Spinning? Well, yes and no. If everything is working correctly (i.e.
pinion is free on its spiral splines) the shaft of the starter is
spinning fast.
However that rotation is working mainly to throw the pinion out to mesh
with the ring gear, as the spiral splines turn the twisting force into
forward movement.
So the pinion is turning slowly if at all until it meshes with the ring
gear, hits the spring at the end of its travel, and is forced to rotate
along with the armature of the starter. My understanding is that the
slight rotation of the pinion was considered acceptable since it would
aid the pinion in meshing with the ring gear. (Ever heard a
"conventional" starter get hung up not quite in mesh with the ring
gear? Not pretty. Trashes a pinion and/or ring gear pretty quick.)
So, theoretically at least, the "chewing up" should be minimal. If the
mechanism gets dirty and the pinion hangs up in only partial engagement,
then ring gear mayhem is likely.
Since the same basic design is used in so many different British cars of
the era (some of them pretty upscale), I don't think it was a matter of
designing down to a price as it was a neat, compact solution to the
problem.
If, however, the little circlip at the end of the armature fails, the
starter will happily vomit the pinion, stop plate and spring into the
bellhousing! (Ask me how I know.)
Chris kotting
ckotting@iwaynet.net
Bob Chamberlain wrote:
>
> Do Lucas inertia starters, by their very nature , tend to chew up ring
> gears? They are spinning prior to engagement aren't they? Was this a case
> of engineering down to a cost?
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