Tom Senior small vertical head axial play

[chris1984Participant @chris1984]

Hi all,

 

I am trying to remove axial play of  both axes in the small vertical head of my Tom Senior.

 

For the horizontal axis, I was kind of assuming that the nut needs to be either tightened or have a shim/washer put behind it. This is a right-hand thread nut, i can tell from protruding piece of thread. Unfortunately, I haven’t been able to loosen this so far. I don’t see what is holding the nut,was glue common?

I’ve tried penetrating oil, carburator cleaner and even heat. No luck so far. Also the lock the spindle, I’ve engaged the back gear. Is that ok or bad practise?

 

Any advise would be much appreciated!

 

Herafter will be the vertical axis, the spindle. It is not clear how to preload that to remove axial play. Both upper and lower bearing seem to float up and down in the housing. Looks awkward …

[Kiwi BlokeParticipant @kiwibloke62605]

 

Hope this helps.

As can be seen, there’s no adjustment provided for axial pre-load of the driving shaft thrust bearings. I suppose shims will be required. The nut should undo, if you can better the strength of the Yorkshireman who tightened it. Don’t rely on gear teeth to react the torque you apply to the nut! IIRC, once the the large diameter mounting ring is removed from the attachment, the end of the driving shaft is accessible, and can then be held securely.

The angular contact bearings on the vertical spindle are clamped to the shaft by the threaded collar at the upper end – it’s not an adjuster. Preload again must require shims twixt bearing outer and cover. Sobering to realise that axial forces are reacted by four piddling little slotted screws…

[not done it yetParticipant @notdoneityet]

Jeremy is quite right re possible (even likely) gear breakage, if relying on locked-up gears to resist turning during nut removal.

I have used a ‘rattle gun’ to remove nuts that have been too tight to remove with a long breaker bar.  Just be aware that the proper type of socket should be used with these tools.

Sometimes a piece of softwood can help to keep the shaft stationary.  There are other means of doing this, depending on the shaft arrangement, if the rattle gun will not undo the nut easily.

 

[chris1984Participant @chris1984]

Hi,

Thank you for the replies. I bought a 26mm socket for my impact driver, we’ll see if that works. Otherwise I guess that I will ask my car mechanic to address that nut.

Washer #20 is missing in my setup. That certainly explains the play on the horizontal axis.

I managed to loosen the lock nut in the mean time, only to realize that i need ship rings under that cover as you suggested. Strange none are there ….

 

Chris

[Kiwi BlokeParticipant @kiwibloke62605]

I’m pretty sure the nut will be an imperial size, so, if a 26 mm socket fits, it’s likely to be 1″ AF. Snug fits are safer…

The unspeakable rogue who ‘lost’ washer #20 possibly plastered Loctite on the threads, so take care: it might require the application of heat, to soften the stuff. I remember having to sit on the end of a six-foot scaffold pole, slipped over the end of a 3/4″ drive breaker bar, to loosen a nut in a Land Rover gearbox which had been assembled with threadlocker. Heating wasn’t practicable. I wasn’t quite so heavy in those days, so it must have been safe…

[David SeniorParticipant @davidsenior29320]

More likely that the fixings would be whitworth size so a 5/8″ BS thread has a nut of 1.01″ A/F (25.65mm) so, in the absence of a proper whitworth socket 26mm is likely to be the best (though a 1″ would probably fit).

[chris1984Participant @chris1984]

For the horizontal axis:

I got the nut loose with an impact driver and a 26mm socket.

I said before that washer #20 is missing, it still is, but I do not see the use of it. The nut tightens the gear against a shoulde on the shaft. There is no way to pretension the thrust bearings. I ended up cutting shims from 0.2mm brass sheet between the bearing 5 and the body. I needed 2 of those. No more axial play, moves freely.

 

For the vertical spindle:

I ended up cutting a shim from the same 0.2mm brass sheet. It sits between top cover 9 and the outer ring of bearing 12. This pushes the outer rings of both thrust bearings towards each other.

 

 

The lock nuts on both horizontal and vertical axis thus do not allow to control any play. Now i need to check if this was worth the effort …

[not done it yetParticipant @notdoneityet]

No axial play may be appropriate, but often a tiny amount is recommended to allow for differential temperate expansion of a warm shaft running in a cooler casing.

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