< Driving Wheel Assembly 3 >
The first and third driving axles are thinned in their middle parts, especially because the first axle must be clear the inner main rod.
The driving wheels are glued on the axle with Loctite. Immediately the keys are hammered into the key groove. I used brass block between the key and hammer to prevent damage.
At that moment I detected the mistake that I announced last month. The inside crank of the second axle is 180 degree opposite from the correct angle...give me a break! At last I realized the key groove angle is incorrect. The key should be opposite to the outer crank pin! I cannot disassemble the cranked axle because the shafts and the castings were permanently fixed with pins. Unwillingly I decided to prepare a complete new set.
First of all, I have to remove the glued wheels from the axle. Pulling the wheel with 'Gear puller', the whole job is heated up with gas torch. Stop the heating when the axle starts withdrawing, and then pull out the wheel with gear puller. The photo shows removed parts. The axle is colored by oxidation.
The shafts and crank castings were machined and assembled in the same manner as before. But this time I didn't thin the axle ends. Spacing of the castings was done with a spacer.
So as to reproduce the phase difference between left and right key grooves, again I set the quartering jig up and traced phase difference of the failed job to new one.
The right hand job is the new one. Note the difference of key groove angle.
Paint of the wheel was damaged by the heating. So I removed the paint by thinner and wire brush, cleaned the wheel with acetone, sprayed polyurethane paint.
I bought a new paint aerosol for the recovery. To save the rest of paint aerosol, I painted the bogie truck. Frame set and other parts are painted separately and assembled again.
I made a mistake again! When I polish a boss, I forgot to protect the counter weight with cloth tape. As a result, paint of the counter weight was damaged. Once again I bought a paint aerosol and painted the boss again. The rest of paint is utilized for the pony truck and the leaf springs.
The polyurethane spray aerosol has to be used up within 24 hours after mixture. I can avoid a waste of paint, managing the remainder by a digital scale. But it means, in case of such mistakes, I must prepare new bottle every time and engage myself in unexpected paint works.
The wheels were glued onto the axle again. And then I examined the quartering result. The axleboxes are piled and glued on a surface table. The wheel assembly with dummy crankpins is mounted on it and the backside crankpin is fixed with a packing of suitable height. Thus the front crankpin's height is measured by height gauge. I measured 6 times for each wheel set (3 times for each side) in rotation. The average is calculated and compared with other wheel sets.
Difference between the first and third sets is 0.08mm, which is permissible. But the second one is deviated 0.3mm from others. I guess the recovery process and the difference of axle diameter caused such large error. I will prepare an eccentric crankpin for the second set.