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Knuckle Coupler

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Posted by cordon on Friday, May 11, 2007 1:50 AM

Smile [:)]

Ed, thank you very much.  You have added a great deal to my understanding of couplers.

One of the original questions in this thread is how does one determine the date of manufacture of a coupler?  There are markings on them, but nothing that looks like a date.

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Posted by edblysard on Friday, May 11, 2007 5:17 AM
Nothing I have seen in 11 years allows me to "date" a coupler...the only things I have seen on them were mill markings and coupler type, no build date.

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Posted by Anonymous on Monday, May 14, 2007 3:01 PM

Thanks Ed for your insight on this subject of coupler function and forces.  I should mention that I have not received any reply to the email (posted on page 4) that I had sent to Joe Gagliardino on 4/28, asking for clarification of these matters.  But I think we have gotten beyond the need for his input.  There is one thing about this whole issue of coupler design and force transfer that stands out as a somewhat unresolved curiosity in my mind.  It is a bit difficult to describe, but I will try to make it as clear as possible.

Since the knuckle tang rotationally transmits a small portion of the coupler pulling force to the lock, one would expect that force against the lock to increase as the overall pulling load increases with the addition of more trailing cars.  However, I do not believe that is the case.  My assumption is that the tang force against the lock quickly rises to a moderate amount, and then can rise no further regardless of how much the train pulling load increases. 

This is because the force bearing ridges between the coupler tang and coupler housing are bearing the majority of the load, and this load would seem to provide friction that would restrict the knuckle from rotating and applying pressure to the lock.  As an analogy, rotating the knuckle when pulling a load would be like trying to rotate a wheel with a brake shoe tightly applied.  The brake shoe and the wheel face would, in effect, be the force bearing ridges.  The wheel would, in effect, be the pivotal knuckle. 

So while some of the pulling load wants to rotate the knuckle (turn the wheel), the majority of the pulling load wants to squeeze the force bearing ridges together, and thus keep their faces from slipping past each other as they would have to do in order for the knuckle to open (applying the brake shoe).

I would expect that at the moment of coupler slack pullout, the knuckle tang would swing into contact with the lock, and begin adding pressure to it.  But just as that contact force would begin to build, it would quickly be arrested by the braking action of the force bearing ridges as the loading pulls them tightly together.  So this would amount to a self-limiting feature that would limit the force that the knuckle tang can exert against the lock, no matter how high the coupler pulling load rises.

Consider a coupler with 100 cars in tow.  There would be some quantity of force by the knuckle tang against the lock.  Now add another 100 cars.  Will the knuckle tang-to-lock force in the first coupler increase?  I don't think it would.  It seems to me that once the coupler load reaches a certain level, the knuckle rotation force is completely canceled by the braking action of the force bearing ridges.  So while the additional 100 cars would add more loading through the force bearing ridges, they would not increase the tang-to-lock force.

To illustrate what I am saying, consider this hypothetical question:  Say a coupler was under load, and somehow the lock simply disappeared while the coupler was under load.  Would the knuckle open when the lock disappeared?  Or would it be prevented from opening by the rotational binding friction between the force bearing ridges that is created by the pulling load.  I know there is no way to actually conduct this experiment, but its purpose is to illustrate a question about the force transfer through the knuckle.  My guess is that the knuckle would not open in this hypothetical scenario.

Now considering the logic of this effect, one might conclude that, during uncoupling, the knuckle would not open when being pulled after the lock is removed by the cut lever.  Why would the knuckle not just bind up against rotation due to the braking effect of the force bearing ridges as described above?  I would guess that the knuckle does not bind up until some force is applied to the lock, and this necessary binding initiation force cannot be achieved with the lock removed.  

If this analysis of the relationship between the knuckle tang, lock, and force bearing ridges is accurate, it strike me as a most ingenious novelty in the design.  It means that the lock is only needed to keep the knuckle closed until the pulling load force is applied.  Once the pulling force is applied, the lock remains crowded against its slop, but not under active compression from the load.  If the slack runs in, the lock is once again necessary only to keep the knuckle closed during the first instant that the slack runs back out as the load build against the force bearing ridges.     
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Posted by cordon on Monday, May 14, 2007 5:20 PM

Smile [:)]

Thank you, Bucyrus.  I agree with the analysis.  It would be very difficult, perhaps not even possible, to quantify the force relationships in greater detail because they involve static solid friction ("stick-slip"), constant vibration, and varying forces over curved surfaces.  In a stick-slip relationship the solid surfaces resist sliding once they come into contact with no relative motion.  Some people use the term "lock together."  The static force can be very large.

I feel we have answered all we set out to, including an expert opinion that we can't get a date of manufacture for a particular coupler.

I will still try to get access to a coupler that I can take apart for photos of all the pieces and how they fit together.  We've had a lot of rain here, and the caboose is in a park under construction, so access is difficult due to sticky mud.

Many thanks to all who have contributed to this thread.  I have learned much more than I thought I could about couplers. 

Don W.

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Posted by edblysard on Monday, May 14, 2007 6:51 PM

As you noted, the small surface of the lock pin being pushed upon by the knuckle tang, added to the fact the lock is also housed in a pretty solid coupler body, prevents the lock from shearing under load, plus the majority of the load is on the tang lands and grooves.

All the lock pin has to do is keep the knuckle from rotating for a very short time before the tangs lands and grooves take up the tension.

More simply, there isn't enough leverage being exerted on the lock pin to shear it...but they have failed, I have had two "come aparts" in 11 years, one due to a coupler key falling out, followed by the entire coupler, and one due, most likely, to a broken lock pin.

Never really know about the second one, the cut leaver dropped out also, got ripped off, so the best the mechanical folks could figure was the lock pin broke, and let the lift mechanism fall...we couldn't figure out which knuckle in the middle of the tracks was from that one car, and the remainder of the leaver and lift stuff was pretty mangled!

I wish there was a way to let you guys play with one for a few minutes, it is a pretty simple design, and once you get some hands on with it, you will see how easy, and reliable they are.

Have you noted that none of the parts of a knuckle/coupler are lubed?

Other than the sill plate, there is no need for it, in fact, lubing it would make it harder for the thing to work.

 

There is no in-between with a knuckle/coupler, it either works or it doesn't.

This is one of the examples of the KISS system...crude and primitive as it is, it works because it is simple, massive and meant to be hammered repeatedly, the parts can be changed out with nothing more that a pair of pliers and it needs only gravity to function.

 

Here is a question for the math whizzes out there...how much force would be needed to shear a two inch square piece of solid cast steel?

Because that's how much force would be needed to shear a lock pin...and I am asking not because I am trying to show off or be smart, but because I really don't know, and would kinda like to!

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Posted by Anonymous on Tuesday, May 15, 2007 3:22 PM

There is still something that I can't quite get my mind around here.  If the knuckle basically pulls against the force bearing ridges, how can it freely rotate when you open it? 

When you open the knuckle, it is pivoting on some kind of axis feature.  Otherwise it would just grab on the force bearing ridges and bind against opening.  So what is the pivot feature that acts like an axle for the opening knuckle?  It can't be the pin because the knuckle pivots without the pin in place.  So it must be the bosses inside the coupler housing knuckle yoke engaging the pockets on the knuckle.  Those pockets are only portions of a full circle, so once the knuckle pivots about 100 degrees to full open, those pockets are positioned so the knuckle can separate from them by moving to the right (when facing the coupler).

But here is the problem.  If the knuckle pivots on those bosses and pockets to open, it must leave clearance between the force bearing ridges so they do not grab and bind the rotation.  That would mean that when you pull on a closed and locked knuckle, it must make contact through the bosses and pockets first.  If that is true, how does it ever load the force bearing ridges?

 
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Posted by Semper Vaporo on Thursday, May 31, 2007 9:49 PM

Video from another thread "NS Conductor pre-hire video"...

http://www.nscorp.com/nscorphtml/video/Conductor_prehire.wmv

At about 4 minutes are a couple of very quick shots of someone putting a coupler pin in the knuckle (don't blink, you'll miss them).  Then at about 7 minutes are several shots of the knuckle falling out and being replaced.

 

 

Semper Vaporo

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Posted by edblysard on Friday, June 1, 2007 12:02 AM

To borrow Cordon's excellent photo as an example.

The coupler has a tenon, and the knuckle has a mortise...they fit together, all the knuckle pin provides is a pivot point and a means to keep the knuckle from tilting forward as it opens...the knuckle rests on the lower mortise,and if you study the casting on the knuckle laying on the ground, you can see the pivot point is the mortise with the pin hole, and the back of the mortise is open, so it can slide into the coupler during replacement.

You are looking at the bottom, back side of the knuckle on the ground.

 

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Posted by cordon on Friday, June 1, 2007 1:01 AM

Smile [:)]

 

Thank you very much, Ed and Charles.  I really enjoyed the video.

Next time I am at the location where I took the picture, I'll ask again if I can handle the coupler and take closer pictures.  Maybe I'll have better luck.

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Posted by BigJim on Friday, June 1, 2007 4:12 AM

ed,

Have you seen any of the plastic knuckle pins yet? They don't even have a cotter pin to hold them in. A conductor I was with said that they had broken a knuckle out on the road and the thing mangled up the plastic pin so bad he couldn't temove the broken knuckle. He had to call out the shop forces to come and drill the thing out!

.

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Posted by Anonymous on Friday, June 1, 2007 7:59 AM
 edblysard wrote:

To borrow Cordon's excellent photo as an example.

The coupler has a tenon, and the knuckle has a mortise...they fit together, all the knuckle pin provides is a pivot point and a means to keep the knuckle from tilting forward as it opens...the knuckle rests on the lower mortise,and if you study the casting on the knuckle laying on the ground, you can see the pivot point is the mortise with the pin hole, and the back of the mortise is open, so it can slide into the coupler during replacement.

You are looking at the bottom, back side of the knuckle on the ground.

 

I understand these configurations, and that the knuckle pivot axis is comprised of the round wall of the mortise on the knuckle turning on the round boss of the coupler tenon.  And I see how these features disengage when the knuckle is open. 

So this pivot axis would exist even without the pin except that the axis features disengage when the knuckle is open.  Thus the pin is needed to keep the knuckle from falling out when the knuckle opens and its pivot axis features disengage.

However, one issue of this study in force transfer that I still cannot understand is what I referred to in my post of 5/15/07, summed up in its last paragraph.

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Posted by edblysard on Friday, June 1, 2007 10:37 AM

Sorry, I lack the verbal and technical skills to explain it any better than this, but here goes.

The pocket and bosses are not a snug fit, nor is the knuckle pin snug.

When you pull on the knuckle's lip, (not the inner face) it will pivot some, you are in essence working a simple lever, and it will rotate until the tang hits the lock pin.

Because I am a puny human, that's where all the forces in play stop the knuckle...when a 175000 pound tank car pulls on it, it is pulling on the inner face, in a straight line and there is enough linear force to cause the tang and grooves to engage...the slop or slack in the pivot point are there to keep the knuckle from breaking the pivot pin and the bosses/pocket...the amount of distance or slop traveled to engage the tang is less then the amount of slop or slack in the pivot point, so it engages before any stress is transferred to the pivot.

Because the inner coupler faces match, and are curved, they tend to lock together...remove the lock pin, and pull in a straight line, the knuckle without the lock pin will pivot, till there is enough space to allow the two faces to slide past each other...this is the only time the pivot pin is under any real force, and that is only to allow the knuckle to pivot...the two faces clear each other before the tang can travel its full distance and hit the small "nose" on the lock pin, the knuckles don't open all the way, only to the point the faces clear...the force on the pivot pin is no more than the amount I generate when I pull on the lip while opening the knuckle.

If the tang is stuck in its grooves, which happens, all the forces are there, not at the pivot point...the knuckle wont move at all...which means you have to try and open the opposing knuckle.

 

If you look at the photo, you will note the coupler has the small bosses you refer to, perfectly round, about ¼ of a inch tall...these act as washers, they are the friction point when the knuckle opens, it floats on them.

They never make contact with the edges of the pockets in the knuckle, except when you are replacing the knuckle.

Because you don't lube knuckles, any friction point that was large would create enough friction that I couldn't open the knuckle, and if the tang fit the groove snugly, again, way too much friction for a normal 160 lb human to overcome.

So, the knuckle is allowed to "float" on the bosses...the true contact point between the knuckle and the coupler is the small bosses only when the knuckle is not under tension or compression..

The tang does not contact the grooves much, if any, so you have the 90 lb knuckle balanced on two bosses.

Because these bosses and pockets are almost dead center of the balance point or the center of gravity of the knuckle, it moves fairly easy...but once the knuckle, in the closed position is pulled straight forward, the tangs lock against the groove inside the coupler...that's the main reason the back of the pocket is open, to allow the knuckle to move forward when pulled.

Because slop here is greater than the slop in the tang and groves, the tang snugs up before any binding happens at the pivot point, and bears all the forces.

 

When I open a knuckle, I am pulling on the lip of the knuckle, providing leverage, and with the lock pin disengaged, the knuckle rotates on the bosses.

With the lock pin engaged, the knuckle pivots ½ inch or so, then stops when it hits the lock...when a railcar pulls, it pulls on the entire inside face, and it pulls in a straight line through the center of the knuckle...the knuckle might pivot the ½ inch, then hit the lock, but because the pulling force is straight line instead of at the lip, the knuckle for lack of a better description, moves forward and jams into the front tangs and grooves.

 

Imagine that you were facing a coupler dead center, as if you were standing in the center of the tracks.

If you pushed on the center of the knuckle, the knuckle will move straight back a small amount, till the backside of the tang hits the grooves in the coupler.

If you grabbed the dead center of the knuckle, and pulled straight forward, the knuckle will move outward some, till the front of the tangs and grooves engage.

This happens because the raised lip in your bosses are floating the knuckle...the lock pin is acting as both a lock, and a shoulder/guide to keep the knuckle moving forward or backward, in or out in a straight line.

Raise the lock pin, and apply the pulling force to the lip of the knuckle, and you create enough leverage to pivot the knuckle.

Often, the knuckle gets jammed so tightly into the lands and grooves of the tang that you can not create enough leverage to open the knuckle...at least puny humans cant!

You have to go to the opposing car and open that knuckle to couple up the cars.

If your unlucky enough that this one will not open too, you leave them both bald headed (closed) and get your engineer to bunch up the cars, giving the two knuckles a little smack...this is usually enough to knock one or the other knuckle back into the pocket of the coupler enough to allow you to open one after you create the proper clearance between the cars.

Again, the slack or slop between the lands and grooves of the tang are less than the slop in the knuckle pin/bosses/pockets...it will always engage or take up its slack before the boss/pin set up is put in a bind, no matter if the forces are pulling or compressing the coupling.

When coupling up the cars, the forces start out as, again forgive my technical numbness...working on a curve, they are pivoting the knuckle back into the coupler pocket...once the knuckle tang hits the end of the groove, the forces translate into linear forces, straight line if you will, and force the knuckle tang backwards into the rear grooves, taking all the force up here, and on the outer face of the opposing knuckle, and the inner face of the coupler pocket...the pivot pin and bosses/pockets are under no force now, because the slack there at the bosses/pin is greater than the slack between the knuckle faces and the tangs and grooves...at this point, you can reach in a pull the knuckle pin out of the hole...it is under zero force, and in fact, if you couple up a little hard, the pin can jump up from the vibrations.

 

I think what is confusing everyone is the translation period...you are expecting the knuckle to fit tight on its bosses and the tang and groove to be tight all the time...similar to the hinges on a door, with no slop or slack.

Close a door, and push on the center of the door, you are exerting the same pressure on the hinges and the door lock bolt, because everything is tight.

Turn the doorknob, (remove the bolt) and push on the center of the door, it will open, but a large amount of force is needed, until the door open past a given point and your hand slides across the face of the door towards the doorknob edge ...if you pushed on the edge, or the doorknob, the door pivots on the hinge and requires less force to open, because you are employing a simple lever.

Put a little slack or play in the hinges and pins, and a bolt or lock on both sides of the door, when you closed the door and engaged the locks, if the locks were tight fitting, when you pushed on the center of the door, the locks would bear the force, not the hinge, yes?

 

And you are expecting the only rotation point for a knuckle to be the pin and the hole it rides in...when it usually is the tang, lands and grooves that bear the rotational force...because the forces in play are huge, any friction the knuckle tang would have is minimal in comparison, and once past a certain point, where the lip of the opposing knuckle bottoms out against the inner face of your k

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Posted by Anonymous on Friday, June 1, 2007 9:59 PM

Ed,

Thanks for that explanation.  I think you did an excellent job of putting it into words, and you addressed my question perfectly.  In my question, I think I made a wrong assumption about what constitutes the pivot bearing features of the knuckle.  I had concluded that it couldn't be the pin and holes because the knuckle can pivot without the pin.  So I thought it must be the walls of the small round bosses and the knuckle mortises.  But if I understand you correctly, these are not the pivot bearing features either.  Instead the knuckle simply pivots while balancing on the end of the round boss below the knuckle.  So it really has no physical axle to pivot on.  It is just balancing on the end of a raised peg.  So with the lock removed, the knuckle would rather pivot on the top face of that round boss instead of dragging forward to load against the ridges.  With the lock in place, the knuckle cannot pivot, so it pulls forward and loads the force bearing ridges of the tang and corresponding features of the coupler body.

 

 edblysard wrote:

If you look at the photo, you will note the coupler has the small bosses you refer to, perfectly round, about ¼ of a inch tall...these act as washers, they are the friction point when the knuckle opens, it floats on them.

They never make contact with the edges of the pockets in the knuckle, except when you are replacing the knuckle.

So, the knuckle is allowed to "float" on the bosses...the true contact point between the knuckle and the coupler is the small bosses only when the knuckle is not under tension or compression..

The tang does not contact the grooves much, if any, so you have the 90 lb knuckle balanced on two bosses.

Because these bosses and pockets are almost dead center of the balance point or the center of gravity of the knuckle, it moves fairly easy...but once the knuckle, in the closed position is pulled straight forward, the tangs lock against the groove inside the coupler...that's the main reason the back of the pocket is open, to allow the knuckle to move forward when pulled.

Because slop here is greater than the slop in the tang and groves, the tang snugs up before any binding happens at the pivot point, and bears all the forces.

When I open a knuckle, I am pulling on the lip of the knuckle, providing leverage, and with the lock pin disengaged, the knuckle rotates on the bosses.

With the lock pin engaged, the knuckle pivots ½ inch or so, then stops when it hits the lock...when a railcar pulls, it pulls on the entire inside face, and it pulls in a straight line through the center of the knuckle...the knuckle might pivot the ½ inch, then hit the lock, but because the pulling force is straight line instead of at the lip, the knuckle for lack of a better description, moves forward and jams into the front tangs and grooves.

 

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Posted by edblysard on Friday, June 1, 2007 10:07 PM

Yes...yes yes yes...

See, you explained it is so few words, but did so precisely.

I am one of those people who can't talk without a pencil in my hand and paper to draw you a picture on....Big Smile [:D]

So I often go the long way around to cover a short distance!

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Posted by cordon on Friday, June 1, 2007 10:49 PM

Smile [:)]

Ed and Bucyrus,

Thank you very much for the explanation and comments.  I find both to be excellent, and I am really pleased that I have learned so much about the inner workings of RR couplers.

Smile [:)]  Smile [:)]

 

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Posted by AnthonyV on Saturday, June 2, 2007 7:13 AM

 

Ed,

What circumstances would cause the pivot pin to fail?

Thanks

Anthony V.

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Posted by edblysard on Saturday, June 2, 2007 7:03 PM

Kicking cars against each other with the knuckles closed will do it quite nicely.

Because the knuckle rides or balances on the boss, and there is some play there, if the knuckle shifts off  the true...tilts if you will from wear on the boss and the knuckle pin hole wearing a little bigger than normal, you can shear one or break it, about 4 inches from the top usually.

Sometimes, the knuckle binds on the tang and groove when opening, and the knuckle slides forward instead of pivots, slams into the pin, and causes a stress fracture.

The forces in play here are huge...I have seen the knuckle exploded, shattered into pieces when a crew kicked a cut of hoppers, loaded with plastic pellets, into a standing cut of cars.

If everything works as it should, this never happens, but then again, when has everything gone according to plan?Big Smile [:D]

 AnthonyV wrote:

 

Ed,

What circumstances would cause the pivot pin to fail?

Thanks

Anthony V.

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Posted by AnthonyV on Sunday, June 3, 2007 4:07 PM
 edblysard wrote:

Kicking cars against each other with the knuckles closed will do it quite nicely.

Because the knuckle rides or balances on the boss, and there is some play there, if the knuckle shifts off  the true...tilts if you will from wear on the boss and the knuckle pin hole wearing a little bigger than normal, you can shear one or break it, about 4 inches from the top usually.

Sometimes, the knuckle binds on the tang and groove when opening, and the knuckle slides forward instead of pivots, slams into the pin, and causes a stress fracture.

The forces in play here are huge...I have seen the knuckle exploded, shattered into pieces when a crew kicked a cut of hoppers, loaded with plastic pellets, into a standing cut of cars.

If everything works as it should, this never happens, but then again, when has everything gone according to plan?Big Smile [:D]

 AnthonyV wrote:

 

Ed,

What circumstances would cause the pivot pin to fail?

Thanks

Anthony V.

Thanks Ed.

What do you think is the theory behind the plastic pins?  Is it possible that because they are more flexible than the steel pins, they can withstand greater slop in the coupler before breaking, at least in theory?

How well do they work in reality?

Anthony V.

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Posted by Anonymous on Monday, June 4, 2007 7:19 PM

Here are a couple of patents for plastic knuckle pins with copious description of their form, engineering principles, and rationale.  There is discussion of how the coupler falls out of tolerance with extended use, and that this can place loading on the knuckle pins.  The loading can break steel pins, but plastic is intended to survive the loading by bending.      

 

http://www.patentstorm.us/patents/6488163.html

 

http://www.patentstorm.us/patents/5630519.html
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Posted by tree68 on Monday, June 4, 2007 9:46 PM

Well - I finally got my hands on a coupler, and a couple of nice close-ups, but things have been explained here very nicely.  I'd have taken more, but the engineer felt the locking pin, etc, were a little stiff, so he'd just doused everything with 30W...

Just goes to show that there are no stupid questions.

LarryWhistling
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Posted by edblysard on Monday, June 4, 2007 11:09 PM

Bucyrus and Anthony...

In my experience the plastic pins seem to fail relatively faster than the steel ones.

Those that do not break tend to get bent or misshapen enough to make it harder to open the knuckle by hand as opposed to the steel ones.

Both, if they break at the 4 inch from the top standard, will still hold the knuckle in...our car department tried using the plastic ones, but after a six month period of replacing more that twice the number of plastic pins, they gave it up and went back to the steel ones.

Now, we are a switching and terminal railroad, lots and lots of kicking and switching out in the plants and yards, so you would expect us to have a higher failure rate on knuckle pins, cut levers and stuff like that than a short line or regional would experience....but a twice than normal failure rate on a product designed and intended to suffer this abuse would tell me it isn't anywhere near as good a product as its manufacture wants you to believe.

 

 

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Posted by edblysard on Monday, June 4, 2007 11:11 PM

Larry,

Lets see them anyway, they may just add the iceing on the cake so to speak!

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Posted by AnthonyV on Tuesday, June 5, 2007 5:57 AM

Thanks guys.

It will interesting to compare the patent claims with Ed's hands-on experience with the plastic pins.

 Anthony V.

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Posted by tree68 on Tuesday, June 5, 2007 6:53 AM
 edblysard wrote:

Larry,

Lets see them anyway, they may just add the iceing on the cake so to speak!

Only one shot - the other, with the knuckle fully open, didn't really show much, at least from the angle I shot it. 

Note the red and green dots I added - the weight-bearing surfaces on the coupler body and knuckle, respectively.

If there are requests for other pictures - I have plenty of access each weekend.

That coupler is on our RS-3.

LarryWhistling
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Posted by Paul_D_North_Jr on Tuesday, June 5, 2007 9:52 AM

In the middle of Warwick, NY there's an opportunity to view and safely play with - excuse me, manipulate - a coupler without a knuckle, so that all of its inner workings are readily visible while moving !

Its on the easterly end (rear) of the caboose on display* in the northeasterly quadrant of the grade crossing of South St. with the Norfolk Southern east-west line through town (former Lehigh & Hudson River ?), about 1 block east of north-south Routes 17A / 94 / Oakland Ave. / Main St.  Just turn east on Railroad Ave., go 1 block east past the station building to South St., and turn left - it's readily visible on the right just after the grade crossing. 

* This caboose is now used as the Chamber of Commerce or Visitor's Center  (not sure which - wasn't paying attention to that).  It is painted red and lettered in yellow (if I recall correctly) as "Lehigh & Hudson River 20".  Lest someone be misled, however, I also recall seeing on another forum last week that it really isn't a former L&HR caboose at all, but some other railroad's instead (I'm thinking Lehigh & New England ?), and that the fellow who actually cut the stencils and painted it assigned/ used a number just above the L&HR cabooses' actual number series (as is wisely often done in such "reproduction" circumstances to avoid confusion and inaccuracies, etc.).

Further, last weekend (Memorial Day, Monday, May 28th) I was able to view this coupler and take some digital photos of it.  Unfortunately, the coupler is pretty much all painted black, so I'm not sure yet how clear those images will appear or how well they will illustrate the mechanisms that we've been discussing and reading about - that's one real advantage of the rusty color in the previous photo.  Also, those images will be static, and I suspect that the coupler's operation will be best understood by viewing a video to see all of those parts in motion.  Nevertheless, if those images seem to add to the collective information here, I'll try to post them in the next day or two. 

The coupler on the other /esterly / "front" end appears to be intact, but it too is painted black, and I couldn't get any part of it to move - whether it is "frozen" from paint, rust, or welding, etc. I couldn't tell.

In the meantime, maybe somebody else could make a short video of a coupler in action and post it on one of those sites ?  And it would be even better to get one and cut it in half lengthwise, too.  (I'm too busy this summer to add that to my list of things to do, but NS has a big yard here in Allentown where I could probably get hold of a scrap one, and it's not that far to the WK&S / BR&W / Steamtown / Strasburg/ RR Museum of Pa / Altoona RRers Museum / B&O Museum, etc., so we'll see what happens with that idea.)

Further, I continue to think that one of these would make a great museum "hands-on" working display, though maybe cast out of a light-weight plastic instead to prevent injuries to children (of all ages).

- Paul North.

"This Fascinating Railroad Business" (title of 1943 book by Robert Selph Henry of the AAR)
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Posted by Anonymous on Tuesday, June 5, 2007 10:39 AM

I would think that the coupler manufacturing industry has 3d cad solid models of all the components of couplers, plus the assembly.  These 3d cad models could be used to make a clearly illustrated pictorial of the kuckle opening, closing, locking, unlocking, knuckle thrower action, and force transfer through the various features when pulling and pushing.  The pictorial could be animated to show all of this with cartoon-like clarity. 

I do not know how to go about acquiring access to this cad data, or whether the sources would release it, however.  If they would not release detail drawings or cad files, cad models could be produced independently by measuring new coupler parts, and modeling them on Solidworks.  You would not know the tolerances, but with new parts, you would know you were modeling parts within tolerance.  

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Posted by cordon on Tuesday, June 5, 2007 2:14 PM

Smile [:)]

I've received permission from the Historical Society to disassemble and photograph the coupler on their caboose here; but as I said several posts ago, there is a sea of very sticky Texas mud surrounding the caboose.  I haven't forgotten about it.  I just don't want to deal with the mud.

Smile [:)]  Smile [:)]

 

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Posted by tree68 on Tuesday, June 5, 2007 3:42 PM
 cordon wrote:

I've received permission from the Historical Society to disassemble and photograph the coupler on their caboose here; but as I said several posts ago, there is a sea of very sticky Texas mud surrounding the caboose.  I haven't forgotten about it.  I just don't want to deal with the mud.

Just remember - no "pocket screws."*

Smile [:)]  Smile [:)]

*That's the leftover parts you can't figure out where they go, so you just put them in your pocket.....

 

LarryWhistling
Resident Microferroequinologist (at least at my house) 
Everyone goes home; Safety begins with you
My Opinion. Standard Disclaimers Apply. No Expiration Date
Come ride the rails with me!
There's one thing about humility - the moment you think you've got it, you've lost it...

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Posted by cordon on Wednesday, June 6, 2007 2:08 AM

Smile [:)]

No, I would never do that.  I checked out another one today (with permission), but the lock was jammed.  I couldn't get it out, but I could see how the knuckle thrower was mounted inside.

Smile [:)]  Smile [:)]

 

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Posted by Anonymous on Wednesday, June 6, 2007 11:44 AM
No need to worry about pocket screws because there are no screws.  I have only seen a couper being disassebled once, but as I recall, there are no fasteners.  They come apart like a puzzle, and it is not completly obvious how to do it.  You remove the knuckle pin, then the knuckle, and after that, it gets a little tricky.  You will probably be able to figure it out.  I admire the elegance of a design that requires no fasteners. 

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