Can anyone explain the 290DP gearbox/cone clutch?

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OK curiousity has always gotten the best of me. Can anyone explain how exactly the cone clutch works on the 290DP drive? I understand how the duo-prop works (lower gears) but the cone clutch is a bit of a mystery to me. Illustrations would be great.

I remember reading before it's like 2 flower pots, one inside the other. When they come together they grip and turn, to come out of gear they come apart - Is this the best way to describe it?

Basic illustration of the drive here, but more just a pretty diagram rather than answering my question: http://vppneuapps.volvo.com/ww/PIE/ViewF...6&d=Product

Thanks guys

 

[[2068]]

I'm sure a proper mechanic will come along in a bit with the red pen, but here's a starter for 10.

The overview below shows the input shaft from the UJ which has at it's end a gear that is permanently engaged with the upper and lower gears. These gears are free to spin around the shaft in the middle of them. Upper gear spins one way, lower gear t'other.

Attached to the bottom of each gear is a "cup".

In between the two cups is a block machined in the shape of two "cones". The block is free to slide up and down the shaft, but can only run along a spiral track.

This shows it all put together, with the shift pin. In neutral, both upper and lower gears rotate, but the cone-shaped block isn't engaged with anything, so the shaft in the middle doesn't rotate.

When you hit "forwards", the pin pushes the cone block along the spiral shaft until it engages with a cup, and "clonk", you are in gear.

Engage neutral again, and the shift pin pulls the cone block free from the cup.

This shows the cone block with one gear and cup. Other one is missing.

 

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S28, that makes perfect sense, thank you for the detailed explination and pictures... Ah the internet, an answer to EVERYTHING! /forums/images/graemlins/tongue.gif

It makes sense now when people say that, eventually, the cone wears out and needs to be replaced

The cone and cup must be connected very tightly so not to slip, am I right in saying this?

 

[[2068]]

The idea is that as soon as the cone makes light contact with a cup, it goes the last fraction of a mm because of the rotation and resulting travel along the spiral track as it grips, hence the healthy clonk as it finally goes home.

If it's worn and not a snug fit, this last bit either doesn't happen or is slower than you'd expect.

Also, don't do what I did, which was to accidentally shift into reverse while doing about 10kts going forwards. Instead of a clonk, it goes in with a BANG: you end up being totally stuck in reverse, saying "Feck" many times, and having to be towed into Cowes and lifted out /forums/images/graemlins/shocked.gif

 

[rlw]

My experience on 2 boats with 290DP drives is that the cones are worn out at about 1000 hours and need to be replaced. This manafests itself by the fact that the engine does not engage in neutral but revs up an then engages at a higher rpm. This get progressively worse. Water in the drive oil can cause something similar though.

Rob

 

[awol]

In these times of recession the cheap solution is to dismantle, lap the cones lightly with valve grinding paste to remove the glaze and then reassemble.

 

[gjgm]

I ve also heard that while they might get damaged, they shouldnt wear and tear until 1000hrs+.
Which is a lifetime in most boats!

 

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I ve also heard that while they might get damaged, they shouldnt wear and tear until 1000hrs+.
Which is a lifetime in most boats!

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Never say never... On my last boat I clocked 380engine hours in a season /forums/images/graemlins/shocked.gif

On the S23 I only clocked about 250 engine hours last season, but plan to clock up many more this season. Considering there was 250 hours on it when I bought it - 1000hours aint too far away!

 

[Pendana]

I had to change the cone clutches on the last boat at 1200 hours. Relatively easy job and about £400 for all the parts and gaskets