hand crank dimensions

[sgtbull]

I've searched the forum, and it's probably here somewhere, but I didn't manage to find it. Can someone provide me the dimensions to fabricate a handcrank? Specifically, I need:

1.Diameter of shaft
2. Lengths of the three segments
3. crank pin diameter and length
4. distance from center of crankpin to the end of the handcrank where it goes into the pulley.
5. Orientation of the pin in relation to the handcrank, that is, if the crank were laying on its
side, is the crank pin also laying flat, or is it perpendicular to the crank?


I need one for myself, and if it comes out good, I may start making them for others.
thanks again.

[Rudi]

Kelley:

Yup, it is right here.. Implement and Part Sketches, Lombard's Cub Hand Crank. Enjoy

[RaymondDurban]

Here you go:

More good information here:
viewtopic.php?f=1&t=31457&hilit=hand+crank+dimensions#p248614
Hope this helps.

Rudi's fast!!

[Rudi]

Raymond:

There ain't no moss on your rear either By the time I had refreshed with the jpeg, yours was already there...

[sgtbull]

PERFECT! thanks gentlemen.

[Rudi]

Kelley:

Just looked closer at the jpeg drawing. Lombard shows the pin horizontally through the hand crank. If I remember correctly, the pin should probably be about 15 degrees off of the horizontal plane... but I am not sure. Maybe one of the others will be able to clarify that.. Cecil Ralph

When I go out to the barn in a bit, I will double check.

[Peter Person]

Rudi,
You are correct.
The pin is off horizontal so your hand is at about 4:00 to crank the engine.
Just don't wrap your thumb around the handle.
Peter

[flyawa]

All of the cubs I've gotten with cranks have the pin at 90 degrees to the handle. That pin is what keeps the handle from slipping around when clipped into the mounting clips. The pin goes into the hole in the floor pan and keeps the handle in place.

[Pony Master]

We had a discussion about this while at the Central Indidana CubFest. Some of the early tractors had the pin offset some. I bought a handcrank with the offset thinking it would be good on the 47. I am not a big fan of it. It will not stay under the crank clips and spends all of it's time in the toolbox. If you plan to mount it to the floorboard like they are supposed to be, put the pin at 90*. You will be much happier.

[sgtbull]

Most all of the handcranks I"ve seen over the years had the pin perpendicular to the crank "plane". It seems that when the crankshaft on most tractors are oriented with the pin horizontally, the firing piston is at tdc. Not really sure why. I"ve been trying to wrap my brain around that, and it would almost seem that if you hit tdc as you were pulling up, say, at about 9 o'clock, you would be less likely to get it kicked back.
As I've always been taught to only crank up, all fingers on one side, it seems that I lose momentum as the crank hits 12 o'clock, as I don't "spin" the crank and really don't have a follow thru once I hit 12 o'clock. Might explain the 15degree offset on older tractors as a safety thing. Magnetos rely on the impluse to retard the spark, so if it failed to do so, you would more likely get a strong kick back. Later distributor's rely on weights to advance the spark AFTER the engine starts, making kick back less likely..... Any thoughts on that?

[Jim Becker]

The orientation of the pin in the drawing is correct. Some of the reproduction cranks have it positioned differently, but I assume that was because of using a twisted crank for a pattern.

You want the engine to fire when the crank is at the top of the swing so that if the crank slips out of your hand your arm will be outside of the path of the handle. One reason for only pulling up is so that if you loose your grip on the crank, you are already pulling your arm out of the way. If you are pushing down and the crank gets away from you, you will be pushing your arm straight into the path of the crank.

Don't ever hand crank an engine that is showing symptoms of a failing impulse coupling.

[Rudi]

Jim:

Thanks for the clarification. I was of two minds on that... on one hand I thought for sure the ones I had with the horizontal pin were correct, (they better had been since I had 20 of them made ). I also figured that the offset pin would be brought up so I mentioned it.

Now I know not to do that again, and leave the offset out! Plus I now know why to boot

[bear32055]

If i can remember i will bring my crank along on saturday