Gentlemen a problem for you to answer

Hi chaps. I am part way through building a locomotive build stand. This is based on a Genie lift. Part of the job is a turn beam which can be used to work underneath the loco by turning it upside down on the beam. And here lays the problem. As you all know a locomotive weighs a lot and the load on the pivot bolt would be high. To help out here I was thinking of bearing. This would help when turning the locomotive over on the beam. The problem I have is two fold. For the beam I am using 4x2 inch aluminium square 4mm thick. And a 12mm shoulder bolt. I could add 2 bearing housings to each side of the beam, or fit a tube running inside the beam carrying the bearings. What would be your best. Idea, and what would be the correct bearings to use. I have material to make bearing housings, but nothing for the tube if I go that way, and with the cost of metal these days and problems with delivery, would housings be the way to go. Thanks

My locomotive spit isn't difficult to turn despite being on two plain bearings. In the interests of controllability it could be that a bit of friction is desirable.

I'm sure you have considered this but remember the CofG of the locomotive is much higher than the buffer beam once the boiler is on; its much nicer to have it pivoting around the CofG than trying to fight gravity! I don't doubt you have already considered this of course.

First, you are not making a centrifuge! You will turning the loco through some angle, slowly, by hand, and only fairly occasionally.

So you don't need an elaborate bearing, just one that will take the load, and a plain brass, bronze or cast-iron bush carrying a mild-steel shaft (I assume the M12 bolt) would be more than enough.

In fact if an ordinary bolt will not be to ever-so-high accuracy even on the plain shank, and for this purpose it would not really matter if the bearing is a plain hole drilled through mild-steel the bearing-length of the shank. Drill it carefully to produce a reasonably smooth wall, and provide an oil-hole or grease-nipple in its top centre.

If you look at commercial engine-hoists, lifting-trolley etc. most don't have anything more than steel pins in steel bushes, though higher-quality ones may have reamed holes and hardened, ground pins.

(You can buy shouldered socket-screws with hardened and ground shanks, precisely for such purposes, and they are not very expensive. I am using two M6 versions for my steam-lorry engine's gudgeon pins... don't worry purists, it's an enclosed engine!)

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Looking at typical loco lifts occasionally featured in the magazine, the fulcrum is usually set at approximately the loco's axis of mass, to balance the load to a large extent.

Some use a worm and wheel for rotation, though that's not essential provided you can control the over-turning and lock the assembly in place, easily. One way for anything like that is a large-diameter hand-wheel, clipped or loose-pinned to the shaft for safety in use, but readily removeable for access to the work itself.

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Looking at your beam description, will that wide alumimium-angle, even with the deeper web pointing correctly downwards, leave sufficient access to the up-turned loco? Or is the beam a frame wider inside than the loco itself?

I had a car rottisery mounted on four 1" plain plummer blocks, don't use ball races and make the buffer beam connector arm adjustable and a drilled circular disc to take a tent peg size locking pin.

Thanks chaps, interesting reply’s. Looks like I was trying to over engineer the thing.

i built a 5.8 l v8 on an engine stand. the stands pivot is just a steel tube in a steel tube one end only. easy to turn

i dowt your engine is heaver. make it adjustable so it ready for next time

A cog with a worm operated by a handle would create a moveable non locking spit

Michael, if you go into my photos you will see the version I made. Very simple and I made it in a few weeks. The design was published in an old ME mag. If you need the mag issue number etc. or a photo copy let me know.

Alan

Michael, if you go into my photos you will see the version I made. Very simple and I made it in a few weeks. The design was published in an old ME mag. If you need the mag issue number etc. or a photo copy let me know.

Alan

I made a spit for a Citroen 2CV van body - used for welding and spraying. I just used a scaffold pole and clamps and a couple of "A" frames.

My loco frame was a couple of 3/8" ply triangles with a couple of bolts locating in the buffers and a third 6mm bolt for the axis. The only problem with that was access to the smokebox.

Bob