Fleischmann Turntable Indexing problem

[drmditch]

I have a very old Fleischmann Turntable, which I purchased in about 1994 or thereabouts.

It has always been built into my storage sidings, and I bought it for ease of operation and reliability rather than for any prototypical appearance.

(The turntable on the 'visible' part of the railway is scratch built and quite different!)

 

When the old railway was dismantled in 2014 it was packed away, and has only re-emerged into the light of day earlier this year.

Its operation was a bit sporadic and noisy, so I thought I had better give it a clean, (including removing fur from my late lamented ginger cat) and a small amount of lubrication.

 

It is now set up again as here.....

 

 

 

 

 

The control switch (and panel for the spur lines is here.....

 

 

 

The problem is that, if I remember correctly, it used to move from one spur to another with a flick of the control. Ie it would automatically index to the next outlet track.

(Unless one held the switch over when it would move over more than one track.)

It now doesn't seem to do that, and one has to stop it in the correct place by eye.

 

Is it just my memory which is at fault, and perhaps it was always like this?

 

 

There is an existing thread for this (or similiar) turntable .....here...., but does not seem to discuss this particular problem.

 

A wider  web search produced some useful material, but again, doesn't seem to address this problem. (Most of what I found was to do with DCC operation which interests me not at all!)

 

I am now familiar with most of the mechanism, having stripped it down and re-assembled it twice. It is now smooth and quiet in operation.

However, I cannot identify any electrical part of the assembly which would provide a 'stepping function', even though the final drive cog with it's plate spring appears to be engineered to provide a mechanical means of 'locking' in the correct place.

As one would expect with Fleischmann, it is a precise and ingenious item, and tricky to assemble and re-assemble, and I'm reluctant to strip it down again unless I know what I'm looking for!

 

Is there just something that I haven't seen?

 

 

 

 

Edited September 2, 2020 by drmditch

[drmditch]

After much examination, testing, adjustment and re-testing, my turntable is now as good as I think I'm going to get it.

At one point the indexing was very good, but very' sticky' to release, and needed frequent override with the manual lever.

Now the indexing is not quite as automatic, but the release is better and the manual override required less often.

Here are the 'works'.

 

 

 

I will set out later how I think this works, and the 'balance of springs' which provides the indexing and locking.

 

Does anyone else have experience of this turntable?

 

[WIMorrison]

I replaced the motor on mine a years or so back for the same problem that you are having

[drmditch]

1 hour ago, WIMorrison said:

I replaced the motor on mine a years or so back for the same problem that you are having

 

Thank you. Was it just the motor you replaced (see below) or the whole assembly (as above).

 

[drmditch]

I have cleaned all the parts, and made sure that there is sufficient but not too much lubrication. (ie not very much at all). I have also made sure that nothing is 'snagging'.

 

Some detail of the Fleischmann turntable drive.

It's clever, and a bit finicky.

 

 

 

I do not understand all of it, but the what I do understand is:-

 

The final drive gear on the left engages with the teeth on the turntable well assembly. The rectangular indentations on this gear are the Locking Points. As you see there are four of them at the four cardinal positions. The number of teeth between the Locking Points are the precise number to travel between the entrance/exit tracks.

A - indicates the line of a nickel-silver (?) plate spring.  and sliding peg (E below) locates in the Locking Point and is held in by the spring. The ends of the spring fit into the slots marked G below.

 

(Keeping that spring in place during re-assembly is very tricky.)

 

 

 

The grey plastic bar has peg E at one end, and at B a hole for a lever from the top-plate of electromagnet D.

 

 

The actual drive is from quite a small motor, and two worm drives.

 

 

Removing the uppermost worm allows the motor to be lifted out.

 

 

 

In operation, the activation of the electromagnet pulls the grey bar to the right. There is a plunger (just above the letter B) which closes contacts at C thus motor. Simultaneously the peg E is pulled out of the Locating Slot thus allowing the final drive gear to revolve.

 

When working properly, there must be a mechanism by which the spring A overcomes the electromagnet and pushes peg E into a Locating slot once the gear has performed a quarter turn.

I cannot identify this.

 

The distance between the spring contacts at C is not (as far as I can test) critical for this function, provided that the plunger on the gray bar can close the contact.

 

On the first worm on the motor shaft, there is effectively a clutch, indicated by the two screwdrivers in the picture. The larger (RH) screwdriver points to a spring around the shaft. The smaller (LH) screwdriver points to a projection I have marked F.

 

It would be logical for F to activate the clutch once the final drive gear is in position for an entrance/exit track, but I cannot see how!

 

I don't think I have lost any parts, and I cannot see what else to adjust.

 

So, any clues please.

 

Vorsprung durch Technik anybody ?

 

 

[WIMorrison]

The motor and gearbox came as a single unit 

[drmditch]

4 minutes ago, WIMorrison said:

The motor and gearbox came as a single unit 

 

Can you remember the source?

(and how you fitted it?)

 

[WIMorrison]

I bought it from Fleishmann and it takes about 5 mins to fit it, just need a soldering iron to make the connections.

[daltonparva]

It's a long time since I took one of these apart, but if I remember correctly there are 3 wires to the mechanism:- a common (-), a positive to the relay, and a positive to the motor. The switch supplies a feed to the motor wire all the time but only supplies a feed to the relay when you operate the switch; a temporary contact on the first position until the switch springs back, a permanent contact on the second position until you release the switch. When you operate the switch the relay moves and pulls back the long grey bar out of 1 of the 4 indents in the toothed cog, and completes the circuit for the motor feed wire. The motor rotates the cog, and the rotating cog is now holding the long grey bar against it's spring to make the motor feed contact until it encounters the next indent, where it falls into the indent and breaks the motor contact. If you make sure the long grey bar is readily trying to spring into an Indent, the relay works when the switch moves, and the motor contacts meet when the grey bar pulls back, all should be well.

 

 

I've just put a thingy on one of your posts to attract your attention.

Edited October 8, 2020 by daltonparva
To attract your attention.

[drmditch]

19 hours ago, daltonparva said:

It's a long time since I took one of these apart, but if I remember correctly there are 3 wires to the mechanism:- a common (-), a positive to the relay, and a positive to the motor. The switch supplies a feed to the motor wire all the time but only supplies a feed to the relay when you operate the switch; a temporary contact on the first position until the switch springs back, a permanent contact on the second position until you release the switch. When you operate the switch the relay moves and pulls back the long grey bar out of 1 of the 4 indents in the toothed cog, and completes the circuit for the motor feed wire. The motor rotates the cog, and the rotating cog is now holding the long grey bar against it's spring to make the motor feed contact until it encounters the next indent, where it falls into the indent and breaks the motor contact. If you make sure the long grey bar is readily trying to spring into an Indent, the relay works when the switch moves, and the motor contacts meet when the grey bar pulls back, all should be well.

 

 

I've just put a thingy on one of your posts to attract your attention.

 

Thank you for the 'thingy'.

Is what you have termed the 'relay', what I have termed the 'electromagnet'?

I think I understand that intended operation. 

The problem is that the electromagnet does not release at the correct time (on at least 80% of occasions.)

 

Could the spring have weakened over time?

[daltonparva]

Yes, the relay/electromagnet is the same thing. The electromagnet releases as soon as you let go of the switch. The loñg grey arm should be sprung so that it is trying to get away from the electromagnet and into one of the cog indents as it's natural position.

[drmditch]

On 07/10/2020 at 17:29, WIMorrison said:

I bought it from Fleishmann and it takes about 5 mins to fit it, just need a soldering iron to make the connections.

 

Thank you. Ordered and now with DHL.

 

Thank you also to DaltonParva. I think I  understand the concept, but either there is some adjustment that I can't get right, or the springs have weakened over time.

 

Hope the parcel arrives before 31st December!

[drmditch]

Just to complete this thread. The parcel did arrive quite quickly. The new drive unit was simple to install, with just three wires to solder.

Problem solved - and my locomotive storage works!

 

Thank you to everybody who helped.

Edited January 9, 2021 by drmditch

[RichD1]

Have you any idea why the replacement motor cured your indexing problem?

 

I've just pulled my one out of storage and am about to give it a good clean and then test.

 

Richard