TRUCK TRACKS

Dec. 28, 2000

Transmissions that shift themselves have emerged as major players in the big truck field this year. While the history of fully automatic and semi-automatic gear boxes can be told in terms of decades (see sidebar), fully a half dozen manufacturers have released major transmission news so far this year. Almost all of it was about reduced manual shifting of transmissions.

A growing shortage of drivers who can handle manual transmissions is one of the reasons. So is the fact that a growing number of drivers prefer "easy-shifting" gear boxes.

By: Ken Kelley

A growing shortage of drivers who can handle manual transmissions is one of the reasons. So is the fact that a growing number of drivers prefer "easy-shifting" gear boxes. On the management side, the advanced transmissions help justify their extra cost with the fuel they save by shifting at the correct time, and by avoiding clutch repairs because conventional clutches are either used less or not at all in drive trains with easy-shifting gear boxes.

Eaton Corp.'s Transmission Division, producer of the Fuller line, and generally listed as the volume leader in the big truck transmission field, has already unveiled two advanced gear boxes this year-a 10-speed and a 13-speed.

Both have the Top 2 feature, which means that shifting of the top two gears is automatic. Those who have offered this feature note that a large majority of shifting in over-the-road driving is in the top two gears. Eaton will add an 18-speed Top 2 in the future.

Volvo announced that Eaton AutoSelect gear boxes are available in its trucks. They are automated mechanical transmissions that led a group of easy-shifters that Eaton unveiled in the fall of 1994, touching off the current swing to easyshifters.

Caterpillar recently announced that its 3406E and C-12 diesel engines are compatible with the Eaton AutoSelects. Cost of those easy-shifters is held down by turning their management over to the engine's electronic controls.

Rockwell's entry in the easy-shifting field is called the Engine Synchro Shift (ESS) system. Working with a nine or 10-speed transmission, it eases shifting work by automatically synchronizing engine speed and road speed during shifts, eliminating use of the clutch for everything but starting and stopping. For its first year, ESS will be available only in Freightliner chassis with one of three Detroit Diesel engines.

Allison Division of General Motors, for years the truck industry's leader in automatic transmissions, isn't sitting idly by while new competition floods into the market. In its most recent of a continuing series of product refinements, Allison has stepped up its MD3066 model to work with engines turning out up to 360 hp, and the gear box has been cleared for on- or off-road use.

While it isn't an automatic, Peterbilt has a new powertrain that provides reduced shifting. The HillClimber is the name of a new system developed jointly with Caterpillar and Eaton (Circle No. 903). It combines a 455-hp Caterpillar 3406E diesel and a specially designed Fuller RTLO-16713A-MT transmission. The engine can develop 1550 ft/lbs of torque at speeds below 25 mph and 1750 ft/lb above 25. Availability of the higher torque "means the driver can reduce shifting by as much as 28%," according to Bob Morrison, Peterbilt's chief engineer.