Engine Problems? Why Some Model Train
Locomotives Are Better Than Others.
The Workings Of A Model Railroad
Locomotive
A loco runs by picking up an electrical current from the metal rails through metal
wheels that ride on the rails. The electricity is transferred from the wheels to the motor, which
causes the motor to run.
The motor connects to the wheels through a mechanical drive system. When the
electricity turns the motor, the motor turns the gears that turn the wheels and
push the engine along the train tracks. Simple!
The contact point where your locomotive wheel meets the rail is extremely small.
That's why; it doesn't take much in the way of dirt, dust, or debris to obstruct
the wheel-to-rail contact. Dirt can build up, so it is important that you keep the
wheels clean and free of accumulated dirt. If the wheels of your loco engine become
dirty, they may not make good contact with the metal rails, and your train will
stall. Remember, plastic wheels don’t conduct electricity.
Locomotive
Wheels And Locomotive Gears Vital To Good Operation
A good model train locomotive needs lots of wheels and lots of gears. A poor
performing loco is often an indication that there is a problem with the gears
and/or the wheels. Although in saying that, some locomotives with only a few wheels
work surprisingly well... although it is considered to be unusual, rather than the
norm.
How many cars will a locomotive pull?
First you need to consider the factors that determine the length of the train
you can run on your layout:
THE DRAWBAR PULL, or traction, of your locomotive is affected
by its weight, contact with the rail, traction tires, motor and the power
available. This pulling power is measured in pounds and ounces at the rear coupler
or drawbar of your locomotive.
DRAG OF YOUR CARS depends on the number of axles, lubrication of
the bearings and if there are track pickups on any of the wheels. The weight of each car is also a
factor.
RADIUS OF THE TRACK CURVES is another factor to consider. The
smaller the radius the more the drag. A reverse curve, without a straight line between, causes even
more drag. Also remember that a clean track will reduce the drag on curves.
GRADE OF THE TRACK can be a major factor affecting the pulling
power of a locomotive. Grade is the ratio of distance forward compared to the change in height.
A forward travel of 100 inches with a rise of one inch is a 1% grade. A rise of two inches is
2%, three inches is 3% and four inches is 4%. You wouldn't want anything steeper than a 4%
otherwise you could experience all kinds of problems. (no more than a 2% grade for garden
railroads).
So, the number of cars a locomotive can pull will depend on a number of factors.
Aim to have a heavy locomotive with adequate power available.
If you want to run really long trains then it's best to have clean track that is level or
with only gentle curves.
Keep your trains well maintained. The wheels on the locomotive should be keep clean,
traction tires clean, bearings lubricated (including side rod linkage on steam). Have the
locomotive motor checked regularly. Rolling stock should have clean wheels and lubricated
bearings. Couplers should move freely to maintain alignment.
When purchasing a locomotive with a decoder installed, look for the wording "DCC equipped", or
"Factory installed decoder", or "W/DCC", or wording like
that. Be careful though, because the words "DCC Ready" usually means that the locomotive is capable
of having a decoder installed and that one is NOT already installed. I repeat, "DCC ready" usually
means there is NO decoder fitted, but the wiring inside the locomotive is terminated with a socket,
ready for addition of a "Plug and Play" decoder. This is an easy installation, no soldering.
If you are still unsure whether or not a locomotive has DCC status, you can try this test. Place
the locomotive on the program track of a DCC system. See if the command station can read CVs... and
if it can't... then no decoder is fitted. Also, without a decoder fitted, the loco would “hum” with
the throttle set at "0".
If the locomotive responds to the throttle on a DC system, then either there is NO decoder, or
the locomotive may have a decoder that has analog operation enabled.
If in doubt, it is always best to get clarification from the hobby store staff, or from the
manufacturer or person supplying the locomotive.
