the MRH Forum

Visual differnce between K and AB brakes Locos and rolling stock
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Prolific poster 1,660 posts IrishRover Prolific poster 1,660 posts
IrishRover

When a car rolls by on an HO scale layout, how much visual difference is there between the various sorts of airbrakes?  I tend to notice the presence of a brake system, but don't know the details.  For now, anyway, if a car will have visible brakes due to its design, and doesn't include them, I'm happy to put Accurail brakes in there.  http://accurail.com/accurail/Direct/Underframe/180.JPG

They are likely far from perfect, but I see a freight car go by, not blatantly missing anything.  I see people mention switcihg brake systems out--how much visual difference does it make from a foot and a half away.  (A foot and a half away if my distance, because that's how far away I am when I'm manipulating my rolling stock, or watching a train go by from close up.)
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blindog10 Prolific poster 3,329 posts
blindog10

AB has more and bigger parts

The normal K brake system used on freight cars had a smaller control valve (usually called a triple valve because it has three actions), and the single-compartment reservoir was mounted on the back of the cylinder. One version of the K had all three on one bracket. The last version of the K (the KD) separated the reservoir and cylinder, so it was often called a "split K" in the field. The AB uses a larger 2-compartment reservoir, a larger 4-action control valve, and sometimes a bigger cylinder (that depends on the loaded weight of the car). They are always separate. Load/empty valves that adjusted braking effort to prevent wheel slide became more common. Over time the control valves got bigger as you went from AB to ABD to ABDW to ABDX. Scott Chatfield
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David Husman dave1905 MRH Author 9,882 posts
David Husman dave1905

Brakes

There is a pretty pronounced difference between K and AB, not so much between AB and subsequent brake systems.  

K has the brake cylinder and reservoir as one long object under the car while AB has separate brake valve, cylinder and reservoir, and the various pieces were typically on opposite sides of the center of the car.

Dave Husman

Visit my website :  https://wnbranch.com/

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JC Shall Prolific poster 1,498 posts
JC Shall

Some Drawings

The NMRA has this PDF file which has drawings that will give you an idea of the differences in appearance.

http://tc-nmra.org/TC-Library/Model%20Railroading's%20Dark%20Underbelly%20-%20Final%20Version.pdf

-Jack

Louisiana Central Railroad

The Louisiana Central Blog
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Gary Yurgil Regular poster 128 posts
Gary Yurgil

Now to practical purposes

I have been waiting for a thread like this forever.  Jack, I really appreciate the link you provided.  My problem is I never know (knew) how to detail the hand brake area on my models.  The first picture shows the brake shaft just ending in space ( by the arrow).  What do I model there?  I think the answers is shown in Jack's link.  Just wrap a small section of chain and attach it under the car.  Am I right?  I've seen some posts where the modeler used a more elaborate connection to the shaft with a bracket around it.  What do you all do?

car%202.jpeg 

 

xcar%203.jpg 

Gary - HO wanabe
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blindog10 Prolific poster 3,329 posts
blindog10

depends on the type of handbrake

The upper drawing shows a "power handbrake." The wheel turns gears that lift that rod that goes to the bottom of the end. It should be attached to a bell crank which pulls on a rod connected to the brake cylinder. If you get one of the Cal Scale, Detail Associates, Grandt Line, or Tichy brake sets you will see these parts. The lower drawing shows how the old "vertical staff" handbrake was connected. The wheel turns a rod and the chain wraps around the bottom of the rod. The other end of the chain (or chain/rod combo) is connected to the brake cylinder. So yes, most kits in the old days were missing some critical parts in the handbrake mechanism. Scott Chatfield
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JC Shall Prolific poster 1,498 posts
JC Shall

Connecting the Handbrake

Yeah, that little piece of information can be elusive.  As Scott mentions, older cars with the vertical shaft simply wound up chain near the bottom of the car.  Check the handbrake article in the November 2013 issue of MRH for some photos.

The modern cars with the gear box typically use the bell crank assembly as Scott mentions.  Here are a couple photos that might help you visualize that arrangement.

%2Bbrake.jpg 

ghtonBox.jpg 

-Jack

Louisiana Central Railroad

The Louisiana Central Blog
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Gary Yurgil Regular poster 128 posts
Gary Yurgil

Thank you

Thank you Scott and thank you again Jack for clearing up my newbie understanding of modeling brakes.

Gary - HO wanabe
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gna Regular poster 193 posts
gna

Modeling Brakes

Ted Culotta has an article on modeling brakes on his Steam Era Freightcars site:

http://steamerafreightcars.com/modeling/articles/brakesmain.html

Has pictures of AB and K brakes, and good info on modeling them and the rigging.

Gary
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richbroo New member 4 posts
richbroo

K and AB brakes

Dang, if the second pic from JC Shall doesn't look more like a layout pic than many I have seen.

I initially thought this thread was part of the (apparent to me at least) posts and articles about super detail being somewhat unimportant during operations.  Although I am not interested in modelliing this era, I learned something.  Thanks.

Rich
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