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
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
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.