Tray-top centilathe problem
Close
Login to Your Account
Results 1 to 7 of 7
  1. #1
    Join Date
    Mar 2018
    Country
    UNITED STATES
    State/Province
    Idaho
    Posts
    15
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    1

    Default Tray-top centilathe problem

    I have a 1950 12.5 inch centilathe. The c-d-e gear selector on the quick change gearbox does not work. The lever moves but no gear change. I have not pulled the gearbox yet. Was wondering if anybody has ever fixed this problem ?

  2. #2
    Join Date
    Jul 2017
    Country
    UNITED STATES
    State/Province
    Michigan
    Posts
    113
    Post Thanks / Like
    Likes (Given)
    10
    Likes (Received)
    22

    Default

    If your Cintilathe is like the one in the TrayTop manual from 1952, the C-D-E shifter is very similar to the one used in the later Hydrashift lathes like mine. A simple arrangement of a lever affixed to a vertical shaft with a taper pin, the shaft running up into the QCGB housing from the bottom, then a short lever inside the housing (affixed to the shaft with another taper pin) with a bronze "fork" on the end the moves a sliding gear horizontally. Maybe one of the taper pins is broken or missing, or the bronze "fork" has broken or worn through on at least one side? The latter seems like the most likely, especially if the lathe has had a lot of use.

    Here's what my Hydrashift QCGB looks like from the backside after removal from the headstock. The end of the inside lever is just visible, as is the bronze "fork" that engages the gear just above it.

    100_0316.jpg

    Unless the problem is the joint between the hand lever and the shaft, I think the QCGB assembly will have to come off of the headstock to get a look inside. It's not hard to do, just tedious. If you have to disassemble and re-assemble the QCGB internals, that's a bit more complicated.

  3. #3
    Join Date
    Mar 2018
    Country
    UNITED STATES
    State/Province
    Idaho
    Posts
    15
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    1

    Default

    I think you are correct. From the diagram and parts lists that I have it looks very similar. I had considered the same possibilities that you mentioned. Now to pull the qcgb and see what I can see. Thanks for the reply.

  4. #4
    Join Date
    Mar 2018
    Country
    UNITED STATES
    State/Province
    Idaho
    Posts
    15
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    1

    Default

    Looks like it is more serious than just a worn shift fork. It is obvious that somebody has been in there before. I don't think even the quick change gears have any effect on lead screw speed along with the cde selector. It is like something is jammed up and causes everything to rotate at the same speed no matter what gears are selected other that the ab selector. don't know how that is even possible. Anybody have a quick change gearbox for sale ? Right

  5. #5
    Join Date
    Jul 2017
    Country
    UNITED STATES
    State/Province
    Michigan
    Posts
    113
    Post Thanks / Like
    Likes (Given)
    10
    Likes (Received)
    22

    Default

    You've pulled the QCGB from the headstock, and can observe the gears from the back (open) side? Could you post some photos or even a short video as you move the levers to show what is (and is not) happening?

    What did you see that convinced you that someone has been in there before?

    A QCGB for a Cintilathe will probably not be easy to find, unfortunately. Unless there are broken parts, the problem may just be improper reassembly by the previous owner, and that will likely be easier and faster to fix than finding a replacement unit.

  6. Likes sfriedberg liked this post
  7. #6
    Join Date
    Mar 2018
    Country
    UNITED STATES
    State/Province
    Idaho
    Posts
    15
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    1

    Default

    Thanks for the reply. How do you post photos ? I may have found the problem. If you have the exploded diagram for a similar model. It looks like somebody welded the gear, feed reverse and spacer - tumbler gear shaft. Parts 26 and 27, 601577 and 601576. Which is okay I guess. It should be an idler. But then they swapped part 6 and 8. These are the shaft retainers. This basically made the reverse idler a driven gear that by-passed the rest of the gearbox. Some other misc parts missing.

  8. #7
    Join Date
    Mar 2018
    Country
    UNITED STATES
    State/Province
    Idaho
    Posts
    15
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    1

    Default

    That was it. Of course one of the keys was sheared off also. The lead screw was being driven at two different speeds at the same time because of the swapped shaft retainers. Thank you to whom ever put the manual on line. Would never have found this without the exploded qcgb view.

  9. Likes Paolo_MD liked this post

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •