Borg Waner Velvet help.

[stevesteve36]

Hi Everyone I don't no if someone could help me . I've been trying to find a Borg Warner Velvet expert to answer a question have.

I have a twin engine boat which I've modified to take to the French canals next year when I retire.

At present both props are r/h and I want to covert my R/H transmission to counter rotate.

I've researched and found that the rotation direction is selected from the reduction box bolted to the rear of transmission.

I've acquired a counting rotation reduction box and was hoping to just bolt onto my transmission but the only difference I can see is the oil return pipe from the oil cooler.

On my current transmission the oil return pipe goes into the top of the reduction gear yet the counter rotating reduction gear has the return going into the transmission .

I need to be cautious as my 1st trip after sea trails is across the channel.

Hope someone can direct me in the right direction. Regards Steve

[RLWP]

Which model gearbox this Steve?

 

Richard

[stevesteve36]

Hi Richard Box is. BW 72 ratio 2.10 To 1 and the counter rotating reduction box is 1.91 to 1 .

A bit of background is the current box in boat has been really good over the last 12 years , I've purchased a complete counter rotating 1.91 to 1 box but the history is unknown .

Thanks Steve

[RLWP]

This one? http://www.marineryachts.com/borg_manual.pdf

 

Annoyingly, it doesn't include a plumbing diagram for the reduction box

 

Richard

 

MORE: How about this one: http://www.marinemechanic.com/fpdb/Borg-Warner-Velvet-Drive-71C-72C-Transmission-Owners-Manual.pdfPage 2

Edited November 14, 2015 by RLWP

[mick55]

Hi Steve

Borg Warner gearbox Velvet Drive 72c is a hydraulic box, and as such will happily run in either direction of rotation, the ratio is the same whichever direction it runs in, this can be done by altering the direction that the selector lever operates, once you have changed one of the props to the opposite hand rotation, it is just a case of changing a cable over at the control lever which is relevant to the gearbox that you want to change rotation of, hope this helps!

Best regards

Mick

[RLWP]

Hi Steve

Borg Warner gearbox Velvet Drive 72c is a hydraulic box, and as such will happily run in either direction of rotation, the ratio is the same whichever direction it runs in, this can be done by altering the direction that the selector lever operates, once you have changed one of the props to the opposite hand rotation, it is just a case of changing a cable over at the control lever which is relevant to the gearbox that you want to change rotation of, hope this helps!

Best regards

Mick

 

I wouldn't recommend running a Velvet Drive in 'reverse' as the standard method of use. The epicyclic cluster isn't really intended for that

 

Richard

[Tony Brooks]

Agreed, although they are probably better lubricated than other marine boxes using sun & planet gears.

[cereal tiller]

Hi Steve

Borg Warner gearbox Velvet Drive 72c is a hydraulic box, and as such will happily run in either direction of rotation, the ratio is the same whichever direction it runs in, this can be done by altering the direction that the selector lever operates, once you have changed one of the props to the opposite hand rotation, it is just a case of changing a cable over at the control lever which is relevant to the gearbox that you want to change rotation of, hope this helps!

Best regards

Mick

Yes,but,The Borg Warner Reverse Clutch assembly is substantially smaller than the Ahead set.

 

Running the Transmission in reverse for extended periods would wear it out rapidly!

 

Would be prudent to use a unit of the correct rotation.

 

CT

[gazza]

Right, I'm going to poo poo all the above.

 

Do not run it in reverse - b position (as it would be in a hurth box), the ratio is slightly different and its not continuously rated in reverse.

 

Rotation is changed by altering a plate in the front of the box. Any box can be run in LH OR RH, giving the option of counter rotating props on twin engine installation as you require. Its marked up for the direction you require, simply pull the box and check where it is at the moment and change to the option position.

 

The reduction box doesn't come into it either AFAIK.

[RLWP]

Rotation is changed by altering a plate in the front of the box.

 

That's to accommodate different rotations of engine input. Turning that plate reverses the oil pump (a gear pump)

 

Richjard

[MtB]

 

That's to accommodate different rotations of engine input. Turning that plate reverses the oil pump (a gear pump)

 

Richjard

 

 

Beat me to it Richiard. That's my understanding too.

[cereal tiller]

 

 

Beat me to it Richiard. That's my understanding too.

Most correct chaps.

The Borg Warner Marine Reversing units were not a Hydraulic transmission ,they were Hydraulically Actuated transmission.

Different rotation for input could be selected by means of shifting the forward cover but these units were indeed handed FOR LEFT OR RIGHT ROTATION on the out put shaft.

One Reduction would be 1.9 to 1 and the other would be 2.1 to 1.

 

As RSVP pointer out, the Epicyclic

reverse mechanism was only intended for intermittent use when reversing

 

CT

[MtB]

Unlike say the PRM D260, which is rated to run the output shaft continuously at full power in either direction, whatever the input shaft rotation direction.

 

Mebbe the OP would be better of getting a D260

Edited November 15, 2015 by Mike the Boilerman

[RLWP]

Most correct chaps.

The Borg Warner Marine Reversing units were not a Hydraulic transmission ,they were Hydraulically Actuated transmission.

Different rotation for input could be selected by means of shifting the forward cover but these units were indeed handed FOR LEFT OR RIGHT ROTATION on the out put shaft.

One Reduction would be 1.9 to 1 and the other would be 2.1 to 1.

 

As RSVP pointer out, the Epicyclic

reverse mechanism was only intended for intermittent use when reversing

 

CT

That is the best mis-spelling of my forum name yet. Hurrah for autocorrect

 

Richard

[stevesteve36]

Thank you all for your time and thought to help with this matter.

Regards turn the oil pump to change direction I found below in a Velvet manual.

All Velvet Drive units except the 2.1O:l In-Line and CR2 units may be used behind engines having either rotation; however, the pump must be indexed for the desired rotation. The reduction unit planetary carrier is’ different for opposite rotating 2.lO:l In-Line units and early failure will occur on these units if they are driven in the wrong direction.

I believe the difference between the 72C (r/h) and 72CR (l/h) boxes is the reduction box bolted on the back. But I can't see why return hose from oil cooler on the 72CR goes into the bottom of the transmission where on the 72C it goes into the reduction box .

Anyway thanks again any further advise will be greatfully received . Regards Steve

[Tony Dunkley]

Hi Everyone I don't no if someone could help me . I've been trying to find a Borg Warner Velvet expert to answer a question have.

I have a twin engine boat which I've modified to take to the French canals next year when I retire.

At present both props are r/h and I want to covert my R/H transmission to counter rotate.

I've researched and found that the rotation direction is selected from the reduction box bolted to the rear of transmission.

I've acquired a counting rotation reduction box and was hoping to just bolt onto my transmission but the only difference I can see is the oil return pipe from the oil cooler.

On my current transmission the oil return pipe goes into the top of the reduction gear yet the counter rotating reduction gear has the return going into the transmission .

I need to be cautious as my 1st trip after sea trails is across the channel.

Hope someone can direct me in the right direction. Regards Steve

 

If you change the starboard propeller to Lefthand rotation (when running ahead) you will then have handed inward-turning propellers which will give you slightly better propulsive efficiency than outward-turning props, but at the cost of very much reduced manouevrability, particularly when operating one engine ahead and the other astern.

The gain in efficiency with inward-turning props is minute, and so the outward-turning option is generally preferred due to the gains in the way the boat handles.

Edited November 15, 2015 by Tony Dunkley