For some reason, I seem to recall
being told that dog clutches were only usable on lower HP engines. Yanmar did use the dog clutches (SD20) on <30hp engines, but cone clutches (SD40/50) on higher ones.
used cone clutches on all of their drives until the relatively recent change to disc clutches. The early problem of burning the clutches was solved
by changing the type of lubrication fluid used. Since then, I haven't heard of any Volvo disc clutch problems, so hopefully the same will be true for Yanmar.
Honestly, though, I cannot understand why Volvo has such a good track record
with saildrives and Yanmar has such a poor one (the SD20 excluded, of course). When you look at the schematics and parts
, they pretty much look exactly the same. I believe they are both built by the same company (ZF).
However, one is hard pressed to find accounts of bad Volvo cone clutches, while one cannot find ANY account of a Yanmar cone clutch that has served a reasonable life. Yanmar publishes maintenance
requirements in their manual of pulling and lapping the cones every 500hrs, while Volvo doesn't mention their clutch, or service
of, at all in their service
Yet, you put the schematics of both on top of each other and they almost match completely.