We have a bunch of those car moving bars at the museum, and they see regular use around the shop. Very handy if you need to move something a few feet, or spot a 80' coach inside a 85' long building.
Every grain elevator and many other industries had them at one time. Far cheaper than a winch or trackmobile.
We used to keep one in a strategic location at work, where we would regularly do a gravity drop to avoid having to shove cars a few miles back to the yard. Sometimes the cars didn't want to roll very well by themselves.
Greetings from Alberta
-an Articulate Malcontent
Lithonia Operator SD70Dude One human can move a loaded railcar, if you use the correct type of pry bar. For example, this guy.
SD70Dude One human can move a loaded railcar, if you use the correct type of pry bar.
For example, this guy.
No - This guy
Never too old to have a happy childhood!
SD70DudeOne human can move a loaded railcar, if you use the correct type of pry bar.
gregcan internal combustion engine only generates force (torque) while turning. while steam pressure entering a cylinder produces a force even when the wheels aren't turning. similarly an electric motor generates maximum torque when not moving, before there is any BEMF reducing the voltage across it's windings and impeding the flow of current (amps). so while a 5 HP internal combustion engine may have enough power to move a train at speed, it doesn't have the force to start it moving without some type of torque converter that can allow it to turn while its output shaft is not turning.
A somewhat similar concern is seen in the direct-drive steam turbines, where there is "plenty" of starting torque but at eye-watering flow, hence mass flow, hence fuel and water budget, at low rotational speed, even when tip loss can be minimized (and on steam turbines that has proven not to be easy). The general obvious solution is to allow the turbine to spin at an efficient range with variable loading, which on locomotives has some interesting complications (the two-speed planetary Westinghouse developed for the follow-on to the PRR S2 design is one example of the thinking; the Bowes drive for the redesigned high-speed PRR V1 is another). The trick is to avoid friction loss (as in 'slipping the clutch' to get started) which as you can imagine for 6000shp into a large-inertia load can be 'interesting'.
The logical solution for a 5hp Briggs in a portable car mover is precisely what was used: a hydrostatic transmission of the general kind found on lawn tractors, with a large heat-exchange surface for the pressure oil instead of just fins on the vane motors or whatever. If I remember correctly there have been attempts to build a range of hydrostatic switch engines over the years, none particularly desirable or particularly well-loved compared to diesel-electric, for not-too-difficult-to-divine reasons.
tree68It's been said that a 5 HP Briggs and Stratton can move a good sized train - just not very fast.
there are several things to consider
according to Armstrong's chart, a loaded car has 2 lb/T of resistance @ 5 mph. a 100 T train would have 200 lbs of resistance.
5 HP at 5 mph or 440 ft/min comes out to 370 lbf which exceeds the resistance of a 100T train at 5 mph and perhaps even at 25 mph. but wouldn't be enough for a 200 T train.
an internal combustion engine only generates force (torque) while turning.
while steam pressure entering a cylinder produces a force even when the wheels aren't turning. similarly an electric motor generates maximum torque when not moving, before there is any BEMF reducing the voltage across it's windings and impeding the flow of current (amps).
so while a 5 HP internal combustion engine may have enough power to move a train at speed, it doesn't have the force to start it moving without some type of torque converter that can allow it to turn while it's output shaft is not turning.
(i guess the electrical interface between the diesel motor turning a generator connected to electric motors turning wheels is a type of torque converter).
greg - Philadelphia & Reading / Reading
Good evening all,
Thank you all for your time and your informative responses. I had no idea how complex all the factors were for determining a locomotive's capability. The answers to the railroad communication question were also very helpful. Thank you again for your responses. I hope everyone has a good day.
Keep on training,
Mike C. from Indiana
tree68 GP and SD40's were speed demons, from what I've read. Slippery, but they could move.
GP and SD40's were speed demons, from what I've read. Slippery, but they could move.
SD's tend to be pretty sure-footed, on account of their much higher weight and two additional axles.
High horsepower Geeps are slippery and gutless at low speeds, I believe the GP40's control system derates it to the equilvalent of about 2000 HP until you get up to around 20 mph.
SD70Dude tree68 It's been said that a 5 HP Briggs and Stratton can move a good sized train - just not very fast. As long as you pair it with the appropriate electric transmission. One human can move a loaded railcar, if you use the correct type of pry bar.
tree68 It's been said that a 5 HP Briggs and Stratton can move a good sized train - just not very fast.
It's been said that a 5 HP Briggs and Stratton can move a good sized train - just not very fast.
As long as you pair it with the appropriate electric transmission.
One human can move a loaded railcar, if you use the correct type of pry bar.
Moving something is one thing - controlling and stopping the moving thing is another.
Watched a B&O SW-1 with 600 HP walk 83 loads of cement (about 8300 tons) from Clark Ave. Yard in Cleveland to the customers facility at Willows (if I remember correctly) about 6 miles from the yard in 3 hours. Taking that train over the Hump leaving the yard one had to gauge movement by looking at a utility pole - but they kept the train moving.
SD70DudeAs long as you pair it with the appropriate electric transmission.
Or gear it down. And you have to have enough tractive effort.
The point is that speed requires horsepower.
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...
One horsepower is 33,000 ft-lbf/min (550 ft-lbf/sec). By some mashup of non-decimal time and other things, 1 lbf at 1 mph is equal to 1.99 watts (approximately 2 watts). This is a lot easier to work with that 1 lbf at 375 mph is equal to 1 hp.
1 hp approximately equals 746 watts.
cheapclassicsFirst concerns engine speed, horsepower, and how it relates to performance.
Horsepower has the units of ft-lbf/mins, work/time. another way of looking at HP is lbf * (ft/min) or pounds-force * speed.
1 HP is 32572 ft lbf / min. applying a force of 325.72 lbf across 100 ft and taking 1 minute is 1 HP. another way of looking at this is that if you can only provide 1 HP, you can only provide half the force if you go twice as fast. in other words, applying 1 HP can only generate ~162 lbf when traveling 200 ft/min and only ~81 lbf at 400 ft/min.
so the locomotive force, tractive effort, diminishes with speed.
the speed a loco can propel a train depends both on the force it can generate and the resistance of a train. the train resistance (bearings, ...) depends on speed, so as speed increases, train resistance increases while tractive effort decreases. at some point they are equal and the train can go no faster.
but force is also needed to accelerate a train, increasing its speed. the difference in force a locomotive (consist) can generate vs the train resistance will accelerate a train faster so that it can reach a higher speed quicker. since that force is greater at low speeds while train resistance is lower, the train can accelerate faster at low speed.
and this is why even a low HP yard switcher can generate enough force to pull a train at yard speeds.
cheapclassics First concerns engine speed, horsepower, and how it relates to performance .... but if a 600 horsepower diesel can turn a generator as fast as a 3600 diesel can, what is the advantage and what relation do the notch settings play in this scenario
First concerns engine speed, horsepower, and how it relates to performance .... but if a 600 horsepower diesel can turn a generator as fast as a 3600 diesel can, what is the advantage and what relation do the notch settings play in this scenario
Speed isn't as important as tractive effort (pulling power). In theory you can gear a 1500HP GP7 for 100MPH but it's not going to pull what a 4300HP SD70 will (which you could also in theory gear for 100MPH).
As far as the throttle notches go, most engines have a set number of discrete power settings on the throttle, instead of a continuous throttle. Think pushing down the gas pedal on your car - ignoring gear changes it's a "continuous" throttle you can push up or down in any position. A train engine's throttle usually has eight specific notches that the throttle clicks into. So "Notch 8" is the maximum power setting on the throttle, so in Notch 8 the diesel engine will be running at full power to turn the generator/alternator at max RPM to provide max power to the electric motors. Notch 1 is the lowest power setting above stopped/idle.
Chris van der Heide
My Algoma Central Railway Modeling Blog
I'm dating myself with my first example, but the second most folks can do right in their driveway.
At one time you could get a bicycle headlight that ran off a generator. The dynamo was powered by a knurled wheel that rode against the bike wheel.
Normally, the generator was adjusted so it wasn't riding on the wheel. When you wanted light, it would be adjusted to ride on the wheel (designed to do so).
If you set the generator to ride on the wheel, then turned the little headlight on while riding, you could feel the increased resistance.
If you want to check out the effect today, start your auto, making sure the headlights are off. Now turn the headlights on - you will hear the engine take on the load. Subtle, but it happens. Not valid for electric cars...
cheapclassicsif a 600 horsepower diesel can turn a generator as fast as a 3600 diesel can, what is the advantage ...
How does a generator work? Around 1820, Faraday found that if you turn a loop of wire in a magnetic field, current will start to flow in the wire. So a generator has a magnetic field inside it, and loops of wire. The current flowing in the wire can do work; we can't get something for nothing, so we have to do work to turn the wire loops in the magnetic field. If we want the generator's current to power motors that total 3000 hp, the diesel has to exert 3000+ horsepower turning the generator.
If the diesel can produce 4400 horsepower at 1000 RPM, that's X pound-feet of torque. We want it to be just that hard to turn the generator at 1000 RPM -- so the locomotive control system must supply the needed amperage to the generator field, to produce the needed magnetic field strength.
Going back to your first question, power from the generator or alternator, Watts, Kilowatts, or Horse-Power, is proportional to the voltage times the current it produces. With fixed excitation, the voltage is proportional to the rotational speed of the diesel and the direct-coupled or fixed-geared generator or alternator. And the current will then depend on this voltage and the load on the motors, which is directly proportional to the tractive effort being provided. And tractive effort times speed times whatever conversion factor number is needed for the measurement units is the power at the rails, which is the power produced by the diesel minus efficiency losses in the generator-alternator and the motors. The excitation is not fixed. It is modified by the load-regulator system, which controls fuel intake, generatr/alternator (and motor for the AC-motored) excitation voltage, and for AC-motored modern locomotives, the frequency of the motor current and voltage, to insure close to optimum efficiency at the different throttle settings.
On AC-motor locomotives, the AC-output (frequency proportional to rotational speed) of the alternator is rectified to DC, varying only slightly around a fixed voltage, then inverted to AC at frequencies directly related to speed.
Scanners - as mentioned, there are resources on-line to tell you what frequencies to listen to. Radioreference.com is a good resource. Some local enthusiasts have been known to stand up websites with that info as well. If you have a hobby shop in the area they may be able to help, too.
All railroad communications, with the exception of the EOT, are in the VHF High Band in the 160-161 MHz range. Any scanner will do, either as a portable (pocket scanner) or a base station.
An important consideration is the antenna. An antenna tuned to the railroad band is useful, especially in mobile/portable situations. For a home antenna, elevation is key. Be careful installing it.
Do you want to listen to other local services - police, fire, EMS, taxies, DPW, what-have-you? You'll want a scanner that will cover them, and it's a consideration for your antenna as well.
For mobile scanning, be aware of any laws regarding scanning. Some areas frown on mobile scanning in particular.
My usual advice is to buy the best you can afford. Virtually any model will have its proponents and its detractors. Read the reviews.
While I haven't heard a timeline, it's been said that the railroads will eventually go digital, probably with NXDN. You may want to consider that now, or simply wait until the transition takes place.
In a diesel-electric the engine RPM is not directly affected by wheel speed. There is no mechanical connection between the engine crankshaft and the axles. Your speed depends on your horsepower, train makeup (tonnage, length, types of cars), and the track you are running on (grades and curves).
A higher throttle notch means higher engine RPM, which means more available power. A diesel-electric's control system can be fairly complex, when you throttle up the governor and load regulator work together to increase engine fuel supply and generator excitation so that the engine revs up smoothly and more current is sent to the traction motors. And just because an engine is revving at a given RPM does not necessarily mean that it is producing the maximum power it is capable of at that RPM.
As for engine and generator size and output, the 3600 HP engine would normally be coupled to a much larger generator than the 600 HP engine. Or if the 600 HP engine were coupled to a very large generator the locomotive's control system would be tuned so that the generator excitation would still match the engine's power output. A large engine can also be coupled to a generator that is not capable of handling that engine's full rated horsepower, in this case the control system will be tuned so that the engine will not produce more power than the generator can handle.
More horsepower means you can go faster, but does not necessarily mean you can move a heavier train. A 2000 HP SD38 can move the same tonnage as a 3000 HP SD40 (assuming they both weigh the same), but the SD40 can accelerate that tonnage to a higher speed.
High horsepower locomotives may not be able to use their full power at low speeds without slipping, and heavier locomotives or those with more traction motors may be able to move more tonnage at low speeds. As an example one of our 1800 HP GP9RM mother-slug pairs (8 axles) will move more tonnage at low speeds than a 4000-4400 HP road unit (6 axles).
There are a number of sources for radio frequences online. Others on here can better explain where to find them and where to purchase a scanner.
I have subscribed to TRAINS for some time now and really enjoy the articles. I have two unrelated questions which I hope to obtain some information.
First concerns engine speed, horsepower, and how it relates to performance. Many times there are references to various notches on the throttle (presuming the higher number meaning more speed). I am not clear on how more horsepower impacts the capacity of the locomotive or the speed. I understand the diesel motor turns a generator that supplies electricity to the electric components that actually turn the wheels, but if a 600 horsepower diesel can turn a generator as fast as a 3600 diesel can, what is the advantage and what relation do the notch settings play in this scenario/
The second question deals with listening to railroad communciations to facilitate train watching. We have on most days one round trip through town and try as I can, trying to determine location and direction from where I am is always a bit of a guess. What type of radio is needed to listen and where do you find the frequencies listed? I know Trains sometimes lists a road's signal in the articles so the information must be somewhere.
I am sure these are basic questions that have been answered in the past, but I am asking here to get it done in one fell swoop. Thank you for whatever attention you can render on these inquiries. I hope everyone has a good day.
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