Driving Eaton's UltraShift LEP 13-Speed
This self-shifter aims for fuel economy by keeping engine revs in the 'sweet spot.'
Eaton Corp. has just added a Fuller 13-speed UltraShift programmed for maximum fuel economy to its lineup of automated mechanical transmissions. Called LEP for linehaul efficient performance, the product is designed to keep the engine in its "sweet spot"– its most fuel-stingy operating range, which with current engines also tends to deliver the best performance.
The LEP is designed with economy conscious fleets in mind. Dedicated gear jammers will still prefer manuals, but others should be happy if issued a tractor with this tranny because the automated shifting means less driving work, while the promise of good fuel economy enhances the chances of qualifying for bonuses the fleet might offer. It also lets drivers concentrate on where they're going and where their trucks are in traffic.
Like other UltraShifts, the LEP is almost as easy to drive as a fully automatic transmission. There's no clutch pedal; clutch actuation is automatic, with engagement occurring when the driver steps on the accelerator and disengagement coming just before the vehicle rolls to a stop. All the driver does is punch D (for drive) on the selector, release the brakes, step on the gas, and steer and brake as needed. All normal up- and downshifting is automatic.
Engineers program the electronic controls of each LEP to work with the engine it will be mated to. They study the engine's "fuel map" to determine what revs will deliver the best economy and set the tranny's controls accordingly. The engine will normally stay inside a relatively narrow range, but will rev higher or lower if the driver elects to select ratios manually.
Two test tractors provided at Eaton's Marshall, Mich., proving grounds had Cummins ISX diesels, which propelled the partially loaded rigs well. Each usually ran between 1,400 and 1,650 to 1,700 rpm, depending on how hard I jammed the foot feed. That limited rev range is also the engines' "sweet spot," meaning that's where they make their maximum horsepower as well as maximum economy.
There is no good reason to rev beyond 1,600 or 1,700 with today's heavy duty diesels, except one: to get more retarding power form the engine brake. The LEP allows this when the driver selects M (for manual), then punches the down-arrow button; the engine will downshift – if the controls determine that the engine won't overrev – then the brake will come on and slow the vehicle. The tranny will stay in that gear until it's told to downshift again, or upshift by pushing the up arrow or back to D.
This feature works with most Ultra- and AutoShift transmissions, though the capability can be program-limited by managers who don't want their drivers "playing" with the tranny.
Clutch engagement from a dead stop is so smooth that the transmission can start out in something higher than Low. But it can't "see" the road, so might not know that the rig's on an upgrade. For this situation the selector pad has an L button, which tells the tranny to start out in a lower gear than it otherwise might. As soon as the rig is moving, the driver can punch D and let it resume working automatically.
A readout on the dash tells what ratio the tranny's in, from 1 to 13 (unlike a manual 13-speed, whose ratios are labeled from Low to 8th-overdrive). At highway cruising speeds, the LEP will usually be in 12th or 13th. The gearbox is the same as a manual's, with splitter and range boxes; but as the LEP up- and downshifts, there is little discernable clicking or thunking as it splits the high-range gears and shifts between low and high range. Highly refined "Gen3" controls always seem to choose the correct gear and never miss a shift.
By keeping revs where they should be, the new 13-speed LEP can save as much as 2 percent in fuel compared to other trannies that let the engine rev higher, according to Eaton's computer simulations. This should help defray the upcharge of about $2,500 over a 10-speed UltraShift and $9,200 over a 10-speed manual. It also makes training of neophyte drivers far easier and faster, and those drivers who like automated shifting are more likely to stay on.
By the way, the UltraShift LEP comes in two torque ratings: a straight 1,650 pounds-feet and a 1,650 pounds-feet. Multi-Torque model with a capacity of 1,750 pounds-feet in the top two gears. The Multi-Torque feature is also newly available in Eaton's LST (for linehaul standard) product, with direct or overdrive gearing.
—Tom Berg, Senior Equipment Editor
Duraplate Correction (May 2006 article)
