SMART Series 451 Service Manual page 77

SN_Typ 451_us.book Seite 76 Freitag, 30. November 2007 1:56 13
Steering
Design
The main components of the electric power steering
(EPS) system are the power steering motor, a DC
brush-type electric motor with maximum 35 Ampere
power consumption and the power steering control
unit.
The power steering control unit communicates via the
CAN data bus and is located in the vehicle interior on
the left of the firewall.
The rack-and-pinion mechanical components for the
electric power steering (EPS) are accommodated in a
steering housing made of diecast aluminum, to which
the power steering motor is also flange-mounted.
To provide steering assistance, the steering gear
pinion shaft transmits the rotational movement of the
steering gear input shaft to the teeth of the toothed
rack. The power steering motor transmits force for
steering assistance to the spur toothing of the hyper-
bolic gear via a worm shaft. The hyperbolic gear is
fixed to the pinion of the steering gear pinion shaft.
The power steering torque sensor is located in the
steering gear housing between the steering gear
input shaft and hyperbolic gear.
76 Introduction of the smart fortwo, Model Series 451
Components of the electric power steering (EPS)
1 Steering gear housing
2 Steering gear pinion shaft
3 Steering gear input shaft
4 Toothed rack
5 Worm shaft
6 Hyperbolic gear
B23 Power steering torque sensor
M19 Power steering motor
N68 Steering assist control unit
P46.10-2933-00