Breaking knuckles

[Mickhall]

How often do "knuckles" get broken and what is the procedure when it does occur?
Thanks for any responses.

Mick

[Anonymous]

Mick knuckles don't break that often but when it does happen it's a frustrating time for the crew. The need to change the knuckle out and so they always carry spares with them. I believe engines carry spares but I'm not sure about the cars. Anyone help? It happens in the mountains more often than the plains as well. Tahachapi loop is nortorious for causing problems ike that.

[Anonymous]

Trust me from past experiance! When the drawbar brakes in the middle of a bridge. It isn't fun.

[Anonymous]

Mick,

I am a civil engineer who happens to like choo-choos. I imagine a knuckle break is something like this ...

Usually ascending a grade, a knuckle will break in a car near the engine where the drag force is greatest. Then when the air hoses come apart the breaks stop the runaway. The crew contacts the dispatcher and backs the engine(s) to the cars. The crew gets out and replaces the coupler (exactly how I don't know). The crew replaces the air hoses, checks the train and pulls out. Then they contact the dispatcher and tell them they are underway.

One question I have, I usually see no more than four engines at the front of a train. Is that about the limit of a knuckle? How much horsepower and force does it normally take to break a coupler?

[Anonymous]

Actually, the frequency of broken knuckles depends on location and grade profile. In fact some certain locations are often refered to as drawbar alleys. If you are lucky, you only break a kuckle. Then it is just a matter of dropping a spare off of the engine and pulling the head end of the train up to the set off nuckle (they weigh 85-90 lbs). Changing it is as simple as lifting the nuckle pin out and replacing the nuckle. Some times the pin may have a cotter in it which can complicate matters a bit. If you are unlucky and pull a drawbar out things can get ugly depending on which end of the car is involved. The trailing end is a simple matter of pulling the headend up to a spur and setting the car out. If it is the leading end, you have to either get help to set it out from the rear of the train or chain up the car and pull it to a spur track. Of course you still have to deal with the broken drawbar that is left between the rails. Usually the Car Dept. or other source with a boom truck is needed. Broken kuckles ar usually the fault of poor or rough train handling, although I have seen some that showed signs of being fractured for some time that finally let go with a minimum of extra help.

[wabash1]

most knuckles i have had to replace were due to improper train handling. and depending on the engineer and the mood of conductor at the time depends if the incident gets reported as a broken knuckle or train seperation. a knuckle goes on engineers record a seperation is just a delay. and you must be careful here to couse false reporting of this can get the condutor fired. and it has always been in the rear 30 cars that most times this has happened to me.

[Anonymous]

I agree. I have seen knuckles break within 6 to 8
cars from the rear end due to the increase in slack force as the train accelerates. Undulating, or "rollercoaster" grades can be a real problem with out the proper brakepipe reduction. Especially for green engineers. Claiming delays for knuckle bypasses can be tricky in CTC territory if you need to make a long reverse move to saw a knuckle back without permission. It's bad enough without cabooses to walk all the way to the rear end, let alone carrying a knuckle, air hose and wrench with you.

[PaulWWoodring]

I'm a newly qualified engineer for CSX. Knuckles are a major area of concern. To answer some of the issues of this discussion:

There are certain situations that are more likely to produce a broken knuckle than others. The most likely reason to "get a knuckle" is allowing the slack in the train to become uneven, that is some cars stretched out and some cars bunched-up and then either start pulling hard on the train going up a hill, or have the train go into emergency for some reason. Another common reason for breaking one is trying to do a "running release" of the brakes on a freight train below about 10 mph. CSX train handling rules specifically recommend against that. On a long train, especially one where there is a lot of slack action between the cars, like auto racks, as the brakes release on the front, you think that the train is rolling freely, but the rear has not released yet, and bang. Supervision always wants to know what percentage of the break is rust. Anything much over 50% rust and they chalk it up to mechanical failure.

About the force necessary to break a knuckle: CSX says a knuckle is good to about 250,000 lbs. of tractive effort, so they limit maximum tractive effort of any engine consist to 240,000 lbs. The limit for engine consists is 24 powered axles on-line, and it's not always the actual number of axles on an engine that is counted. High horsepower AC's are counted as 9 axles. There are timetable exceptions to this for specific places. The base line standard for these limits are SD 40's for most of CSX and GP 40's on the RF&P sub.

[wabash1]

i can not understand why you make a brake pipe reduction in rip rap territory. that to me would defeat the perpose of train handling. not to mention keeping your train at track speed. and in abs,ctc,tc,rc track warrant or otherwise as long as the rear of the train dont move then you can do as you want with the front half. meaning if the last car is cut off, you can pull the front ahead to pick up a knuckle then shove back to fix the car couple up and walk to the head end and leave. all legal with out special permission.

[Anonymous]

Freight cars don't carry spare knuckles or any other parts. It would be a good idea, but the lighter they are, the more freight they can carry.

[PaulWWoodring]

Freight cars may not carry knuckles, but most engines on CSX carry one of each major type - "E" or "F". They are stored on the pilot of the long hood end of road units.

[Anonymous]

The engines on my road are also fitted with spare knuckles - I suppose all roads would do this.