Thrust on Super 7 Counter Shaft

I am just rebuilding my Super 7 after having the bed reground by Slideway services (what a good job and how helpful is Brian!). I have assembled the counter shaft and clutch but the boss on the double pulley (112 in the manual) is rubbing on the support casting (120 in the manual). I can see how the thrust in a left direction is taken by the bearing (99) but what about in a right direction?

Jan T

Hi Jan; I recently had to rebuild my S7 countershaft as the Oilite bushes were badly worn. My countershaft has a fibre washer, about 1 -2 mm thick, between the pulley and the casting. It shows little sign of wear even after many years of use, so it must be OK.

Maurice

I think you've pulled the LH oilite bush in too far. I've just had my countershaft stripped down for service and there is no fibre washer there. There is a slight step in the countershaft which bears against the end of the oilite bush and the bush is about 1 mm proud of the casting, so the pulley boss can't rub.

I think there must be more than one version of S7 countershaft. Mine is parallel its enter length; no steps at all.

Maurice.

If my memory serves, and with a look at the Super 7 manual –

If you look closely at the motorising assembly drawing in the manual you will see item 98 Part no A3329 “Abutment Washer” which fits between the clutch body and the Swing Head casting.

The bearing bush in the Swing head protrudes slightly from the casting, such that it lines up with the shoulder on the countershaft when this is inserted. The Abutment washer bears on the shoulder and the end of the bush on one side, and its other side bears on the centre of the Thrust bearing (item 99) in the rotating clutch body, so it is mostly hidden inside the centre boss of the clutch. This prevents the rotating clutch fouling the Swing head. The shoulder toward the left end of the countershaft can be clearly seen in the diagram.

The Abutment washer is 1” ext dia and 5/32” thick, so not a small item. Like most Myford bits it is chemically blackened, which helps it to hide from view!

Myford’s exploded diagrams are wonderfully informative, but their big drawback is that unlike a regular drawing you can’t see where each part belongs unless you’ve dismantled a perfect example.

So the simple answer to the original question is there should be a fat washer in there!

Edited By Robbo on 19/02/2018 23:20:26

Thanks for all the replies and the problem is now solved. On my lathe there are two ball bearings separated by a spacer in the lathe pulley. They are retained by a pair of circlips. There is a further spacer between the inner circlip and the bush in the swinging arm. This keeps the pulley away from the swinging arm. I don't think mine was an original and it was too short. A further spacer (filed by hand since I don't have a working lathe) and everything is silent. I hope I have got it right!

I have seen questions about reassembling the clutch. I had no trouble pushing the threaded rod and spring in far enough by hand, with a short length of bar, to start the nut on the other side. I had removed the large pegged washer. I then tightened the nut as far as it would go to compress the spring and then the plunger, ball and actuating leaver fitted in easily. I then simply unscrewed the nut and refitted the pegged washer. When dismantling I placed an old, very heavy coat over the leaver end of the shaft to catch the spring - it can be a little dangerous so be warned.