Drawbar safety chains or safety bar

[alanstepney]

Over this side of the pond, some clubs require chains as an additional safety measure.

I'm not convinced.
If the "correct*" coupling is properly designed and constructed, it should not break or come apart, so the addition of a chain is superfluous.

(*By correct, I mean the one allowed by the specific track / club.)


As for full size, chains used to be common practice, back in the mid-Victorian days. The main problem they had was cast iron mountings breaking, etc, so the chain did prevent runaways.

[ccvstmr]

Excess vertical motion in the drawbar pocket won't do any good if the drawbar can't "swing/pivot" vertically with respect to that pin. You can oversize the drawbar hole one or two drill sizes...or as suggested, use at least (1) rod end ball joint. Using ball joints on both ends of the draw bar would be better yet...even if that doesn't look prototypical.

I've thought about converting to the ball joints for some time, but this is a low priority item for now and the oversized holes serve the purpose with only a slight slack action play in the drawbar. Drawbars need to allow for horizontal, vertical and twisting motion...and sometimes all three motions at the same time. Carl B.

[bcody]

First of all I couldn't care less about scale appearance. I don't care if the prototype had chains or not. I know we should run safety chains between the engine and the engineer's riding car. It is a matter of safety. On a full size engine the engineer is ON the engine and can still control the engine, we are not. If the connection between the engine and the engineer's riding car fails the engine goes on its merry way until it runs out of steam with no one on board to close the throttle. I run a vertical boiler beam engine which has no counterpart in full size so scale is not important to me. I just like running a steamer with more than adequate power and speed that will do most anything I ask of it. I run link and pin couplers between the engine, engineer's riding car (tender) and the propane fuel car as well as safety chains. I also run double (crossed) safety chains between every car in my train.

IF IT IS A QUESTION OF SCALE APPEARANCE V SAFETY I VOTE FOR SAFETY EVERYTIME. Bill

[LivingLegend]

Attached is an illustration of the drawbar for a UP Big Boy. This is the way most modern full size drawbars were made.

Note the elongated hole for the drawbar pin at the engine end of the drawbar.

The secondary "safety" bar (not shown), is basically the same as the drawbar, except the pin hole on the tender end is elongated instead of round.... But not nearly as elongated as the hole for the drawbar pin on the engine side of either the drawbar and safety bar.

Also note the edges of both the drawbar and safety bar pin holes have a slight radius break to avoid a sharp edge from digging into the drawbar pin.

LL

[Tom_Dininio]

First of all I couldn't care less about scale appearance. I don't care if the prototype had chains or not. I know we should run safety chains between the engine and the engineer's riding car. It is a matter of safety. On a full size engine the engineer is ON the engine and can still control the engine, we are not. If the connection between the engine and the engineer's riding car fails the engine goes on its merry way until it runs out of steam with no one on board to close the throttle.
IF IT IS A QUESTION OF SCALE APPEARANCE V SAFETY I VOTE FOR SAFETY EVERYTIME. Bill

You seem to be implying that chains are safe and link/pins are not! If your so concerned about safety, why not just require a minimum dimension for the pins and link.

I think a 5 inch diameter pin and a 15 x 10 inch cross section link might have enough strength to keep the engine and tender connected. Then again, that's only 150 square inches cross section. At 60,000 lbs tensile per square inch, this arrangement would provide only 9,000,000 pounds to hold the loco and tender together. (This should be sufficient to hold nine full size Big Boys in the air -- after all they weighed about 1,000,000 pounds each.)

If your concern is about the pins falling out, why not weld them in place and then have the government come in to X-ray the welds.

By the way, what is the tensile strength of the chains you are requiring? Will they support anywhere near 9,000,000 pounds? Are they welded to both the tender and loco, or can they become detached?

My point is that YES, safety is important. Why should I be required to use a chain to couple my loco and tender instead of being safe. And I am one who could care less about running around in circles. I do care about scale appearance.

[Tom_Dininio]

How many live steam locos have either of these safety items? Are they really needed? My assumption on live steam is that the drawbar pin is inserted from the top and cannot fall out from anything unscrewing, so the pin would have to shear or the drawbar break for this to happen.

Thanks,

Dan,

Sorry for my little hissy fit above. Most of the replies above seem to have answered your question.

As additional information, I too have a 1.5 inch Mike (NYC H10b). I have the original blueprints from 1922. No safety chains. There is one draw bar and one safety bar underneath the draw bar. Both the engine and tender have 1/2 dia. (scale size) pins.

In the original, the pins were inserted from the bottom and retained by a scale 1/16 inch thick plate in a slide. FYI, I chose to insert the pins from the top because I wanted to be safe.

Tom

[tsph6500]

I think a 5 inch diameter pin and a 15 x 10 inch cross section link might have enough strength to keep the engine and tender connected. Then again, that's only 150 square inches cross section. At 60,000 lbs tensile per square inch, this arrangement would provide only 9,000,000 pounds to hold the loco and tender together. (This should be sufficient to hold nine full size Big Boys in the air -- after all they weighed about 1,000,000 pounds each.)

Holy Bananas! It's TRUE! I seen it on the Interweb...

[rwmorris]

Air Planes!!!! Gorilla's!!!!! Choo Choo's!!!! OH BOY!!!!

Priceless follow-up My Man....... Priceless.....

Robert

[Fender]

In the original, the pins were inserted from the bottom and retained by a scale 1/16 inch thick plate in a slide. FYI, I chose to insert the pins from the top because I wanted to be safe.
Tom

Tom, I like your reasoning on this. I think part of the reason for the pins being inserted from the bottom is because many locos had a water-bottom tender, and that's the only way the pin could be inserted. After reading all these responses, my current plan is to use a single drawbar with pins inserted from the top, and two safety bars to the sides (with seprate pins), which should satisfy any club that requires chains. The safety bar is, in essence, a chain with only one link.

P.S.
Jim, great visual!

Dan

[Tom_Dininio]

Air Planes!!!! Gorilla's!!!!! Choo Choo's!!!! OH BOY!!!!

Priceless follow-up My Man....... Priceless.....

Robert

OH BOY!!!! ??? Don't you mean OH BOY BIG BOY!!!!

[Mike Walsh]

Air Planes!!!! Gorilla's!!!!! Choo Choo's!!!! OH BOY!!!!

Priceless follow-up My Man....... Priceless.....

Robert

OH BOY!!!! ??? Don't you mean OH BOY BIG BOY!!!!

thats what she said

[Fred_V]

one of our guys is looking at putting a steel ring on the coupler shanks and a chain between the rings. one of those screw links will connect the chain. the idea being that it will be hidden under the coupler and you don't have to drill holes in the car bodies.

any thoughts on this?
fred v