Partial Tranny Engagement

[BlowMeAway]

At the end of last season I discovered that I didn’t need to fully latch the shift lever of my propeller transmission (forward or reverse) into locked position to get rotation on the prop. My latch mechanism is pretty stiff to unlatch on the Edson pedestal going from F to N to R or vice versa. I learned that it was so much easier, and affords a lot more speed control, to just lighty “bump” into gear under idle RPM’s when drifting into or out of the slip, without full engagement (locking) of the shift lever. So my question is, am I doing any harm to the tranny with this partial engagement?

 

[jssailem]

@BlowMeAway, Wayne have you ever driven a stick shift car... What happens when you ease it into gear and keep your foot on the clutch?
Known as "Riding the Clutch".
You burn the clutch up.

Your boat transmission has: Clutch type - Mechanical parallel servo cone
When you "Partially engage" the clutch you are riding on a part of the servo cone. The prop is spinning slower than the engine drive shaft is spinning.
Keep it up "Riding the Clutch" and you will burn up the Mechanical parallel servo cone. Transmission failure and You'll be in for the joy of a transmission clutch repair/replacement. $$$ and down sailing time.

Better to fully engage or disengage and drift.

 

[BlowMeAway]

@jssailem Hey John, thanks for the heads up. I wasn’t aware that the clutching mechanism between F and R was a cone. I was thinking plates, so I didn’t even consider clutch issues. I’ve driven manual transmissions all my life and get it. Sure, I’ve feathered auto, tractor trailer, and motorcycle clutches a lot too. So I’m guessing your thinking that even a brief (5-10 second) F to R bump on the cone clutches is undesirable? Based solely on the sound of the drive shaft, at low RPM’s, and resultant propulsion, it seems (seriously) like the tranny is fully engaged without latching the lever. It that possible?

 

[LeslieTroyer]

@BlowMeAway not all transmissions are based on cones. The Hurth and ZF trans have clutches like the car automatics but are compressed manually where the automobile has a hydrolic pump connected to the input shaft. Read your trans manual and see if you are getting the required throw.

Here is a helpful site (pointing to zf & Hurth)
https://www.foleyengines.com/products/marine-transmissions/

Mahalo