Pipedreams

[grendel]

make sure it has oil, and make sure the oil isnt full of water- or it makes a helluva racket when it gets hot.

[BroadAmbition]

The drive plate does the job a clutch does in a car is the simple description

 

Erm actually the drive plate doesn't do anywhere near the same job as a clutch in any sort of car.

 

A clutch on a car will disengage the flywheel from the gearbox input shaft via a pressure release bearing and springs on the pressure plate, separating the clutch face from the flywheel, thereby disengaging the gearbox from the engine drive even if  still 'In Gear'

A driveplate on a boat engine will constantly spin the input shaft on a gearbox whenever the engine is running - It cannot be disengaged (Other than mechanically stripping down or catastrophic failure)

The driveplate is bolted to the flywheel.  There is a splined female fitting fixed in place by a 'Cush' or heavy duty rubber fingers in the centre of the driveplate.  The splined input shaft from the gearbox fits into the splined female fitting.  Whenever the engine is running the driveplate and gearbox input shaft are constantly turning.  Engaging Fwd or Aft via the morse control will engage the fwd or Aft gears within the gearbox instantly from the input shaft.  The driveplate and input shaft remain rotating in the same direction constantly together at the same speed as each other.  The rubber 'Cush' allows some movement akin to a shock absorber / taking up the slack.  Applying more rpm's to the engine of course speeds up the driveplate / input shaft / gears / prop shaft.  It is to be avoided going from fwd to astern without pausing as this can cause premature wear on the driveplate cush /splined fitting and the splines on the input shaft, to such a degree that drive will be lost entirely.  I suspect Pipedreams cush has failed and the spline female fitting is spinning free of the rest of the driveplate

Hope this helps?

Griff

 

[kpnut]

So in a clutch, the two parts come apart. I remember that from ‘cut-out’ tractor engines at college.
And the difference in a boat is the two parts stay joined all the time and just go the other way when you change from forward to reverse or vice versa. And there’s a bit of leeway given by the ‘Cush’ (I’ll remember that by thinking of it as a soft cushion) to soften the result of changing direction. Done too fast over many manoeuvres might wear out the Cush.

Now, what’s this about oil that Grendel mentions?
Is that just the oil in the engine, or the oil in the gearbox (both of which I check and top up when and if necessary) or is there another oil input I’m missing? If so, yikes!

[BroadAmbition]

Just to be crystal, the drive plate & input shaft do not change direction of rotation at all ever - for that to happen you would have to turn off the engine then start it running backwards ( Grendel could possibly achieve this unheard of feat )

What does change direction of rotation is the prop shaft via the internal gearing in the gearbox, drive / power / torque which of course is supplied by the input shaft from the driveplate

Griff

[RumPunch]

Interesting, and I learnt someting there !

[kpnut]

1 hour ago, BroadAmbition said:

Just to be crystal, the drive plate & input shaft do not change direction of rotation at all ever - for that to happen you would have to turn off the engine then start it running backwards ( Grendel could possibly achieve this unheard of feat )

Got it (at last he sighs😂) Thanks. 

[grendel]

oil in the gearbox.(often overlooked)