Engines > Restoration of Model Engines

An incomplete Grasshopper

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Sanjay F:
I was going to start on a new build with a set of castings, but am waiting for some tooling to arrive and being Christmas goodness knows when that's going to be.

Here we have my first beam engine which is a Stuart Half-Beam or Grasshopper; is has some parts missing such as the link rods from the beam to the A-frame. Also there's some strange goings on such as the flywheel and pulley being incorrectly postioned on the crankshaft . The whole thing feels very tight and some things like the eccentric are just rotating on the shaft and others like the valve gear are non-operational. I think a complete strip down and bottom up rebuild is best then I get to see what's what and what's not! I have no drawings but I have the measurements for the link rods, but can always send off for them from Stuarts if need be..............

I made a start on the wooden base as the existing plinth bottom, as you can see, is a horrible piece of chipboard and there is nowhere for the outer bearing to sit during the rebuild.

Again this is another engine where I'm not sure if it has been run before given the missing bits, tight components and general finish, so let's see if we can inject some life into this Grasshopper.  ;D

crueby:
I've got a Stuart Grasshopper if you need any pics or measurements.

Sanjay F:
Oh brilliant, I may come knocking for those or just for some advice as I make some headway.

From videos I have seen its an interesting movement, with both the usual up & down motion of the beam combined with a slight lateral movement

crueby:
Its a neat movement - just needs a Hula Hoop!   :Lol:
I do not have the plans, those are lost in the mists of time and many spring cleanings, but can measure parts.

Jasonb:
A lot is similar to the other 1" x 2" Stuart engines, particularly the beam which shares the same valve gear. It is just the grasshopper bits that are particular to this engine.

Looks like most parts are there so if you have the length of the links you may not need the drawings. Link length really needs to be set with them screwed into the central brass shaft as length will alter if you drill the support ends then try to screw them into place. Not the best of designs having two rods that need to be exactly the same length but with screw threads. I'd redesign it with a solid pivot shaft. Fixed length links and retaining caps.

Check that the brass shaft in the middle of the beam is free to rotate when done up tight, some drawings show it's length as 15/32" which would clamp it tight to the beam but it needs to rotate so 0.502" would be better.

You may also want to turn the beam up the other way then the boss at the bottom can be drilled for an oil cup to lubricate the central brass shaft.

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