Great white,
yes it does wear them out, but it is at such low rate of wear that probably you will not need to replace anything within 10 years, and with modern
winches even more.
This is what happens:
Two speed
winches or single speed
winches have these little tangs, often callew PAWS, that are inside these slots are forced out my means of a little spring.
These paws are inside these sprockets that have teeth on the outside and notches on the inside. When you rotate the wich one way, (say for example in low speed), the paw in the low speed gear stick out and leans against the slot wall that is at 90 degrees to the paw and engages the sprocket..when you roatate the other way around, the paw is now rotating with the sprocket, but the notch is sloped so it just doesn't allow the paw to engage.
When you rotate the other way, now it's ther high speed sprocket that rotataes, because it has a similar mechanism, but with notrches in the opposite direction.
The wear on the outside of the gears and sprockets will be the same no matter how you turn them, because thrust is allways in the same direction, as the
winch only rotates one way...so no wear there..they harden the side of thrust, normally anticipating that fact.
However...you do get wear, yes, inside the sprockets, where the paws are, but normally the solution is a cheap fix..they harden the notches and make the paws softer being the sacrificial component..
My say...don't worry...it's a cheap fix...
Now..I am a big fan of
Lewmar winches, that to me are far better than
HArken. The reason is I've had Harkes strip for no apparent reason...