Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Let's call it a day on the valve linkage / steam chest side of this beast, and head back up to the flywheel / crankshaft assembly. With the valve linkage fully disconnected, the noticeable bind in flywheel rotation was still present. So my next move was to disconnect the crank rod from the crank and see how that might be affecting rotation.

Sure enough, rotation smoothed out almost completely with only a slight and fairly even resistance felt through 360 degrees of rotation. Whew!

With just a very slight loosening of the cap screws holding the bearing clamps in place, the flywheel spun easily through several rotations coming to a slow and even stop that bodes well for the shaft and bearings I think. With the bearing clamps in this ever so slightly loosened condition I tried to wiggle the crankshaft and felt no noticeable movement. This seems real good ... perhaps too good to be true?

Along the way, I thought I'd take the time to check for any bend in the crankshaft, with the shaft still cradled in its bearings. So I got out an indicator set-up and with the tip set as close to the hub of the flywheel as I could manage, took a set of rotational readings that gave me less than .002" runout, and some of that could easily be due to old varnished oil, though probably not.

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In any event, it is now apparent that the drag/bind issue was going to be found in the piston/cylinder/crosshead-slide/ linkage system, and not with the crankshaft or bearings ..... again, WHEW!!!

I should add that perhaps surprisingly, the connecting rod's holes at both ends seem fairly well centered, though not perfectly, and both the crosshead-slide and crank arm holes while not too well centered, are both adequately so, as to have plenty of "meat" around them, and should offer no problems. The crank end of the connecting rod has a set of brass bearing inserts that will need some adjustment as there is a little slop on the crank arm bolt (crank pin), and the adjusting screw for that bearing set cannot further tighten, so the edges where the two bearing halves meet will need to be filed back ever so slightly to allow further adjustment range.

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