Allison Transmission addresses operating efficiencies
With a reputation for its design and production of fully automatic transmissions for a wide variety of vocational applications, Allison Transmission, Inc., Indianapolis, IN, is dedicated as well to helping its customers operate as efficiently as possible, particularly in a down economy.
For example, test results suggest the company’s fully automatic transmissions in conjunction with the appropriate duty cycle for that particular vehicle can provide superior fuel efficiency and optimum fuel economy.
Allison breaks a vehicle duty cycle into four separate components: acceleration, cruise speeds, deceleration and idle, with acceleration and cruise speeds having the greatest impact on fuel consumption.
According to Lou Gilbert, North American marketing director, the greatest fuel efficiency comes with smooth, seamless full-power shifts from an automatic transmission that transfers uninterrupted engine power to the road. He says manual and automated manual transmissions interrupt engine power with every shift.
“Any interruption in engine power during a shift creates powertrain inefficiencies,” says Gilbert. “It creates a loss of vehicle energy and lower average speeds for the amount of fuel consumed. Drivers will recognize higher average speeds in full-power shifts as opposed to manual or automated manual transmissions.”
The U.S. Environmental Protection Agency (EPA) SmartWay program will soon include 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 fuel consumption metric for this test will be fuel consumed per amount of work performed, which is not the same as simply miles-per-gallon (MPG).
Allison Transmission says it commissioned Transportation Research Center (TRC), East Liberty, OH, an independent, third party test facility to conduct fuel consumption testing. The recently completed research provided TRC with two medium-duty trucks of equal specs — one equipped with an Allison 2200 HS; the other with a comparable automated manual.
Allison says at cruising speed the recommended engine RPM is the most critical component to maximum fuel economy.
“If a vehicle used in town runs 60 percent of the time at 40 mph, it does not make sense to spec that vehicle to cruise at 65 mph, which happens to be the engine manufacturer recommended RPM rating,” says Gilbert. “Fleet managers know how their vehicles are used and should write their specs according to that duty cycle.”
TRC test results show that the Allison-equipped vehicle produced significantly lower engine RPM versus the automated manual-equipped truck at many cruise speeds below 40 mph, which resulted in less fuel used. At higher cruise speed ranges, the two transmissions produced comparable engine RPMs and fuel usage.
Allison offers a choice of operating modes to best suit the driving conditions and duty-cycle needs of end-users.
The magic of the shift mode button
The company says its primary and secondary shift mode button located on the shift selector for the Allison Highway Series enhance fuel savings or add more power. In economy mode, the transmission shifts at lower engine speed to improve fuel economy by as much as 5 percent. In performance mode, the transmission upshifts at higher engine speed to provide quick, smooth acceleration.
Switching oil significantly extends drain intervals
The recent addition of new advanced prognostics capability to its entire range of Allison automatic transmissions provides operators with an electronic fluid and filter change indicator that monitors the specific operating conditions for each bus.
Allison says a 6,000-hour drain interval for city transit buses is possible with synthetic oil, and operators using mineral oils should consider a switch. In the UK, Plymouth City Bus proactively investigated the use of synthetic oils to improve operating efficiency in its fleet of more than 170 buses. The agency reports lower costs and reduced environmental waste after increasing drain intervals by more than three times.
Allison says conventional petroleum-based transmission fluids can oxidize quickly and undermine the effectiveness of the additives, viscosity enhancers and detergents. Allison recently announced its new fully synthetic fluid specification TES295. Working with Castrol, Allison developed TranSynd oil, but states that any TES295 fluid can deliver the same maintenance, environmental and operating benefits.
Allison recommends fluid analysis as the primary method for determining fluid change intervals, which assesses oxidation, contaminant levels and viscosity. The company notes that glycol and water are probably the most common and harmful contaminants found in a transmission. Water is a poor lubricant and can cause corrosion. Glycol can attack the bonding material used to join the clutch friction material to the steel plates. BR