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2 standard rotation engines?

Posted: Mon Nov 07, 2016 8:43 am
by Leviathon
Can you use 2 standard rotation engines, and just change the rotation on one of the Velvet drives?? :?:

Re: 2 standard rotation engines?

Posted: Mon Nov 07, 2016 11:21 am
by EWRice
No, and yes. When we talk about changing the direction of a velvet drive, it means matching it to the engine rotation. With one exception, the output of the transmission matches the input direction. Since you want your props to spin opposite directions (to counteract the rotational force of each other) you would have to have one trans that has an output that spins opposite of input in fwd. There is a reduction version that does this, but there is not a transmission with the same ratio that has input/output directions the same. You could find one with a close ratio and adjust your props, but that is alot of screwing around.

Plus, having two flywheels and rotating assemblies spinning the same direction, in an inboard boat, can have some strange gyroscope type effects. You don't get this in boats with I/O.

Re: 2 standard rotation engines?

Posted: Mon Nov 07, 2016 2:18 pm
by Leviathon
Thanks - that is what I thought. Appreciate it!

Re: 2 standard rotation engines?

Posted: Mon Nov 07, 2016 6:40 pm
by spdracer
You could if you switch to a ZF or Velvet Drive 5000 or Liberty series. Those transmissions use LH rotation inputs and can output LH or RH without an issue.

Re: 2 standard rotation engines?

Posted: Mon Nov 07, 2016 8:19 pm
by EWRice
Does the ZF 1:1 have this ability? Or can you only do this with a reduction? I have never delt with either transmission (other than routine service). They must be good units.

Re: 2 standard rotation engines?

Posted: Sun Nov 13, 2016 5:42 pm
by spdracer
The down angle transmissions are all reductions. ZF does make a copy for a velvet driver cast iron 1:1 in aluminum, but the same principles still apply.