Ballpoint Pen Mechanism

I searched the archives, but couldn’t find any information. I have been trying to figure out how the click forward then retract mechanism works in a ballpoint pen. I sacrificed two pens and cut one accross and the other lengthwise. There 3 tubular pieces and it appears to be some sort of ratchet but I still can’t quite figure it out. I would really like an explanation, but I suspect that a cutaway diagram is the only way to understand it. Any suggestions as to where I can find an illustrated explanation?

I have with me a little Pilot pen that has a clear body, so you can see exactly how it works. The thing you push down (A) and the thing on the top of the ink tube (B) are kept from rotating by guides in the body, but because of slanted surfaces, A is trying to make B rotate by a little bit. When you push it down, part B goes down far enough that the guides are not restricting it anymore, at which point it rotates just a little bit. Then when it retracts, it can’t go straight into the guides, but the guides also have slanted surfaces that cause it to rotate a little more, in the same direction. So with every up/down cycle, part B rotates one notch. The notches are arranged so that in every other one, part B is restricted from moving up all the way, so holds the ink tube (and the point) in a down, extended position.

I hope this explains it, if not, go get yourself a clear click pen.

I can’t find a visual aid online, but here is a description from this site:

When the push-button is pressed, the catches of the thrust tube are fully inserted into the fixed slots with which the top part of the body of the pen is provided. When the button is released, the action of the large spring retracts the reservoir. The catches of the thrust tube (connected to the reservoir) engage with the small teeth on the rotating sleeve. The reservoir is then in the writing position. When the push-button is pressed again, the catches of the thrust tube plunge into the fixed slots. The rotating sleeve, which is spring-loaded by a small spring bears on the sharp edges of the fixed slots, while at the same time the sleeve rotates an amount corresponding to one tooth.

When the thrust tube moves back, the rotating sleeve is first lifted and, at the same time, turned. The catches of the thrust tube can then plunge into the large tooth gaps of the sleeve, so that the reservoir is fully retracted. The action is again controlled by the sleeve, which performs a small rotational movement whenever the push-button is actuated.

There is a much simpler form of retraction mechanism. It embodies a ball catch. When the push button is pressed, the steel ball rotates in the clockwise direction in a heart- shaped cam recess the side of a cylindrical sleeve attached to the push-button. The position of the ball within the cam recess determines the position of the ink reservoir. When the push-button has been pressed, the ball is at the top holding point of the recess. It is held there by the pressure of the spring. The reservoir is then in the writing position. When the button is pressed again, the ball goes to the bottom holding point of the recess, and the reservoir slides back into the body of the pen.