Posted by Rick Denney on June 03, 2002 at 10:47:50:
In Reply to: Re: Re: Re: Re: Swedging Your Rotors posted by Mark on June 01, 2002 at 10:16:43:
Pin bearings quickly pump out the lubricant and run dry, unless there is a mechanism to pump lubricant into them. At the center of the pin, the bearing speed is almost zero and the force is quite high. If you put a hole at the end of the pin, it helps, but then the pin wears much more quickly.
Every railroad truck I've ever seen used a journal bearing with pumped lubricant. If the lubricant pump fails, the bearing quickly overheats--railroaders call this a hot box. Incidentally, car engine bearings are built the same way, with cast iron shafts running in bronze sleeves that have oil pumped into the bearing surface. If the oil pump fails and the engine loses oil pressure, you have about a minute or two before things begin to melt.
Rick "thinking that overheating would not be the problem on tubas unless Pat Sheridan was the tubist" Denney