Hi,
New member here and had a question regarding the control of tractive effort.
are there any passenger EMU's without any throttle system? something like a gas pedal in cars? If yes, then how do they work? is it like that driver can basicaly apply any value of tractive effort? or is it like a throttle system with just so many throttle levels?
Thanks for your help!
Any vehicle that needs to run at varying speeds will have some form of control system - often called a throttle or controller in the rail business.
On rail vehicles, said control will be hand operated - I've never run into anything other than a deadman's pedal located on the floor for foot operation.
The throttle/controller usually has some number of steps - "notches" on Diesels. Much like a car, you apply enough throttle to attain the appropriate speed without spinning the wheels.
Modern locomotives (and probably EMUs) have some pretty sophisticated circuitry controlling the power to the wheels.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
mehrdotare there any passenger EMU's without any throttle system?
The original PATCO cars that operated between Philadelphia and Lindenwold had a semi-automatic operation in that there were two buttons for the operator to push. #1 to close the doors, and #2 to start the train. Automatic throttle would bring the train up to speed, and then stop it at the next station and open the doors. Worked fine in dry weather. In wet weather, the train might slid through the station. Operator had a manual throttle lever and on my trip, he ran the train outbound using the buttons, inbound, he used the manual throttle. When asked why, he explained about the problem being a fixed braking rate initiation that did not compensate for the condition of the wet rails and that he was keeping his proficiency up.
The original PCC streetcars had foot operated controls (except for Chicago) which was uncommon back in the 30's. Otherwise, I think most rail vehicles (Light rail, Streetcas, Locomotives) use hand operated throttles.
mehrdotare there any passenger EMU's without any throttle system? something like a gas pedal in cars? If yes, then how do they work? is it like that driver can basically apply any value of tractive effort? or is it like a throttle system with just so many throttle levels?
I've never seen an electric MU car with a foot-pedal control; in fact, most of the ones I know don't even have engineer's seats more complex than the sort of arrangement for a built-in ironing board. Pedals only work ergonomically for fine control if your tail is parked in a good stable position...
The usual sort of controller on things like MP54s and subway cars involved a very limited number of notches, far more 'quantized' than for example a GG1 throttle. What it turns out you do ... or at least this is what I saw being done, whether or not it was "good" for the equipment ... was to use the brake to provide some of the intermediate fine control of acceleration at starting. You arrange to bail off the brake coordinated with opening the controller to first position, and this reduces the otherwise-pronounced starting 'jerk'; you can also apply a little brake before 'notching up' to get a smoother transition. I got the idea that much of the speed-holding on rolling profiles was done with the brake rather than coarsely notching up and down frequently to approximate a particular speed. It was fun to ride to and from college in the last car of one of the old Silverliners which would easily get up above 100mph between stations; you could pull out the 'board' seat in your own miniature observation-car vestibule and watch the gauges work to get some approximation of how the brake was being modulated ...
Most MU, multiple-unit, PCC cars had the equivalent of a gas pedal. The widest use was in Boston, where three-car PCC trains operated on the Commonwealth Avenue, Beacon Street, and Riverside lines during rush hours. I believe Illinois Terminal two-car operations, Shaker Heights, Toronto, and Pacific Electric were the same, although Chicago (not mu) and perhaps some other properties used hand control throttles. I think also St. Louis, the streetcar system, not Illinois Terminal.
On a PCC car, the left foot presses a deadman's pedal and must press it continuosly to avoid an emergency stop. The right foot can press a service brake pedal, pushed to the floor also means emergency stop, and alternatively, not at the same time, the power-and-acceleration pedal. The service brake pedal applies braking effort to the degree that the pedal is depressed. The acceleration-and-power pedal determines the acceleration to the degree that the pedal is depressed, unless top speed for grade conditions is reached, in which case the power is simply maintained as long as the pedal is depressed.
When you press the service brake pedal half-way down, and then release the dean-man's pedal, the parking brake is automatically applied.
This arrangement is specific for PCC streetcars, including those that are mu, and is not found on any other type of car, although I think the Atlantic City Brillliners and sample Brilliners in Philadelphia and Baltimre had only slightly different controls. Note that on Pacific Electric and Pittsburgh Railways, PCCs provided interurban service, and on PE and IT, on tracks shared with interchange freight service.
So, because of PCCs, the answer to your question is YES.
Electroliner 1935 mehrdot are there any passenger EMU's without any throttle system? The original PATCO cars that operated between Philadelphia and Lindenwold had a semi-automatic operation in that there were two buttons for the operator to push. #1 to close the doors, and #2 to start the train. Automatic throttle would bring the train up to speed, and then stop it at the next station and open the doors. Worked fine in dry weather. In wet weather, the train might slid through the station. Operator had a manual throttle lever and on my trip, he ran the train outbound using the buttons, inbound, he used the manual throttle. When asked why, he explained about the problem being a fixed braking rate initiation that did not compensate for the condition of the wet rails and that he was keeping his proficiency up. The original PCC streetcars had foot operated controls (except for Chicago) which was uncommon back in the 30's. Otherwise, I think most rail vehicles (Light rail, Streetcas, Locomotives) use hand operated throttles.
mehrdotInteresting! Do you know if this train uses those typical notch numbers (discrete control) or not (continuous control)? It should be like an automatic coast control, right?
I refer you to this Wikipedia link for more on the PATCO operation.
https://en.wikipedia.org/wiki/PATCO_Speedline
Also, I do not know whether the PATCO throttle had detents. I did note that the Boing-Vertol cars that I rode in San Francisco had what seemed like a continually variable throttle that the operator operated with their left hand and would use to hold a car on a hill, advancing it to a balancing point where the car would be stationary. Then when the traffic light changed, he would advance it and away the car went. I believe it was also the brake.
CTA cars in Chicago built in the fifties had a Cineston controler which was a single handle controller for acceleration, braking and emergency braking. See: https://en.wikipedia.org/wiki/Cineston_controller. This article has I believe an error. The ones I am familiar with have the handle rotating on a vertival axis and the handle extends toward the operator. One moves the handle clockwise from the coasting (center) position to accelarate and counter-clockwise fron the coasting position to brake. This had detents, three positions (rates) for braking, a coasting position, and four points of power. I operate these at the Fox River Trolley Museum. They are similar in the control circuitry to an all electric PCC car. The later CTA cars had (as the article states) the handle moving in a forward and backward plane on a horizontal shaft that is in a left to right axis.
Some seemingly notchless hand throttles are really just very many-many notches, as many as 24 or 32. or more. Especially with electronic control of ac hysaterises-non-synchronous motors, such controllers seem notchless, with the controller realliy controling a tap on a potentiometer that determins the control voltage to a control transistor or thyristor. Wirewound resistor-potentiometers do effedctively provide taps as opposed to the cheaper carbon-element type.
daveklepperWirewound resistor-potentiometers do effedctively provide taps as opposed to the cheaper carbon-element type.
Having operated stage lighting dimmers using the large resistance wire rheostats that had a wiper arm contacting taps, then the variac tranformers with a brush contact on the turns and then the slider type carbon resistor controller chopper dimmers, I agree that we have come a long way in controling electic power. Your older audio systems used variable resistors to control volume. Now, I have a clock radio with discrete volume levels set by pushbuttons. But to get back to the original thread, does anyone know what type of throttle do the new Amtrak Electrics have?
I don't know if they had any MU cars or not but Italy used to have an electric operation where the locomotives had 3 phase syncronous motors with two different field windings. The trains ran at two speeds. About 17 MPH and about 34 MPH. All the engineer could do was select which speed.
Right. Rode it in 1960. Via Alipina Railway, Tirano-Sondrio. Arrived in Tirano from San Moritz on Ratian Railways meter-gauge international interurban, 1000V DC, two wood green-and-cream mu motor cars pulling several varieties, about five cars, of freight, with LCL service at a number of on-street stops along the way. Boarded a thru car to Milan, last coach, typical steel European, of a three-car train with a steeplecab with two side-by-side pantographs. At Sondrio, the loco pulled the two forward cars away, and a streamlined "autorail" articulated electric backed down onto the car, pantograph wide enough for both wires, presumambly siwtitched to 3000V DC, coupled on, and soon we were on our way. This line also now 3000V DC from my understanding. And there were a lot more three-phase lines earlier.
Was of course, in my pre-Kosher days. A large Italian family asked when I had last eaten, in English. I told them about 6 that morning at the hotel in San Moritz. They insisted I share their copeous late afternoon meal with them, which I did since I was quite hungry. The articulated autorail may have had food service, but there was no way of going forward of the car we were riding into it.
GN's three phase motors on the 1909 Cascade Tunnel electrification had three speeds (7,14, 28 MPH) using a technique known as cascade control (after the practice of cascading the motor connections, not the mountain). The motors also had DC windings in the armature run off a small mo-gen to give a little adjustability. In practice the DC control was seldom used.
This may be slightly off-topic but the air throttles used by Baldwin and some early FM locomotives could be considered notchless. As you might imagine, they were not so satisfactory for MU operation and many roads restricted locomotives with air throttles to four units or less when operating in multiple.
Our SW1 has no notches.
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