NEB&W Introduction to Rolling Stock

From NEB&W Railroad Heritage Website
Jump to: navigation, search
Rolling Stock Table of Contents
Freight Cars Table of Contents
Freight Car Guide Table of Contents


In general, freight cars are divided into "house" cars and open top cars. How an actual car is classified relates somewhat to the evolution of the type. For instance, box cars, refrigerator cars, and stock cars are considered "house" cars. A milk car evolved from a specialized type of refrigerator car, but then those used by private owners (such as Hood's, Borden's, etc.) were given an internal set of twin tanks to carry milk in bulk. Yet normal tank cars are considered "open top cars", since they evolved from tanks added to flat cars. By the same token, covered hoppers evolved from "open top" hoppers, and thus are not considered "house cars".

By the way, "reefer" is railroad lingo for "refrigerator car", "gon" for "gondola car", and "hopper" for "self-clearing hopper bottom car".

Overall dimensions

In general, the length of a car is depended on two things, both related to the trucks, or more directly, the journals. The size of the journal determined the weight that could be carried, and thus a dense load, like iron ore, was shipped in shorty 20 foot cars, while light loads like furniture, autos, and auto parts went in long 50 box cars. (Passengers, while rather dense per person, are not expected to be packed like sardines, so passenger cars are the longest cars, up to 80 feet long.)

The other thing was that as trucks improved over time, the length increased. It wasn't just a matter of being able to make, say, a 70 ton truck back in the days of when 50 trucks were the norm, but also if such trucks would be reserved for special cars or every day cars. Thru the steam era, 70 ton trucks were used on covered hoppers, triple and quad hoppers, flat cars, and ore cars. It wasn't until the mid-50's that 70 trucks became the norm and 100 ton trucks for the bigger cars.

The industry needed to standard replacement parts, as cars off-line would need to be repaired far from home. This quantized trucks into discrete values of 30, 40, 50, 70 and 100 tons capacity. (This figure is based on the total weight on the truck, minus a typical weight of the car itself. If the car could be made lighter, there was more capacity for the load.)

In the broadest sense, there are three eras of freight cars - the archbar era, the cast steel truck era, and the roller bearing era. Up until 1900, trucks were all but universally the archbar type, strap metal bolted together to form an arch. Although 50 ton arch bar trucks were used, this strained the ability of this type of car, and in general freight cars ranged from 30 to 40 tons capacity. And house cars were 30 to 36 feet long, with some 40 foot or even 50 foot cars built for the lightest commodities at the time, such as carriages.

Enter the cast steel truck c. 1900 - the so-called Bettendorf and others, and the standard capacity jumped to 50 tons, with 70 tons a stand-by size for special cases. And it took decades for roller bearing trucks to the kinks to be worked out for roller bearing trucks, but when they became standard late '50's, freight cars jumped up to 70 and 100 ton cars.

The width of freight cars stayed constant to all intents and purposes forever because they was based on the standard clearance diagram. (It crept wider by inches over the decades, but in terms of modeling, the same.) And the cars were built right to the outer limit of the clearance.

In general, only box cars were built to the maximum height, so I will discuss this aspect under box cars. (In post-steam, this also affected covered hoppers - see that section.)

Type Of Construction

Many of the variations in freight cars can be related to how the builder intended to support the weight. Unlike a house, which sits on a continuous foundation, a freight car sits on a pair of trucks, and the cargo spans the distance just like a bridge. Wood can be used to form trusses, as could steel, which are made from uprights and diagonals. But steel can also be made into sheets that support weight across the plane, as long as there are uprights to keep it from buckling.



House Cars

Box Cars

Box cars are designed around an average load, although each railroad might have a different average in mind, due to what they specialized in. A northeast road might ship a lot of manufactured items, including things made out of steel. A western road might design their box cars to carry mostly lumber, so would go for bigger cars.

In the 20th century, there are three eras box car length, related to freight car truck technology. When arch bar trucks were the norm, the standard box car was a 30 or 40 ton capacity car, and kept to 36 feet long. There was a sudden jump just about WWI, when cast steel trucks allowed a 50 ton car, which was made 40 feet long. The acceptance of roller bearing trucks after WWII made 70 and 100 ton cars common, and caused the standard box car length to go to 50 feet. Of course, there were many exceptions, which sort of obscures this relationship. But for instance, while 50 foot box cars go back to the 1920's, as do 70 ton hoppers, there were not any 70 ton box cars until the mid-'50's.

The height of all-wood box cars doesn't seem to have been a point of contention. With the development of composite and steel cars, car builders kept pushing to "raise the bar" as to how high they could make them. The industry would agree on a certain height, and while some taller cars were built as restricted-use cars, all the cars from the point on would be about that tall. Then they would argue and finally agree to notch up the standard height, a bunch of overhead obstacles would have to be fixed, and the next generation of cars would match this new height. So the height of the standard car increased in a series of discrete steps.

The norm at the turn-of-century was for an 8 foot inside height. (Of course, it is the outside height that will snag an overpass or tunnel, but the industry talked in terms of the inside height.) In the early '20's, it was officially set at 8 ft. 7 ins., then 9 ft. 4 ins. in '32, 10 feet even in 1937, and 10 ft. 6 ins. in 1944.

Why such an odd dimension in the 1920's? The industry started with 8-1/2 feet, and asked for feedback as to how much higher they could go. All that they could agree on was to add an single inch. (Squabbling over issues like this eventually tore the American Railway Association apart and it had to be reorganized as the Association of American Railroads in 1934.)

With each official increase in height came a new box car design to reflect both this dimension and the latest ideas about construction (mainly for all-steel cars), including the latest type of ends and roof. Thus we in the hobby talk about a 1937 AAR box car or a '44 AAR car.

Double-Sheathed Box Cars

Throughout the 19th century, box cars were given a wood truss. Like the proverbial covered bridge, which also had wood trusses, the outside sheathing was used to protect the supporting timbers from rotting, the primitive paints at the time not up to the task.

On all-wood cars, truss rods were used to allow the car frame to be tightened as the wood shrunk over time, or loosened from the undulations of travel. While an all-wood underframe was outlawed on cars used in interchange, an all but invisible steel center sill could be used to transmit the draft gear forces from car to car. This allowed cars with truss rods to be seen off-line into the early '50's, when such a composite underframe itself was outlawed.

The first use of steel was to provide an underframe to help carry most of the weight. The center sill had to be made thicker at the center, giving a fishbelly profile. This is a relatively inefficient way to use steel. Sometimes a steel truss was used, but still covered with wood, so some wood box cars have a straight center sill.

"Old Time" Box Car Roster

36 Foot Double-Sheathed Box Cars

  • ACL Watermelon Car
    Al Wood modified a Con-Cor kit.

40-Foot Double-Sheathed Box Cars

Throughout the steam era, in general, box cars needed an inner wood sheathing so the shipper could nail various bracing to secure certain loads. The term "double-sheathed" can refer to a second layer of either wood or steel on the outside, but generally is understand to mean wood. And we often use the term a "wood box car" meaning a double-sheathed wood box car, whether it has an internal steel or timber trusses. (Also, an "all-steel" box car still has this internal wood sheathing.)

USRA Double-Sheathed Box Cars

  • A standard design distributed to a number of roads.

  • Just got in a couple of the new Accurail USRA box cars. This is their best kits, in my opinion. Even the running boards have been reduced in thickness. Plus they are identifying the repack date of the scheme, so the modeler has some clue as to era.

Other 40-Foot Double Sheathed Box Cars

  • I started with a Train Miniature/Walthers double-sheathed reefer to model this Southern double-door box car.

Single-Sheathed Box Cars

In general, steel trusses were left exposed, as I guess it was better to let them dry out after a rain, rather than provide an outer sheathing of wood, although sometimes this was done. If the diagonals point to the top of the door, sort of like an sawhorse as seen from the end, this is called a Howe truss (from a type of bridge named after the inventor). A Howe truss is the best way to use wood timbers, as it puts the diagonals in compression. The use of a Howe truss for steel bracing is a carry-over from wood freight cars. Howe truss single-sheathed box cars were mainly the earliest ones.

The other orientation was to point the diagonals to the bottom of the door, sort of like a hammock. This puts the diagonals in tension, which works out better for steel.

36 Foot Single-Sheathed Box Cars

Fowler Cars

The Fowler design was the first single-sheathed box car, first built in 1909. The use of steel truss frame had apparently been used on a few cars earlier, but the Fowler car was the first to strip off the outer or second wood sheathing to expose the ribs. Apparently, this allowed the steel to dry out, rather than keeping it contact with damp wood, which would tend to rust it out faster. The Fowler car was introduced back when the standard box car was only 36 feet long.

The CN and CP got thousands of these cars. A number of American roads also got some Fowler cars, but these were retired earlier than on the Canadian lines.

Westerfield cast-resin kits.

Steel Box Cars

One of the things that makes freight cars so interesting for steam-era modelers is that from the experimental one-of-a-kind box cars of the early 1900's to the standard all steel box cars after the Depression, there were a lot of fumbling around with different designs. The first all steel box cars were too heavy (which wasted expensive steel and for a given truck capacity, cut into how much cargo could be carried).

Experimental Box Cars Of The '30's

  • The B&O rebuilt many of their wood box cars to this "wagon-top" design.

AAR Standard Box Cars

The more steel used on the car, the more the arguing among the various railroads. Wood was a construction material with centuries of know-how behind it - the car builders knew how to use it without trial-and-error. Composite construction was debated in the '20's, then became a moot point, as this type of construction became obsolete. But oh, all-steel.

At first the industry settled on over-all parameters, like type of couplers and standard journal sizes. It wasn't until after WWI they got around to trying to decide on a standard box car.

X29-Type aka ARA Box Car

A plan was drawn up in '23, but failed to get enough votes to pass the next year. In the meantime, the PRR used the plan to build thousands of cars. (The ARA proposal was basically the Pennsy's to start with, and part of the fight was the intense rivalry between the PRR and NYC.)

This 1920's unofficial standard goes by a couple of unwieldy names - I'd have to look them up to get them right. Since it kept coming up again for a vote, even the year can't be used as name. Some just call it the "ARA box car" while I prefer the name "X29-type". (The Pennsy car was called X29 in their class system and technically the similar cars built by other roads are not 100% identical. That's why I add "-type".)

The key features of this car are its low height of 8 ft. 7 ins. inside, the 10 steel panels for the sides, the double rivet lines, and the straight line of the bottom of the side, with no gussets.

But closely associated with this is the "flat" or "plate" end (which actually had three vertical supports inside, as indicated by the three pairs of rivet lines) and the "flat" roof, with the rafters inside as on a house. (It turns out it is better to put them on the outside, where they can also function as a seam cap.)

1932 ARA Box Car

I've been told that the issue of the steel design was so divisive, the industry association broke up and reformed over this issue, making new rules to avoid less deadlock. (I've also been told this wasn't true, it was just an administrative change from ARA to AAR.) The new design, promulgated in '32, was finally adopted.
The height reflected the new standard, but there were radical changes in the construction details. Externally, the double rivet lines were made single, and the side sill got a series of gussets like a series of widely spaced teeth.

Coming about in the depths of the Depression, only a handful of cars were built to this design. They differ so much in choices of roof and end types that these cars probably will remain the province of the cast resin car makers.

1937 AAR Box Car

Basically this was the same as the '32 car, but the inside height increased by 8 inches, to an even 10 feet. By this time, Standard Railway Equipment Co. so dominated the industry in terms of ends (Dreadnaught) and roof (raised rectangular panel type) that these two features were shown on the official car design.

In '42, an alternative taller design was agreed on, at 10 ft. 6 ins., and sometimes you will see the term "1942 AAR box car". This can be sort of confusing as in '44 the 10-1/2 foot size was made the new standard, and shown with the latest end, the Improved Dreadnaught.

1944 AAR Box Car

In this year, the standard design was officially increased to 10 ft. 6 ins. inside, but the plan also showed the new Improved Dreadnaught End. The height change was not as drastic as the previous changes, so to a first approximation, the type of end rather than the height is more apparent.

Technically, the Pullman-Standard's PS-1 might be considered a '44 car, but since most of the components were Pullman's, it generally is not lumped into the '44 category.

RBL Box Cars

In steam days, there was a classification for an insulated box car ("XI") which had a regular box car door, and one for a reefer without end ice bunkers ("RB", the "B" for beverage or beer). The RB had a hinged reefer type door.

After WWII, the plug door (which allowed a wider door opening for fork truck access) gained acceptance, first on reefers, then in the mid-'50's, on box cars. So the type of door no longer separated an "RB" from an "XI". Finally, the use of loading devices was designated with an "L". Around 1955, they came up with the new category of "RBL" which functioned in the shadowy area between commodities that could use insulation, but didn't needed cooling. (Ice reefers could not be used for many of these, as their interiors were often damp, and their four foot wide door was too narrow for efficient loading. And box cars with their sliding doors didn't really keep out the heat. It was the plug door that made such cars possible.)


These 1960's box cars were 89 feet long, used to carry light-weight auto parts. I believe it was the development of rolling bearing trucks which allowed freight cars in general to grow drastically post-steam.

Exterior Post Box Cars

The development of load restraining devices in the '50's made the wood liner inside box cars unnecessary. (The wood allowed a shipper to brace a load because he could nail into the wood.) So the wood was gotten rid of and the outer steel shell moved to the inside of the bracing to give a smooth surface.

Stock Cars

Hol Wagner (Burlington Bulletin No. 25) said that at first livestock was transported in ordinary box cars with barred openings, which could also be used on a return trip with ordinary cargo, or use the openings for ventilation for carrying product. (Such a car was shown in the 1888 Cyc., and a similar car offered by IHC as an "old-time" ventilated box car.)

The slotted stock car was developed in the 1870's and became common in the next decade.

Wagner also said the solid top of the car was usually added to protect the hay racks inside, which by the early 20th century, was made obsolete by the federal laws that required the livestock to be let out every day or so, and by the practice of simply scattering the hay on the floor for the short term interval.

The typical car prior to WWI was 36 feet, wood bracing in a 7 panel Howe truss arrangement and a five foot wide door. The 40 foot car arose later, particularly when obsolete wood or composite box cars were converted to stock cars. The use of steel ends was more just a carryover of house car construction, when it was probably cheaper just to use them than to order a special end.

The 50 foot stock car was post-steam. At first, this was also just a result of 50 foot box cars becoming old enough to become obsolete. The Burlington devised a temporary affair that could fit on a flat car when needed, and this was matched to the length of the flat cars then in use.

In terms of operation, stock cars with livestock were placed right behind the loco, as far upwind as possible from the caboose, but the real reason was to be able to cut them out right away and spot them near the pens, so the animals could get out and stretch their legs, etc.

But stock cars have often been used for just about everything else. I've heard of boards being placed inside and the car used for coal. Rough lumber, watermelons (ugh!), even rail.

Refrigerator Cars

Wood was used for the body of reefers long after it had been superseded with steel on other types of cars, because it is a better insulator than metal. Eventually it was found that a wood body was more likely to leak and allow water into the actual insulation in the walls. Damp insulation is useless to keep out the heat and as most of these were natural products, like horse hair, the water rotted them. Thus steel took over.

Up until after WWII, most cars were cooled with ice. The ice couldn't come in contact with most ladings, such as produce, so it was kept separate in bunkers, generally placed at the ends of the car. (Cars intended for beverages such as milk or beer could have crushed ice scattered on top of the metal milk cans or kegs, so didn't have ice bunkers.)

In general, ice refrigeration was pressed to its limit to keep produce cool enough in the volume of a 40 foot car. The colder temperature needed for meat tended to keep meat reefers shorter, 36 or 38 feet long. Cars that were sped to their destination, express reefers, were generally 50 feet long. Once mechanical refrigeration became practical, reefers jumped to 50 feet long.

Milk Cars

A rule of thumb is that almost all railroad-owned milk cars (including the B&M ones lettered for the Bellows Falls Co-op) shipped milk in 40 quart milk cans. They were in use through the end of railroad milk shipments. And all (ALL) privately owned milk cars shipped milk in bulk, in a pair of tanks. This is true whether the private-owned cars were wood or steel. ALL!

See our Milk Cars & Milk Trains section for more info.

  • Borden "Butterdish" Car
    Borden stripped away the wood superstructure of their bulk milk tank cars and sheathed them to form a streamlined milk car. From about 1939 to at least when this picture was taken (mid-'50's?), they were painted an orange-red. (The photo shows the color used, but these were detachable tanks, meant to be shifted to a truck in NYC for the last mile or so of its journey.)


It is important to remember that a flat car is a terribly inefficient way to use steel, and so while you might think these being the simplest cars, would be super-common, it was really the other way around. It took about five tons more steel for a given capacity for a flat than to build a box car. The only loads that tended to travel in flats were those they couldn't get into other cars.

Flats almost never travel with stakes in the pockets without a load on the car - this is a model railroadism to have all the stakes up. Also, most loads only require a few stakes. The idea of all those pockets is merely to provide flexibility in where the stakes get placed.

Most model flats come with the decks painted the body, but this is extremely rare on the prototype. Normally the decks are unpainted wood. I don't even think they bothered with creosoting the wood, as it got so chewed up with moving heavy items on and off it didn't last long enough to require weather protect. (Creosoting ties allowed them to last for upwards of 30 years - untreated, they might have lasted five. Flat car decks might get replaced every couple of years or so, I'm guessing.)

Forty foot flats were being built through the '20's, but then the emphasis shifted to 50 foot flats. Actually, the all-but-universal length of these was 52 ft. 6 ins., allowing it to carry a 50 foot piece of steel.

Open Top Loads


Also see Gons Table of Contents

Composite Gons

  • EJ&E Composite Gon
    I cut down the truss-sides on an IHC War Emergency gon to sort of model an EJ&E composite gon. (I say "sort of", as the trusses no longer quite connect at the bottom, and the car would collapse under load.)

Steel Gons

  • A Pennsy G27.

  • A couple of CNJ gons with crated airplane parts being unloaded in an unknown Canadian seaport.

Open Top Loads


Ore Hoppers

Ore cars are essentially hoppers, except . . . And it is a big except, which is why we normally distinguish between the two.

Hopper car designs are so closely tied to one commodity, coal, particularly in terms of coal's density. Ore cars, too, are closely tied the particular ore density, and since ore is SO much denser than coal, ore cars are short. Ore cars are the shortest revenue freight cars.

But there is another important distinction. While there are many cases of solid coal drags and lots of hoppers pretty much kept in captive service, there were also many cars shipped off-line to be distributed to small retail outlets. Ore is only shipped to other specialized industries, and thus the number of routes are extremely limited - often only one. Thus ore cars pretty much are kept in unit trains (even back in steam days, when that term wasn't really used), and normally kept on line. I would love to see a single photo of one of these shorty MDC or Walthers ore cars in the consist of a "regular" freight train.

Now I do know that the Adirondack iron ore companies DID ship off-line, to a number of destinations, but their ore was normally shipped in regular coal hoppers. The Port Henry, Chazy Marble & Lime Co., and Lyon Mt. companies did have shorty ore cars, too, but again, I can't find any evidence of these on D&H freight trains.

Covered Hoppers