Got to messing with a gas engine that has an output flange to stub shaft, which slips into slick (no splines) u joing socket. The shaft is held in place in relation to the socket with a Woodruff key and crosspin.
My Woodruff key is a little wedge thing that looks like a sliver of a circle. Why are they made that way? Looks like it'd be stronger to have a rectangular shaped wedge. Just curious.
As a guess - the slot in your shaft is probably circular. (A rectangular key wouldn't fit.) A circular slot will trap the Woodruff key so it can't move or slide out the end of the shaft (assuming a rectangular slot is cut to the end of the shaft).
-- bud--
It is much easier to machine the socket in the shaft in a semi circle than another shape. I also would tend to think that you could assure a tight fit easier as well.
Well, you're right about the strength factor. You're just thinking about it from the wrong angle. First, think about how the woodruff slot can be cut into the shaft; a rotating cutter plunged into the shaft along its axis will yield a semicircular groove, and a semicircular woodruff key will fit just fine. Or make the machining process just a little more complex and cut a slot by moving the cutter along the shaft axis and you can use a square woodruff key. Their purpose is to provide alignment between the mating parts, particularly for timing or balancing purposes. The actual clamping is from shaft taper or a crosspin. In some applications the key is counted to shear to prevent damage to rotating equipment in the event of a jam or over torque condition.
That's probably more than you wanted to know.
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