Given equal legnth freight and passenger trains is there a difference in the operating them as far as acceleration, hill climbing and descending, braking, etc.?
Good train handling is always a plus, but passengers generally seem to dislike rough handling a great deal more than most freight.
I can’t give you a thorough explanation, but there is such a thing as “Freight schedule” brakes, which are used on Auto Train, but probably no other Amtrak trains. It has to do with the handling characteristics of a longer, heavier train. A locomotive engineer could give you a far better answer than I can. I’m presuming the notion of handling a passenger train more gently is taken for granted; but even so, a freight engineer who breaks a knuckle or pulls a drawhead will have some ‘splainin’ to do. Several years ago a rather famous N&W engineer, who was noted as an excellent modeler as well as a very good author, rode our train. He sent a letter to Mr. Claytor (President of Amtrak at the time) complimenting the crew on its excellent train handling. That’s the only time I’ve ever heard of a passenger noticing good train handling, but they always notice when it’s bad.
Sure. If the freight is the length of a typical passenger train the handling is simple, you just don’t run it, its too short. 
Now for REAL passenger trains and REAL freight trains, the difference is very different. Passenger trains are shorter, lighter, have more horsepower per ton and more braking power. They accelerate waaaay faster and they stop waaaaaay quicker.
Freight train may well be considerably heavier, unless it is mostly empties, as passenger equipment is generally roughly equal in weight to an empty freight car, even when fully loaded with passengers.
Aside from that - and also a concurrent result of it, too - passenger trains are usually assigned a higher power-to-weight ratio (horsepower per trailing ton), so they will accelerate faster and climb grades faster than freight trains. The same considerations mean that a passenger train can usually descend a grade faster than a freight without risking a runaway from brake shoe fade, etc.
Finally, most passenger train air lines are set for 105 or 110 psi, whereas the standard freight train pressure is 90 psi.* That means the passenger train can make more of a ‘reduction’ = harder brake application before the reservoirs equalize with the brake pipe (see: http://www.alkrug.vcn.com/rrfacts/brakes.htm#pressurevariation ). So, passenger trains can go somewhat faster closer right up to stops and speed restrictions, etc., thus resulting in faster over-the-road time than an equal length (and even an equal weight) freight train.
*See: http://www.railway-technical.com/brake2.shtml - “3. Air Pressure Variations” at the bottom of the page.
“Air Brake Pressure on Amtrak Trains Using Freight Power” at: http://www.trainorders.com/discussion/read.php?4,2422482
http://www.sdrm.org/history/timeline/amatic.html
Rule 100.6 on page 6 of: http://www.blet75.org/2013-05-01_abth_updated.pdf
- Paul North.
There are a few differences as far as air brakes go. I’m not a locomotive engineer so these are both very simplified:
- Passenger trains typically use an operating pressure (in the brake pipe and elsewhere) of 110 psi, while freight trains use 90 psi. That extra pressure allows an engineer to apply the brakes harder and/or more times within a certain period.
- In addition, passenger trains have graduated braking, allowing the engineer to “ease off” the brakes to some degree. Freight equipment can only be released completely.
All bets are off when you’re talking about historic equipment, whether passenger or freight. I’ve worked for a railroad that runs passenger trains at 70 psi with a manually-lapped brake system in the cab…
So coming down a major grade like Cajon or Horseshoe curve controlling speed on a passenger train is with air or dynamics?
Yes.
He means air AND dynamics if the locomotives are dynamic equiipped. This is true both for freight and passengers, although my observation is that a more blended approach is used on passenger trains, while on frieght, the effort is to keep the slack (much greater on a freight, even of equal length) bunchd, using mainly the dynamic with variations contrrolled by the air brake used gently. In addition to less slack because of tighter coupling, commuter trains often have electric apply and release (both mu electric, and push-pull diesel and electric) in addition to train-line air control, and this means that all brakes apply and release at close to the same time, where as brakes on a freigh train with power only at the head end release and apply in sequence, approximately 1040 feet/second front-to-back.
Ninety pounds, but ditto on the brakes (NYC RS3)… Manual transition, too, but that’s a different thread.
Engines used by Amtrak, and maybe some of the commuter lines, have a system called, “blended brakes.” It combines dynamics and air brakes with one control. I don’t really know much more than that, except I’ve heard it really makes train handling easier. Passenger equipment is generally also equipped for graduated release. The brakes can be partially released so the engineer can reduce the amount of braking effort on the train. Conventional freight equipment can only be fully released, no partial release. (ECP brakes would be able to have a graduated release, but other than test trains I haven’t heard of there use in the US yet. Actually haven’t really heard much about ECP braking at all lately.)
I’ve had Amtrak detours and company business car trains. All have been with a freight engine (The detours because of ATC/cab signal requirement.) with the air brakes set up for freight service, even if the engines have the passenger option. The last passenger train I had was company equipment, and we always have a officer riding in the cab, even if it’s just deadheading equipment. He told me not use dynamics, only air, and that I didn’t have to “clean up” the air brake application. (In freight service they want at least a 10 psi set, unless you will be using the brakes again real soon. The Minimum service position on the brake valve only takes off 6 to 8 psi, usually requiring one to “clean up” by increasing the application.) I ran them the way he wanted, fully understanding that the next officer probably would want it ran a different way. (Interestingly, they don’t assign anyone to ride with us on Amtrak detours. I’ve had 3 and only once did the Amtrak engineer ride up front. That was more to just see the scenery or maybe to give advice should he think a freight engineer needed it. He ne
Thank you for the blended info. I had the opinion that dynamics would be too much braking on a passenger train. That supports my opinion guess.
It should be noted that the latest mu and electric locomotive equipment have a blend of air, dynamic, and regnerative brakiing, where braking current generated by the motors can be returned to the catenary or third rail if the load by other trains or train on the section is available and not just dissapaited in resistors. Some of the latest electrifications even have storage substations, using batteries or flywheels. In Europe, this is true of electric freight locomotives, not just passenger.
I don’t doubt that this is true now, but was it when most (or all) passenger cars were what we now call “heavyweight” cars? I have always been under the impression that a heavyweight Pullman, empty or loaded, was about as heavy and offered similar rolling resistance as two or even three freight cars.
There were 100-car freight trains during WWII. A single loaded coal hopper can weigh more than a heavyweight Pullman. Ditto an ore gondola. And the N&W ran 80-car coal trains.
Not all freight cars were 40-ton boxcars or refers.
Back in the day -
Heavyweight passenger cars were considered to be 80 tons.
Lightweight passenger cars were considered to be 60 tons.
In the days of wood cars with steel underframes they had a lightweight of 20 tons.
All steel cars had lightweights between 25 & 30 tons.
The nominal loads for freight cars were between 50 & 70 tons + the lightweight of the car.
I think the 100-ton coal-carrying car goes back to WWII. With the light-weight, that would be 120-130 tons.
Dave,
You are partially correct and partially incorrect.
There were a few major coal hauling railroads, the Norfolk & Western and the Virginian are two of them, that operated oversized 90-100 ton capacity gondolas (with 6 wheeled trucks in N&W’s case) and hoppers even before the second World War but they were not the industry standard.
I know in the 40’s and 50’s many coal haulers (L&N for one) used 70 ton coal cars and IINM there were still many 45 ton cars in operation.
100 ton capacity didn’t become the norm until the 1960’s.
From The Virginian Railway (Kalmbach 1961):
… the railway placed orders in 1916 and 1917 with [four different builders] for the four classes of G–50000–3 experimental 120–ton gondolas.
and
They weighed 82,600, 83,300, 87,800, and 73,900, respectively, and were regarded as lightweights when originally built.
Good. Excpt for the 45-ton, loaded, all are heavier than a heavyweight Pullman.