We modelers all have locomotives of different brands that we like to run together so for us speed matching is a must,wich can be achieved with careful decoder programming.Honestly not my piece of cake I admit,but this isn’t my question anyway.
My curiosity has brought a question to my mind…do prototype railways try to match the locomotives when they build consists?Or do they simply take whatever power available and join them together?Are locos matched already (based on some standards) or are they equipped with some reprogramming features that allow to mix them together?Or is it manual adjustments from operators?
With all the different locos with different technologies (DC vs AC,different HP ratings and ratios),I believe there should be important differences to deal with.Simply put,could a SD90 be coupled with let’s say a SD60,or further away with a GP40 or an older GP9,or yet an AC4400 be coupled with an SD70?I may be pushing a little too far here but…I’m curious to know.Thanks.
Basically locomotives can be combined in almost any combination the control systems will allow (some earlier engines had air operated throttle instead of electrical, some had different MU cable arrangements). I have seen pictures of CNW GP7’s operating with C44AC’s.
Having said that, there are limitations. Engines with higher gear ratios have different limits on the minimum speed they can be loaded. AC engines have virtually no minimum speed. An AC and a DC engine can both run together all day, but if you get on a grade and the speed drops less than 10 mph or so, the traction motors on the DC engine will begin to overheat after a while but the AC will just keep pulling. On the other hand if a locomotive geared for 100 mph service matched with an engine geared for 70 mph service and they are operated at 100 mph the lower geared engine may be damaged because the traction motors are spinning too fast.
So yes you can put them together, but at either extreme, very slow service or very fast service, the differences can cause problems.
Looking back to the transition era and before, there were occasions when locomotives of radically different speed characteristics were run on the same train:
The N&W Class A 2-6-6-4 was a high-speed locomotive. Where it couldn’t maintain high speed, the railroad would put a low speed Class Y(something) against the caboose to push it (and whatever was in front of it) up the hill.
The L&N bought a class of 2-8-4s to expedite coal trains on relatively level ground - and an ABBA set of covered wagons to act as pushers on the one bad hill. The steamers developed their maximum power above 40MPH, while the diesels had all their horsepower available clear down to a near standstill.
OTOH, if units are intended to travel the full length of a division in tandem, the RFE would usually try to supply locomotives of matching operating characteristics.
Steam engines wouldn’t really factor in, since they have someone running each engine. As long as you don’t go beyond the top speed of the slowest engine, the engineers would do the “speed matching”. In diesels you can have several engines running in “Multiple Unit” all controlled from one cab. Then it would depend on gearing, engines geared for passenger trains wouldn’t be a good choice to M.U. with freight engines for example.
This is a serious question, not really answered well here yet. The responders, tho respected, knowledgeable modelers, do not appear to have ever operated any of the prototype engines being discussed, in consist. The replies do ‘make sense’, but simple bystanders’ reasoning, however logical sounding, is not really what is wanted here.
I’ve been looking for an answer to this question, “Specifically, how do you do this, without pulling engines apart and / or breaking knuckles?”, from a real operator with real prototype experience - not just accumulated railfan knowledge.
Have I misread this? Are any of you such past operators? If so, forgive me.
Your question is very similar to one posted in the past, about each locomotive “Pulling it’s Fair Share” where a poster asked about mixing say a GP 38 with SD 40s or similar.
The answer would also apply here (as explained by REAL working railroaders) when the throttle of the lead unit is advanced, all the throttles open to the same setting, say 50%, and each exerts whatever effort it is designed to put out at 50% throttle, and the speed of the train will be whatever the cumulative of the consists power produces. As long as there are no horribly mis-matched gearing combinations, like trying to combine a yard geared MP 15 with a Passenger geared F 40 PH, all will be fine.
It would be similar to trying to pull a too heavy trailer with a Toyota Pick up, add a Full size truck to it, and run both at similar throttle settings, the combined effort will now pull an 18,000# trailer that the Toyota couldn’t handle alone.
How do you know the people that have answered the question don’t work for railroads?
The answer is you don’t 'speed match" the engines on the prototype. That’s something you do with model engines because the motor is directly geared to the wheels.
The engineer isn’t setting the speed of the engine, he is setting its pulling power. All the engines pull the to whatever their capability is at the throttle setting chosen. The sum of that pulling power moves the train at a certain speed depending on the weight of the train, the drag on the train and the grade the train is on.
Think of it as 3 different guys pulling a car with a rope. All three have different strengths, all three have on different shoes, so they have different traction. But all three are pulling the car at the same speed.
So a train could be going 10 mph in run 8 at one spot and 70 mph in run 3 at another. The engineer adjusts the throttle to control the pulling power and by controlling the pulling power he controls the speed. If the pulling power is more than the drag, the train acelerates, if the tpulling power is less than the drag the train decelerates, the pulling power matches the drag the train travels at a constant speed.