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Starter (truck)
Function
It is the same as the one used in passenger cars. Only in this case, with 10 times as much torque. This influences, among other things, the specifications of the
flywheel cogs and
complicates the meshing alignment.
How it works
The thrust-screw-drive starter has just about edged out the thrust-drive starter (figure) in the utility vehicle sector up to 16,000 cc. It is built up similarly to the starter in passenger cars. In this case, only the field coil is
not yet substituted by a permanent magnet. The working current flows, as before in the passenger car starter, first through the field coil and then the armature winding (series-characteristic motor). Also the choice of
material is adapted to the necessary high torque.
The second specific feature is the two-stage meshing alignment. In this case, the current flows through a pre-relay with a large switch cross section (like the
solenoid) reduced by a
resistor to the solenoid. This also operates, almost simultaneously, with draw- and hold coiling the starter itself. In this way the meshing alignment, which is followed by the full activation of the starter motor, should be
made easier.
Thrust-drive starters work with a solenoid, which is not mounted near to the pinion gear, but on the other side of the starter motor. From there it tries to push the pinion through the hollow armature spindle into the
gear rim of the flywheel. In this action, the pinion does not twist itself. In the most favourable case the full current can be applied, in the most unfavourable case the start process must be repeated. 07/08
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