SMART Series 451 - Shift Mechanism

Shift mechanism
Automated manual transmission
49
Introduction of the smart fortwo, Model Series 451
Shift mechanism
The central components of the shift mechanism are
two selector drums for moving the shift forks. Each
selector drum is driven by a separate electric motor
via two sintered spur gear sets. One selector drum
shifts the odd gears, while the other shifts the even
gears and reverse gear.
The position of the selector drum, and thus the
current shift position, is determined by two incre-
mental sensors in each electric motor.
Both electric motors and the spur gears are located in
a common aluminum housing, the actuator unit, which
is mounted on the transmission.
The two selector drums are arranged to allow over-
lapping shift operations to minimize shift times. It is
possible to skip gears (e.g. double downshifts).
P26.60-2320-00
Design of shift mechanism
1 Shift fork for shift collar 5
2 Shift fork for reverse gear sliding gear
3 Shift fork for shift collar 1/3
4 Shift fork for shift collar 2/4
5 Main shaft
6 Selector drum 1/3, 5
7 Selector drum 2/4, R
8 Input shaft
M17/3 Transmission motor 1
M17/4 Transmission motor 2
SN_Typ 451_us.book Seite 49 Freitag, 30. November 2007 1:56 13