Motor Removal
October 2014
The last part is the heavy work. Firstly the lathe itself needed moving so I could get at everything, so it was out with the engine hoist. No problems there, especially with lots of it removed. Secondly, the pulley and motor assemblies are both very heavy - I'd guess at around 30Kg each, and in quite a confined space so care is needed. You can't just reach in and lift them out. The book is pretty good here and the procedure is spot on.
Motor
The whole motor and pulley assembly is hung from a large pivot (below, 1). The motor is then hung from another pivot from this first one (below, 2). The main pivot controls the tension of the main flat drive belt, and is controlled by the handle next to the door. The bottom pivot controls the tension of the twin belts which drive the pulley shaft. The tension is adjusted by a large threaded rod (below, 3). So this needs to be loosened or removed so that the tension can be released, and the twin belts removed. An easy way to hold it while removing the tensioner rod is to use a g-cramp:
The twin belts can then be removed by rotating by hand and gradually levering them off with a screwdriver. The lower shaft (2 above) is then driven out to the left hand side using a drift, via the handy hole in the side of the motor plinth. This is a plain shaft which bears directly on the cast supports, (since it doesn't actually rotate once the belts are tensioned).
As per the book, I chocked the motor with a couple of bits of 3x3 timber, and it just dropped gently onto them. I then had to disconnect the cable - on this one just done by choc-block connectors in a small enclosure. Inside I found a note from when this motor had been fitted, in 1991 by the looks. He'd also handily left instructions on how to reverse the motor, which was very nice of him since a reversing switch is something I definately want. My thanks to whoever it was:
I noticed two grease nipples at either end of the motor, so I squirted some more in there using a gun. The motor itself is simply bolted to the large cast mounting using 4 bolts.
Cone Pulley
With the motor out, the top mounting can be removed, and with it the cone pulley. First, remove the crank assembly which is used to tension and detension the main belt. I rather liked this, it's a nice, solid, simple bit of engineering. Definately was due an overhaul though - the main pivot pin at the top had nearly worked its way out (top arrow). The bottom arrow shows the taper pin which holds the handle on the bottom of the shaft - awkward to remove, and as it turned out, no point in doing so. Should have just left it there.
Before removing the handle, some method of supporting the whole affair seemed to be in order - I didn't fancy trying to lower it gently down with one hand while unscrewing with the other. Easy enough with a bit of rope though.
The whole assembly then pivots down to rest against the inside back wall of the plinth. To remove it, the pivot shaft must be driven out like the previous one. BUT this one runs in Babbit (soft, white metal) bearings. I've only come across this used for oiled bearings, I'm assuming that they were used here to prevent anything sticking over the years? Anyway, being soft, the book warns to take care not to damage them while removing the shaft - the bearings were poured in place so can't be easily replaced.
So I looked at the shaft....ugggh:
Lots of gunge and corrosion, didn't fancy driving that through the bearings really. So I spent a while awkwardly trying to clean it up as best I could with various brushes and white spirit. It was a bit impossible given the lack of access, but I got the worst of it off. Then the shaft is driven out to the right, it came out without scoring the bearings too badly. Then I lowered the whole assembly down using the rope.
The oiler set up on the cone pulley is quite interesting. Under each bearing is a sump fed by the side oil caps. a large metal ring hangs on the shaft and into the oil; as the shaft turns, this ring transfers oil onto it, from where it runs along into the bearings. Again a nice, simple idea.
Looking down from above the shaft - the copper-coloured ring can be seen hanging on the bearing. The oil cup screws into the hole on the right hand side.
I wanted to take this out and make sure that all the bearings were ok. To remove it, the large pulley has to be removed from the end. This is held on with another taper pin. Given my success with these so far, I set about it.
After an hour I'd achieved nothing, so I left it soaking in penetrating oil and came back the next day. Things didn't go much better, despite trying blowtorches, ever larger hammers and ever stronger swearing, I ended up with nothing except a broken punch.
The next approach is to drill the pin out, but it was going to be rather difficult as there isn't enough space to get the drill in there. At this point I took a step back. The shaft runs freely without binding, and there's no noticable play in them; I was on the cusp of a "doing more harm than good" moment. Getting the pin out is going to require some butchery, and will only probably confirm that actually, it's all ok. So I gave up trying to remove the shaft, and instead elected to clean it out as well as possible with lots of solvent.