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Post by chameleonrob on Oct 26, 2004 23:14:47 GMT
On the loco I'm in the process of designing and building I've reached the stage where I have to make a final decision about the diameter of the axles. the engine is fairly small 50mm x 50mm cylinders, 150mm dia wheels, 0-4-0, 100 PSI steam pressure, ball bearings inside frames and 7.25" gauge. by using all the stress alnalasis (simple but comprehensive) I came to the conclusion that 15mm dia was more than enough if the wheel was fixed well, but every similar sized loco i've seen has axle diameters of 25mm to 35mm aprox. have I forgotten about something vital or do most people just err on the side of caution?
rob
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Post by alanstepney on Oct 27, 2004 4:26:37 GMT
The sizes of components you mention are similar to many 5" loco's and the only difference is the length of the axle.
As I was reading your post, the quick answer that came to me before reading your suggested size, was " 3/4" " and that is probably what I would use in those circumstances.
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Post by chameleonrob on Oct 29, 2004 9:18:43 GMT
thanks for that, I assume that you would take a couple of mm off the end to locate the wheels.
rob
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Post by Tel on Oct 29, 2004 9:40:53 GMT
Yep. 3/4" would be the size of choice. If it was me I'd user PGMS as is & just cut the wheel seats to about 5/8"(after clocking dead true of course)
Now I gotta say I've seem a lot of 5" g locos - but I never came across one with 35mm dia axles (or anything even close)
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waggy
Statesman
Posts: 747
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Post by waggy on Oct 29, 2004 15:47:49 GMT
Refer to full size practice, the Midland used narrow axleboxes resulting in less bearing surface area, thus resulting in hot box problems. Along came William Stanier who increased box width and as result bearing surface area, no more hot boxes. The bigger you can make the journal and the wider the box, the less trouble you will have. Its all between the frame, you can't see it!
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