Class 47 bogies.

With all the recent discussions on the accuracy, or not, of some recent diesel locomotive models, I had a look at some details of the Class 47.

One thing I can't work out is exactly how the compensation arms on the bogies are fitted. The outer ends of the links are obviously coupled to the underside of the outer axleboxes, but what happens to the inner ends of the arms - are they coupled to the underside of the centre axlebox, or to a point on the side frames beside the centre axlebox.

I'm using the late Monty Wells' article in MRJ63 as my main source of information where he supplied two excellent series of photos of the bogie sides, but in both series of pictures, the inner ends of the arms are hidden and it is impossible to deduce what happens with them..

Having looked at other Brush six wheeled bogies, as fitted to Class 31 locos, there the compensation arms are shaped to act on the top of the axleboxes and the inner ends both bear on the top of the centre axlebox, so I assume that the same principle applies on the Class 47 bogies.

As an aside to a matter discussed a week or so ago, Steve Jones might want to look at these series of photos, especially at the joins, and see the amount of horizontal distortion that can happen with photographs which are taken 'straight on' to the subject

Jim.

Reply to
Jim Guthrie
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Correct, the inner ends of the compensation arms must apply their loading onto the axleboxes. You really need a very clear 3/4 view to show this up, the pic on page 149 would if it was not so dark. But you can make it out from the big pic at the bottom of page 157.

Note that the bottom ends of the frame horncheeks are tied together with channel section pieces. Behind these on the end axle you can see that the compensating arm is pin jointed to a downward extension of the axlebox. At the same position on the centre axle you can see that the downward extension of the axlebox appears as a plain rectangle, this is essentially a horizontal square tube and the ends of the compensating arms sit inside the tube so that both of them act on the axlebox.

Keith

Make friends in the hobby. Visit Garratt photos for the big steam lovers.

Reply to
Keith Norgrove

Keith,

Thanks for that. I thought it might be something like that, but wasn't sure. That arrangement would also give a certain amount of horizontal play in the system.

Is this the prototype of springy beam compensation? ;-)

Jim.

Reply to
Jim Guthrie

Not really they are rigid beams! But the weight is on springs above the beam, not so easy on models so we reverse it making the spring into a rigid bearer and the beam into a spring. ;-) Keith

Make friends in the hobby. Visit Garratt photos for the big steam lovers.

Reply to
Keith Norgrove

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