the past weeks were quite on my blog, but not in my workshop. Today, I like to show you the latest improvement and rebuild I spend to my Resita loco.
The prototype uses Klien-Lindner-axles and I was trying to equip my model loco with the same feature. The Klien-Lindner-axles allow the end axles of a steam loco to follow curves, improving the running on tight curved tracks. To show how this working on the prototype, I’ll explain my model version in detail, which is close to the prototype setup.
My model version was finally made from some 20mm round brass, 12x1mm copper tube, ball bearings, springs and brass balls. The brass ball original was a ball-nut and gut drilled and reamed to fit a the 4mm steel axle of the loco. Next the ball is hold in a four-jaw-chuck to drill a 2mm hole in exact 90° to the 4mm bore, halfway through. Once the ball is fit to the steel axle, a 2mm pin-screw will fit through the cross hole and will get screwed into the M2 cross-thread in the steel axle. The pin-screw should be long enough to provide a pin sticking from the ball acting as link to the copper pipe.
Next I cut two segments from 12x1mm copper tube, fitting exactly between the hubs of the wheels. Use the mill to cut a 2x7mm slot to the center of the pipe. This is where the pin from the brass ball will slide in, transporting the rotation from the steel axle to the copper tube and allowing the tube to slide 2.5mm to each side. The ends of the tube gut turned truth on the lathe to take 12x18x4 ball bearings. The brass collars are made from round brass-bar with 12mm bore and 17.5mm outer diameter. They are 9mm long with two M3 holes to take set-screws. Once the inner hub of the wheels are turned down to 12mm as well, the collars are used to mount the wheels on the copper tube. Check the correct gauge of the rebuild wheel sets. Don’t change the 8mm core-bore of the wheels. They will hold the centering springs and limit the angle-travel of the finished assembly.
To provide a self-centering of the hollow axle, we insert a spring on each side of the ball, pressing against the inside of the wheels. They will keep the hollow axle with the wheels centered above the ball when traveling on straight track. It also reduces the vertical move of the axles. Unfortunately, I have no photo from inserting the springs.
To guide the hollow axle into the curves, they are also supported by a drawbar just like a pony truck. There are several different versions used on the prototype locos and I was able to determine the one used on the Resita locos and tried to model it the same way. The housing is made on the lathe from 20mm round brass and milled to final shape. The housing is riding on the ball bearings to eliminate any friction. At one end, a 3mm steel rod is mounted which is guided in a frame-crossmember. I made theses cross members from steel sheet.
When the loco is rolling into a curve, the tracks will push the wheels to the side. While the hollow axle with the wheels is sliding, it is also hold/guided by the drawbar which will turn the sliding move also into a rotation. Finally, the wheels will keep in parallel with the rails through out the curved track. This reduces friction between wheels and rails and leads into better and smoother running. Once returning to straight track, the springs will push the wheel back into center position.
At least, here’s a video from first test runs after the rebuild.
Happy railroading, Gerd