Drawbars vs Couplers?

[Anonymous]

Why is the connection between a steam locomotive and its tender a drawbar as opposed to a knuckle coupler (kadee, mchenry et al)? Or is this not always the case? Can it be converted to a knuckle coupler? Should it NOT be converted for some reason?

Trevor

[IRONROOSTER]

I would think it is a safety feature. You certainly wouldn't want the coupler to part while underway. In addition to losing the coal and water supply to the engine, the fireman and possibly the engineer would also be at risk of falling. Since these would not normally be uncoupled very often a knuckle coupler would not be needed. In a sense the tender is part of the engine, without it the engine would have to be dragged (or have something hooked up to it to supply steam) rather than moving under its own power.
Enjoy
Paul

[jwr_1986]

Drawbars are used in any situation where cars are not normally uncoupled. A great example is the Thrall well cars that usually run in permanently coupled three or five car units. Thus only two actual couplers are needed for that entire set. Save time, save money.

Jesse

[Anonymous]

QUOTE: Originally posted by IRONROOSTER

I would think it is a safety feature. You certainly wouldn't want the coupler to part while underway. In addition to losing the coal and water supply to the engine, the fireman and possibly the engineer would also be at risk of falling. Since these would not normally be uncoupled very often a knuckle coupler would not be needed. In a sense the tender is part of the engine, without it the engine would have to be dragged (or have something hooked up to it to supply steam) rather than moving under its own power.
Enjoy, Paul

[#ditto]

There is a steam engine that doesn't have a tender and works with no fire!
Click here for more info.

[Anonymous]

QUOTE: Originally posted by jwr_1986

Drawbars are used in any situation where cars are not normally uncoupled. A great example is the Thrall well cars that usually run in permanently coupled three or five car units. Thus only two actual couplers are needed for that entire set. Save time, save money. Jesse

And to reduce coupler slack action which can damage cargo. Roadrailers use the same concept.

[tatans]

I posed this same question and received some great answers, including when the engine backs up it does not push on the drawbar but on the opposing half round push plates on engine and tender ( you always wondered what those things were didn't you) Try looking up on this forum under "tender drawbars" in past forums ( I don't know how you do it)

[cacole]

If you're speaking about prototype railroads, most tenders had couplers on the front, not drawbars. The amount of slack action between the locomotive and tender would have been negligible because these couplers were mounted solid to the front of the tender and rear of the locomotive. Model makers use drawbars because they're cheaper to make than using two couplers.

[tatans]

I found the reply to my question, try the Trains magazine forum, under "Archives" from SDR NORTH (coal tender drawbar) Feb.22, 2005 for a full explanation as to why they do not use a coupler from engine to tender on real steam locomotives.

[dinwitty]

QUOTE: Originally posted by cacole

If you're speaking about prototype railroads, most tenders had couplers on the front, not drawbars. The amount of slack action between the locomotive and tender would have been negligible because these couplers were mounted solid to the front of the tender and rear of the locomotive. Model makers use drawbars because they're cheaper to make than using two couplers.

standard couplers are susceptible to breakage/disconnecting.
A steam loco has many pipes/interconnections and you DONT want them separating, why you have a permanent coupling between the two.

[gmpullman]

I'm familiar with a certain USRA light Mikado and it actually has two drawbars parralel to each other. One has the opening for the pin slightly elongated thus only one drawbar was doing all the work and the other was a backup in case the first one broke (they did).
Once a year the drawbars had to be removed and magnaflux tested. It took quite a bit of compression force to pu***he buffer plates together to get the drawbar pin back in. I have never seen a coupler between a locomotive/tender however I have seen several tenders converted to diesel fuel service and they had a coupler mounted in the former drawbar socket.

[gmcrail]

QUOTE: Originally posted by cacole

If you're speaking about prototype railroads, most tenders had couplers on the front, not drawbars. The amount of slack action between the locomotive and tender would have been negligible because these couplers were mounted solid to the front of the tender and rear of the locomotive. Model makers use drawbars because they're cheaper to make than using two couplers.

Sorry - not true at all. Prototype steam locomotive tenders were always connected by a permanent drawbar to the locomotive which they served. Tenders used as auxiliary tender would have a coupler mounted in the front, but they don't really count, since they were not the primary tender.

Tenders are considered part of the locomotive, just like a fuel tank on a diesel is part of the locomotive, since the locmotive cannot run without it. And yes, the "tank" engines don't have a tender, because they carry the fuel and water on board. The only times a tender would be disconnected from the locomotive would be for repairs toi either the rear of the locomotive or to the tender itself and/or for replacement.

[Anonymous]

QUOTE: Originally posted by tatans

I found the reply to my question, try the Trains magazine forum, under "Archives" from SDR NORTH (coal tender drawbar) Feb.22, 2005 for a full explanation as to why they do not use a coupler from engine to tender on real steam locomotives.

Here's the link http://www.trains.com/community/forum/topic.asp?page=-1&TOPIC_ID=31523&REPLY_ID=314782#314782

[ndbprr]

Also there is the safety issue of crews standing on the connection between the two. If they ever parted it would be instant death.

[Anonymous]

QUOTE: Originally posted by ndbprr

Also there is the safety issue of crews standing on the connection between the two. If they ever parted it would be instant death.

I wonder if that ever happened.

[dinwitty]

boiler explosions were more common, I can't think of drawbar separations, they were tough built.
BTW, the NKP 765 drawbar initial restoration needed to separate the drawbars, several methods were tried, the only one that worked was a heavy duty hydraulic ram, lifting the pin brute force.

[tatans]

QUOTE from SDR North::
Originally posted 22 Feb.2005 by SDR North:
Usually the drawbar(s) between a steam locomotive and it's tender was made of steel shaped like a wooden popsicle stick with a hole at each end for a pin.
Depending on the size of the locomotive the drawbar could measure 12 or so inches wide by 6 or so inches thick by 6 or 7 feet long.The pin holes 6 inches.
Somewhat like the drawbars between the couplerless flats or coal cars, but not as square.
All measurements are general just to visualise shape.
A large locomotive could have two drawbars, one above the other.
On both engine and the tender there were sockets to accept the rounded ends of the drawbar and these sockets had holes to accept the drawbar pins which passed vertically through the upper edge/drawbar/lower edge of socket.
The vertical pins were a close fit and were oiled or greased so they would not rust in.
The vertical drawbar pins were secured in place by horizontal rods or other keepers.
There were usually two heavy safety chains with hooks on each side of the drawbar in case it broke. Years ago passenger cars had safety chains also.
When backing up,t here were rounded buffers on the engine and tender that met and the push force was thru the buffers rather than tryinyg to skew the length of the drawbar and shove the tender sideways. Getting a seized drawbar pin out is a terrible job in a very dirty place.
This is just a general idea how it worked.
Posted by SDR North