Velvet Drive doesn't work reverse but forward

Dear Friends

This is the time I need your help / advice:

We are on our way to the Baltic Sea to celebrate our summer vacation. Docking in Wolgast our starboard engine suddenly doesn't work reverse, although stopping the vessel just before the harbor it did as I always did.

After docking I checked ATF level and position of the gear lever, both o.k.
Engine, to be correct: gear is working forward, but not reverse. Gear is a Velvet Drive 10-13.

Any idea ? And how to fix it?

Am I right that our issue might be related to the reverse clutches? And if so might those be replaced while the vessel is in the water?

Family / crew is down like me, please advise with good ideas.




best regards / med venlig hilsen
wadden

waddenkruiser said:

Dear Friends

This is the time I need your help / advice:

We are on our way to the Baltic Sea to celebrate our summer vacation. Docking in Wolgast our starboard engine suddenly doesn't work reverse, although stopping the vessel just before the harbor it did as I always did.

After docking I checked ATF level and position of the gear lever, both o.k.
Engine, to be correct: gear is working forward, but not reverse. Gear is a Velvet Drive 10-13.

Any idea ? And how to fix it?

Am I right that our issue might be related to the reverse clutches? And if so might those be replaced while the vessel is in the water?

Family / crew is down like me, please advise with good ideas.




best regards / med venlig hilsen
wadden

Click to expand...

try and put the trans in gear in the engine room my be the cable is not adjusted right.see if you can get it in reverse by doing it by hand.make sure that the clip that holds the cable on the trans is not loose

If it's not linkage as Capt J. suggests, then it's internal to the transmission.

In that case the transmission has to be parted from the engine to repair. If there is sufficient space behind the engine and space to unbolt the propeller shaft and transmission from the engine and back it out, a mechanic and a couple of strong lads can remove it from the engine room for service while in the water.

First thing to do is have a qualified mechanic trouble shoot the cause and give you an estimate.

Good luck
Larry B

The fact that one direction works well (apparently) should indicate no flex/drive plate issues, oil pump is flowing well and chances are the forward pack pressure relief valve is seating as designed and supplying enough flow (and pressure) to the forward pack. So an internal problem has already been indicated.

Reverse clutch pack piston is activated from oil supplied by the pump. There will be a few areas this flow/ pressure is disappearing to.
**Control spool for pack pressure. With the shift cable disconnected does it feel the same when it clicks into reverse as it did in forward?
**There is an "oil distributor" on the end of the clutch pack shaft (s) that may use steel, Teflon or rubber sealing rings. It directs oil flow into a hollow hole the length of much of the shaft- and then the oil flow is directed into the piston through a small hole for the respective clutch pack.
**Which leads us to the last opportunity for fluid loss in our reverse circuit. The reverse clutch piston has an inner and outer seal that can fail and not keep the pressure applied to the clutch discs and plates which turn the shaft. A piston seal leak can lower the pressure so much that the piston can't compress the discs/ plates.
The reverse clutch pack is rarely used compared to the forward side. The discs probably won't show much wear.

Good Luck!
You can do this!!


1983 Present 42 Sundeck
Twin Lehman 135's

Looking for simple explanations still, before you end up with expensive interventions, I will mention my one experience of sudden reverse failure for what it is worth. My gearbox is a Paragon, not Borg Warner Velvet Drive, but perhaps this might help. Is it possible someone topped up the tranny fluid just before you set out, and that you had not actually needed reverse on that engine until the failure..? Why I say this is because one time when I did this, because the filler hole is closed by a rather long bolt, just in case I needed to take it out again to add more, I ran the engine in forward and reverse without screwing it fully back in, thinking it would make no difference, but be easier to remove if I did need to add more fluid. Forward worked fine...reverse failed to engage. Initially I panicked, then logic took over and I thought, ok how could I have ruined reverse when the only thing I have done is add fluid...then I remembered the bolt in the filler hole. I screwed it right back in, and lo and behold, the reverse worked again. Just a thought, in case these boxes share some features...

Wadden
Any good news yet??


1983 Present 42 Sundeck
Twin Lehman 135's

The cylinder for the reverse piston might be rusted preventing engagement. That almost happened to mine but I pulled it for a rebuild before it failed.

That's a real possibility. I wonder if a flush might loosed a stuck piston? There should be a reverse pressure test port. Possibly remove and load with Kroil followed by pressure from a rubber tipped blow gun and 120 psi. Just throwing a few ideas out. But the reality is that even if it did start to work, that little sailor on your shoulder would be constantly reminding you "it could happen again".


1983 Present 42 Sundeck
Twin Lehman 135's

Many Thanks to All of You.
Unfortunately we were not been able to figure out a simple, quick and non-expensive solution. Finally we decided to get the gear out and shipped it to a Velvet repair shop. Image of gear ready for shipment enclosed.
We left the boat (still swimming, to get the gear out the shaft was just shifted by 8 cm) at the Baltic coast since the repair will for sure last longer than our vacation.
Will give you an update on root cause when repair is finished.


best regards / med venlig hilsen
wadden

Thanks for the update Wadden. Sorry your cruise got shortened. Please keep us updated on getting her back together.


1983 Present 42 Sundeck
Twin Lehman 135's

Good news: Got a phone call yesterday that all needed spare parts arrived from the U.S. It will last only ten more days until we can pick up our boat again. Unfortunately no holidays left, so it will be just an extended weekend to get her back home from the Baltic coast.

What happened to the gear? The reverse clutch plates (part # 90/91) were broken into three pieces each and all the inside teeth were broken of the plates. In addition almost every part was worn by metal chips. A lot of the internals have to be changed. Looks like huge forces have been acting inside the gear box.

However, in the three years we are owning the boat there wasn't any event which I could bring in correlation with unreasonable high forces. Nobody shifted the gear at high rpm or load, we had no blockage of the turning shaft caused by an obstacle or ground contact of the prop, no ...

My theory on root cause is therefore: the initial damage was caused years ago by one of the previous owners who had e.g. a severe ground contact with the prop. And over the time wear and tear ...

But: I changed the ATF every year and every time the fluid looked and smelled like at the day I filled it in. Especially there were no metal chips or rubber particles in the extracted ATF!
Is it better to open the ATF return line from the cooler to drain the fluid out of the gear box than to extract the ATF via dip stick (as I did it since years on my boats)

Any opinion on root cause or method of ATF extraction / drain?

View attachment 43719



best regards / med venlig hilsen
wadden

Try to upload the drawing ...


best regards / med venlig hilsen
wadden

Yup that sure sounds like failure from tremendous shock load. Being that it was a "metal failure" you'll want to address the cooling lines and HE- course you probably thought of that .


1983 Present 42 Sundeck
Twin Lehman 135's

Seems I did not update the end of our gear story. Sorry for that.

At the end everything was fixed including a new ATF cooler. We left the boat there for all the work to be done on this gear issue for two months and returned it back to our home port end of September.
Total costs were 6'500 Euro, most of it for the gear shop nearby Wilhelmshaven / Germany.

Thanks for your support and advice!
Wish you all the best for 2016 and "Immer eine Hand breit Wasser unter dem Kiel"!


best regards / med venlig hilsen
wadden