IDLE THOUGHTS: Reducing idle time by 25% (shutting down while unloading) can result in a mile per gallon improvement of 2-4%, say Caterpillar officials.
FERGUS, Ont. – If you’re a 5.5 mile per gallon driver, a few adjustments to your driving habits could result in a pay hike of more than US$18,000 per year (based on diesel prices of US$3/gallon).
That’s the message Phil Hook, senior specialist, truck operations, On-Highway Engine Department with Caterpillar, delivered at a seminar on fuel efficient driving at the Fergus Truck Show.
Hook pointed out that a 7.5 mpg driver will earn 14 cents per mile more than a driver operating the same equipment at 5.5 mpg. And achieving 7.5 mpg on a well-spec’d truck is achievable, he added.
“A lot of times, there’s not nearly that much profit in the freight you’re hauling so it’s the difference between staying in business or going broke,” he said. “A lot of companies can’t afford a certain driver because he can’t get the fuel mileage and it’s costing them money.”
Hook knows a thing or two about getting the best fuel mileage out of his engine. He won a national award for fuel consumption in 1981 and was soon recruited by Cat to help educate drivers on how to do drive more fuel efficiently.
“I’m not an engineer, I’m not a mechanic – I’m a truck driver,” stressed Hook. “I haven’t learned a lot of things in my life but I guess I learned a lot about driving a truck. I’ve preached the Gospel to thousands of drivers. They don’t all listen, but those that do come back years later and say ‘Thank God I talked to you.'”
According to Hook, there are four controllable factors that affect fuel mileage: Driving speed; shifting habits; idle time; and the use of cruise control.
“The simplest thing you can do to improve fuel mileage is just slow down a little bit,” suggested Hook. “It wasn’t easy for me to slow down but when I saw what it was costing me in fuel, that was a good incentive.”
While it’s always tempting to get in the left lane and be the first to the top of the hill, Hook said drivers need to think like businessmen.
He said a 10 mph increase in speed requires an extra 95 horsepower from the engine.
“The only way to do that is to put your foot into it,” he said. “Speed effects the fuel mileage more than anything and its just laws of physics that you can’t do anything about. If I go out and run, I lose more weight than when I walk.”
Cat says fuel economy drops by 0.10 mpg for every 1 mph the vehicle is driven over 55.
Progressive shifting is a driving technique that requires the driver to upshift as early as possible when working their way through the gears. Cat recommends upshifting at around 1,100-1,300 RPM in lower gears and 1,400-1,500 in the upper gears.
“Years ago, we couldn’t do that,” said Hook. “We used to preach high RPM, but all of today’s engines are high torque and you get that at the lower RPMs. You don’t have to wind them up like you used to.”
Hook explained there are two reasons why it’s important to upshift as soon as possible.
Firstly, the engine spins easier at lower RPMs. The further you wind it up, the more power it takes to pump the oil and fuel through the engine, turn the crankshaft and slide the pistons up and down. At lower RPMs, it takes less energy to do those things and more of the power the engine is creating can be used to move the trailer, Hook said.
Secondly, all transmissions shift on a percentage of the engine RPM. When you’re shifting at 2,000 RPM the transmission spends more time in neutral before it can be shifted into gear. While the 35% drop in RPM that’s required to make the shift remains constant whether it be 1,000 or 2,000 RPM, a 700 RPM drop is required at 2,000 RPM compared to a mere 350 RPM drop at 1,000 RPM.
“In each gear, you need just a little more power,” explained Hook. The trick is, don’t take it any higher than you have to and then you spend less time in neutral and you spend a higher percentage of your time under power rather than in neutral waiting for the RPM to fall.”
Shut it down
Caterpillar recommends shutting down the truck if it will be parked for more than five minutes. Reducing idling time from 50% to 25% will result in a mpg improvement of 2-4%, the company says.
Hook said some drivers sacrifice an entire mile per gallon due to idling when considering many idle an hour for lunch, an hour for dinner, two hours for loading/unloading and six hours while sleeping.
“If you work at it and only run it when you have to to stay warm or cool, you can get it down 30%,” insisted Hook.
Not only is excessive idling bad for fuel mileage, but it also causes the engine to wear out quicker – about 20% quicker when excessively idled, Hook reminded attendees.
He said one hour of idling causes as much wear on the engine as two hours of driving. He also said today’s truck engines don’t require long warm-up or cool down periods.
Cruising for profits
Hook also suggested drivers use cruise control whenever possible. Doing so helps maintain average speed and good fuel economy. Cruise control applies a more gradual power-on/power-off, improving fuel mileage by 1-2%.
Hook also had a few words of advice for fleet managers who may want to measure their drivers’ fuel mileage and provide incentives for top performers. Simply measuring their miles per gallon isn’t fair or accurate, he said.
The driver has no control over three variables that significantly impact fuel mileage: the weight of the load; the types of highways they’re driving; and the weather (cold air is thicker and more difficult to push through, Hook noted).
Electronics found on today’s engines can measure five factors the driver does control, including: average engine speed; average driving speed (which should only be measured when over 50 mph); what the driver is doing when his foot is on the throttle; the driver’s shifting points; and idle time.
“Companies should set targets for those five things and measure what the driver does against each target,” suggested Hook. “(The data) can be downloaded once a month. The information is automatically available on all our engines and it’s up to the fleet whether they want to use it.”
Finally, Hook advised customers to ensure their engine is properly spec’d for the application.
“We don’t want people turning 1,700-1,800 RPM at road speed,” he said, noting an engine will get a extra mile per gallon when operating at 1,200-1,300 RPM compared to the 1,400-1,900 range.
In closing, Hook urged drivers to “Get as good as you can at progressive shifting. Learn to take advantage of how far down you can lug the engine. Just because you’ve been driving a long time doesn’t mean you can’t learn. Challenge yourself, compete with your buddies and it becomes fun.”