Problem With High / Low Speed.

M

Marc

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Hello,
I have a problem with the high/low speed selection from my AVM AS125 lathe.
While I was working on my lathe in low speed suddenly the spindel of the headstock blocked. After checking what happend I found that I can't select high/low speed anymore, the selector switch is working fine, and the sprocket can move freely.

When I now select low speed the spindel is blocked. I have opened the the headstock but can't find anything broken or wrong, has anybody experienced this before, or does anyone know how I can solve this problem ? I'll ad the drawing of my headstock maybe it will help.

Regards Marc.

ImageUploadedByTapatalk1439035485.986668.jpg




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I would look very close at the gears #867, 869. Something there must be the problem.
 
One method of locking the spindle on an old manual lathe with a back gear is to put it in both conditions at the same time, back gear pin engaged-front gear engaged, this will lock the spindle.
 
High gear 2.jpg

Hi
The drive from 868 to 867 in high gear is ok.
but the drive from 868 to 869 to 867 low gear is not.
as 869 moved or locked in some way ???
jeff
 
Last edited:
Hello Jeff,

Gear 869 is moving freely in high gear, but in low gear it is stuck.
Everything is nice and tight nothing has moved.

Regards Marc.


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It looks to me like gear 867 is a sliding gear that is keyed or splined to the spindle. When 867 is slid to the left, it engages the cone pulley and transfers power directly to the spindle which is then is in high. When 867 is slid to the right, 867 engages the teeth of 869 which is in constant mesh with the cone pulley but 867 should not engage the cone pulley at that point and the spindle is in low. Based on all of this, I see three possibilities:
1. A chip or other foreign object is preventing the 867 sliding gear from moving far enough to the left and it is engaging both the cone pulley and the 869 gear at the same time.
2. The cone pulley is no longer in its proper position and his slid to the right far enough to engage the 867 sliding gear while it is also in mesh with the 869 gear.
3. The 869 constant mesh gear is no longer in its proper position and it has moved to the left enough to engage the 867 sliding gear while it is also engaging the cone pulley.

First thing I would check would be the bolt that holds the 869 gear to its stub shaft. If that bolt loosens up the gear could slide to the left and cause the problem.
 
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