Laying a a scrapheap, I chanced upon a Union PD4 floor standing pillar drill. Remarking that it looked too good to go to scrap I was told 'yours if you want it'. Needless to say I did not need telling twice! I dismantled it to transport home and have conducted, thus far, a very cursory inspection and checked the details on lathes.co.uk. The machine is reasonably complete, the electrics have been butchered (possibly when converted from 3-phase) and has remarkably little 'drill rash' on the table which makes me think it has not hard a hard life or the main fault I found precluded it being used much in its former life and worthy of a little restoration work. It appears to be the two-speed model, at least that is indicated on the speed information plate, and the fault seems to be that the spindle will engage with the pulley wheel only when the gear lever is in one position which makes me think there is stripped gear somewhere in the head.

So, the question is this: does anyone have any information on this machine, other than what is on the 'lathes' site and an exploded parts diagram they could let me have? I would, of course, cover all photocopying and postage costs if the information is not in an electronic format. And, has anyone dealt with type of fault in this model of drill, if so what was their solution?

Phil,

The penny has just dropped. PD4 = 4 speed, PD8 = 8 speed, i.e. geared. Sorry, I haven't been stupid very long!

Hopper,

Yes, I will try to post some photo's as soon as I get the drill-head back on the pillar which I think will make dis-assembly easier. At the moment I am still cleaning off 50years of dirt and rust and replacing some ugly and not very spherical steel ball handles which someone has either brazed or glued on to the clamp screws. The easy jobs first!

It turns out that my assumption was completely incorrect. The gear change is not effected by some in-line epicyclic arrangement on the spindle. What I took to be a blanking plate on the top of the head casting was actually concealing the Tufnol gear assembly, minus its shaft which had dropped out and that which I found in the lower casting void. This shaft is clearly meant to run in the two bushes parallel to the main spindle, which is obvious to me now, and had originally been retained by two circlips judging by the grooves at each end of the shaft. The Tufnol gear and its accompanying steel gear on the same shaft act as sort of lathe back-gear arrangement. When the top speeds are in use the drive from the pulley is direct by the engagement of dogs on the split spindle with the steel gear being dis-engaged. When the lower speed is in use the gear assembly on the on the main spindle is moved down, disengaging the dogs and engaging a larger gear mounted on the gear-change sleeve with the smaller steel gear on the Tufnol gear shaft, which I should now really call a layshaft. The driving key for this larger gear was displaced and gear was just running free around its spigot. So there were actually two faults with the mechanism both of which are now just simple repair jobs.

Which fault caused the drive failure first is hard to say, the layshaft bushes in the casting appear to be quite worn so will need replacing, although the gears rotate freely on the layshaft which could actually stay stationary. I don't know what the original intention would have been. The large gear is running a little too free on its spigot so I will have to possibly bore it out a little and fit a bush so it doesn't rattle its key out again. But in any event I will have a machine which will well outlast me, I think. I will take some more photographs of the arrangement in case someone else encounters the same, or a similar fault, with this type of machine.

Edited By Chris Crew on 17/01/2023 13:49:41

Well, I have got the drill re-assembled for a test run but then I noticed a discrepancy. The machine, as recovered from the scrapheap has 3-step pulleys on both the motor and drill head, not the 4-step as indicated on the speed plate. I guess that makes it either a PD3 or PD6? So, may I ask if anyone has the PD8 model could they kindly measure the diameters of the pulleys on both the motor and drill head end and let me know so that I can try and source the correct pulleys from somewhere and if anyone can tell me where these pulleys may be available (I don't expect them to be OEM parts), so much the better.

Phil,

Thank you for taking the trouble to measure the pulleys on your drill. I will try to source some suitable replacements for mine although I think the sizes will have to be approximate as OEM items will not be available.

It was my error in placing the pulley the wrong way up on the spindle. I had just hastily put it back on to take the photograph and had not quite figured out at the time how everything fitted together properly. Obviously, I know now that the belt guard casing will not fit over this inverted pulley.

Clearly, the drill will be usable with the 3-step pulleys until they are replaced. It rattles slightly in back-gear, but there again so does my lathe, so I think this is normal for straight cut gears. I have fitted a new key-less chuck and given everything a good cleaning and lubrication so I think this machine will now serve as the 'proper' drill I promised myself 40 years ago when I had to buy some 'cheap Chinese rubbish' because that was all I could afford at the time. Actually, it's a Taiwanese branded Nu-Tool bench model that has given 40 of good service, still works perfectly well and cost me £150 in 1983, second-hand from a local tool dealer. Amazingly, they still cost about the same 40 years later but are branded differently.