In a steam… could we use the reverser to slow down ?
Started by Rail4Pete8 posts6 min read
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Hi train lovers,In a steam loco when we want to slow down, for sure we can use the brakes, but is it possible to use the reverser on backward position and increase the throttle ? Is it gonna break something or it's gonna have a kind of dynamic brakes effect ?When I was a kid I think that I saw on T.V. the engineer of a 4-6-0 in the "Iron Horse" with Ben Calhoun (some will remember) doing this.Thanks for answersPierre VeilleuxP.-S. Could'nt find any pictures of that loco in the "Iron Horse", if someone did or found a link, it would be interesting !
RE: In a steam... could we use the reverser to slow dow, oldrailfan, Dec-30-02, 10:59 PM, (1) RE: In a steam... could we use the reverser to slow dow, BlakeTyner, Dec-31-02, 03:12 AM, (2) RE: In a steam... could we use the reverser to slow dow, LARKIE, Dec-31-02, 04:15 AM, (3) RE: In a steam... could we use the reverser to slow dow, MadMike, Dec-31-02, 09:36 AM, (4) RE: In a steam... could we use the reverser to slow dow, pwillard, Dec-31-02, 10:39 AM, (5) RE: In a steam... could we use the reverser to slow dow, jonathanmlewisrgs, Dec-31-02, 10:44 AM, (6) RE: In a steam... could we use the reverser to slow dow, Rail4Pete, Dec-31-02, 04:48 PM, (7)
RE: In a steam... could we use the reverser to slow dow
Uh, if you place the reverser (or the Johnson Bar on older loc's) in reverse while the train's moving forward, and then open the regulator, something's gotta give. If you're lucky, the wheels will break loose and start spinning backwards. 'Course, that means you'e likely to spin the tires right off of the wheels. If they don't come loose, then you're either gonna twist a con rod or bust the valve gearing. In any case, I don't want to be there when the Road Foreman gets hold of you.
JOhn Oldrailfan Railfan means anything on rails! Trains Trolleys Rollercoasters - you name it.
RE: In a steam... could we use the reverser to slow dow
When driving a steam loco, speed should be mostly controlled with the Johnson bar. That is: you find your "sweet spot" throttle setting and speed up/slow down with the Johnson bar. On our locomotive once we start up we're running the bar about 3/4 forward, but if we pick up too much we've been known to run it at exactly halfway.With regards to stopping by going full reverse: no. Even IF the pistons and rods held up to the torque all you'd end up doing would be to spin the drivers backward...might as well just lock 'em up as much use as that would give you. And of course you'd probably throw the tires off...as the driving wheels are not all one piece. The tire is merely sweated on and the excessive heat generated from spinning or locking is enough to "unsweat" them. NOT a situation you'd want to find yourself in.Blake Harris Engineer/fireman, Jefferson and Cypress Bayou Railroad
Vice Dean, Limbaugh Institute for Advanced Conservative Studies
RE: In a steam... could we use the reverser to slow dow
It is acceptable practice to slow down recipriocating steam engines by putting into reverse,and applying as much steam as necessary to stop.Note,at no time must you allow wheelslip to happen as once initiated,you've lost the advantage of the steam braking you.That's why anti-skid brakes are fitted to cars as standard now.(initially developed for aircraft)As far as steam driven road vehicles are concerned,this is the only way of maintaining full control,especially going downhill,as the friction brakes(wood onto steel)are really only for parking conditions.The notion that excessive torque will damage your machinery is a fallacy as the maximum torque applied on a steam powered locomotive is at the point of wheel slippage.(this can happen,when trying to pull away too quickly). Thus when trying to stop by using the reversing gear,the wheels will slip at this same limiting value.Driving steam machinery is an an art form,as no other mechanical equipment requires the same intuition of the operator to manage and control it.PS.What is a "Johnson bar?",as no such term is\was used in the triple expansion engines,and other steam recipriocating engines I've worked on.Is it the equivalent of the "Jesus nut" on a helicopter?
RE: In a steam... could we use the reverser to slow dow
LAST EDITED ON Dec-31-02 AT 09:46 AM (EST)
HelloOn the run, if you put down the the power to 0 and the reverser to backwards, the cylinder have to work like a compressor. They take the air for that through the chimney. This technik was often used by Traindrivers, but there was a disadvantage. Taking the air through the Smokebox means bringing dirty air throug the cylinders. The temperatur in the, now working cylinders, crow up and the soot burns into the cylinderwalls. They get damaged. So, how to save money with it and dont damaged the machine ? On special downhill routes in Germany witch high costs on brake repair, the Locos get a system, known as the "Riggenbach Counter-pressure" Brake. A Simple thing, if the Brake was used, the way to the Chmney get closed and a ventil opens up that takes clean air from outside for the work. By regulating this ventil, how many air can pass through, you have a fine working system. If you see a German Steamloco and it has a little brass cylinder right behind the Chimney, that is the muffler of the "Riggenbach Counter-pressure" Brake.I wish you a healthy and peacefull new year...MadMike
