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> Hornby M7 problem
Al Harding
post 27 Mar 2021, 14:41
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My old Hornby M7 is a temperamental runner so I decided to strip it down and investigate.
I have noticed that the front driving wheels and therefore the gear wheel are pulled to one side in the chassis by magnets fitted into the frame on both sides.
It always pulls one way because behind one wheel there appears to be a spacer, possibly built into the wheel, that prevents it being pulled across.
Two questions,
1 What function do the magnets serve?

2 should there be a spacer behind the wheel to hold the axle central?

I have a photo but not sure how to post that!



Thanks
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hoonsou
post 27 Mar 2021, 23:06
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Those magnets would have been for "magnadhesion." They were for use on steel rail and intended to increase pulling power. Totally useless nowadays if you use Peco nickel silver track. You can take them out. I'm not sure they were of much use even with steel rail.


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SRman
post 27 Mar 2021, 23:14
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QUOTE (hoonsou @ 28 Mar 2021, 10:06) *
Those magnets would have been for "magnadhesion." They were for use on steel rail and intended to increase pulling power. Totally useless nowadays if you use Peco nickel silver track. You can take them out. I'm not sure they were of much use even with steel rail.



They worked really well on steel rail, increasing the hauling power considerably.

As you said, though, they can be removed. In the past, I tended to remove the magnets and fill the space with lead and Plasticene to get a bit of adhesive weight back in.
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Graham Plowman
post 28 Mar 2021, 00:53
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As SRman wrote, they worked really well on steel rail. They also compensated for the issue that in those early days, the 4-4-0 and 0-4-4 mechanisms weren't balanced (the bogie did not carry any loco weight), so the "magnadhesion" helped keep driving wheels touching the rails for pickup.

Now-a-days, the magnets have no use if you are using nickel silver track.


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Graham Plowman
(British outline 00 - NCE PH PRO-R, Lenz 100 - DCC Sound and computer controlled signalling/interlocking of Ashprington Road with SSI software)
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34C
post 28 Mar 2021, 12:02
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Several things you can do to help this old stager perform:
Add a washer to move the driven wheelset to a better centred position.
Replace the overweight 'no roll' bogie, with a fold up brass item with modern wheelsets, and fit it lightly sprung to help the balance on track.
If you are up to removing and replacing the driving wheels while maintaining correct quartering, substitute denser lead for the redundant magnets.
Add weight to the body forward of the rear driven axle by any and every means possible; metal chimney and smokebox door, lead packing the interior, etc.

Then there's the radical option of selling, and putting the money toward the current model. This is as good looking a tank loco as any now available in RTR OO, with a fine mechanism, and once run in and patiently given careful adjustments to optimise traction will realistically slowly start and move a dozen coaches on level track, enabling it to do the Waterloo ECS jobs for which the class was finally and famously used, in model form. The traction all goes to pieces (= significantly reduced) on gradients, but it still outperforms the old model by some distance.
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