Shift Up and Throttle Back to Save Fuel LSU AgCenter Engineer Suggests

Linda Benedict, Parish, Richard L.  |  4/19/2005 10:28:30 PM

News You Can Use For August 2004 

As fuel prices rise, tractor owners are looking for ways to reduce fuel consumption. LSU AgCenter engineer Dr. Dick Parish says that when performing light-duty operations such as mowing grass or making hay, it’s sometimes possible to reduce fuel consumption by shifting to a higher gear and reducing engine rpm.

Although tractors are often run at a high engine rpm to give the rated PTO (power take off) speed, this speed is not necessary if the PTO is not in use.

"Shifting up and throttling back can give the same ground speed while the engine works harder but at a lower rpm, thus operating more efficiently and consuming less fuel per hour or per acre," Parish says.

The engineer cautions that this process is normally not practical when using PTO implements, since the PTO shaft should turn at the rated speed of 540 rpm (or 1,000 rpm on larger tractors) for proper implement operation. Some tractors, however, have a 2-speed PTO that provides 540 rpm on the PTO at two different engine speeds.

"Using the lower engine speed to provide 540 rpm on the PTO is more efficient if you don’t need full power," Parish says. "You must avoid increasing engine speed too much while using this PTO setting to avoid overspeeding the PTO."

He adds that some current tractors have an interlock built in to prevent PTO overspeeding under this situation.

"Shifting up and throttling back is an easy way to reduce fuel consumption if you are not using the PTO or if your tractor has a 2-speed PTO," Parish says.

For related topics, look for Gardening and Get It Growing links in the Feature section of the LSU AgCenter Web site:  Additional yard and garden topics are available from an extension agent in your parish LSU AgCenter office.


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Source: Dick Parish (985) 543-4125 or

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