Myford Super 7 back gear won’t engage

[Andrew Phillips 4Participant @andrewphillips4]

Hi All, I have a Myford Super 7 lathe. I wanted to clean up a thread so engaged backgear to get an appropriate speed. I engaged the backgear lever in its upper position, released the backgear key, as I have done many times before. I released the clutch, and the spindle did not turn, while the gears made a graunching sound. Checked everything was set properly, but still the same result. I have checked all relevant gears and can see no missing/broken teeth. Confession time: I have in the past engaged backgear to remove chucks before I knew better, but, as I said, no teeth were missing or appeared damaged. The only thing I can think of is the backgear lever is not lifting the gear high enough to engage teeth on spindle gears. Has anyone out there had this problem? All suggestions welcome. Cheers, Andrew

[Andrew Phillips 4Participant @andrewphillips4]

[Chris TriceParticipant @christrice43267]

I'd loosen the belts and turn everything forward and backwards by hand to find the problem. Can you turn the back gear cluster under the spindle by hand when it's not engaged? If it rotates freely, it's not that. Similarly, with the key in the disengaged position, can you turn the belt pulleys independently of the spindle? It is possible your back gear lever is out of adjustment. Its position is adjustable via a grub screw.

[Russ BParticipant @russb]

check the vee pulley hasnt siezed to the spindle ie. with the backgear disengaged, release the backgear key and check that the spindle is able to turn freely from the vee pulley or visa versa.

Check the back gear is also able to spin freely when disengaged with a suitable long pointy thing poke down into the bottom and spin the backgears on their shaft.

If they're both turning freely…… who knows

 

Edited By Russ B on 06/02/2019 12:39:43

[Russ BParticipant @russb]

Sorry Chris beat me to it

[Chris TriceParticipant @christrice43267]

Great minds….

[Andrew Phillips 4Participant @andrewphillips4]

Chris, Russ, thanks for your prompt replies, very helpful. Chris, you were right about backgear lever going out of adjustment – I have readjusted it and I can now engage backgear and it works under power. Cheers, Andrew

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