OPERATION OF THE U.S. GEAR DUAL RANGE AUXILIARY TRANSMISSION
The U.S. Gear Dual Range Auxiliary Transmission is a highly
versatile unit offering a variety of separate and distinct final
drive ratios while providing the necessary strength requirements
that are mandatory in many vehicle applications. The 20% Overdrive
OR Underdrive ratios are uniquely designed to complement the
driveline of your vehicle while, at the same time, retaining the
existing factory, direct-drive ratios.
The Dual Range is designed to offer you the option of selecting
up to twice the number of forward and reverse driving ratios.
However, unlike many auxiliary transmissions, the Dual Range
offers you these ratios WHEN YOU NEED THEM! And, by
maintaining a 35,000 lb. GCVW (Gross Combined Vehicle Weight)
rating, the Dual Range sets the standard as the heaviest unit in
the industry.
The Dual Range is an electronically-controlled,
mechanically-shifted transmission which when operated properly,
can provide a controlled shift between auxiliary and direct
ratios. This shift can be accomplished at ANY speed; however,
because the unit requires a certain level of gear rotation to
ensure proper gear alignment, THE UNIT SHOULD NEVER BE SHIFTED
WHILE THE VEHICLE IS STOPPED!
Although the unit is adaptable to both manual and automatic
transmissions, the methods of operation of these two, distinct
types of transmission applications are very different.
AUTOMATICS - In automatic applications, the main
shift from direct to auxiliary range (or vice versa) is
accomplished through the utilization of a high-torque spring lever
assembly. This spring assembly, which is loaded by the
electronically-controlled shift motor rotating a worm gear (drive
screw assembly), then forces a collar gear (slider), which couples
the output shaft to the direct input gear, to mesh with the
auxiliary ratio output gear. This complete action is induced when
the control module inside the vehicle is actuated.
To shift the Dual Range:
1) While the vehicle is moving and the driveline is under load
(the accelerator is depressed), push the control module button on
the transmission control lever.
2) WAIT APPROXIMATELY 2 SECONDS! This will allow the
spring assembly to load the Dual Range shift mechanism.
3) Quickly, relax the pressure on the accelerator pedal and
then re-apply full pressure. This action will NOT require the
removal of your foot from the accelerator pedal.
It should be noted that the quicker this complete action can be
accomplished the more likely the unit will be to shift smoothly.
If properly shifted, a CLUNK should be noticeable upon gear change
along with an obvious change in engine RPM.
When using the Dual Range to split-shift from 1st O/D to 2nd
Direct, or similar change, it is strongly suggested that the
automatic transmission be shifted to the higher gear prior to
shifting the Dual Range from HIGH to LOW. This will allow for more
flexibility in driveline stress and ensure proper load transferral
to the subsequent gear.
MANUALS - As with automatics, the internal shift
design of the unit (and the mechanics of the shifting) remain the
same; however, the method of electronically inducing the shift
mechanism does, in fact change.
To shift the Dual Range:
1) While the vehicle is moving and the driveline is loaded,
either pull UP or push DOWN on the shift actuation switch
connected to the transmission lever.
2) WAIT APPROXIMATELY 2 SECONDS! This will allow the
Dual Range shift assembly to load.
3) Quickly, flash the clutch pedal to briefly relax the
driveline pressure. Complete depression of the clutch pedal is not
required and can cause substantial momentum loss.
Again a small CLUNK and a change in engine RPM should be
noticeable upon the gear change.
*** NOTE ***
If using the Dual Range to split-shift in the manual applications,
at least 2-seconds should still be given for the spring assembly
to load prior to clutch depression. However, because the clutch
depression during the shift of the manual transmission will
completely relax the driveline, it is not necessary that the
primary transmission be shifted to the higher gear before the Dual
Range is engaged.
It is very important in any application that the shift assembly
of the unit be allowed to load before the driveline pressure is
relaxed. Failure to do so will cause all of the shift load to be
transferred to the shift motor, which is not designed to accept
this load on a prolonged basis.
By providing for the use of additional gearing with minimal
effort, the Dual Range Auxiliary Transmission offers complementary
driving ratios to, in most cases, an already over-taxed driveline.
By using gearing as a "partner" with your engine's horsepower,
properly operated, the Dual Range can give you miles of worry-free
service and substantial gains in both performance and economy.
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