Back In The Days of Steam?

Question

When high tonnage freights with Steam locomotives crested the 'hill' how did they deal with their brakes? [Considering there was no such thing as 'Dynamic Brakes'?]
Was it possible to put them [steam engines] into reverse to act as braking?
Those trains used to haul ***! And the braking system was 'pressure= brakes on'. 'No pressure = brakes off'.
Example:
Big-Boy cresting Sherman Hill with 100 car freight of reefers then going down-grade with this enormous load. How was engine used in braking then?

Answer 1

First, you are mistaken about the air brakes. The Westinghouse system was in use on all American railroads by 1880 or so. So the method was to reduce the train line pressure to apply the brakes, just as it is now.



Second (and I am surprised at some of the people who don't seem to know about this) steam locomotives DO have a form of dynamic braking. There is an excess of steam pressure in the dry pipe as the locomotive moves. Later "super power" steam locomotives had a "back pressure" gauge the engineer could use to set the cutoff for optimum performance. But in general, the back pressure is higher when the cutoff is too late; that is, when the reverse lever is kept too far forward as the locomotive accelerates.



So the engineer can get some braking effect by advancing the reverse gear so as to use the back pressure as a retarding force. It's very much like modern electric dynamic braking in that it creates more of a "dragging" effect than a "stopping brake" effect. Just as dynamic brakes on a diesel electric locomotive cannot stop a train, so the "advance cutoff" effect cannot stop, but only retard, a train.



And it has a limited amount of effect on a really heavy train. In the steam era, it was much more common than it is nowadays for crews to stop the train at the top of the hill and turn down the retainers to keep the brakes partially applied on cars back of about the first third of the train. This helped keep the train from speeding up very much on the down grade. Then you have to stop again at the bottom of the hill to turn the retainers up so the train can attain normal speed on the flat.



I have the diary of one of my great uncles who worked on the Santa Fe in the 1930s and 40s. He was out walking a train one night to turn the retainers up, when he heard an animal running toward him. He jumped for the nearest box car ladder, and just barely missed being grabbed by a nine foot grizzly bear. As he tells the story, the bear got one of his boots, but he kept the foot that was in it!



So it was a combination of air brakes, the sort of "imitation dynamic brakes" of the back pressure in the steam locomotive, and sensible, prudent practice by the train crews. And keeping clear of grizzlies!

Answer 2

George Westinghouse invented the air system we still use today in 1872.Before that was straight air but the trains were very small.When i hired out old head engineers would stretch brake everything even though they had dynamic brake(very few ever used it though).In stretch braking they would set the air while the throttle was wide open or close to it.Then they would just pull it with the engines.It's harder with empty cars because they squat down and want to stop.Another trick they used was a soft set.They would set the brakes then when they slowed down a bit they would release them.Then before they got a recharge on the whole trainline they would make another set.Because the trainline isn't all recharged not all the brakes on the cars would set up again if they set the same amount of air as before.It takes a 1 1/2 pound differential to initiate a set so the cars that weren't recharged enough wouldn't set up.Then they would just pull it down the hill.It burnt a lot of fuel but nobody thought about it back then.I'm sure some of my fellow engineers will be able to add to this for you.

Edit Some of the others mention retainer valves.Yes they were used if absolutely necessary,but it was a source of pride to be able to brag that an engineer brought a train off the hill without having to use retainers.I remember hearing my dad say it more than once lol.I remember asking him many years ago what a retainer was and his answer was something a sissy engineer uses and that a real hoghead didn't need them.They were a crazy bunch back in the day!

Answer 3

On a steam locomotive the drive wheels are directly connected to the pistons . On a diesel electric they are not.. When going down hill, and the throttle closed, the pressure that built up in the cylinders would perform the function of a dynamic brake On a steam locomotive you didn't select forward or reverse.,there were many degrees or notches of reverse.The engineer would start the train, with the" power reverse or johnson bar"set for full power forward.As the train picked up speed, he would move the reverse lever towards the centre. This action altered the valve gear causing less steam to be admitted to the cylinders .When operating speed was reached the reverse lever would have adjusted the valve gear so that steam was entering the cylinder for a very short period of the stroke.Going down hill the engineer would close the throttle and the steam pressure in the cylinders would assist in braking. On steep grades the train would stop before descending , The brake men would set the retainer valve on a prescribed percentage of cars in the consist and the train would descend the grade

Answer 4

I cannot speak for all areas, but I, as well as those that hired out in that generation, were fortunate to have hired out when and where we did. The men who taught us were engineers in the days of steam and they themselves were only one generation removed from the men who wrote the book on railroading in heavy grade territory, including the Cascade, Siskiyou and Tehachapi mountain ranges, as well as the Donner Pass route over the Sierra Nevada mountains. the latter of which were our mentors on SPs Sacramento Division.



The latter were also true air experts and, for my money, some of the best engineers ever to ply the rails. Dropping from the summit at Norden, slightly over 7,200 feet in elevation, to Roseville on the valley floor, covered a distance of nearly 90 miles, with only a mile long flat at Gold Run and a four mile long one called Weimire to release and recharge. So, slugging them with enough air to hold them back while working power wasn't always an option. You'd have to stop every so often for wheel heat radiation, just as required when there are retainers employed. Not having to stop is the whole point of NOT turning up the pops.



So how did these guys do it? Why, illegally, of course.



Some of the best improvements to air brake systems were a direct result of illegal activity that worked so well that they were actually incorporated into newer air brake components' design. This includes retaining valves themselves. Their genesis was when trainmen would plug the vent pipe from the brake cylinder with pointed, home made, wooden dowels. Those so effected kept the pressure in the cylinder while the engineer could release the brakes and recharge on the fly.



The next biggest improvement ever, right behind dynamic brake as number one, is the "pressure maintaining system," incorporated in all locomotives in use today. What it does is maintain the pressure in the brake pipe after an application has been made against leakage and can maintain that pressure for leakage up to 7 psi per minute. Legal leakage is 5 psi per minute. So, in the steam era when there was no pressure maintaining feature, when the engineer made a brake pipe reduction to apply the brakes, leakage would cause them to apply more and more. But, leave it to a hoghead to get around a problem.



On the old air brake schedule, when a reduction had been made, the brake valve handle was returned from the service application zone to a position called "lap." This would cut the brake pipe off from the main reservoir air supply, stopping the reduction, but also allowing the leakage to begin to apply the brakes harder over time. The solution was an illegal action that was called "bridging." One skilled in the practice could position the brake halve handle just right on the "bridge" of the brake valve quadrant between the release zone and the application zone after a brake pipe reduction was made, which maintained the pressure of the brake pipe and, presto! The birth of the pressure maintaining system was had. This would allow the engineer to work power or, much more often, drift downgrade against the set over long distances without over heating the wheels, since not as much air is used when drifting.



But, someone trying it had better know the air, or an undesired release of the brakes would occur. This is the primary reason why it was illegal. So, as a question within an answer, does anyone know if this illegal method was practiced elsewhere?

Answer 5

Steam locomotives that were frequently used on long downhill sections had a "Riggenbach counter-pressure brake" that allowed to use the cylinders for a constant braking force. See the Wikipedia link under "Source" for how it works.



For the exact working of the air brake, see the second link. The indirect air brake starts braking by lowering the pressure in the air pipe. That is a safety measure; in case of a broken coupling the sections of the train will automatically come to a halt even without a locomotive.



"The days of steam" were long, over a hundred years! So things gradually developed during that time. In the 19th century each car had a brakeman who had to operate a manual brake to stop the train.

Answer 6

Until they got the modern "no pressure=on" brakes in the 1870s, trains stayed small.



The steam cylinder brake wasn't really used much.



Brakes don't work like you think. It's not a spring. Each car has air reservoirs and a control valve.



First you charge the brake system. The valve charges the reservoirs from the brake pipe. Once charged, if the brake pipe pressure falls, the control valve applies air from the reservoir to the cylinders, in proportion. If brake pressure goes up, at all, the brakes FULLY release.



Back then, they typically ran a brake pipe of 70 psi. In that case, charging would result in 70 psi in each car's service reservoir. For each pound of brake pipe reduction, the valve would throw 2.5 pounds of pressure into the cylinder. For instance reduce to 60, and cylinder pressure was 25, and the demand of that would leave about 60 psi in the reservoir. Reduce to 50, and cylinder pressure was 50, reservoir was 50, and that's all you got.



Later brakes had a second, larger reservoir just for emergency, equalizing out at about 63 psi.



Nowadays they run around 90 psi. All psi's go up in proportion.



Here's how you descended a long grade with a steam engine. You stopped the train at the top. Crewmen walked the train setting "retaining valves" on each car. This controls the brake cylinder exhaust. It had 2-4 positions.



a) normal release

b) retains 10 psi of pressure in the cylinder

c) retains 20 psi of pressure

d) brakes would release fully, but verrrrrry sloooooowly, giving time to "pump the air back up".



Positions c and d weren't on all cars.



Then you'd descend the hill. When grade allowed, you'd throw brakes into full release. The retaining valves kept 10-20 psi so you kept 20-40% of max braking. If you did it right, you had time to fully recharge the car brakes. Repeat as necessary.



Now you see why they like dynamics. :)

Answer 7

Air brakes, that is all.



There was no braking system on the engines available. The locomotive brakes were only to be used in extreme emergency for controlling train speed.



They had a "tire" of cast steel that was fitted tightly over a wheel center, and if allowed to get too hot the tire would expand and slip or come completely off.



added later: I had never heard any of the old timers talk about the back pressure system for steam locos, I I will have to do some reading up, interesting.

Andy on retainers, yes it was the same here, most hogheads figured if you needed retainers it was too late.

Like they said "you cant retain what you didnt have inthe first place"

Answer 8

The Boys all have good input here. The accepted way was to set the brakes and pull the train downhill and control speed with the throttle. Putting a locomotive - steam or diesel - in reverse wouldn't do anything to reduce speed. Any time wheels spin, it is like your car on glare ice. All possibility of any beneficial traction is gone. Good question.



A couple weeks ago I sat in the cab of a 525 ton DM&IR 2-8-8-4. I couldn't imagine having to take that sucker on a main line with 18,000 tons of ore train. Made me appreciate stepping into the office of a good ol' SD unit.