Used to live in Rolla. Most eastbound freights had a pusher on the rear coming up the hill from Newburg. Pusher cut off in Dillon (10-12 miles east of Rolla) and backed down to Newburg. In the early 1930s, a big old "spot". ....2-10-2 often was the pusher. Rods were so heavy they were hard to counter balance. Spots were "redlined" somewhere in the thirty MPHs..over that speed the could really damage track. As the spot backed thru Rolla and all the way west to Coleman's cut you could hear the rods clanking...clanking...My older brother said it sounded like "flop and flanter...flop and flanter..." Spot's rods had plain bearings, I think. Now here's what's bothering me...the new 4500 4-8-4's had roller bearings I believe. And when some of them were new and came thru Rolla...there they were....clank....clank...clank. I'm not sure, but I think roller bearings have an adjustment to roller and cup clearance. Anybody have any enlightenment ?
I'm not familiar with those locos (too young primarily), but in general, tapered roller bearings have to be adjusted to a certain pre-load in order to fit properly and wear correctly. This type of bearing is used in many applications in heavy machinery. The cup is a press fit into the outer part (this is highly generalized), while the inner race is pressed or locked to the inner shaft. A bolt on the shaft is used to compress the bearing along the axisof the shaft. Each bearing size has a recommended pre-load to make sure that the parts don't move except in rotation. This helps to seat the rollers properly within the cages & makes up for the machining tolerances of the bearing components. Hope this helps & doesn't confuse.
Jmannmanny, I think the 2-10-2's had the straight roller bearings in the frame/axel bearings, but still had the brasses in all the rods. That is why you heard the rod slap. If roller bearings were slapping baddly enough for you to hear them, they would have lost some or all of the rollers, and would have beaten off the crank pins. My Dad was a Master Bearing Smith with Peerless Bearing Company when I was a little boy. (That was a couple of years before Adam met Eve). I remember he would pound the Ring into a rod, then slip the core sleeve over a crank pin, and I would watch as one of the older boys would wipe the outside of those rollers with grease and hand them to Dad as he would "pack" them in around between the ring and sleeve. The last one had to be tapped into place with a hardwood peg and a small mallet, also wood. Then a cap plate was bolted onto the crank pin and held in place with a huge (to me) hex nut and cotter key (almost as big around as my little finger). In later years I remember he said they used wood because all the parts of the bearings were so hard that to hit them with a steel hammer, would have chipped them. Those were straight cylindrical rollers, no taper, which is a Roller Bearing. Some of this type bearing had a retainer called a "cage" to separate the rollers and maintain alignment parallel to the axis of the crank pin. The demonstrator engine for roller bearings was Timken's #1111. Later, when Timken came out with the tapered roller bearing, their advantage was that they could be adjusted for slack fit. This bearing had one cone two races, called "cups" and two roller retainers. One cup was press fitted against a shoulder in a rod with the cone shape facing the center of the rod. Then a retainer was inserted, then the cone. The second retainer was turned around and inserted on the cone, then the second cup was turned around and slip-tapped into contact with the assembled bearing. A pressure ring was then bolted to the rod to hold the cups against the stack up which removed all play and slack between the crank pin and the rod. A sleeve was then fitted over the end of a crank pin, and a big hex nut was tightened to hold the cone in place. These rods would not "clank" when rotated, but had considerably less friction than the standard brasses did. As these Timkens would wear down, they could be re-tighted by simply tightening the bolts to remove the play. They would also run much cooler at high speeds, and they became standard on the Northern Pacific starting around 1933, I think. That was when young boys could go to work with their fathers and learn the trade. It was many wonderful summers for me growing up! We got to go to many different roundhouses and manufacturing plants. [ 21 June 2002, 08:33: Message edited by: watash ]
