Steam engine Question

When a steam locomotive sounds like that it is because the valve gear needs set. The 734 is "out of time" because the exhaust beats do not occur evenly. When one exhaust beat is noticeably louder than other, the engine is said to be "out of square."

There are a lot of variables which come into play when setting the valves. The position of the eccentric cranks, the position of the valves themselves in the gear, worn parts in the valve gear itself...all can contribute to this problem.

It can be a serious problem because the engine pulls an uneven draft on the fire, the loads on the running gear are also uneven and may have higher loading peaks than when the engine is properly timed. Tractive effort is also uneven and the pulling force at the drawbar is pulsating, which could be a problem when maximum tractive effort is needed.

Rode behind #734 on 6-30-12  and noticed the exhaust beat was really out of time.  Depending on your perspective it was 1-2-3--4-1-2-3--4-1-2-3--4  all the way up the mountain - and there was a perceptible "jerking" in unison with the exhaust.  You could "see" it in the water glasses.  Interesting - hope it isn't a major maintenance issue - but we all know how steam locomotives are - just like OGR Webmasters!

Larry

Thanks for the information Rich and Larry! 

I seems like a railroad like that would take care of the problem quickly in hope of getting the issue taken care of. Knowing that the 734 is the only operating steamer there I sure would want the issues taken care of so that no future problems would occur. 

The 734 definitely sounds better when she is on "time". 

Maybe they are just trying to get thru this operating season, and then when the 734 is "down for other work", during this coming winter, the machinery will be repaired along with boiler work.

Granted I'm far from a steam expert but....

The engine has been WAY out of time for at least the past two seasons...my understanding is it is approaching the end of its 1472 day service time and I would imagine it would be taken care of then. A lengthy discussion on rypn.org beat this subject to the ground in the last month or so. 

Not to change the subject but speaking of out of time engines and jerking/pulsating in the cars....

I'm a regular attendee at the annual B&O Musuem's steam days. Their 1950 Porter 0-4-0T pulls their passenger trains consisting of 4 or 5 stainless coaches. Last time I was on the train with the Porter, the train was jerking consistently back and forth the entire trip with the engine pushing and pulling...from what it sounds like, the engine isn't that out of time but, if I'm not mistaken, the "squeal" coming from the cylinders at start up indicates some blow-by... would that pulsating indicate out of time/blow-by or simply lack of controlling the slack? 

That "squeal" is an indication of worn or broken valve packing (rings, to you guys), where the steam is "blowing by" a broken or worn packing segment. She needs a "valve ring job", in blunt language!

Now, the pulsing is just part of a two cylinder reciprocating steam locomotive. We can even feel that same sensation, to a much smaller degree, behind the SP4449 or UP844 when they are starting and accelerating a train.

RE: "squealing"

Squealing could also be a sign of a lack of adequate oil lubrication in the valve and  cylinders.

Yeah that is true Hot Water but wouldn't that just cause more work for them in the winter? More work equals more money spent? I don't know if this is true I'm just bring up points. It seems to me that it would be more economical to get it done now and get the money back through revenue from trips. 

Not likely. Lack of lube to the point where things were dry enough to squeak would also cause excessive heating. That in turn would quickly lead to serious damage and perhaps even a seizure. BIG problem.

The squealing sound is steam whistling past the broken/worn rings.

Opening day saw two stops up the mountain and a couple of stops down the mountain as 734 returned to Cumberland without the train.   Talk was a tight crosshead bearing, Fireman side. Apparently that had been rebuilt, and was much tighter than the Engineer side. They were continually working with the Nathan Oiler.
They checked this cross head several times.


They were hand pumping oil from this Nathan Oiler.


My bike buddy for the day found all to be fascinating.


Micah got left in the smoke after the second stop down the mountain.


Even as they turned on the table, note the concern about the crosshead.


My buddy for the day. Note that these powered vehicles had one chuff per revolution.

Mike thanks for the post. How long ago was your visit there? I remember seeing the same pics in a photo forum post. 

If it was recent then it might be the reason why the chuffing is so off time. 

I've known this lady, 734 since 1999. She has always had an offbeat chuff, and it's likely she always will.

Check the included photo, and look at her left steam chest, on the right of the photo. You will notice two welds, needed because of a result of a wreck, or a crack that developed after she was in service.

Evidently it is either part or all of the reason she can't be squared.

The reason she had such a bad time the first day is most likely the repairs where done at the last minute to the crooshead bearings, and she was never run in or checked out before hauling paying passengers.

Ed

Thanks Hot Water...answers my question well!

As for lubrication, I know that is NOT the issue as the B&O Museum takes mighty fine care of their operating cars, steam and diesel engines. 

Wow! I just took time to watch Mike's video..she's always been out of square, but my goodness, never THAT much!

Ed

Yeah that is why I was surprised when I saw the video! 

Just out of curiosity, what would the welds in the steam chest have to do with it?  I can't imagine that they wouldn't have ground down the welds after welding was completed.

It has nothing to do with grinding down the welds. If the original damage moved the valve and cylinder assembly slightly fore or aft, it would affect the valve timing. Even 1/64" in this area would make a big change.

However, given that the engine is so badly out of TIME, I suspect one of the eccentric cranks is out of position by a degree or two. If it was just one of the valves out of position fore or aft, that would affect the squareness (even volume of all exhaust beats) of the exhaust, but not the timing. The 765 ran this way for several years in the 90's. Her exhaust was evenly timed, but one exhaust beat was louder than the rest. In this case with the 734, we've got both an "out of time" situation and an "out of square" situation.

I'm sure that when the 734 goes down for her 1,472 day overhaul, the WMSR crew will take care of this.

I don't know that the welds would have to do with it but I must say by the look of the weld it must of been a really really bad crack. Who knows maybe it does affect the locomotive's performance?? 

Well this makes my post irrelevant! 

Yeah I agree Rich it definitely will be taken care of during their overhaul period. When the 765 had its issue did you guys wait to take care of it when her overhaul period was up or did you guys get it fixed right away?

Ok I understand now, thanks Rich. 

The lubricator might be working ok, but one of the lubricating oil lines may be plugged. Hope that they check those!

Rich, it is highly unlikely that the cranks are out of kilter since they are attached to the crankpins with two bolts, one through the center of the pin and the other through the crank and a groove in the pin.  As you know, these are not sloppy fits. 

Most likely the offbeat exhaust can be corrected either by lengthening or shortening a radius rod or eccentric rid on the side affected, or moving the valve slightly either back or forward on the valve stem.

I knew an engine with Stephenson Valve Gear that had slipped a backup eccentric, and gave only three exhausts in reverse: chuff chuff chuff ----- chuff chuff chuff ----- . . .  Forward, it sounded pretty normal.

It was N&W 421, the only N&W 4-8-0 I ever saw that still had Stephenson gear.

EdKing