Velvet drive gear lever position

[Blackbadger]

Hello, I've just connected my engine and have it running. It's has a borg warner velvet drive gearbox. I've strobed the crank and gearbox and it appears to be 2:1 ratio. According to the manuals (I've no id plates unfortunatley) the 2:1 gearbox can be handed, if running in the wrong direction for extended periods may damage it. My question is, the manual states on the drawings of the other boxes that the gear selector toward the engine is forward. The drawing for this box only points towards the gear lever and gives no indication of either.

Am I correct in the logical assumption that mine being the same? Before I order the handed propeller can anyone confirm please ?

Thanks for the replies in anticipation ?

 

[Hadenough]

Forward = forward and aft = reverse.

 

[omega2]

They can be handed by changing the reduction box, but as stated forward for forward and back for reverse.
Did you save the link? if so read it.

 

[Blackbadger]

Thank you, all fine sorry for the delay in replying and manual confirmed this. Will pay more attention to them in future

 

[oldgit]

Had pair of 72 Velvet drives attached to pair of Perkins M135.
The engines both rotated in the same direction, in order to get counter rotating shafts one gearbox was
set up to run counterclockwise.
Whoever set them up did so in the non preferred direction from the norm.
Did not seem to make much difference unless going astern.
As result the forward and reverse ratios of my gearboxes were different and the prop pitches were different to compensate by around 2-3 ".

 

[Blackbadger]

Have since ordered the propeller following researching and she is now launched. Although she is a new build, or rather an unfinished project we have managed 8 knots at about 1800 rpm. Although twin engines would be desirable for us not an option currently. I guess, noting the differences having the gearboxes running the same way makes the mechanism easier.

 

[scottie]

I have thought about 1.99-1 and 2.01-1 ratios when handing velvet drive boxes which would account for difference in pitch?
The odd figure decreases wear I understand

 

[oldgit]

My gearboxes were AS 17 72 CR.
Forward 1.91:1
"Reverse" 2.10:1.
Cannot remember for the life of me remember which rotated clockwise and which counter clockwise.
A robust gearbox by all accounts up to around 250 HP..
Still have the workshop manual.

 

[spearfish2018]

I have thought about 1.99-1 and 2.01-1 ratios when handing velvet drive boxes which would account for difference in pitch?
The odd figure decreases wear I understand

The odd figure comes from the adoption of the "hunting tooth " in the mesh(es) of gear pairs -
Often achieved by prime nos of teeth in a mesh which evens out wear by ensuring no regular wear pattern can develop