harrison 140 screwcutting gbox

Hello All,

I'm hoping that there might be someone familiar with the metric ( 3 rotary selector knob) norton gearbox on the Harrison 140. My problem is that the selector knobs are not functioning correctly. If I change either of the 2 left hand knobs I usually end up with a false neutral - i.e no rotation of the feed shaft and lead screw. If I waggle the knobs and manually rotate the output and input I can usually get things working but what a royal pain. So my questions are:

  1. What is the likely cause of this fault.
  2. How do I get the g'box off. The casting appears to be doweled and bolted to the headstock. It looks a bit daunting to me as I'm a newby and anxious not to bugger up what is otherwise a great lathe.

thanks in advance


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Is this the 8 speed (34-750) model? If you need a manual see

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you can get a copy from there.Give Tony a ring he's a nice guy and loves his machine tools.It's a great site,set aside a couple of days for a proper look.

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Hi, My lathe is an 8 speed variety (aren't they all?) covering 45 -

1000rpm. Infact I do have a manual (a photocopy) albeit one for an L5/L6 - which I believe is essentially identical internally to the 140. There are a few sectioned drawings showing the guts of the gearbox, but these diagrams are too small and indistinct for me to make much sense of them. What I want to know is what I need to do to get the gearbox off so that I can have a proper look inside. It is not clear to me how I disconnect the feed shaft and lead screw. I'm also in the dark about the gearbox mounting. There appears to be dowels locating the box. Do I need a special puller once the allen screws have been removed?

thanks, tim

snipped-for-privacy@tiscali.co.uk wrote:

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Hello Tim,

Probably no consolation, but mine did that too... To be honest it never occurred to me that there was anything wrong, so I just put up with it!

Good luck,



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