Date
1  11 of 11
Car capy and LO's
Jeff Aley  GCD PE <jaley@...>
Dave Nelson, the Master of STMFC Statistics, sent me some interesting info
the other day. The data shows that in 1955, wheat, corn, and sorghum were loaded at an average of 54 tons per car. Before you start yawning, realize that this leads to some interesting conclusions, if my assumptions are correct. Assumption 1: Cars are either 50ton or 70ton capy. There's no such thing as a 55ton or 60ton car. (Right?) Assumption 2: LO's were 70ton capy cars in 1955 (don't have my ORER handy to check). Assumption 3: Box cars were 50ton capy cars in 1955. (Where there many 70ton boxes at that time?) If Assumption 1 holds, then a little bit of math tells us that 80% of the cars that carried wheat were 50ton cars, and the other 20% were 70ton cars. If all three Assumptions are true, then we know that 20% of the wheat traveled in LO's. Furthermore, if one looks up data for various years, we can see how quickly the grain industry moved from box cars to covered hoppers. For those of you not modeling granger roads, one can probably make similar interesting inferences from other commodities (e.g. Anthracite Coal at 57 tons / car; or Pig Iron at 58 tons / car). Regards, Jeff  Jeff Aley, Development Engineer jaley@... Graphics Components Division Intel Corporation, Folsom, CA (916) 3563533 

Tim O'Connor <timoconnor@...>
Good reasoning Jeff, very logical. But possibly wrong, since a 50 ton car's
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"capacity" was typically below the same car's "load limit". I'm sure that the elevators tried to jam as much as possible into every car load, just keeping below the load limit. I'd be VERY surprised if more than 5% of grain in 1955 was carried in LO's. It probably was much less than that.  Original Message 
From: Jeff Aley  GCD PE <jaley@...> Assumption 1: Cars are either 50ton or 70ton capy. There's no such If Assumption 1 holds, then a little bit of math tells us that 80% of the 

Jeff Aley  GCD PE <jaley@...>
Tim,
Thanks for pointing out the capy vs load limit; that's why I posted my assumptions to the List. I guess I'm still a little bit fuzzy on the "50ton" rating. I was under the impression that 50tons comes from the trucks, and on further reflection should be the weight of the car + load. If that's true, then the weight of the load (wheat) is LESS than 50 tons (?). If that's the case, then MORE (a greater percentage of the cars) would have to be LO's to make the 54 ton "average". [I'm assuming that the ICC tonnage data indicates weight of the load alone]. Am I misunderstanding the various weights? If so, please help me out. Thanks, Jeff On Apr 30, 2:28pm, Tim O'Connor wrote: Subject: Re: [STMFC] Car capy and LO'scar's "capacity" was typically below the same car's "load limit". I'm surethat the elevators tried to jam as much as possible into every car load, justkeeping below the load limit. I'd be VERY surprised if more than 5% of grain in1955 was carried in LO's. It probably was much less than that.many the70ton boxes at that time?)If Assumption 1 holds, then a little bit of math tells us that 80% of 70toncars that carried wheat were 50ton cars, and the other 20% were http://docs.yahoo.com/info/terms/cars.
 Jeff Aley, Development Engineer jaley@... Graphics Components Division Intel Corporation, Folsom, CA (916) 3563533 

Mike Brock <brockm@...>
Jeff Aley writes:
I guess I'm still a little bit fuzzy on the "50ton" rating. II am certain that I should stay away from this sort of thing and concentrate on more straight forward stuff like why the number of driving axles on a steam engine has nothing to do with traction or what is the purpose of the third truck on a shay, but, what the hell. It all depends on the car. A 40 ft box car with 50 ton code D trucks might have a capacity of 100,000 lbs. However, the allowable weight on the rails is the light weight plus the load limit which must add to 169,000 lbs [ in '54 ]. In the case of the PS1 this might be 44500 + 124500= 169000 lbs. The max weight of the stuff carried is 62.4 tons. All this assumes AAR or Alternate Standard tubular axles on the trucks. This also assumes that no little "*" is sitting there next to load limit. Now, why put Capacity on the car if it can be exceeded? How should I know? For guys that work for Intel or even NASA, this might be puzzling. At least it is to me. I mean, if the load limit says 124500 lbs, I can usually tell that the car can carry 62 tons of stuff without breaking in two. I now bow to our more learned frt car gurus and learn about this oddity...again. Meantime, if any of you want to discuss the slipping of drivers or what that third truck on the Shay is doing back there...feel free. Oh. Jeff, you must get an ORER. Mike Brock......Hmmm. Wonder how far out on this ice I can walk without falling in. Let's see. Hmmm..... 

Dave & Libby Nelson <muskoka@...>
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Original Message Assumption 1: Cars are either 50ton or 70ton capy. There's no suchThere were many cars that rode on 55 ton trucks  NYC I believe and I think also in Canada. If all three Assumptions are true, then we know that 20% of the wheatOthers have already commented on capacity vs. ld limit.... A more accurate understanding of car use in this specific instance could be had from the ICC's 1% waybill samples (all waybills ending in the number 1 were sent to the ICC) which reports on the the types of cars used. My only copy is from 1949  too early to test your comments on the grain industry (but it does cite the occasional use of stock cars, gondolas, and ordinary open hoppers to carry wheat). Jeff, you'll just have to convince Connie that you need more time in the stacks at Stanford and less time at the Winchester Mystery House. 8) Dave Nelson 

Jeff English
Jeff Aley  GCD PE <jaley@...> wrote:
Assumption 1: Cars are either 50ton or 70ton capy. There's no suchAlmost all NYC 40ft allsteel box cars were rated 55ton capacity.  Jeff English Troy, New York Proto:64 Classic Era Railroad Modeling englij@...  R U T L A N D R A I L R O A D  Route of the Whippet  

Jeff English
"Mike Brock" <brockm@...> wrote:
Now, why put Capacity on the car if it can be exceeded? How should I know?1) The capacity is a nominal rating which allows car clerks and shippers to quickly ascertain whether a given car is suitable for the order of magnitude of their intended shipment. The load limit is the absolute limit and is used after loading the car to compare the car's total weight on the scale to the allowable weight. Now, not that many cars were actually weighed, but a shipper could get into hot water if they released an overloaded car. 2) The load bearing capacity of a car is not determined by the structural engineering of its carbody but by the size of the journal bearings. Apparently carbody structure is predicated by other considerations that place its loadbearing capability far above that of the bearings. Among those other considerations are the AAR requirement to withstand a static 800,000lb compressive force through the center sill. Also probably the fatigue factor over a 40 year life calls for an extremely robust structure. For the above reasons, there is no probability that an overloaded car would break in two. Moreover, a car's capacity and load limit can be changed by simply rolling different trucks under it, with absolutely no other alterations. The RRs did exactly this fairly often.  Jeff English Troy, New York Proto:64 Classic Era Railroad Modeling englij@...  R U T L A N D R A I L R O A D  Route of the Whippet  

Richard Hendrickson
Moreover, a car's capacity and load limit can be changed byWell, yes and no. Jeff is certainly correct that the size of the truck journals was the primary factor in determining nominal capacity. However, the AAR specs for the standard steel box cars were different for forty and fifty ton versions, with the fifty ton cars having somewhat heftier center sills and some other components, and this was also true of the earlier ARA standard designs. This may, as Jeff suggests, have had more to do with overengineering the cars to compensate for wear and tear, etc. but just putting 50 ton trucks under a 40 ton AAR standard box car didn't make it a 50 ton car. Richard H. Hendrickson Ashland, Oregon 97520 

Guy Wilber
In a message dated 4/30/01 12:49:51 PM Pacific Daylight Time,
brockm@... writes: << Now, why put Capacity on the car if it can be exceeded? How should I know? Mike, The nominal capacity was stenciled on freight cars which corresponded to the listings in the ORER. It would have been impossible to print all "true" capacities in the ORER though for many years various railroad entries noted the allowance of loading 10% higher than the nominal capacity. As the axle loading increased the AAR mandated the additional LD LMT stencil. This allowed shippers to know the actual loading capacity of an individual freight car. Regards, Guy Wilber Sparks, Nevada 

Jeff Aley  GCD PE <jaley@...>
Thanks to Tim, Mike, and the gang for educating me on capy.
I guess it all boils down to the fact that my "assumption 1" was wrong, so my conclusions were similarly flawed. This just goes to show you that there are three kinds of lies: lies, damned lies, and statistics! Regards, Jeff On Apr 30, 3:32pm, Mike Brock wrote: Subject: Re: [STMFC] Car capy and LO'sconcentrate on more straighta shay, but, what the hell.might have a capacity of 100,000 lbs. However, the allowable weight on therails is the light weight plus the load limit which must add to 169,000 lbs [in '54 ]. In the case of the PS1 this might be 44500 + 124500= 169000 lbs.The max weight of the stuff carried is 62.4 tons. All this assumes AAR orno little "*" is sitting there next to load limit.know? For guys that work for Intel or even NASA, this might be puzzling. Atleast it is to me. I mean, if the load limit says 124500 lbs, I can usuallytell that the car can carry 62 tons of stuff without breaking in two.http://docs.yahoo.com/info/terms/
 Jeff Aley, Development Engineer jaley@... Graphics Components Division Intel Corporation, Folsom, CA (916) 3563533 

Guy Wilber
In a message dated 4/30/01 12:49:51 PM Pacific Daylight Time,
brockm@... writes: << Now, why put Capacity on the car if it can be exceeded? How should I know? Mike, The nominal capacity was stenciled on freight cars which corresponded to the listings in the ORER. It would have been impossible to print all "true" capacities in the ORER though for many years various railroad entries noted the allowance of loading 10% higher than the nominal capacity. As the axle loading increased the AAR mandated the additional LD LMT stencil. This allowed shippers to know the actual loading capacity of an individual freight car. Regards, Guy Wilber Sparks, Nevada 
