whats the advantage of using a drawbar over a coupler on a well car?
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Ease of repairs in the event that separation of the units is required.
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Greater well capacity–you have two trucks fully devoted to each well, as opposed to at least one truck whose gross rail load has to be split between two wells.
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Uniform truck and wheel sizes can be used for every truck on the car.
Downside - when the drawbar breaks, or otherwise becomes detached from one of the car segments or the other - you have a mess of monumental proportions. When you get a broken drawbar on a regular single car - you only have to deal with the mass of that individual car when attempting to set the car out, even if the drawbar is out of the ‘wrong’ end (wrong = end that you would desire to couple to to effect the set out), chaining such a bad order up to set it out is not that big of a deal.
When you have disconnected drawbar in a multiple bottom car, you have car ends, neither of which now have a coupling device - depending upon which segment of the multiple bottom car the drawbar becomes disconnected at you can have 1 to 4 car segments to handle in order to make the set off - the additional weight of multiple car segments compounds the issue of chaining the segments together for set off.
Recently had a 5-pack car have the bottom securement bracket for the coupling break and it allowed the securement pin to drop to the ground - (and not be located) - First call was to the Car Department who dispatched their ‘over the road’ truck to attempt repairs. Without being able to locate the pin, they were not able to make any repairs. Forgot to mention this occurred in mountain territory with up to 2% grades being involved. I took 2.5 hours from the occurrence to get the Car Dept. on scene. Car Dept used another hour and a half searching for the securement pin, without success. Nearest set off track that was not occupied by MofW equipment being used for a curfew in this line segment was 17 mile from the point of failure. Car Dept chained the car segments together and the crew for the train proceeded the 17 miles at the rule specified 4 MPH with the chained up bad order to the set off location - 4 hours 15 minutes to get to the set off location.
Carl,
I believe that the OP is asking about multiple 2 truck wells connected with drawbars rather than couplers at each end, NOT 2,3 or 5 well articulated well cars, with shared trucks at each intermediate joint.
The advantage that I would see in useing drawbars rather than couplers between wells would be reduced slack action, and fewer points such as glad hands to cause trouble in the trainline.
Doug
Doug, I’ll go with you on the slack action, but most of these cars still have separable hoses.
However, I’ve noticed that in many cases, cars that were at one time connected by drawbars have been split into three stand-alone cars (FEC did this to nearly all of the three-unit cars they had).
Even though the air hoses are still separable, eliminating the slack eliminates trainline air loss that slack action can cause.
I have no idea the advantage of using a drawbar over a coupler on a well car, but on a pipe organ, well…a coupler can be a drawbar which is sometimes caused a piston.
I return to the world on lurking. 