844 Side Rod Knock

No it's not a normal thing, several other people and experts have watched the videos and said the same thing . I'm sure Hotwater or Rich could chime in since they are more knowledgeable on the subject

Since the rods have plain bearings, I would say it is normal.

My personal opinion is,,,,,,it is NOT the rods. Although I must admit I don't have a whole lot of "track-side time" watching 844 go past with such a short/light train, I can not recall her ever sounding THAT loud with hardly any exhaust sound.

Any number of things MAY cays such a knock:

1) Since the UP FEF-3 locomotives are equipped with Franklyn Railway Supply automatic wedges for the driving box shoes, one of those automatic wedges may be stuck, and NOT automatically adjusting the roller bearing driving box.

2) The Engineer might NOT have the proper reverse gear setting for such a light throttle.

3) Although highly unlikely, one of the main rod bearing brasses may be wearing prematurely. 

What is creating the knock make the running gear to run hot?

Dominic Mazoch posted:

What is creating the knock make the running gear to run hot?

What makes you think it is "running hot"? Nobody has said ANYTHING about that!

The clank of side rods is more easily heard when the locomotive is drifting, and there is no competing exhaust sounds.  Today's excursion engines get a lot of attention from the same small group of people who maintain them (and know them), and, therefore, the rods are not allowed to become too loose.  Some wear is tolerable, but I would not expect much rod clank from an engine just out of an overhaul.

If you listen to locomotive audio recordings from the 1950's, when the engines recorded were still in revenue service, side rod clank is often quite pronounced.  However, those locomotives were not given the same amount of mechanical oversight that today's excursion steam engines are.  (And many were having the last bit of life wrung out of them until the next order of GP9's arrived and thus not being "over-maintained.")

Always one VERY important thing to remember concerning steam locomotive side rod plain bearing clearance; it is ALWAYS better to hear them, than to smell them! Hopefully the current manager learned his lesson from 2011, after he had the bearing clearances tightened up to HALF of what Union Pacific mechanical department drawings specified for FEF-3 rod bearings.

It isn't just this one video, but, I think it is any video that I have watched of the 844. 9/16/89 is one of the many. And this goes for videos and recordings of any plain rod bearing loco.

For the rest of the story & photos; Click here.

Gary / Railfan

Gilly@N&W posted:

I've been enjoying watching the 844's recent trip on YouTube this afternoon. If my ears are not deceiving me, it sounds like there is some side rod knock. I'm assuming it is likely normal, but was surprised to hear it given its recent overhaul. I have seen an old N&W Y6a film in mine shifter duty with some pretty loud knock. What I am hearing it no where near that bad.

Is this normal operating sounds for the 844?

My memories of steam are from the early to its mid-60s demise in Britain. The one sound that sticks in my mind is the clanking side-rods. Thanks for the reminder!

A little clanking here around 0:17 - 

2156 was really noisy when it went past on its way to Roanoke. 

Plain bearings in side rods need more clearance than a typical plain bearing application where the bushing is in a fixed position relative to the mating shaft.  As the locomotive moves over the track, the wheels move up and down in relation to each other.  At extreme points of suspension travel, the center-to-center distance between the crankpins is increased by a certain amount compared to when the wheels are even with each other.  Although this amount of elongation would be considered negligible by the average person, it can easily exceed the typical clearance of a plain bearing in a fixed application (such as inside an internal combustion engine).  As Hot Water pointed out, the mechanical department has specified a clearance for the side rod bushings.  The mechanical engineers would have taken into account the extra clearance needed for the wheels to be able to travel to the extreme limits of the suspension travel, and the accompanying elongation of the center-to-center distance between the crankpins.  To further complicate matters, a dip in the track (such as a low joint) will make the adjacent drive axles move out of level with each other, which is exaggerated at the crankpins since they are past the ends of the axle.  Without sufficient clearance in the side rod bushings, it will try to impart a twisting force from one end of the side rod to the other. 

All that adds up to more clearance on the side rod bushings than you would see in almost any other plain bearing application.  It has to be this way.  It is designed to be this way.  Yes, the clearance can be reduced by half and the locomotive will still roll out of the shop.  But in the real world, that lack of clearance will lead to excessive friction, overheating, and in due time, seizure.

The downside to all this is that when the locomotive is drifting along, all of the extra clearance will run in and out with every revolution... producing some pronounced clanking.  When the locomotive is up to speed, the clanking tends to disappear, since centrifugal force has the side rods trying to move to the outside of the wheel, and the crankpins exert a centripetal force that restrains them.  The rod bushing never comes out of contact with the crankpin, and thus doesn't clank.  Also, under load, the clanking can be minimized since the side rods are transmitting energy to the wheels, which tends to take up slack, and the louder exhaust sound tends to drown it out, too.

So, some clanking is normal for a steam locomotive with plain bearings in the side rods.

Great Scott..makes you wonder how roller bearing rods will even work!

I was born, as many of you know, in Piedmont West Virginia, right at the bottom of the Baltimore and Ohio's

17 mile grade. As a youngsters, I and my friends got used to side rod clank..as many helpers drifted back to

Keyser West Virginia to shove another train.

Is the engine back on the road?

HW and Wind Up Guy, thanks for those details.  Not things normally though of, but the explanations make since out of it all.

Thanks 645.. what a great pic... notice the  diesel behind the aux tender....

Gregg posted:

Thanks 645.. what a great pic... notice the  diesel behind the aux tender....

That was there specifically for the Memphis "event".

Thank you Kelly. Wondered how that works.

Ed

WindupGuy posted:

Plain bearings in side rods need more clearance than a typical plain bearing application where the bushing is in a fixed position relative to the mating shaft.  .....

Good write-up, James.

Thanks

Jim