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  1. #1
    Join Date
    Apr 2012
    Posts
    0

    Lagun Variable Drive problem

    I have a newly acquired completely rebuilt older Lagun vertical knee mill with variable speed head. The variable speed has gone awry and the rebuilder says it is due to the newness of the bearings and probably needs some more lube. I removed the top plate and poured oil down the shaft and bearings areas as he recommended. The tilter did start to move some, but the speed adjustment chain mechanism is not working correctly. It changes the speed only slightly. Also, upon start up there is a high pitched screeching in the upper head area. Sounds very scary, like a bearing.

    Anyone know how to reset that silly little chain and sprocket?

  2. #2
    Join Date
    Feb 2009
    Posts
    6028
    Re-builder got something wrong IMO. Our guys do those heads all the time, never seen one fail like that afterwards. Probably a belt squeal, and the motor pulley is probably not moving up and down like it should.

  3. #3
    Join Date
    Jan 2009
    Posts
    63
    Not knowing without more details what vintage or HP your varispeed is, but I've got a '79 FTV-3 with a varispeed I'm in the middle of rebuilding. A couple things:

    - Whether you knew this or not, DO NOT try to change the speed on a varispeed head without the motor running, or you'll probably wreck something

    - Assuming youre up against a stop on the speed adjuster, you can "reset" your chain by getting as much slack as possible, then unbolting the adjuster from the head and rotating it around to get it within the range you need

    - Is your brake hanging up or chattering? Do you have a manual or air-powered brake? Brake resistance or spindle resistance could certainly be causing your belt to slip and make terrible noise.

    - I don't know if your backgear shift has a neutral position, but if it does shift into neutral and make sure that the spindle can be spun easily by hand - you can do this by rotating the drawbar with your hand with the quill all the way up

    - Can you pull a cover and verify that when you change speeds that both of the varispeed sheave sets are moving in opposition to one another? The squeal sounds like a belt slipping, could be that one of the sheaves is not putting pressure on the belt as it should be. The front one is linked via chain to your handwheel on the front, the back is spring loaded.

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