Recent test results show fully automatic Allison transmissions, along with a vehicle spec that is appropriate for the particular duty cycle, can provide superior fuel efficiency and optimum fuel economy.

According to Lou Gilbert, Director, North American Marketing, Allison Transmission, “a truck’s duty cycle can be broken into four components: acceleration, cruise speeds, deceleration and idle. Of these, acceleration and cruising are the main factors impacting fuel consumption.”

During acceleration, an Allison Automatic provides smooth, seamless full-power shifts to put engine power to the ground in the most fuel-efficient way. Manual and automated manual transmissions interrupt engine power every time a shift is made. According to Gilbert, recent data log analysis of two North American P&D fleets shows an average of over 600 upshifts during an eight-hour timeframe.

“Any interruption in engine power during a shift creates powertrain inefficiencies, loss of vehicle energy, lower average speeds and, ultimately, less work is accomplished with the fuel consumed,” according to Steve Spurlin, Executive Director, 3000/4000 Series Transmissions and Application Engineering, Allison Transmission. Adds Gilbert, “With full-power shifts, fleet managers will recognize higher average speeds versus manual or automated manual transmissions. Higher average speeds over a day mean the Allison Automatic accomplishes more work for the fuel utilized. So it is more fuel efficient."

This is in line with how the U.S. Environmental Protection Agency (EPA), as part of its SmartWay Program, is formulating a test protocol proposal to measure the fuel efficiency of medium– and heavy-duty commercial vehicles for the first time. According to industry reports, the EPA’s fuel consumption metric for this test would be fuel consumed per amount of work performed, which is not the same thing as simply milesper- gallon (MPG).

The Transportation Research Center (TRC), an independent, third party test facility located in East Liberty, Ohio, recently completed Fuel Consumption Testing commissioned by Allison. For the test, TRC was provided two equally spec’d mediumduty trucks; one equipped with an Allison 2200 HS and the other with a comparable automated manual.

When cruising, the most critical component to achieving maximum fuel economy is engine RPM. Operating in the engine’s recommended RPM range is the best way to reduce fuel consumption and increase MPG, according to Spurlin. “If a truck is used in town and spends 60% of its time at 40 MPH, it doesn’t make sense to spec that truck to cruise at 65 MPH at the engine manufacturer’s recommended RPM rating. Fleet managers know how their trucks are used and should write their specs according to that duty cycle. ”

Part of the test conducted by TRC assessed the transmissions’ impact on engine RPM at various cruise speeds. The results show that the Allison-equipped truck produced significantly lower engine RPM versus the automated manual-equipped truck at many cruise speeds below 40 MPH, which resulted in less fuel used. And, in higher cruise speed ranges, the two transmissions produced comparable engine RPMs and fuel usage. Says Gilbert, “Allison fully automatic transmission internal gear ratios produce lower engine RPM in many areas below 40 MPH, resulting in less fuel used and better MPG. And, with most medium-duty truck applications, this is where much of the operational time is spent.”

While gains made in fuel economy and fuel efficiency are an important factor, they are still just one part of the overall value of any Allison Transmission product. Increased durability, reliability, shift quality, maneuverability and productivity are other benefits found with Allison Automatics. Not to mention reduced maintenance, driver fatigue and driveline stress. Gilbert sums it up like this, “All the factors add up to prove Allison Automatics provide superior life-cycle value.”

For more information about the fuel economy and efficiency of Allison Automatics, visit

www.allisontransmission.com/RealProof