240D Connecting shaft assembly / one way clutch

[svcguy]

I am running a 5 foot PTO snowblower on my 240D and notice that when I come to a stop and push in the clutch, I hear what I think is the connecting shaft assembly / one way clutch in the transmission. Although it doesn't happen every time, it does a lot of the time - sounds like a slow speed gear grind. Not too dramatic, but it seems odd to hear it. Do other 240D owners experience this?

Thanks, Tom

 

[California]

'They all do that.'

I think what you are hearing is the overrun clutch (ratchet) inside the PTO part of the transmission. I get the same sound when I stop and the rotary mower winds down. It sounds like the coaster mechanism on a bicycle except sized huge, made for 24hp.

This over-running clutch* is built in to the American Yanmars (YM240 etc) but was not included on the Japan-market version (YM2000). That and the reverse throttle lever are about the only differences between the US and Japan versions. (I've read the US Yanmars are equipped with a wider seat - unverified.)

______________
*That's what they called it. See the third page in the Yanmar brochure referenced from my sig, below.

 

[svcguy]

Thanks California, the over-running clutch referred to on page 3 of your link is what is listed as the connecting shaft assembly / one way clutch in the original shop manual diagram. It doesn't seem to mention it anywhere, just pictures it. I figured it was about the only thing capable of making the sound, but wanted to check it out with someone else who has experienced it.

Over the weekend I went down to help my neighbor with his 1947 Case. It was hardly running for about a month or so and now wouldn't start after blowing the muffler off the manifold. I looked at the distributor and the mounting plate for the points had broken loose from the shaft. Put a bead of stainless around the bottom of the plate, turned it flat on the lathe and machined .085 off the distributor base to compensate for the height difference. Put it back in and tried it out. Apparently, it must have been loose when he bought it in 1972, because he said it never ran smoothly and never had the power it has now. He just figured Case never made a very good tractor. The thing barely worked in second gear for 40 years and now he is plowing snow in 4th gear. After thinking about his experience of 'normal', I started worrying about my rachet sound. I appreciate knowing that it isn't damaging anything.