crank problem

[cabr]

Good evening to the specialists,

yesterday my paddlewheel is finishied, today I've got a serious problem. Please look at the picture showing the stern of my boot. If I mount the wheelaxis on the designated place, then I have only 15 to 18 mm for free crank rotation. I think it's to short for the 120 mm wheel. For a longer crank there are two possibilities, first move up the axis from the beam, which lifts the wheel out of the water depending on the waterline. Second cut the plywood to make room for pitman and crank to rotate.  Any other suggestion's or is a length of 15 mm enough to drive the wheel ?[img]problem.jpg[img]

[Eddy Matthews]

The 5mm plywood should have a slot cut in it to clear the crank/pitman arm..... I hope the following photo will show what I mean more clearly?

Regards
Eddy

[cabr]

The 5mm plywood should have a slot cut in it to clear the crank/pitman arm..... I hope the following photo will show what I mean more clearly?

Regards
Eddy

Yes, I've seen this in other pictures before, but my plan shows nothing like this. Maybe because they are using gears to drive the wheel.

How long the crank should be ? I haven't seen any other plan before so I don't have an idea. My plan is a steamer without a reallife example, so there are no pictures exist to look and compare. I think there must be a specific relation between wheel diameter and crank length, otherwise I make the crank for the best appearance. 

[Eddy Matthews]

No doubt there is a length of the crank which is correct, but this will all depend on the bore and stroke of the engine. From the various boats I've looked at, the crank appears to be 1/4 to 1/3 of the wheel radius, so in your case a crank length of 15mm-20mm would be about right.

Regards
Eddy

[andy]

Hi,

when using a steam engine, these 15mm for the crank were enough, because the steam engines always have a very good torque. But I think, with an electric driven engine, it was ok, too. Depends on the mechanics, you plan do drive the wheel.

Andy

(Munich/Ammersee)