Folks... I'm having trouble understanding the mechanics (and some of the electrics) for the 744 Windshield Wiper.
For each wiper, a DC motor drives a gearbox/converter which converts the motor's rotary motion into oscillating motion (i.e. there is no requirement to change the direction of the
motor when the wiper is running). If the gearing is purely mechanical, then it follows that the angle of sweep will be fixed (about 70 degrees on the 744)
How then, does the wiper arm park itself several inches off the windscreen (outside the normal sweep range).
As far as I know the motor does not mechanically disengage itself from the gearbox.
I read that when the switch is set to OFF, the electric motor reverses. This, presumably reverses the sweep of the arm. However, surely the range of sweep must still be bound by the mechanics of the gearbox/converter (70 degrees).
Neither the Maintenance Manual, wiring schematics nor training notes make any sense of this.
All theories welcome
Cheers.
NSEU