HMV 145 gramophone

[Techman]

I mentioned in a couple of previous threads that I’d been given an HMV 145 cabinet gramophone. It’s not huge as far as some of these cabinet types go and was smaller than I’d pictured it would be. I’d posted a couple of pictures in these previous threads. It’s not in good condition due to having obviously been somewhere very damp for many years, although the innards were in a lot better state and I did try a bit of chrome cleaner on the tone arm etc. and it looked like it would clean up quite well. The outer cabinet being largely veneered, had suffered badly in some parts as shown in the pictures and even the veneer at the back of the inside area just below where the lid hinges had rippled and was coming away. Also, there’s no winding handle.

I really don’t need one of these gramophones taking up space, but thought as it was a bit rough, that I could use the excuse that it would make a handy garage gramophone to casually play some of the many 78s that I’ve got stored on a steel shelving unit in there that’s bending under the weight!

I removed the motor board and the lack of grubby finger marks on the lubrication diagram that’s pasted onto the underside, led me to believe that this unit hadn’t had a lot of attention during its life. I do know however, that the person that had given me the gramophone had removed the motor board and retrieved quite a few of needles that had dropped down under it and into the cabinet. He had told me that he’d wound the platter backwards to wind it up enough to play half a record – I did tell him off a little for doing that! I found a bolt of the right thread and wound it up a bit with a socket. I found that after so many winds that the spring seemed to slip. I wound it to a point just before it slipped and after giving a little oil to a few of the bearings and cogs, I popped the motor board back in place and it played about half of a 10” 78 rpm record. It sounded good and the sound box seems to be in perfect order.

I thought there might be a chance that it was slipping due to hardened grease and the fact that he’d been messing about winding the turntable platter by hand and one of the two springs had come off its hook and couldn’t find its way back on again. I removed both springs and as can be seen in the pictures the lower one has its outer hook end broken off, also, the hook part on the inside of the spring barrel has been bent out straight! I don’t now actually think that him winding the platter backwards has caused this, and this has happened a long time ago. I couldn’t at first find the broken off end of the spring, but I did in the end hidden in the middle of a chunk of hard grease – the broken piece can be seen at the very bottom of one of the pictures that shows the inside of the empty spring case showing the lower hook bent out.

I think that due to the hardened grease, someone has over wound it to try to get it to play a full record and wound it so hard that it’s done the damage shown. It could be repaired, but due to the overall condition, I don’t think it’s worth the time and trouble as this isn’t a particularly rare model. The spring could be shortened, and the end re-formed – I’ve shortened and re-done clock springs before. You might get away with bending that hook on the barrel back, but I think it’ll be weakened. The rivet could be drilled out and a new hook made and re-fixed with another rivet or a nut and bolt.

It’ll probably be broken up for parts for others that may pass through here sometime, but I thought I’d document its story on here for future reference. I’ve at least got one good spring for use in another machine if necessary, then there’s all the other useful parts such as the governor springs – I recently successfully rebuilt a governor in another motor from parts saved over the years and mentioned in another recent thread regarding a different gramophone. I coiled up the springs and popped them into a handy biscuit tin with a cardboard spacer between them to keep them apart and prevent them from getting tangled together when I come to remove them again for use sometime in the future.

I’ll let the following pictures tell the story :-

[Techman]

Some more pictures :-

[Techman]

And some more pictures :-

[Herald1360]

Might be interesting to mount a small LS in place of the tonearm and see how much noise you can get from a 200mW tranny.......

[RojDW48]

It's sad but probably the right way forward - one has to draw the line somewhere and spares for old wind-ups are not ten-a-penny!

[Techman]

The horn would certainly amplify the sound from a small speaker - how about mounting it on top of your car and adapting a standard car horn to it - that would make folk jump! Three of the four tone arm bolts come out easily, but one of them needed tightening slightly before it would move. I've had it moving for a couple of turns by very carefully turning it backwards and forwards in stages as I can do without it breaking off.

I agree that it is sad to have to give up on it, but as you can see, it is in quite bad condition. There's some worm in the rear panel, it's not 'riddled', but several of the holes are quite large, maybe a touch of the old deathwatch beetle! The holes look to be old, so probably long gone.

I'm temped, when I get a bit of spare time, to perhaps clean up that barrel and the springs, bend that hook back into position and take a blow lamp to the end of that broken spring and re-make the end. The worst that can happen is it'll go 'twang' again!

It's worth mentioning that the only reason that it was possible to wind it up enough to play half a record was that the 90 year old grease was hard and sticky enough to hold the broken spring in place to allow it to get some tension in it. If the grease was as it should be, there would have been no winding tension at all with a broken spring.

The grease really was solid in that one and needed a squirt of diesel to free things off. The shaft that the barrel revolves on, after removal of its holding grub screw, needed drifting out with a long bolt and a big hammer, it was so solid, and that was even after a squirting of diesel.

[1100 man]

I have an HMV 520 radiogram from 1927 in a very similar condition cabinet wise. This has an early electric deck & pick up. The cabinet is exactly the same style & design as your windup.
If you decide not to break it up I would be glad to give it a good home as it would be interesting to have both an acoustic & electric machine from the same manufacturer. I recently repaired an HMV 101 for a friend and it was great fun so have been after a larger machine.
I also like a challenge and basket cases are appealing! There would, of course, be logistical challenges getting me and it together geographically!!
Apologies if that sounds a bit cheeky but if you don't ask....!
Many thanks
Nick

[Herald1360]

I've got a rather large reentrant horn PA speaker I last used in anger in 1977 on a carnival float that I could do that with. Be better mounted on the front bumper, though. Up top it would increase the height just enough to foul the 2.25m height limit in the local Waitrose carpark.

I've only ever repaired one gramophone spring motor- a single spring job where the anchor point was just a punched in tab which had sheared off. ISTR a Meccano screw, washer and nut was pressed into service. Getting the spring back in was "interesting" but I've still got all my fingers.

[Techman]

Originally Posted by 1100 man

I also like a challenge and basket cases are appealing!

Hi Nick, I think I can already tell that to be the case, as by your name and avatar, you're into restoring the Austin 1100. I once had the Wolseley version and I remember jacking it up and the engine and subframe remained where they were on the floor while the rest of the car lifted up!

No worries about being cheeky - it's always worth asking. I've not made up my mind exactly what I'm going to do with it just yet.

[Techman]

Originally Posted by Herald1360

I've only ever repaired one gramophone spring motor- a single spring job where the anchor point was just a punched in tab which had sheared off. ISTR a Meccano screw, washer and nut was pressed into service. Getting the spring back in was "interesting" but I've still got all my fingers.

Did you see that post I made in another thread where I showed a spring drum which had a nut and bolt in place of one of the rivets in a Thorens motor? That had obviously suffered a similar problem at sometime in the past. I haven't needed to remove the springs for cleaning on that particular motor.

When I was a kid, my dad brought me my first wind up gramophone home from work where a work mate had given him it, as he knew his son liked that sort of thing to mess about (play) with. It was a rather attractive Decca portable, but it had a broken spring. I remember eventually dismantling it in the garden. I got a big screwdriver out of the shed and just levered the spring out. Well I didn't know what would happen and no one had told me that it might be dangerous! I had no idea that the spring would be under tension and expand very quickly to several times its size. It started to unravel and fly round flicking about all over the place. Luckily I was holding the barrel and I just chucked it and it went into the flower bed, bouncing around and taking the heads off all the flowers. That was my first lesson in gramophone springs. It's very lucky I managed to survive in one piece with all those things I got up to back then!

[rontech]

If any of your 78s are in good condition i.e. few visible scratches, chips, scuff marks or a pronounced "greying" indicating groove wear; then I would recommend separating the good ones and reserving them for use on later electric pickup systems.

Acoustic soundboxes track at playing weights measured in several ounces

[Audio1950]

Originally Posted by Techman

He had told me that he’d wound the platter backwards to wind it up enough to play half a record – I did tell him off a little for doing that!

Why? It's a very good way to wind the motor if the handle is missing. As you turn the table backwards, the winding shaft that goes through the centre of the spring is turning in exactly the same direction as it would do if the spring was wound with a handle, so no harm can be done. But I reckon it would be a long and tiring job to do this with the two huge springs in this particular beast of a motor!

Barry

[1100 man]

Hi Barry,
I'm intrigued as to why they have used two springs? Do they just sit side by side in the barrel?
As you may remember, I removed the spring from the case on the HMV 101, cleaned & re-greased it.
I found, with a full wind, it would easily play 2-3 sides of a 10" record. I was surprised how much power it had. I was also surprised at the excellent speed regulation: in fact, the whole project yielded many surprises!
How does the size of each spring compare with the 101? Just curious! Will this player play more sides between winds?
It would certainly be an interesting challenge to repair the spring ends and make the deck functional again.
Cheers
Nick

[Techman]

It's a good question as to whether any harm can be done by winding the motor backwards. I always understood that it was bad practice, although whether this has anything to do with the springs, or perhaps to do with the helical cut gears and worm drives being cut and angled in such a way as to ideally run in only one direction, I don't know.

The shaft that runs right through the middle of both springs is just a straight forward shaft that the whole lot rotates on, and is not connected to either of the springs or anything else. The winding gear only winds one of the springs and is connected to the first spring and winds it from the middle. The two springs are wound into the barrel in opposite directions. The first spring that is the only one connected to the winder, is wound into the barrel in an anticlockwise direction. The second spring that is completely separate from the winder, is wound into the barrel in a clockwise direction. I believe that this effectively puts both springs in series - they're not in parallel for more power as many would think. The idea is to give one long length of single powerful spring for a long playing time per wind.

Although I've been playing with gramophones since I was a child and probably before I started messing with electronics, and I'm now retired, it's been sporadic and occasional, as I'm not particularly a collector of such things, except when they happen to come my way for whatever reason. Whereas, as I understand it, Barry is an avid collector and has no doubt worked on hundreds of gramophones, so can probably explain the exact mechanical theory better than I can. I seem to think that Barry's main interest is in portable models, so whether he's had direct experience of this particular motor, I wouldn't know. I expect he'll post soon to put us in the picture.

[PJL]

You need someone with clock repair experience. Springs are often supplied in standard lengths and the fitter has cut to size and terminate. It involves tempering by heating, bending whilst soft, then heating up and quenching to restore the hardening.

However, you might want to check that the two springs are correct before you start.

[Audio1950]

The motor in this machine is the HMV No.32, and takes springs an inch and a quarter wide. They are readily available, if somewhat expensive.

This motor is unusual in that the central shaft is completely smooth, whereas on the vast majority of motors, there is a cog attached to one end, and either a pin, or a shaped indent that holds the inner end of the spring half way down the shaft. This one is wound by a large cog on the top side of the spring drum. It is also unusual in that the two springs are contained in one single drum, whereas on other motors, each spring drum is individual. However the principal is the same, so my comment that no harm can be caused by winding the turntable backwards applies to all motors. Now, after 50 years of collecting gramophones, the question of how the two springs work in tandem when the two spring are working in opposite directions is one I have yet understand. The theory that as one spring unwinds it winds the other one up doesn't make sense, because a spring winding down wouldn't have enough power to wind the other one, and conversely, the one being wound up would surely cause the one already unwinding to struggle to turn the motor? If anyone can explain, I for one would be grateful!

[Techman]

Originally Posted by Audio1950

Now, after 50 years of collecting gramophones, the question of how the two springs work in tandem when the two spring are working in opposite directions is one I have yet understand. The theory that as one spring unwinds it winds the other one up doesn't make sense, because a spring winding down wouldn't have enough power to wind the other one, and conversely, the one being wound up would surely cause the one already unwinding to struggle to turn the motor? If anyone can explain, I for one would be grateful!

I left it a bit ‘open ended’ (a bit like the broken spring) in my second paragraph in post #14 and didn’t finish the explanation of the full line of power transfer to the output of the spring unit and onto the rest of the motor.

As the first spring is wound by the spring winding gear connected to its centre, the outer end of the spring would normally be expected to be held firmly by its connection method (be it hook, eye or whatever) to the spring barrel. This barrel in a single spring motor (or a clock) would be held firmly in a stationary position by the gear wheel directly fixed to it. The big difference with the double spring motor described here, is that the barrel is NOT held firmly by the method just previously described, but is anchored ONLY by the outer (or tail) end of the second spring. The output gear that drives the rest of the motor is NOT fixed directly to the barrel, but is connected to (driven by) the centre of the second spring.
So, assuming the motor is stationary with the platter brake applied, the winding handle is rotated which starts to coil up the first spring from its centre. This immediately causes the outer end of the spring to exert a turning force on the spring barrel. This would normally be held firm and stationary in a single spring arrangement, but in this instance it’s held from this turning force by the outer end of the second spring which is coiled in the opposite direction to the first spring. The turning force from the outer end of the first spring immediately starts to wind up the second spring from its outer end, having its inner end held firmly by the output gear connected to it. Thus, the two springs ‘should’ wind together and should also unwind together, all things being perfect. In reality, I suspect that different frictions with varying hardness of old greases etc., probably cause a bit of unevenness and in extreme cases, as we’ve had here, the power delivery between the coils in the two springs would have been very hit and miss to say the least. It's possible that sometime in the past, someone has wound it up really tight and caused the end to break off the second spring, probably because half the coils were stuck together by old hardened grease further down the spring. When the platter brake is released after winding, the power from both the springs is transferred to the motor from the centre of the second spring via the large output gear. This is different to a single spring motor where the large output gear is fixed to the spring barrel and the drive to the rest of the motor is taken from the outer end of the single spring via the barrel and its fixed on gear cog.

Looking at the ‘mechanics’ of how the springs relate to each other, the statement regarding not winding the motor backwards would seem to relate either to possible damage to helical and worm drive gears, or has possibly been misunderstood and it was to not turn a platter forwards with a good spring in place, as this would wind the spring backwards causing it to either come off its hook or possibly snap. The subject is very debatable, and I certainly should have thought about the mechanics involved before passing it on, but if I hadn’t, then we probably wouldn’t have had occasion to have this analysis of the gramophone motor, so all’s good in my opinion. When I was a kid I certainly used to rotate turntables forward with my finger on the centre label on records on gramophones with broken springs so as to play them. In both cases I can think of, one was a single spring motor and the other a double spring motor and as far as I remember (it was a very long time ago) both had springs broken in the middle, which is where I’ve found they usually break. This is a first for me with a spring broken at the outer end.

To further the debate on helical gears being used for rotation in one direction only, I’ve dragged out another motor and photographed the helical gear arrangement used in place of a ratchet on the winding mechanism. If you study the picture you’ll see that there’s NO conventional ratchet, either silent or otherwise. The spring is wound up via the winding handle through the helical gear, and the fully wound spring is held in this state by those gears NOT turning in a reverse direction. The maximum force that those gears resist is just the force exerted by the fully wound spring. The winding handle releases if it’s turned in the reverse direction.

Pictures below of helical non-reversible winding gear arrangement used in a gramophone motor. The motor we have in the HMV gramophone uses a ratchet arrangement, so it should be remembered that the pictures are of a different motor and are being used for demonstration and comparison only -

[Techman]

Originally Posted by Techman

The turning force from the outer end of the first spring immediately starts to wind up the second spring from its outer end, having its inner end held firmly by the output gear connected to it.

I'm perhaps confusing the issue with the way I've described this part and perhaps I should have explained it in a slightly different way. Although a turning force is being exerted on the barrel, the effect of the turning force against the stationary output shaft effectively would be the same motion as exerted from the winding gear connected to the centre of the first spring. What I'm trying to say is that although the barrel of the springs is being rotated by the tail of the first spring effectively pulling on the tail of the second spring, it can be thought of as if the second spring is actually being wound from its centre, even though the centre is being held stationary by the rest of the motor and the platter brake - if that makes sense.

[1100 man]

So in effect, both springs are in series rather then parallel. I assume this would give more playing time per wind? I wonder why they needed to do this? The down side would be to wind it fully would take twice as many turns as a single spring motor. The HMV 101 single spring motor took more than enough turns to fully wind it!! Interesting!
Nick

[julie_m]

It does not make any difference whether the springs are in "series" or "parallel"; the total amount of potential energy stored when they are both fully wound will be the same either way. Now, work done in Joules = metres moved against force * opposing force in Newtons. Two springs in "parallel" will push twice as hard as one spring but will only move the same amount as one spring; whereas two springs in "series" will move twice as far but only push as hard as a single spring. But all this can be taken care of in the gearing anyway.