Aug 9, 2010 by Scott Garvey

Shut it down

“Roger, go with throttle up” is one of the most memorable statements heard in recent history. Those words were spoken by the space shuttle Challenger’s commander just moments before it exploded. For producers, a variation on that phrase, “Go with throttle down” sums up what engineers have bee encouraging them to do.

Run equipment at low throttle paired with the fastest gear is the mantra we’ve all been hearing. It allows farmers to maximize a machine’s efficiency and minimize fuel consumption. But are we really listening? Many seem to be a little blasé about how much fuel they use. 

Maybe because a farm’s annual fuel bill now pales in comparison to other seasonal inputs, such as GM seed and fertilizer, at least some producers aren’t paying as much attention to it anymore. 

Case in point: on a warm spring evening my wife and I decided to take a trip to the local Dairy Queen for ice cream. As we pulled into the lot, a Cummins-powered Dodge pick up, its box filled with tools and, of course, a slip tank was idling in the parking lot. There was no one around it.

After finishing our cones and coming back out, about 20 minutes later, the Dodge was still chugging away by itself. Why would anyone let an engine idle for that long?

Engineers and engine specialists all agree five minutes of idle time before shutting down is ample for turbos to cool, even after working an engine hard.  Running engines longer is a waste of fuel.

To prevent damage from low oil pressure at idle, many over-the-road trucks are equipped with automatic shut down systems that prevent prolonged idling periods. Owners manuals for most new tractors suggest long idle periods should be avoided. They usually advise setting the throttle at no less than 1,200 RPM if the engine will run for any length of time at low speed.

Even John Deere’s engineers have noticed the excessive-idling trend. In a survey done by extracting data from the diagnostic feature built into Deere engine control modules, they noticed a remarkable statistic. Roughly 30 percent of all the time logged on field tractors was due to idling. 

Deere’s marketing people have no explanation for the reason behind it, and –not surprisingly–they suggest farmers need to get out of the idling habit. Aside from bumping up the fuel bill, it contributes to logging excess engine hours that could reduce a machine’s eventual resale value.

So it’s clear, extended idling is wrong on many levels, yet it remains a common practise for many. Knock 10 percent or more off your annual fuel bill by reducing idle times and how much money would that save you?

As for carrying all that equipment around in the back of your pick up, it’s costing you money, too. A real-world test done by one of the popular automotive television shows revealed reducing the weight of a four-wheel drive pick up by just 362 pounds improved mileage by 0.9 miles per gallon. How much does a slip tank filled with 75 or 100 gallons of fuel weigh?

Unless, like the owner of the Doge parked in the Dairy Queen lot, you’re happy with zero miles per gallon, taking a look at your current driving practices, both on the road and in the field, could pay dividends. Even if it’s just enough to buy an ice cream sundae, it’s worth it.

Scott Garvey

Scott Garvey


Grainews' machinery editor Scott Garvey follows trends and innovation in equipment technology, takes a look at new farm machinery offerings, tracks their performance and goes into the workshop to find better ways to keep them up and running.


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