Myford Super7 low speed range problem

This topic has 8 replies, 7 voices, and was last updated 18 January 2017 at 17:23 by mick.

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18 January 2017 at 10:22 #32876
mick
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@mick65121
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18 January 2017 at 10:22 #278566
mick
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@mick65121
I've had my pre-owned Myford for seven years now with no real problems apart from readjusting the spindle bearings about a year ago. I'm experiencing a drive problem in the low speed range which has started without any apparent warning. It doesn't matter which belt setting is selected the spindle only just rotates while the motor is at full revs, you can stop the motor rotating by holding the chuck, which doesn't need any pressure to halt it. The lathe behaves perfectly okay when the high speed range is selected. I've tried adjusting the clutch from no engagement to full engagement but without any effect to the underlying problem, any input would be appreciated. Thanks.
18 January 2017 at 11:00 #278570
ASF
Participant
@asf
There is a two toothed driving washer (not sure of correct name) that may be the issue. I had this fail on mine but cant remember full symptoms. It did drive but relied on friction to power it. It can be found on the clutch assy underneath the nut on the left hand side.
18 January 2017 at 11:27 #278575
KWIL
Participant
@kwil
That part is called a "driver plate" A3320/1
18 January 2017 at 11:42 #278578
Brian Wood
Participant
@brianwood45127
Wouldn't the driver plate, if faulty, affect the drive in both speed ranges?

Brian
18 January 2017 at 11:44 #278579
Brian Oldford
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@brianoldford70365
Is the bull-wheel "turn-over" tab being dis-engaged properly?

Edited By Brian Oldford on 18/01/2017 11:46:45
18 January 2017 at 12:49 #278591
daveb
Participant
@daveb17630
It sounds as if the back gear is not engaged, check that the back gear lever has not slipped on the eccentric. Also check that there are teeth on the back gears. There have been occasional problems with the drive pulley slipping on the bronze sleeve, may be worth checking this too. Just re read your post, if you can turn the machine in low gear without undue effort by pulling down on the drive belt, it is most likely a motor problem

Edited By daveb on 18/01/2017 12:52:14

Edited By daveb on 18/01/2017 12:59:20
18 January 2017 at 15:36 #278608
Mike Poole
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@mikepoole82104
Where does the drive stop turning when you put your hand on the chuck? Does the headstock pulley set still rotate? I think there are a few possibilities to lose drive, as already mentioned check the driver plate on the end of the countershaft, is the key and grub screw in the countershaft four step pulley intact, if the grub screw has come loose the key may have sheared so the countershaft spins in the pulley. Check the lever that disengages the headstock pulley from the shaft is working, if you hold the pulley then you should not be able to turn the chuck. Does the clutch engage properly?

Mike
18 January 2017 at 17:23 #278639
mick
Participant
@mick65121
Hi. All. Thanks for the replies, I've had another play with it. When I first tried to reset the clutch the adjustment lock nut was tight so I thought it had to be something other than adjustment as the clutch was engaging as before and I haven't had to touch it all the time I've owned the machine, however as I tried to fine tune the adjustment to the 0.010/ 0.015 gap described in the manual nothing appear to be changing, but as health and safety don't regularly inspect my shed I tried adjusting the screw with the belts in the lowest speed position, the clutch engaged and the motor running, this way I was able to find the sweet point when the clutch started to bite, which appears to have worked and things look to have returned to normal, but it doesn't fully explain why the adjustment, that was locked, failed without warning, hay ho, the joys of owing an iconic British machine!!
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