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Electronically Controlled Fully Automatic Transmissions for Commercial Vehicles
Technical Paper
785109
Sector:
Language:
English
Abstract
This paper concerns mechanical fully automatic power
transmissions for buses and trucks. Their design concept offers an
additional two-pedal-controlled mechanism in conjunction with any
conventional gearbox. The prototype consists of a five-speed
gearbox and a single-plate clutch actuated by a transistorized
electropneumatic control system. The electronic unit computes the
shift points according to the accelerator pedal position, the
vehicle speed and the selection of shift modulation, and controls
the electric and pneumatic units for both clutch engagement and
gear shift. The principal functions of the prototype are: (1) the
selection switch of shift modulation offers either a high-power
acceleration shift mode or an economical-power cruising mode, (2)
thyristors ensure the correct sequence control of clutch and gear
operations, (3) the clutch servomechanism engages the clutch in a
three-stage (quick, slow, quick) action and disengages quickly and
(4) for a non-synchromesh gearbox, the double-clutch-action control
mechanism and the throttle servomechanism actualize the
synchronization of gears.
The proposed transistorized electropneumatic control system was
installed in a sixty-passenger bus and tested under various
conditions. The results show that the prototype has practical
applicability in view of its performance and feasibility of
production.