tires tend to be more efficient than lugged designs, but the traction needs for a Canadian climate will probably dictate tread patterns.
The biggest impact on fuel-related improvements will relate to proper air pressure and alignment programs, says Goodyear’s Al Cohn.
If you are changing a tire size, meanwhile, also be sure to re-program the engine’s electronic control module to compensate in the change to pulses per kilometer. Otherwise, your fuel-economy data will be skewed.
MAINTAIN THE MAINTENANCE: Regular maintenance in the form of valve adjustments and tune-ups can also make a difference in fuel economy, adds Coldwell. So can checking for air leaks, which will force compressors to work longer and harder.
DON’T BE IDLE: Today’s engines need no more than five minutes at start-up and shutdown, Redpath reminded those attending the conference. These may be small steps, but they can collectively make a large difference in profit margins.
Cleaner engines face maintenance challenges
Engines built to meet tighter emission standards are still more prone to breakdowns than their predecessors, speakers suggested during a recent Technology and Maintenance Council meeting in Toronto.
While Penske Truck Leasing found that 2001 engines could be maintained at a cost of as little as .002 cents per mile in the first 120 days of operation, those fees jumped to .012 to maintain 2003 model year equipment, says Ken McKibbon, senior vice-president of field maintenance.
Even though 2004 engines could be maintained for .006 per mile, the difference was still significant.
“Any time we run a mil a mile or more, that’s $100. If we’ve got 66,000 trucks, that’s $6.6 million,” McKibbon adds, referring to various equipment challenges. “We had more charge air cooler problems this year than we ever did before.”
“There’s a world of difference between ‘pre’ and ‘post’ tractors,” agreed Duke Drinkard, vice-president of maintenance for Southeastern Freight Lines, referring to equipment built before and after 2002.
In fact, the 16.3% increase in fuel used in the first 50,000 miles (80,500 km) of a 2002 engine’s life – 497 US gallons (1,881 litres) per tractor every month – actually led the company to toy with the idea of bypassing the systems.
“We had to go out and find almost US $5,325,000 in freight just to break even on the fuel,” he said of the fleet that traditionally operates with a 0.90 operating ratio.
Various under-hood components were also more likely to fail on the late-model engine designs, Drinkard suggested.
Compared to their counterparts, the first 120-truck fleet of post-2002 engines required 12 times as many water pumps, almost three times as many injector assemblies, more than double the number of exhaust flex pipe repairs, and recorded several failures relating to emission-specific equipment. The fleet also experienced 12 times as many surge tank failures, and almost five times as many dip sticks – both of which are simple repairs, but result in costly downtime.
Costs weren’t limited to repairs, either. The fleet attributes US $139,635 in additional rental fees to the problems.
“Combustion components, piston rings and liners, are showing increased wear,” adds Ken Claar, program manager at Lubrizol Corp., referring to oil analyses that show increases in iron (wearing cylinder liners and valvetrains), chromium (damaged piston ring plating), and aluminum (worn piston skirt bearings).
But a slight drop in lead could indicate that new oils are better able to protect bearings, while controlled soot levels could be linked to the better mapping of engine control modules, and the set-up of Exhaust Gas Recirculation rates, he adds.
Even at 300,000 miles (483,000 km), “the report card is almost incomplete,” admits Carl Kirk, executive director of the Technology and Maintenance Council. “We won’t know the full performance of these engines until a few years out.”
Is there enough air back there?
It sounds like one of the math problems that kids bring home from school: A tandem-tandem tractor-trailer with a GVW of 80,000 lb. travels 10 kilometres down a six per cent grade, as the driver snubs the brakes every 10 seconds. Assuming the truck has no retarder, and each snub requires 20 to 30 psi of air, how much air does the compressor need to deliver?
Before you reach for the calculator, a U.S. study already came up with the answer – each axle will require one cubic foot of air per minute. But what about the added draw of suspension systems, lift axles, tire inflation systems, and air-powered slider systems?
Challenges such as these have led the Ontario Trucking Association (OTA) and Canadian Transportation Equipment Association (CTEA) to lobby for a way to rate tractors for the trailer configurations they’re designed to haul.
“We want every tractor to come with an air delivery rating,” says Rolf Vanderzwaag, OTA’s manager of maintenance and technical issues. “Ultimately, we want to know if this is a good match or isn’t it?”
Tractor’s spec’d to haul lightly loaded tandem trailers, for example, could be a poor match for a multi-axle trailer loaded with garbage.
While such a rating would go above and beyond the federally mandated CMVSS 121 rules that govern the design of brake systems, the groups have already played a key role in adding equipment to Ontario’s SPIF trailer designs.
The province’s new five- and six-axle configurations include split air systems to ensure that leak-related failures can’t interfere with the brakes on more than three axles. There is also a red LED located by side marker lamps to warn drivers if air pressure for the service brakes drops below 70 psi.
The next focus is to ensure that trailers can’t be “starved” of the air that they need, Vanderzwaag adds. That involves asking three questions about every combination: Do the compressor and dryer produce enough quality air? Can the air be delivered from the tractor fast enough? And how much air does the trailer actually need?
The answers will also involve more than an analysis of a compressor’s physical size. Calculations involving bore, stroke and cycles may give a unit its rating of 16.5 cfm, but it will only produce six to 10 cfm of air under normal operating conditions, and 13 cfm at a maximum of 2,300 rpm.
“During the build-up, the volume coming out of the compressor cannot exceed the air dryer capacity,” Vanderzwaag adds. “During the purge, the dryer needs enough time to recharge the desiccant.”
Indeed, the added moisture can be as problematic as the lack of air.
“Moisture aggravates particulate contamination,” says Ed Tschirhart of the CTEA, referring to the resulting “muddy sludge” that can slow the movement of valves.
Vanderzwaag suggests that a four-axle trailer should have two air dryers running in parallel, or a model with a continuous flow.
And while many contaminants can be captured by the 0.013-inch gladhand screens mandated in SPIF trailers, additional filters can be added to protect ABS valves from smaller particles, Vanderzwaag says.
What can be smaller than that? Think of the desiccant from an air dryer.
Pay the price for added safety: FMCSA
The U.S. Federal Motor Vehicle Safety Administration suggests safety has a price – and it comes in the form of available technology that could dramatically reduce the number of collisions involving trucks.
Lane departure systems could reduce crashes and rollovers by 20% , while roll stability control systems could eliminate 53% of the rollovers that occur in curves, says Amy Houser of the FMVSA’s Office of Research and Analysis. Meanwhile, Collision Warning Systems that use adaptive cruise control to maintain 2-1/2-second following distances could reduce rear-end collisions by 20%.
“They don’t replace good driver judgment,” she says of the technologies. But they can make a difference.
While such equipment will all add to the purchase price of a truck, there are ways to justify the expense, says Karl Kerstetter, manager of fleet maintenance for Linde Gas, which has installed Vehicle Stability Systems that control traction and brake applications.
Even though the Compressed Gas Association suggests that 25% of its members’ accidents involve backing up, these crashes cost an average of about US $300 each. It’s the 2% of crashes involving rollovers that have an average cost of US $148,000.
But what safety systems will have the biggest impact? Drivers have offered some insight through a recent American Transportation Research Institute study that graded several “fatigue management” solutions designed to keep trucks between the lines.
Among the systems that were tested by Challenger Motor Freight and Con-Way drivers were:
* SafeTRAC Lane Tracking (Applied Perception and AssistWear Technology) – This system offers a warning if a truck begins to veer across the lines on the road, and 61% of drivers said it made them more attentive.
* SleepWatch (Precision Control Design) – These watch-like devices that track a user’s level of fatigue were originally designed for the U.S. Army. While drivers said SleepWatch offered useful information on any “sleep debt” they were accumulating, 66% suggested it wasn’t comfortable to wear.
* CoPilot (Perclos) – The system that keeps a close eye on a driver’s drooping eyelids found the least amount of acceptance. Only 16% of those at the wheel said it made them feel safer; 37% actually found the dash-mounted equipment to be distracting.
* Howard Power Center Steering System (River City Products) – Seventy-nine per cent of drivers said this equipment was able to reduce driving-related fatigue, while 76% found it particularly helpful when battling crosswinds. In terms of fatigue management, 61% said it removed stress from their arms and shoulders.
* Alertness and fatigue management courses – Never underestimate the value of driver education. About 94% said they used the lessons that were delivered.