Another 'problem" that doomed the friction bearing was the problem of the brass top bearing plate shifting. Part of a pre-trip inspection of our older, friction-bearing equipped passendger cars to lift the lid, check the oil level and waste and make sure the brass is still where it’s supposed to be. It’s a bear to jack up the springs and beat it back into place.
A brass plate? this is between the top of the block and the spring? The bearing itself, a half shell resting on the top side of the axel, hhhmmmmm, how is the shell kept from spining out ? How is lateral movement of the axel limited? Is there a step in the spindle ?
Brass is pretty soft, why is it between the bearing block and the spring ?
Some of this friction-bearing tech stuff is covered in the American Passenger Car book (alas, don’t have my copy at hand)
The bearing brasses ARE the upper bearing plate, whether or not they are lined with a different material. The assumption was that a bearing with hard metal in both faces would show rapid wear anywhere surface asperities broke through the oil film which is actually providing the ‘hydrodynamic’ bearing – and with steel or other alloys, you’d get point welding wherever these rubbed at high speed under typical load, leading to very rapid galling and… well, hotboxes. So you want a metal that doesn’t undergo welding to a steel journal, and that preferably ‘wears’ in preference to the more expensive polished steel of the axle.
MCB designers didn’t think there could be loads UP on a bearing that had a share of a whole railcar’s weight bearing (no pun intended) down on it. So they did not include positive location of the brass in the shell. Now, there are a variety of situations that can knock the axle or car in ways that reduce the instantaneous load at the same time as the axle moves – and this either lets the plate shift a bit around the axle, or ****. Of course, Murphy’s and Finagle’s laws dictate that when you can detect this problem, full weight will be back on the journal…
Unfortunately too, as on old clocks and watches, it turns out that wherever there is dust or dirt in the lubrication, something quite different happens with wear. Many of the particles in the contaminant materials are very hard – quartz dust etc. If these particles get into the bearing joint, they preferentially embed in the softer material, and then proceed to ‘machine’ the harder material. This may have the effect, over time, of increasing the ‘wetted’ facing areas of the bearing and journal substantially.
Even a little contamination can destroy the oil film in a spot, and cause friction heating sufficient to degrade the lube oil in the film. The use of 'w
Wow! talk about the good old days! In my senior year (56-57) of High School I was on limited classes because I had a job oiling freight trains and inspecting, changing brake shoes, hoses, etc. at Oakland’s desert yard across from the 16th St. station. I remember one old oiler had a real old car that he filled up the engine with 50 weight journal oil every night. It got him home and back to work the next night and he would have to fill it again. Bearings and main seals were all shot, but it still ran! Good memories of the last of the cab forwards, and the beautiful black widows. After them I thought the the geeps were plug ugly.