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Heavyweight vs Lightweight and Six vs Four wheels

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Heavyweight vs Lightweight and Six vs Four wheels
Posted by MJ4562 on Sunday, June 14, 2020 5:35 PM

Was the switch to lightweight cars strictly an economy measure or where they actually an improvement in comfort and ride over the older heavyweight cars?  

Additionally, did all heavyweights ride on six wheel trucks and lightweights on four?  Or is their more to it than that?  What were the pros and cons of four vs six wheel trucks?  

I've done some general background reading on this but I know there is a lot to this topic so appreciate everyone's insight.  Thank you. 

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Posted by timz on Monday, June 15, 2020 11:17 AM

"Heavyweight" and "lightweight" have no official definitions. PRR P70 coaches were heavyweights, but they had 4-wheel trucks, as did lots of other heavyweight coaches. "Lightweight" is almost a synonym for "built with smooth sides and roof"; some "lightweight" cars had 6-wheel trucks.

The American Flyer coaches were an in-between.

I'm guessing a heavyweight Pullman rode at least as well as a lightweight sleeper, but I was never in one. Maybe the heavyweight was quieter?

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Posted by Overmod on Monday, June 15, 2020 11:43 AM

Just as a note: plenty of 'lightweight' cars rode on six-wheel trucks, both when articulated and needing three axles' worth of load-bearing and when the full weight of the car required it (the 'poster child' perhaps being the Superdomes).

These six-axle trucks could involve just as modern a high-speed OSH design as any contemporary 4-wheel truck and shouldn't be thought of as a rewarmed 'legacy' truck design from the Great Steel Fleet era.

You will find a surprising number of these things in pictures once you know to look for them...

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Posted by Deggesty on Monday, June 15, 2020 2:30 PM

The only times I rode in heavy weight Pullmans they were on not so fast trains (L&N's train from Cinicinnati to Montgomery that used the old main line above Decatur, Alabama, and the Pullman Lake  Pearl on at least two steam excursions out of Birmingham). They seemed , as I recall, to ride well. I did spend some nights on heavy weight coaches, which did not disturb me by the ride quality. I do not like sleeping in seats that do not recline--but the last night I slept in such a coach (from Atlanta to Charlotte), I had the seat right by the men's washroom, and could stretch out on it, and I slept all night.

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Posted by Overmod on Monday, June 15, 2020 3:08 PM

Deggesty
The only times I rode in heavy weight Pullmans they were on not so fast trains

An interesting subject, which ought to get and perhaps has gotten more interest than I've seen, is the modification of heavyweight trucks for higher 'streamliner era' speeds.  This is distinct from converting them to newer trucks (as in some private cars, and office cars like PRR 120)

There are examples of this in some railroad museums, where you see six-wheel frames of what may be considerable antiquity now fitted with roller bearings, better bolster damping and compliance, modern primary springing, multiple Spicer drives, etc.  I believe there were manufacturers in the '40s specializing in these conversions.

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Posted by charlie hebdo on Monday, June 15, 2020 4:50 PM

Overmod

 

 
Deggesty
The only times I rode in heavy weight Pullmans they were on not so fast trains

 

An interesting subject, which ought to get and perhaps has gotten more interest than I've seen, is the modification of heavyweight trucks for higher 'streamliner era' speeds.  This is distinct from converting them to newer trucks (as in some private cars, and office cars like PRR 120)

 

There are examples of this in some railroad museums, where you see six-wheel frames of what may be considerable antiquity now fitted with roller bearings, better bolster damping and compliance, modern primary springing, multiple Spicer drives, etc.  I believe there were manufacturers in the '40s specializing in these conversions.

 

Illinois Central had some heavyweights with six-wheel trucks modified for higher speeds.  They were used on some second tier trains and student specials for holidays. 

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Posted by Paul Milenkovic on Monday, June 15, 2020 9:00 PM

The difference between heavyweight and lightweight appears to be in the roof.

Just what was a "clerestory roof" and was this for better natural ventilation?  Why did they do away with it in the lightweight passenger car?  Because of air conditioning?

The Amfleet cars appear to have a lower roof line than "lightweight", and the Canadian LRC cars yet an even lower roof line.  The Santa Fe Hi-levels, it seems, had a pretty low roof when you consider that the passenger rode on an elevated deck.  What changes did they make to allow a lower roof apart from making the passengers stoop when they walked along the aisle?

If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?

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Posted by BaltACD on Monday, June 15, 2020 9:05 PM

Paul Milenkovic
The difference between heavyweight and lightweight appears to be in the roof.

Just what was a "clerestory roof" and was this for better natural ventilation?  Why did they do away with it in the lightweight passenger car?  Because of air conditioning?

The Amfleet cars appear to have a lower roof line than "lightweight", and the Canadian LRC cars yet an even lower roof line.  The Santa Fe Hi-levels, it seems, had a pretty low roof when you consider that the passenger rode on an elevated deck.  What changes did they make to allow a lower roof apart from making the passengers stoop when they walked along the aisle?

A fuller discussion of the clerestory roof

http://cs.trains.com/trn/f/743/t/282587.aspx

Never too old to have a happy childhood!

              

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Posted by Erik_Mag on Monday, June 15, 2020 11:20 PM

Overmod

Just as a note: plenty of 'lightweight' cars rode on six-wheel trucks, both when articulated and needing three axles' worth of load-bearing and when the full weight of the car required it (the 'poster child' perhaps being the Superdomes).

High speed 6 axle trucks were also used on the AT&SF Hi-level dining cars as well as the UP boiler cars. IIRC, the UP did rebuild many of their heavyweight cars for streamliner service - a couple examples are a streamlined heavyweight coach and lounge car at OERM. Think the ttrucks had been modified to use roller bearings.

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Posted by MJ4562 on Tuesday, June 16, 2020 8:40 AM

My understanding was that heavyweights had floors made of poured concrete so they rode better.  Not sure if improved suspension systems could make that unnecessary.   

A trip on the Grand Canyon Rwy got me thinking about this issue.  I was observing all the different types of cars.  I'm aware from reading their history articles that their cars are sourced from many different places so what is currently high or low end to them doesn't necessarily correlate to what was high or low end back when they were all new.  

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Posted by Overmod on Tuesday, June 16, 2020 10:09 AM

Paul Milenkovic
The difference between heavyweight and lightweight appears to be in the roof. Just what was a "clerestory roof" and was this for better natural ventilation?

Personally, I think this was a convention (like using stagecoach styling in early passenger cars) which came to denote 'real-railroad' vestibule cars.  Where you see it in narrow-gauge, interurbans, etc. I think it's likelier to be an establishment of 'visual legitimacy' more than ventilation or light; it certainly doesn't add to strength or decrease cost and it's more difficult to keep maintained than an arch.  
Note that there was little perceived difficulty in 'rounding off' the heavyweight roofs with air-conditioning ducts and suchlike in later years, by which time a matched set of highly-varnished palace cars was no longer a competitive aesthetic necessity...

Why did they do away with it in the lightweight passenger car?

Succinctly, because in lightweight construction the carlines and purlins are structural.  While the arch roof may be less stressed in something like a Pullman-Standard 'fake Budd car' than in early UP Streamliner practice following the general Stout Railplane practice, it is still significant.  A clerestory roof without 'tie bars' as in some Renaissance churches does not offer this strength...

The Amfleet cars appear to have a lower roof line than "lightweight", and the Canadian LRC cars yet an even lower roof line.

Amfleet uses the 'tubular train' construction of 1956 as later refined and applied to the Metroliners, and this is something that essentially treats the carbody above the windows as part of the roof.  You could approximate a clerestory with windows in this construction if you wanted a sort of Skytop effect, but there is little perceived point in this, especially given the complex changes in formed components and jigs that would be needed to produce it... or the advisability of using it 'under wire'.

LRCs have the roof low for the same reasons the early Streamliners and the crop of stillborn lightweight trains of the '50s did.  In particular the design was optimized for "negative cant deficiency" (tilt) systems that could function fully within the existing loading gage at minimum tare weight -- the universal formula for doing this non-queasily (i.e. with the roll center about where vestibular canals for a person standing in the aisle would be) without complex mechanical arrangements perhaps familiar to you likely involves low carbody and relatively high pivot or swing position (as seen more dramatically in the Cripe TurboTrain).

The Santa Fe Hi-levels, it seems, had a pretty low roof when you consider that the passenger rode on an elevated deck.  What changes did they make to allow a lower roof apart from making the passengers stoop when they walked along the aisle?

It has always been my opinion that ATSF could have adjusted the deck height to be relatively lower in this proprietary equipment had they wanted, increasing "ceiling" height and lowering effective roll center and metacenter without concern for the 'lower deck' as a true bilevel design would.  I suspect the reasons for the actual design dimensioning are covered in historical discussions of these cars and trains; I'm far from an expert there.

 

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Posted by Overmod on Tuesday, June 16, 2020 10:36 AM

MJ4562
My understanding was that heavyweights had floors made of poured concrete so they rode better.

This is part of the reason they were 'heavyweights' -- aside from the ballasting and suspension preload this produced a certain amount of 'inertial stabilization' of short-period track forces communicated up through the trucks.  Perhaps the finest flower of this were the 'late' PRR P70s that had something like 2" of concrete (that might have had steel-mill slag in the aggregate) in the deck, and the refined high-speed trucks.  It is difficult to describe how beautifully and quietky these things rode on indifferent PC track in the early-'70s NEC (much of which was still jointed rail in no more than 128' sticks then).  On the other hand when you arrived at 30th St. on a typical clocker the sheer amount of stinky blue brake smoke would attest to the extra weight...

Not sure if improved suspension systems could make that unnecessary. 

It can, and it does, and in fact in many modern trains probably including any true TGV the use of inertial ballasting would be a waste.  Lightweight cars often featured a kind of 'poured floor' underlayment for noise and shock blanketing; if you look at some of the contemporary car builder advertising you can see this was very much like a 'cement deck', just with lighter materials.

The basic issue with good riding in lightweight cars is the difference between loaded and empty; an associated concern is the change in ride height accompanying this where the train uses 'Continental' platforms.  The usual-suspects approach to this is to use those big airbag springs in the bolster secondary suspension, airing them up or down to get level at the doors.  This adds much of the cost of a full-active suspension even if reservoir air can be safely tapped to run the ride-height system.  
If you use negative-cant-deficiency systems, much of the necessary complexity for better active suspension may be present.  The fun then becomes the magnitude of the actual road and running shocks you have to correct for (I'm assuming that noise, including what may be significant and annoying noise from active suspension, can be and has been satisfactorily blanketed, and that NVH in general has been considered and 'engineered out' to the greatest extent practical)

As noted in previous threads the magnitude of peak shock can be dramatically high, and systems capable of absorbing this while of low enough mass to work at high speed can be difficult, and expensive, to provide.  (Or to have to rework, but that's another discussion...)

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Posted by blue streak 1 on Saturday, June 20, 2020 7:53 PM

The Santa Fe Hi-levels, it seems, had a pretty low roof when you consider that the passenger rode on an elevated deck.  What changes did they make to allow a lower roof apart from making the passengers stoop when they walked along the aisle?

Observed when riding the Starlight that the floors were about 4 " lower on the Sante Fe lounges than Superliners.  Always felt it was a tripping hazard going from lounge to SL but also somewhat the other was.  Plus had to duck when going from SL to lounge.  Another problem noted that the lounge only had one hand hold when going between cars.  Not as safe as could be.

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Posted by blue streak 1 on Saturday, June 20, 2020 8:05 PM

Cannot imagine trucks would need anything but adjusted for one weight.  If we were to take every passenger, luggage , and potable water as 250 pounds per passenger and overload of 80 passengers that is only 20 thousand pounds difference.  Tune trucks at 10k above empty weight and ride would not be that different ?  Now if Amtrak changed weight of seats maybe ? ? 

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Posted by Deggesty on Sunday, June 21, 2020 7:49 AM

blue streak 1

The Santa Fe Hi-levels, it seems, had a pretty low roof when you consider that the passenger rode on an elevated deck.  What changes did they make to allow a lower roof apart from making the passengers stoop when they walked along the aisle?

Observed when riding the Starlight that the floors were about 4 " lower on the Sante Fe lounges than Superliners.  Always felt it was a tripping hazard going from lounge to SL but also somewhat the other was.  Plus had to duck when going from SL to lounge.  Another problem noted that the lounge only had one hand hold when going between cars.  Not as safe as could be.

 

Yes, I remember that difference in height. It took me by  surprise the first time I moved from a Superliner car into the former Santa Fe car. I do not remember seeing anything about that difference in all that I had read about using the Santa Fe cars on the Seattle-Los Angeles train. Thereafter, I remembered. I always enjoyed riding in those pre-Amtrak cars.

Johnny

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Posted by Paul Milenkovic on Sunday, June 21, 2020 2:18 PM

Yes, the Superliners are taller, with maybe the higher upper deck to have a more usable lower deck.  I think Plate C is 15'6" and the Superliners exceed that and are at an even 16'?

As to building a Hi-level car with a lower floor and taller ceiling, I read that one rationale of the Hi-level is to have the passengers ride higher to be able to see more out the windows.  This is part of why people like SUV automobiles over sedans -- to ride up higher and see out more.

I rode the Amtrak Southwest Limited from Chicago out to Pasadena, CA once in the mid 1970s when coach class was Hi-level and the sleepers were conventional "lightweight" cars.  This was the combined El Capitan (coach) and Super Chief (all sleeper) that Santa Fe sued to prevent Amtrak calling it the Super Chief (is it now called the Southwest Chief?).  In the 40-hour 2-overnight trip in a coach seat, a deep recline leg-rest seat, but still a squirm-inducing coach seat, I remember encountering the other "train sets" covering daily service on this route.  I noted some odd Hi-levels that had slightly angled instead of straight sides and wondered about them.

I later learned that "sprinkled" among the multiple train sets (consists) were the prototype Hi-levels built in the Santa Fe shops before they gave the main order to, was it, Budd?  I read that these had the seats up on a step relative to the aisle way to give more elevated Hi-level goodness.  The theory was giving coach passengers assigned seats that were like riding in a dome car.

Part of the dome car experience is the glass dome where you can look out the sides on the passing scenery whereas in a regular coach seat, your view through a narrower window is more limited, expecially from an aisle seat.  The other part of the dome car is that it is meant to give some approximation of the view out the front of a ride in the locomotive cab, which is really something you can offer only with a short dome.  On a Superdome (GN-style full-length dome car riding on 6 axles, by the way), you really cannot see out the front apart from the first few rows of seats, I suppose, and as to a Hi-level car, I have been in a Budd dome car and the Hi-level is no dome car.

The crazy thing about stepping outside of a Hi-level car to stretch one's legs at a station stop was hearing what sounded like a bus engine going a mile-a-minute.  Each Hi-level had its diesel engine to run the airconditioning, which was a solution to the head-end (also called hotel) power problem between the axle generator-and-batteries days and locomotive-supplied HEP.

In one sense, you could think of a diesel engine in each car to run the air conditioning as a maintenance and servicing nightmare.  On the other hand, a diesel running the refrigeration is the standard solution for reefer OTR trucks as well as railroad freight refrigerator cars.  I know of someone who owns and operates a private railroad car and described it has having such diesel gensets for lights and environmental conditioning, which is not such a bad idea if you are entertaining guests with your private car parked in a siding someplace.

So the diesel genset on each coach idea was a road not taken but perhaps not a completely silly idea.  I imagine that Amtrak has pulled out those gensets and converted those Hi-level lounges on the Coast Daylight/Starlight train to their HEP system used by Superliners, Amfleet or whatever else they have?

If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?

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Posted by Overmod on Sunday, June 21, 2020 5:33 PM

I'd always heard the purpose of the Hi-Level cars was predominantly to raise passengers above track and 'truck' noise, with the view advantages real, but secondary.  It would not have been rocket science to give them 'overhead' windows (as in some cars that ran in the East with essentially glass roofs over the lounge area -- I don't recall if these were cleared to run under catenary or not).  If you thought HVAC was tough in Hi-Levels where ATSF often ran -- imagine the tons of further cooling needed with the added non-low-E glass, and the added duct and return systems to distribute the air.

I had thought that use of individual gensets on 'electrified' cars was fairly widespread even in the '30s.  As an alternative to a couple of Spicer generators and a whopping bank of batteries it could be attractive.  I'd like to be able to say to google 'Waukesha Enginator' (one of the more famous period devices) but you'll immediately come upon misinformation puled on stupidity that confuses 'Enginator' as a term meaning what we now call 'Genset' with Waukesha's production of gas engined skid-mounted equipment.  See also the Ice Engine for air conditioning compressor operation with fans, duct motors, etc. supplied from axle generation if needed...

You might have to go to RyPN to locate correct information on generators for individual cars and their 'best' fuel source and controls.  In the meantime here is some potentially-illuminating light reading (I'll stop with the puns now):

http://www.erixrailcar.com/techpubs/Waukesha_Ice_Engine_E_and_Engine_Generator_C.pdf

An amusing detail is that at least one company has actually made up a replica Enginator shell meant to be installed around a modern, smaller genset to give a historical look to the installation!

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Posted by Erik_Mag on Sunday, June 21, 2020 10:59 PM

The stated purpose of the AT&SF high level cars was to minimize weight per seat. By having the entrance/exit and restrooms on the lower level, the whole 80' or so of upper floor space could be given to seating space. The ride may have been better as the inverted pendulum effect would have softened lateral shocks.

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Posted by CSSHEGEWISCH on Monday, June 22, 2020 10:13 AM

The "El Capitan" was close to maxing out in length with conventional coaches and Hi-Levels were an imaginative way to increase capacity of individual cars.  As a comparison, conventional coaches seated 48 to 52 while the Hi-Levels seated 68 or 72 per car.

The daily commute is part of everyday life but I get two rides a day out of it. Paul
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Posted by rcdrye on Tuesday, June 23, 2020 12:25 PM

The two 1954 pre-production Hi-Level coaches were 15'4" tall, the 1956 and 1964 production coaches 15' 6" tall (same as a Budd Dome) and the Superliners are 16'2".  The key dimension for Hi-Level floors is headroom in the lower level bathrooms, lounges and kitchens.  There were several variations is "step-down" end stairways to match single level equipment, with some cars having front-end steps, some rear-end, and some no step-down.  "Front" meant towards the end of the car when the stairway is on the left.  A fair number of cars from the 1964 order were fitted to have convertible step-downs, but it's not clear how many were actually converted.

Santa Fe assigned H-Levels to the El Capitan and later the San Francisco Chief. Amtrak regularly assigned Hi-Levels to the Super Chief/El Capitan (Southwest Limited), The Chief, the Texas Chief(Lone Star) and the Sunset Limited.  Later the cars were mixed in with Superliners, usually as step-down cars in mixed consists.  The last all-Hi-Level trains were the Heartland Flyers which eventually received Superliner coaches.

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Posted by CSSHEGEWISCH on Wednesday, June 24, 2020 10:04 AM

Hii-Levels were also assigned to the Texas Chief prior to Amtrak.  I remember seeing Hi-Levels on the Texas Chief at Dearborn Station with a mix of GE's as the motive power.

The daily commute is part of everyday life but I get two rides a day out of it. Paul
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Posted by daveklepper on Thursday, June 25, 2020 2:48 AM

The East Coast single-level lounge cars with glass-roof area where the Seabord's Sun Lounges.  They ran as mid=train lounges, usually between the diner and the sleepers, often on "Silver" trains that also had a round-end obs.  And yes they ran under catenary.

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Posted by 1702 on Tuesday, June 30, 2020 4:28 AM

Those ex-ATSF Hi-Level diners with six-wheel trucks gave many years of good service for Amtrak.  They were converted to diner-lounges and were used as such on the "Desert Wind" between LAX and DEN in the summer season and LAX-SLC in the off-season.  They were also used on the "City of New Orleans", albeit strictly as lounges.  Not familiar with any other routes that Amtrak may have used them on.

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Posted by swagner on Tuesday, June 30, 2020 5:25 AM

Just a very limited non-technical contribution:  A not very prosperous railroad could and do a fine job making riding overnight in modernized heavyweight cars as pleasant as possible. 

My first solo long-distance journey was in August 1963, the month of my 17th birthday, between my family's home outside Philadelphia and Lawrence, Kansas, using trains except west of St. Louis.  On the outbound trip: public transit to 30th Street Station.  PRR to Baltimore.  Then B&O trains to Washington, DC, Cumberland, MD (standing until Harper's Ferry), and St. Louis.  The longest leg was aboard the National LImited.  It was rerouted overnight on secondary lines in West Virginia that hadn't had passenger trains on them in many years, because the railroad was enlarging tunnels to accommodate larger freight cars; I saw almost nothing of this rare mileage because I slept okay.  The coach I rode in had reclining seats with decent legroom, largish windows, and storage space for large, comfortable pillows that were distributed free to all passengers.  Lights were properly dimmed.  The ride was very smooth indeed over what was most probably quite rough tracks. 

On the return trip I had a similar overnight ride on the B&O between St. Louis and Cincinnati.  From there to Washington, DC, passengers with B&O tickets were sent on the C&O.  The coach was a PS-built postwar streamliner; from my perspective its best feature was end doors that could be opened by pushing a button with your shoe. 

In April 1970 I had great, smooth rides in a modernized heavyweight Illinois Central coach and a heavyweight diner on Canadian National and Grand Trunk Western (where I spent as much time as possible in preference to staying in a roomette from which I could see the outdoors only on one side of the train).  The Erie also did a fine job of revamping heavyweight cars, some of which went to the Delaware & Hudson.

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Posted by D NICHOLS on Tuesday, June 30, 2020 7:38 AM

timz

"Heavyweight" and "lightweight" have no official definitions. PRR P70 coaches were heavyweights, but they had 4-wheel trucks, as did lots of other heavyweight coaches. "Lightweight" is almost a synonym for "built with smooth sides and roof"; some "lightweight" cars had 6-wheel trucks.

The American Flyer coaches were an in-between.

I'm guessing a heavyweight Pullman rode at least as well as a lightweight sleeper, but I was never in one. Maybe the heavyweight was quieter?

 

The US Army knew the answer to that question. In 1944 and 1945 they had 200 Hospital Cars built. They were streamlined heavyweights and rode on 6 wheel trucks. They weighed in at 80 tons. In 1951-2 they had 52 new ones built that rode on 4 wheel trucks and were lighter. When they were told that they had to get rid of some of the cars, guess which ones they got rid of due to ride quality? Yep, the newer ones on the 4 wheel trucks. The difference in load between full and empty is not as noticed in a heavyweight as the percentage of the total weight is less.

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Posted by Overmod on Tuesday, June 30, 2020 8:08 AM

swagner
The coach was a PS-built postwar streamliner; from my perspective its best feature was end doors that could be opened by pushing a button with your shoe. 

I suspect you missed an even niftier feature -- the washroom faucets were probably worked with pedals, too.

According to Trains this was a Robert R. Young thing -- he had a horror of germs, and so had the massive equipment order that would have become the Chessie streamliner built with some touch-free systems.  (I thought when the story came out that these were nifty ideas, and they still are.  Designers only recently 'discovered' that foot controls for trunks and liftgates are highly useful in automobiles ... I'm hoping to see someone get the haptics of touch-free handwashing right (without the expense and conplication of, say, electrical proportional valves turned in by an optical or ultrasonic proximity sensor now probably with gesture recognition...)

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Posted by charlie hebdo on Tuesday, June 30, 2020 12:24 PM

Washroom taps were worked with foot pedals on some older DB coaches, as I recall. 

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Posted by ANDREW R TOWNSEND on Tuesday, June 30, 2020 10:15 PM

There's probably as many exceptions to the rules as anything else in railroading, but from my take, the definition is mostly in the construction. The cars of the heavyweight era had most of the structural strength in the frame structure and center sill, think more of a metal box sitting on a flat car. Generally heavy, too, diners and Pullmans could get up to 240,000 lbs. From my experience they ride very smooth though, when I've car hosted you see both kids and adults nodding off with a smile pretty often. 

Lightweights are constructed more along the lines of a modern car or airplane fuselage. The strength is distributed through the whole car body and the center sill structure, so thinner sheetmetal can be used. Usually lighter that way, more in the 130,000 - 140,000 lb. range. Less weight means you don't need as much horsepower in the locomotive(s) and less fuel burned. My opinion is they rock and roll more and you feel the rough spots in the track more, but that can be due to the truck's design or state of maintenance, too. Milwaukee's home designed and built lightweight cars with Nystrom trucks can ride really well at speed when in good shape. 

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Posted by MJ4562 on Friday, July 3, 2020 9:25 AM

The modern car analogy combined with a rail trip is what led to my thinking about this.  In modern sedans, lightweight is economy while the high end is dominated by enormously heavy and solidly built vehicles.  Also I noticed private business railcars being rebuilt from heavyweights*. It seems if someone is going through that much expense they would pick the nicest riding railcar as the base.  

*I'm sure there are examples of lightweight cars being used as well.

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Posted by wjstix on Tuesday, July 7, 2020 11:40 AM

Overmod
Overmod wrote the following post 21 days ago: Paul MilenkovicThe difference between heavyweight and lightweight appears to be in the roof. Just what was a "clerestory roof" and was this for better natural ventilation?Personally, I think this was a convention (like using stagecoach styling in early passenger cars) which came to denote 'real-railroad' vestibule cars. Where you see it in narrow-gauge, interurbans, etc. I think it's likelier to be an establishment of 'visual legitimacy' more than ventilation or light; it certainly doesn't add to strength or decrease cost and it's more difficult to keep maintained than an arch.

Not sure what the clerestory roof has to do with the vestibules at the end? Anyway, early passenger cars had essentially flat roofs - a bit rounded but nothing protruding up. These cars were dark and had poor ventilation. Adding the clerestory section on top allowed more glass for light, and a better position to vent in air from. It wasn't 'cosmetic'. When lightweight cars came along, mechanical air conditioning for passenger cars was viable, and electric lighting (instead of dull smoky oil lamps) was well established, so there was no longer a need for a clerestory. Many heavyweight cars that were converted for use in later streamlined trains lost their clerestory roofs.

Also, note that heavyweights were generally steel pieces bolted together where lightweights were lighter weight metal like stainless steel, welded together. It's not just the trucks or roof, the entire car construction was different.

Stix

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