Hey has any body ever notice the hammer efect on o gauge steamer?

I do not know what you are observing, but it is highly unlikely that the prototype dynamics would translate to our very scaled down models.

  We can't touch this...

 

 

Jerry

 

I can't see or hear hammering.

 

i agree wih Art.

If by hammering effect you mean it is running unvenly, where it is faster and slower at different parts of the wheels rotation, yes, I see it on my MTH Premier Berk, but I have it narrowed down to slipping traction tires and or it is pulling too many cars. At least I think that's I think is whats happening, as the phenomenon gos away if it is pulling fewer cars

 

Nick, Once I was working on my first car's brakes.  When the part would not fit, I used a hammer to drive it home.  The resulting "hammer effect" was not pretty.   

I thought the OP was referring to rail hammering from the drivers of steam locomotives.  If so, I agree with Tinplate Art that it's highly unlikely for prototype dynamic effects to scale down to model size.

 

The protoype doesn't "hammer the rails" either. If it did, the engineer and fireman would likely be bouncing  all over or out of the cab and the loco would beat itself to death. They are balanced machines, and the better balanced they are the smoother they run.

 

I believe that Rich has stated that the 765 since its most recent rebuild rides better than ever.

 

If we're talking side rod noise/clank. Lionels legacy locomotives have some of this in the soundset, most noticeable at moderate speeds.

 

...and don't forget that the real ones are powered by steam expanding against pistons attached to main rods attached to wheels and distributed by side rods.

 

Ours are driven by either a gear attached to one axle with the power transmitted by side rods, or by gears to all axles in the case of spur drive engines.

 

i don't think there is much to compare.

 

Jim

Properly balanced steam locomotives do NOT "hammer" the rails. It was only a handful of badly balanced Baldwins that had that characteristic.

 

Since the overhaul, the 765 rides smoother than our tool car!

You guys apparently have no understanding of rail hammering by steam locos.  It was always a serious problem and limited the speed of steamers.  The big Mallets were limited to 30 mph due to balance problems with the front engine.  These Mallets had front cylinders as large as 36 inch diameter or larger.  The pistons were very heavy, and it is not possible to balance single cylinder reciprocating engines by adding weights to the wheels.  A steam loco is actually two single cylinder engines since the cylinders and cranks are a good distance apart.  

 

If a single cylinder reciprocating engine is balanced by adding a balance weight equal to the rotating weight + half of the reciprocating weight, that is as good as can be done.  The result is a rotating imbalance force that rotates in the opposite direction of the wheel and is equal to half of the reciprocating weight.  For a large Mallet, this imbalance force can be huge.  This is what causes rail hammer.  This is discussed in detail on the Internet and was a real limitation of steam engines.

Oh Boy! Here we go again!

Let me get into the proper attire for the oncoming "discussion".

 

Yep, dynamic augment ("hammerblow" is more a British usage) was a problem with

reciprocating steam locos, especially on the main drivers. One of the reasons that high-speed locos would have larger drivers when possible was that they offered a better balancing opportunity. It hurt the track and roadbed.

 

I hate to disagree with Rich on this, especially in light of his extensive real-world experience with the NKP loco, but I respectfully do. I have never heard/read anything on dynamic augment that reflects his comments.

 

The PRR 6-8-6 steam turbine was a 100-mph loco, but had very small drivers considering

its useage. This was because it had no Main Drive Rod thrusting the Main Driver back and forth; the turbine was geared to two (I believe) of the axles and the outer two were connected by the side rod. It could, therefore, be well-balanced at high speeds even with small drivers.

 

Yes the pounding of rails was a real steam locomotive problem, resultant from the reciprocating weights. Balancing and counter-weighting must have been a real art. The forces seen on the large American steamers were probably the highest ever seen, as even marine steam engines were low speed and ran props in that handy slippery stuff, water. The main balancing is for the fore-and-aft motion of the locomotive rods, pistons, etc. The problem lies in the vertical un-balance that creates rail hammer. The pounding increases exponentially with the rotating speed;(I done forgot the formula.)

In model form, it could be wheel slip, a sticky car somewhere, or it could be a little conflict in the side-rods of a steamer or maybe mis-quartering after some major wheel maintenance. Just my $0.02

 

I guess you haven't heard of "Cross Counter Balance" (Found here on the internet) which solved a lot of issues.

 

The only N&W loco that I have ever heard having a balance problem (and it has been well documented in word and photos of kinked rail) was their K3 class 4-8-2 with 63" drivers. I've never heard a word about balance problems with their 58" drivered "Mallets", which could do well over 50mph with no kinked rail.

 

And to think they did it all without the internet or even computers!

 

Ohhhhh dear, There is a lot of misinformation being thrown about by y'all that will be picked up by others and repeated until it becomes 'fact' and I don't care much for it so here's the Gospel Truth:  I'm new here but I am a mechanical engineer who spent many a lecture learning the intricacies of balancing reciprocating engines, plus I have quite a bit of experience as support crew riding in the cabs of steam locomotives at speed so I actually do know what I am talking about.

 

It is not possible to fully balance a two-cylinder engine.  It IS possible to fully balance a THREE cylinder engine, but in the case of a two, they can only ever be made to run smooth at some speed that is chosen by the designer, and at speeds other than its 'design speed' the locomotive will exhibit hammer blow to some degree.  Hammer blow, for the uninitiated, is the rapidly varying downward force applied to the rails as the result of the driving wheels being 'out-of-balance' as they rotate.  At low speeds, of course, the force is small and not easily noticed, while at high speeds, driving wheels have been observed to lift slightly off the rails - an extreme case, for sure, but it has happened.  Now, this is not saying that the locomotive's entire weight is being tossed about because the springs will prevent this, and it was usually limited to the main driver only (because this is the one carrying the connecting rod - the other driving wheels don't, hence different-sized counterweights), but it still amounts to several tons bouncing up and down on the rails.

 

There are in fact two different forces at work, a vertical component which pounds the track, and a sideways 'wiggle', if you like, due to the fact that the cylinders are only a quarter of a turn apart, so that the front of the locomotive 'hunts' i.e. wiggles from side to side.  Pause for a moment to think of first one piston arriving at the front of the loco, and then as it is starting to go back the other way, the piston on the other side reaches the front.  I was shown this by an engineer who pointed it out as we rode at about 25mph, a very pronounced rapid side-to-side swaying that gradually eased as we accelerated to that particular loco's design speed of 40mph.

 

I would suggest that 765's smoother ride after its rebuild had more to do with springs and compensating gear being properly adjusted than any changes to balancing.  Someone would have had to have added or removed weight from the wheel counterweights to alter the balancing.  I would also suggest that 4449 and 844 were probably built to be properly balanced at 70-80mph since this is where they would spend a lot of their time, being express engines.  To see the effect of dynamic augment you would have to ride a locomotive with much smaller wheels, faster than its design speed.

 

Regards

Paul Woods

It is a rather complex and deep subject on hammerblow to the rails by steam locomotives. Lead to a different schools of engine design all over the world even to this day, from the American outside two-cylinder dominance to the British three cylinder compound. As for model trains there should be a slight amount, given you have a weight spinning around at speed. Emotional magnification aside, if you see it your engine most likely needs servicing, for some sort of issue or you could have a track problem like my old layout inherently had (given O-gauge and how track works that is a near nil chance of that here being the cause.)

Some folks on the New Have noticed "hammering" back when. From one of my replies back in September in the 'New Haven' thread:

 

Also, according to my uncle who worked for NH at the time, the L-1 2-10-2 'Santa Fe' locos were limited to 25mph because of wheel counterbalancing problems. This was lowered to 15mph on swing/draw/lift bridges due to that counterbalance problem causing the wheels to hammer the bridges so hard the operators were afraid the bridges would come apart. They threatend to open the bridges and walk out if the speed on these monsters wasn't lowered.

Obviously I don't know anything at all about this, so I'll leave it to the "experts."

 

I'm all done here...

 

Jerry

 

Jerry

 

Jerry

 

Jerry

The N&W 1218 was a simple expansion loco with 24" diameter cylinders.  There is a huge difference between a simple expansion loco and a compound expansion loco.  The compound expansion locos typically had front cylinders 36" in diameter which made the balance problem very difficult due to the weight of the piston and reciprocating mass.  The UP Challenger and Big Boy use simple expansion which allows use of a smaller cylinder and eases the balance problem.

 

The imbalance forces go up as the square of the speed.

 

It is not possible to perfectly balance a two cylinder steam engine using cross counter balancing.  Some improvement is possible, but perfect balance is not possible.  Remember, the imbalance force is equal to half of the reciprocating weight, and it rotates in the opposite direction of the wheel.  This is well understood and has been in the text books for many years.  Single, two cylinder, three cylinder, four cylinder, and 5 cylinder reciprocating engines cannot be perfectly balanced.  Six cylinder, V12, and straight 8 engines are inherently perfectly balanced.  V8s have a four per rev rocking couple that cannot be balanced.

 

Some years ago, I had a lawn tractor with a 12 HP Briggs and Stratton motor that had a "Syncro Balance"  It was a pair of weights on either side of the crankshaft that rotated in the opposite direction of the crank.  It was quite smooth.  

 

A 3 cylinder engine can only be statically balanced.  It cannot be dynamically balanced.  

 

 

I was thinking of the effect a hammer could have on a frustrated O Gauger's faulty new locomotive purchase.  Although on second thought, that would probably void the warranty.  Better use a ten pound sledge.

You Know, I do have a 336 Northern with a bent front axel that kind of moves like that when it goes down the track.

This is well understood and has been in the text books for many years.  Single, two cylinder, three cylinder, four cylinder, and 5 cylinder reciprocating engines cannot be perfectly balanced.  Six cylinder, V12, and straight 8 engines are inherently perfectly balanced.  V8s have a four per rev rocking couple that cannot be balanced.

 

It IS possible to fully balance a THREE cylinder engine

 

Servoguy and Woodworks are in disagreement.  Perhaps Servoguy should check his textbook again. I think he is reading the chapter on four stroke cycle single acting internal combustion engines.

 

A three cylinder double acting steam engine has crank throws 120 degrees apart and delivers a power stroke beginning with every 60 degrees of crank rotation.  They are very smooth engines. They are similar in power delivery to a four stroke, internal combustion V-12.

I wasn't talking about N&W 1218. I was talking about the Y6 class 2-8-8-2.

 

Now, it is common knowledge to those students of the steam locomotive that a "perfect" balance cannot be achieved. It was written about long before the internet was even dreamed of.

 

However,

It should be more than obvious from the observation of all of that beautiful smooth rail in thousands of photos taken of all steam locomotives through the years that the art of balancing a steam locomotive had reached the highest level possible before diesels took over. The art of balancing was well understood by the chief mechanical engineers of the day. The speed of Pennsy's T1 & Milw. A is nothing less than amazing and attained with no kinked rail. And, while they weren't designed for light warp factor speeds, the same was true for the N&W's refined Y5 & 6 class locomotives. Speeds of 50+ AND NO KINKED RAIL!!!

quote:

Six cylinder, V12, and straight 8 engines are inherently perfectly balanced.

The mechanical balance may be perfect (I doubt it), but, you are talking about an internal combustion engine, a totally different beast. Now you have to deal with harmonic balancing that will tear an engine to bits. Just ask Porsche what happened to their 917's 12 cylinder engine.

HEY!  You can't leave me here, all alone with these foaming rivet-counting experts!
Hello?  Hello?  He's gone.  

 

That had to do with the wheel arrangement and not hammer blow, due to a set of odd couple drive wheels having the drive shaft attached to the center driver they rocked back and forth horribly from a form of occilasion (sp?) it was amplified from the displacement of mass by the large cylinders required for a set of ten drive wheels, it was hard on crews and locomotives.

Wow!!Well it seems I have steped in it this time.I have to say a few things here.1 I have some some early railking steam locomotives.You know the one with out the sound system.2I had good sized track and ran some fairly long trains.3Yea they had traction tires.And if a traction tire came off.I stoped the train(hey I don,t want ruin it.)I would have the tire replaced.4I read a book called yonder comes the train.It cover american railroads pretty well.It metions the ACL had 4-8-4 northerns to compete with SAL mountain type 4-8-2.ACL northerns had balance issues.5Guys I didn,t not mean to start any thing.I should have metion some times.I would just run the trains and lay down on the floor and just watch.With runing a long freight train at a good speed.You are going to hear sounds of the trains.Yea I would even put my ear to the floor.I know what I heard and thats my story.Oh one more thing I didn,t mean it would do damage to the locomotive or track.And speaking of track you guys be careful when you buy track for your layout.Had to replace a rh switch and cut some more track work.

"The mechanical balance may be perfect (I doubt it), but, you are talking about an internal combustion engine, a totally different beast. Now you have to deal with harmonic balancing that will tear an engine to bits. Just ask Porsche what happened to their 917's 12 cylinder engine."

 

It is clear that you know nothing about balancing engines.  Harmonic balancing is a different problem.  This has to do with torsional vibrations in the crankshaft which can cause the crankshaft to fail.  This is why all engines have a harmonic balancer on the front of the crankshaft.  This harmonic balancer isn't really a balancer but a harmonic damper to damp the torsional vibrations of the crankshaft.  And it is true if this isn't done correctly, the crankshaft will fail particularly it is driven at resonance.  In other words, if the engine RPM is at the crankshaft torsional resonance frequency, the stresses in the crankshaft get very high, and the crankshaft will usually fail.

 

Here is a good article on engine balance:http://en.wikipedia.org/wiki/Engine_balance

Hilarious.  Just absolutely priceless.  Just compare the last two posts in not only content, but intent.  I think something got off track, if you'll pardon the expression.  You gotta love it.

Lol, i have just read a great deal on steam locomotives, good point.

So, what are you actually seeing, when your train looks like it is exhibiting a hammer effect? I really want to know.

 

The discussion of and lessons on the real world topic a interesting and educational (I even think I know enough that our trains have spinny things that drive pointy thing, to make the wheels roll, but no cylinders to balance

On a serious note, I wasn't suggesting you would ignore a lost tire, it's just the closest thing I've seen in O, to any kind of irregular running. Some N gauge steamers are prone to being out of quarter, so you get all kinds of weird motion.

 

But to make this about me. That's Atlas O track, directly on carpet!, which is what I want to start doing next Christmas, with 1 loop, but thought i'd have to build a base for it. Did you do anything to keep sections from pulling apart?

Wow, lively thread lol. Those are cool videos, and I have to say that this is one of the main reasons I got into O scale - the noise and the weight. Seeing these carpet layout videos re-inforces my opinion that once we have the noise and the motion,our imaginations fill in a great deal of the rest. The hammering included in the "real" train noises, of course. ;0) 

 

I hesitate to add more to the - um - debate, but here's a link ( I warn you, it's a British explanation ;0) )

http://5at.co.uk/index.php/def...s/hammer-blow-2.html