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Mechanism: single direction lathe spindle, dual direction motor.

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  • Mechanism: single direction lathe spindle, dual direction motor.

    Because I am not going to open it up, but I am still a curious guy

    I have a speed lathe. It has a motor with dual shafts that is integrally mounted with the lathe body on one side. The other side has the shaft ground to a Jacobs Taper and fits a drill chuck. The control has a forward and reverse. In either position, the lathe portion (with the 3-jaw) always rotates in the same direction. The motor shaft with the drill chuck, of course, changes rotation with the control position. The body of the lathe has an oil reservoir for, I can only assume, a gearbox.

    When the motor is turned off, the 3-jaw chuck will rotate in only one direction (same as driven by motor). It is very easy to turn and the motor shaft does not rotate in conjunction---the motor shaft (drill chuck) does not move at all. The 3-jaw chuck spindle will not rotate the opposite direction at all. It is solid and I feel no backlash from, say, a ratchet or gear mesh. When you rotate the motor shaft by hand, it does simultaneously rotate the 3-jaw chuck.

    I feel like this is a game from the petting zoo when I was a child. Stick your hand in the box and guess what is in there before lifting the cover. Only this time, it is "Name This Mechanism!" Personally, I have no idea. What kind of driver can rotate both ways but produce only one driven rotational direction? At the same time, what kind of driver only allows itself to drive---and not be driven? Sounds fun. Any guesses what is inside this mystery iron box?

  • #2
    Unidirectional clutches. Imagine angled spring loaded fingers (think a spiral, though they don't have to be spiral shapes) on a shaft rotating inside a drum. It transmits force much better in one direction than the other. If you have two of these, with the fingers pointing in opposite directions with one connected to the spindle through an even number of gears and one through an odd number, then the spindle will only rotate in one direction. An additional mechanism of this type can prevent the spindle from rotating backwards when back driven.

    In a variation, the motor drives two drums, side by side, one clockwise and the other counterclockwise. One set of angled fingers inside will preferentially bind with the drum which is rotating in the preferred direction. If the spindle is driven by hand, the fingers will allow rotation in one direction and will bind in the opposite direction since it will bind with both cylinders and try to rotate them both in the same direction which the gearing to the motor will not allow.

    Another way to make a unidrectional clutch is to have ball bearings between inner and outer races. But one of the races isn't round; instead it has angled steps in it which cause the ball to bind in one direction but not the other. A sprag clutch is somewhere in between these two. The two races are round but there are angled cams in between.

    Another mechanism is like the idler mechanism on a VCR. Gear on shaft, another gear meshed with it on an swing arm which pivots around the shaft. Depending on which way the shaft turns, the swinging idler gear moves and hits one of two other gears. A variation is kinda like the tumbler reverse on a lathe, but the driven shaft is the one which the arm pivots around and the arm is allowed to swing freely rather than being locked into position.


    • #3
      I was thinking some kind of sprag - but more likely a roller-type clutch such as is used for motorcycle starter motor clutch engagement.
      Peter - novice home machinist, modern motorcycle enthusiast.

      Denford Viceroy 280 Synchro (11 x 24)
      Herbert 0V adapted to R8 by 'Sir John'.
      Monarch 10EE 1942


      • #4
        What is the make of the lathe?


        Problems worthy of attack prove their worth by hitting back
        - Piet Hein


        • #5
          It is a true odd-ball. The manufacturer is Swiss: Vektor AG, model ("Kom.") 1400. Dated 1960. The motor is made by Landert Motoren. The 135mm 3-jaw is by Amar. The cross and compound (not shown) is an adapted Schaublin unit. The base is modified; otherwise, it is exactly the same as fits a Schaublin 102. The drill chuck is manufactured by the German company "Veritas". Other than some superficial aesthetics, it is constructed exactly the same as a 10mm Albrecht. In fact, I am very close to certain replacement Albrecht jaws would fit it.

          I have next to nothing regarding this lathe's history. I know of only one other person, a toolmaker in the south of Switzerland, that has ever seen one. Given that he has, I must assume there are others. It is dubious if this is in fact the maker: I have never actually inquired of them. Landert Motoren does appear to be around too: I have never heard of Amar, but the chuck is the nicest one I have ever owned.


          • #6
            Wow, incredible shape for being 50 years old.


            • #7
              I'm puzzled why it would need a non-reverse mechanism? Is the drill chuck actually to allow some live tooling to be added? (I'm thinking something like a flexible cable with rotary brush or burr for polishing etc.)



              • #8
                Purchased as "NOS", I was skeptical of such at first. After it arrived, it was clear the thing may never have been run. The crate was even original, marked as passing through New York Harbor all those years ago.


                • #9
                  Just a thought...

                  Which way does the chuck turn? There is more table to the back(?) of the machine than the front suggesting it runs the opposite direction to a normal lathe.



                  • #10
                    Originally posted by BillTodd
                    I'm puzzled why it would need a non-reverse mechanism?
                    No idea. It is worth noting that both spindles have thru-bores. You can insert a bar clear through the drill chuck, through the motor and body of the lathe and exit out the other end. The 3-jaw spindle also has a generous 36mm bore.

                    Originally posted by BillTodd
                    Which way does the chuck turn?
                    The direction is as a normal lathe. The chuck turns toward you when the spindle is on your left.
                    Last edited by Arthur.Marks; 12-03-2010, 12:51 AM.


                    • #11
                      Any patent or design pattern numbers ?

                      Bill - (very intrigued)


                      • #12
                        I suspect the reason for the one direction design is the chuck speed control shown on top of the device. The lever probably controls an eccentric, which will increase or decrease the speed of the chuck.

                        Just my guess.



                        • #13
                          I'll see what is listed in a moment. In the meantime, here are some further images to clarify its construction.


                          • #14
                            The speed control on top is an electrical switch. The motor is 2-speed, forward & reverse. The control progression is a bit unusual in that between each setting there is an "off". So as you turn the switch, it goes:

                            off, slow forward, off, slow reverse, off, fast forward, off, fast reverse. This corresponds to the labeling on the switch plate as: 0,1,0,2,0,3,0,4.

                            There is no serial number markings for the machine or patent listings. The motor is serialized, though, as well as the chuck. Otherwise nothing other than already listed. The only mark I could find is on the upper right of the flat, unpainted portion on the face of the machine where there is a small stamp, "FH".

                            Last edited by Arthur.Marks; 12-02-2010, 07:33 PM.