Pros and Cons of jackshaft power.

[alan white]

Better all around, I think!

Thanks for the offer, Terry. Let me first decide if such an offer is going to convince me to finally learn CAD.
Regarding the last drawing... if a common auto crankshaft has its bottom bearing at 45 degrees, and there is a chopped-off connecting rod wrapped around it, you could replace the chopped off part with a pin like the male part of a U joint has (so the pin is on an axis at 45 degrees to the crank axis). If another crank is located with an axis at 90 degrees to the crankshaft (seen in the drawing coming on the right), which has a bearing the pin fits into (upper right corner inside the case), rotary motion can be transmitted from either direction.
The ring that is similar to the bottom end bearing of a con rod is shown trapped between the two pressed-together ends (top and bottom) of the crankshaft. You see it sectionally in the drawing, tilting to the right at the top in the center of the case. The pin inside the bearing of the shaft on the right (the biggest shaft) is a solid part of that ring. Each time the vertical crankshaft makes a revolution, the ring is tilted, so that a half revolution ahead of the drawing would show the ring angled down 45 degrees to the right instead of up 45 degrees.
Every shaft and bearing in the drawing has an axis that passes through the very center. The lines where the two crank halves are joined by a press fit should be disregarded in terms of function. I show them as simple lines only, whereas all actual bearing connections are shown as either needle or tapered roller bearings.

Alan

[BillyDoc]

Alan, please do me a favor and take a look at this old post: http://boatdesign.net/forums/showthr...612#post137612 showing a design for a wind-vane self steering device. I am very curious to see if you can improve it and get rid of some of those gears. The friction from some of them doesn't matter as they are just for setting a course, but the friction from the ones in the error signal path matter very much!

I didn't know how to upload images when I made that post so I had links to a web site that had them . . . which no longer exists. So the images got lost and the post is too old to edit. To correct this I just added them again in post #10.

By the way, for your information you can upload images by clicking on the "Manage Attachments" button when you are composing a post, entering the image location (using the Browse button is easiest) and then clicking on the "Upload" button to the right of the "Browse" buttons.

BillyDoc

[alan white]

I read what you wrote back then. I saw the pictures. I haven't used windvanes, but I know what they do. I know that the position of the vane is relative to wind direction, and tab position is relative to the rudder/boat. I know that the degree difference between the two changes depending on point of sail changing, so reindexing is required as the wind shifts and also when on a different point of sail.
Then the tab is mounted on the rudder (usually), and it serves to swing the rudder in the direction opposite the tab is angled, causing the boat to maintain an ongoing relative angle to the wind. The other type is an entirely seperate rudder. Which type are you designing?
I've seen several methods of pivoting a windvane. The one you show appears to be the type that pivots on a horizontal axis. Your coil-spring "shaft" accomplishes the turn to a vertical axis, fine.
I imagine the coil is pretty efficient but weak for its bulk, and is well suited to the task you've asked it to do, since high rpm would eventually fatigue it, but small movements won't for a long time. It has zero backlash and it also absorbs a bit of shock, which so far looks good.
Down to the gears...
Here is where I'm mystified. There appears to be a lot of gearing (each connection between will add to backlash). The effort is to get mechanical advantage and something else I think.
Alan

[alan white]

A sketch of the L drive... still learning about attachments. Disregard the picture on the keft. It's the one to the right I wanted to upload. I think longliner was asking for a more descriptive sketch.

[BillyDoc]

Alan,

I can see that I really screwed up my description of the self-steering gear so I'm going to give it another try, but I don't want to hijack this thread doing it so please meet me over at: http://boatdesign.net/forums/showthr...=self-steering in an hour or so.

BillyDoc

[alan white]

Originally Posted by BillyDoc

Alan,

I can see that I really screwed up my description of the self-steering gear so I'm going to give it another try, but I don't want to hijack this thread doing it so please meet me over at: http://boatdesign.net/forums/showthr...=self-steering in an hour or so.

BillyDoc

Okay.

A.