Velvet drive slipping?

[Rduval]

I have twins and have heard that it saves fuel to have the non-running engine in gear so I thought I'd try it the other day.

Problem is that whether in neutral forward or reverse the propshaft keeps turning unless the engine is running. Is this normal?

Also, the non-running engine started to make a very loud noise that almost sounded like a very loud powerboat passing us (both my wife and I we looking for it but when there was none around I quickly isolated the sound to the engine bay and restarted the engine and the sound went away.

It also is the same no matter which engine is running and which is shut down.

Is is normal for Borg Warner Velvet Drives (circa 1984) to freewheel like this? If not, are there clutch packs in there that are worn out? If so can I assume that they are also slipping when driving normally?

 

[River Cruiser]

Some gears do not lubricate the internal parts if the engine is not running, on these you need a shaft brake. My Hurth hbw 450 can freewheel without any problems, I do not know if yours can or not but I wouldn't do it before I talked to a mechanic familiar with your gear.

 

[capt jerry]

might have something to do with the prop free wheeling?????

 

[capt jerry]

what it could be that the shaft is wobbling without a load on it because the cutlass is worn a little and it don't have a load on it.

 

[psneeld]

pretty sure they will just freewheel...some trannys do ....some don't.

looked at the BW website..no help I could find.

 

[meridian]

trans fluid will not be cooled if engine is not running.

 

[BruceK]

BW generally ok freewheeling one engine at trolling speed, but even trawlers go faster than that. You need to find and check the manual for your particular transmission.
Obviously something did not like what you were doing. Was the engine being turned?
There was a tired cruise ferry in Sydney on which the engine was started by towing at speed and throwing it into gear, like a clutch start of a car.

 

[Edelweiss]

Velvet drive transmissions Model 70 through 73 both C and D's can be freewheeled at trawler speed. But you should have the freewheeling transmission in Neutral. . . not in gear. It's in the BW manual I posted a couple of weeks ago. I'm on my boat and don't have access to it right now. But you may be able to search TF for it. Yes the propeller shaft will spin as the prop is turned by the water passing through it.

Do you have wet shaft logs? If not you may be doing bad things to your dripless seals. I hope you didn't damage anything!!

 

[Rduval]

Lots of info thanks, but a big concern it should it freewheel while in gear if the engine is not running?

 

[Ski in NC]

Shift lever on velvet drive does NOTHING unless engine is running. It is just a hydraulic valve, and engine spins the pump. No spin from engine, fluid does not move and valve does nothing.

Some mechanical gears (smaller sailboat boxes, old crash boxes, etc) you can lock the shaft by putting in reverse. Not so with velvet drives.

If allowed to windmill, check the tranny periodically to make sure it is not getting too hot. If it does get hot, idle engine for a while to cool it down.

 

[High Wire]

Lots of info thanks, but a big concern it should it freewheel while in gear if the engine is not running?

Assuming BW 70/71. If there is no hydraulic pressure to hold the clutch plates engaged then yes the prop shaft probably will turn. Damage in gear? I would guess yes eventually. Was the noise you described in neutral or in gear? The manual is silent other than the engine is shutdown. Would it be reasonable to assume you should shutdown the engine in gear? No. So leave it in neutral.
PS plenty of BW operation and service manuals online.

 

[Rduval]

Ok, that makes me feel a lot better knowing that it needs hydraulic pressure to run and it's not just slipping.

I've only had the one bad experience with that noise so hopefully there is no damage but I wasn't going very fast, about 4.5 knots.

Sounds like a shaft lock of some kind would be the ticket if you wanted to extend your range by using only one engine.

 

[Rduval]

BTW, I found a different manual than the others I've seen online at http://www.longpointmarine.com/BorgWarner.htm

It says:
3-4. Freewheeling
* It has been determined by tests and practical experience that all Velvet Drive marine transmissions can be free-wheeled without risking damage in sailing or trolling applications. Caution should be taken to be sure that proper oil level is maintained prior to freewheeling as well as normal running. Freewheeling one propeller of a twin engine boat at trolling speeds will not cause damage to the transmission connected to the freewheeling propeller.

Which confirms what many of you have said.

 

[psneeld]

BTW, I found a different manual than the others I've seen online at http://www.longpointmarine.com/BorgWarner.htm

It says:
3-4. Freewheeling
* It has been determined by tests and practical experience that all Velvet Drive marine transmissions can be free-wheeled without risking damage in sailing or trolling applications. Caution should be taken to be sure that proper oil level is maintained prior to freewheeling as well as normal running. Freewheeling one propeller of a twin engine boat at trolling speeds will not cause damage to the transmission connected to the freewheeling propeller.

Which confirms what many of you have said.

That's the same advice given to many Twin Disc trannies also.....the Twin Disc manuals did say I'm pretty sure to run them for an hour every 24 or so and just keep an eye on temps and fluid level.

 

[ranger58sb]

BTW, I found a different manual than the others I've seen online at http://www.longpointmarine.com/BorgWarner.htm

It says:
3-4. Freewheeling
* It has been determined by tests and practical experience that all Velvet Drive marine transmissions can be free-wheeled without risking damage in sailing or trolling applications. Caution should be taken to be sure that proper oil level is maintained prior to freewheeling as well as normal running. Freewheeling one propeller of a twin engine boat at trolling speeds will not cause damage to the transmission connected to the freewheeling propeller.

Which confirms what many of you have said.

TROLLING speed varies, but around here for striped bass that's about 2.5 kts. FWIW, we idle at about 5 kts on twins, about 4.5 kts on one engine, given no wind, tide, current, etc.... so we have to use trolling valves to get down to the speed we target.

Anyway, my point is it might be useful to examine that speed thing a bit.

Another FWIW, we often trolled on one engine but found the AP does better on both engines. Possibly to the point where our original AP rudder reference went south, had to be replaced earlier than I'd have expected. That could have been coincidental, though.

-Chris

 

[Edelweiss]

I believe all the references refer to "trolling or while under sail" those are examples only. But instead of focusing on "trolling", how fast is "under sail". Because sailboats, which don't have a feathering prop, folding prop, or shaft brake, are freewheeling their prop while "under sail."

So for all you ex-sail boater. . . what would you say is the speed a sailboat might experience while under sail?

ranger42c
A troll valve is a very good idea. Idling a diesel in gear for long periods is really hard on the flexplate between the engine and tranny. The low speed torque pulses of a diesel will cause premature failure. You can then idle the engine a little faster which is good for the engine and drive train and still get your 2.5 knot troll speed.

 

[psneeld]

Trolling really doesn't refer to fishing specifically because it can be anything from backtrolling to trolling for tuna at greater than 15 knots.

Whenever I have researched it and talked to manufacturers reps...trolling is the vessels speed at idle...it's more of an rpm thing than actual speed...yes...yes it can be vastly different depending upon application how fast a twin or sailboat would go with that engine/tranny not in use.

Usually the response is definitely under 10 knots and the 8-10 seems OK...anything less than 8 knots is pretty universal for trolling when I have looked it up.

Usually a boat that idles above 6-8 is looking for a "trolling" valve to help slow it down without constant shifting....I use that as a gauge also...

 

[ranger58sb]

ranger42c
A troll valve is a very good idea. Idling a diesel in gear for long periods is really hard on the flexplate between the engine and tranny. The low speed torque pulses of a diesel will cause premature failure. You can then idle the engine a little faster which is good for the engine and drive train and still get your 2.5 knot troll speed.

Yeah, sorta. There's an RPM limit stated in our documentation. Think it's 1000, can't remember off-hand. Also, no shifting when the trolling valves are active.

Anyway, we have almost 2000 hours on our engines; probably a bit more than half of that is idling at trolling speeds.

-Chris

 

[Underway]

That's the same advice given to many Twin Disc trannies also.....the Twin Disc manuals did say I'm pretty sure to run them for an hour every 24 or so and just keep an eye on temps and fluid level.

There was a post a while back with an excerpt from a Twin Disk manual or service bulletin that said free wheeling is OK for most models (including the ubiquitous 502) if run for 5 minutes every 8 hours and oil temperature remains below 100 degrees C. The document also mentioned an auxiliary pump that can be piggybacked on the transmission as the normal lube pump is engine driven.