Car capacity vs load limit, was Late 40's to mid 50's military rail movements


Bruce Smith
 

Ed,

Excellent question! Here's what that data on the side of a car means. 

CAPY (or capacity) is the nominal weight allowed by the truck bearings, axles, and of course, car construction. On the F30A that is listed as 140,000 lbs or 70 tons.

Lt. Wt. (or light weight) is obviously the empty weight of the car (or tare weight). That is important as many shipments are charged by weight so you have to know what the car weighs so as not to charge for that.

Ld. Lmt. (or load limit) is the actual weight allowed for the load. This is determined by subtracting the Lt Wt from the total allowed weight on the rail (in this case) for a car with 6" x 11" journals, which is 210,000 lbs. The exception to this are cars where the Ld Lmt has a star in front of it, indicating a structural restriction on the weight of the load to less than that allowed by the truck bearings (the star actually indicates to anyone reweighing the car not to use the mathematical formal I've given to calculate Ld Lmt.)

This confusion comes about because railroads wanted an easy system to classify capacity, (40, 50, 55, 70 ton, etc...) but it is really the total weight on the rails that matters for the given bearing size. 

When a car is reweighed, the number determined is the Lt. Wt. If that changes, then the Ld Lmt has to change by a corresponding amount. The Capy does not change. That's why, when showing reweigh data as freshly painted on weathered cars, I often only protect the last 3 digits of the Lt Wt and Ld Lmt and I always make sure that they add up to the correct total for that capacity car.

Thus, my comment that the load limit on the PRR F30A is around 158,000 lbs, well within the ability to carry a 60 ton tank or even a 65 ton tank. 

Regards,
Bruce Smith
Auburn, AL


From: main@RealSTMFC.groups.io <main@RealSTMFC.groups.io> on behalf of spsalso via groups.io <Edwardsutorik@...>
Sent: Monday, October 18, 2021 10:48 PM
To: main@RealSTMFC.groups.io <main@RealSTMFC.groups.io>
Subject: Re: [EXT] Re: [RealSTMFC] Late 40's to mid 50's military rail movements
 
Bruce,

The capacity of the car in the photo reads 140000 pounds.  Can you crowd that up to 158000 pounds?

The T43 was reported to weigh 60 tons in the New York Times, back in the day.  It was also reported to weigh 50 tons.  In the New York Times.

Wikipedia says an M103 weighs 65 tons.

Military things generally weighing a bit more than hoped, I will lean towards the T43 being a heavy tank.

Anyway, it clearly arrived at its destination.


Ed

Edward Sutorik


Thomas Evans
 

So Bruce, let me paraphrase what you are saying & see if I've got it right:

CAPY is just a handy way of classifying cars & can be ignored when actually loading a car.
Ld. Lmt. indicates the actual weight of freight you can put in the car.

This is something that has puzzled me for probably 60 years, but I've never been motivated to actually go out & find the answer.

Thanks for the enlightenment! - Tom E.


fire5506
 

This is from the CSX dictionary,

Capacity (Freight Car) The normal load in pounds, cubic feet, or gallons which the car is designed to carry. These figures are stenciled on the car and are identified as "CAPY". Capacity is not to be confused with load limit, which is the maximum weight that can be loaded on a given car.

Load Limit The maximum load in pounds which the car is designed to carry.


Richard Webster


Bruce Smith
 

Tom, Folks

Correct. 

And I want to stress another thing... even loading a car to the Load Limit is not "pucker" inducing. That's the SAFE maximum load. As with all engineered structures, there is an additional safety margin. Elden Gatwood has shared correspondence regarding the overloading of PRR's heavy duty flats (eg. F38) and the subsequent discussion of repairs previously. 

Finally, most rail cars, including most flat cars, cannot take the entire load limit on the center of the span. Thus the steel box beams on the T43 load (no wood there, in spite of what some have posted) are longer than the treads to help spread the load away from the center of the car. So while there was no issue what so ever with the weight, there appears to have been a concern about the weight at the center of the span.

BTW, the dunnage in the T43 photo is the first time I've even seen a tank loaded in that manner.

Regards,
Bruce Smith
Auburn, AL


From: main@RealSTMFC.groups.io <main@RealSTMFC.groups.io> on behalf of Thomas Evans via groups.io <tomkevans@...>
Sent: Tuesday, October 19, 2021 8:01 AM
To: main@RealSTMFC.groups.io <main@RealSTMFC.groups.io>
Subject: [EXT] Re: [RealSTMFC] Car capacity vs load limit, was Late 40's to mid 50's military rail movements
 
CAUTION: Email Originated Outside of Auburn.
So Bruce, let me paraphrase what you are saying & see if I've got it right:

CAPY is just a handy way of classifying cars & can be ignored when actually loading a car.
Ld. Lmt. indicates the actual weight of freight you can put in the car.

This is something that has puzzled me for probably 60 years, but I've never been motivated to actually go out & find the answer.

Thanks for the enlightenment! - Tom E.


Daniel A. Mitchell
 

I never said the beams under the T-43 were wood … but MOST such beams I have seen, under M-48 and M-60 tanks, ARE wood. Large timbers, maybe 8” X 16” or larger, and 25-plus feet long.

Dan Mitchell
==========

On Oct 19, 2021, at 1:09 PM, Bruce Smith <smithbf@...> wrote:

Tom, Folks

Correct. 

And I want to stress another thing... even loading a car to the Load Limit is not "pucker" inducing. That's the SAFE maximum load. As with all engineered structures, there is an additional safety margin. Elden Gatwood has shared correspondence regarding the overloading of PRR's heavy duty flats (eg. F38) and the subsequent discussion of repairs previously. 

Finally, most rail cars, including most flat cars, cannot take the entire load limit on the center of the span. Thus the steel box beams on the T43 load (no wood there, in spite of what some have posted) are longer than the treads to help spread the load away from the center of the car. So while there was no issue what so ever with the weight, there appears to have been a concern about the weight at the center of the span.

BTW, the dunnage in the T43 photo is the first time I've even seen a tank loaded in that manner.

Regards,
Bruce Smith
Auburn, AL


From: main@RealSTMFC.groups.io <main@RealSTMFC.groups.io> on behalf of Thomas Evans via groups.io <tomkevans@...>
Sent: Tuesday, October 19, 2021 8:01 AM
To: main@RealSTMFC.groups.io <main@RealSTMFC.groups.io>
Subject: [EXT] Re: [RealSTMFC] Car capacity vs load limit, was Late 40's to mid 50's military rail movements
 
CAUTION: Email Originated Outside of Auburn. 
So Bruce, let me paraphrase what you are saying & see if I've got it right:

CAPY is just a handy way of classifying cars & can be ignored when actually loading a car.
Ld. Lmt. indicates the actual weight of freight you can put in the car.

This is something that has puzzled me for probably 60 years, but I've never been motivated to actually go out & find the answer.

Thanks for the enlightenment! - Tom E.


Gatwood, Elden J SAD
 

Group;

 

Thanks, Bruce, for the clarifications.

 

I obviously blew it in relating in this case, the pucker is for the High & Wide guy who has to guarantee it fits within the clearance diagram.  There were many cases where that went wrong!

 

Elden Gatwood

 

 

From: main@RealSTMFC.groups.io <main@RealSTMFC.groups.io> On Behalf Of Bruce Smith
Sent: Tuesday, October 19, 2021 1:09 PM
To: main@RealSTMFC.groups.io
Subject: [Non-DoD Source] Re: [RealSTMFC] Car capacity vs load limit, was Late 40's to mid 50's military rail movements

 

Tom, Folks

 

Correct. 

 

And I want to stress another thing... even loading a car to the Load Limit is not "pucker" inducing. That's the SAFE maximum load. As with all engineered structures, there is an additional safety margin. Elden Gatwood has shared correspondence regarding the overloading of PRR's heavy duty flats (eg. F38) and the subsequent discussion of repairs previously. 

 

Finally, most rail cars, including most flat cars, cannot take the entire load limit on the center of the span. Thus the steel box beams on the T43 load (no wood there, in spite of what some have posted) are longer than the treads to help spread the load away from the center of the car. So while there was no issue what so ever with the weight, there appears to have been a concern about the weight at the center of the span.

 

BTW, the dunnage in the T43 photo is the first time I've even seen a tank loaded in that manner.

 

Regards,

Bruce Smith

Auburn, AL

 


From: main@RealSTMFC.groups.io <main@RealSTMFC.groups.io> on behalf of Thomas Evans via groups.io <tomkevans@...>
Sent: Tuesday, October 19, 2021 8:01 AM
To: main@RealSTMFC.groups.io <main@RealSTMFC.groups.io>
Subject: [EXT] Re: [RealSTMFC] Car capacity vs load limit, was Late 40's to mid 50's military rail movements

 

CAUTION: Email Originated Outside of Auburn.

So Bruce, let me paraphrase what you are saying & see if I've got it right:

CAPY is just a handy way of classifying cars & can be ignored when actually loading a car.
Ld. Lmt. indicates the actual weight of freight you can put in the car.

This is something that has puzzled me for probably 60 years, but I've never been motivated to actually go out & find the answer.

Thanks for the enlightenment! - Tom E.


spsalso
 

Looking at the photo of the T43 load, you can see two triangular or wedge shapes underneath the rising track.  They appear to be steel, because they are relatively thin and  appear to have welds on the bottom.  If so, that means they are likely attached to a long steel tube (you can't weld steel to wood).  At the end of the thing I'm calling a steel tube is a ramp-looking object.  Notice that its width is about the same as the pair of steel triangular shapes.

OK.  Please note that that steel tube is directly over the car side, for good reason, I think.  And also note that it is NOT directly under the track.  It is under the inside of the track and of the inner road wheels only.  While this arrangement loads the car itself nicely, it doesn't look so swell for the tank suspension.

So I think someone thought it wise to put something under the outer road wheels, also.  The COULD have used another piece of steel tubing.  But it looks to me like they used wood.  I can see what looks like knots in the wood.  I can also see what look to me to be two or three holes in the wood, where I would have place bolts to retain the wood.  It's possible they weren't used, however.  I also see three cables or ropes or strings hanging from stake pockets.

Height of the load was about 14' - 10".  PRR had boxcars with a max height of 15' 3 3", at the time.  So vertical clearance doesn't look like a problem.  Width of the M103 is 12' - 2".  The max width of an F30 was 10' - 2".  I am just not seeing the track overhanging the stake pocket by a foot, in the photo.  I see the overhang as about 4", which would give a load width of 10' - 10", not 12' - 2".  A puzzlement.


Ed

Edward Sutorik