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Motor Blocks for Large Scale RR Modeling

March 15, 2006

An Inexpensive Motor Block for Large Scale RR Modeling

New Brite, Scientific Toys and others manufacture many
inexpensive plastic battery powered cars and trucks that
can be easily modified to run on 45mm gauge track. Most of
the models offered are four wheel drives and are available
at toy and discount stores. They can be used as the basis
for light duty motor blocks to power projects such as
speeders, inspection cars or very light duty locomotives.
To see if the model cars are suitable for your needs it
will be necessary to determine that the power chassis is
narrow enough to fit between a set of properly gauged
flanged wheels. These vehicles are displayed in see-through
style packaging so that is possible to take a wheel and
axel set from a piece of rolling stock with you to the
store and hold it up against the end of the box to check
the width of the chassis. Another option is to take along a
piece of stiff card board cut to the proper back to back
wheel spacing of any wheel sets you may be wanting to use.
The wheelbase of the models can also be measured at this
time to determine if it is suitable for your needs.
The toy cars I am describing here are made up of a body
and chassis which are held together by a few screws or
locking tabs. Most have the on/off switch and battery box
mounted on the chassis. Once to body is separated from the
chassis you will need to remove the tires and wheels from
the drive axles.
Take care during this operation, the gear sets can be
damaged if the wheels are twisted on the axles. Use a cut
off disk in a motor tool to slowly remove material from the
cast wheel centers until the metal axles are free of any
plastic. Now is also the time to remove any parts of the
motor casing that might interfere with mounting your
locomotive frame.
To prepare the flanged wheels for mounting onto the motor
block it maybe necessary to remove some or all of the
spacer shank or insulation material from the back sides of
the wheels. Use a small saw to cut the shanks off flush
with the inside face of the wheels.
Measure the diameter of the motor block shafts to
determine if you will need to drill out the flanged wheel
hubs to fit onto the axles. Use a proper sized drill bit in
a drill press to enlarge the hubs if needed. Be careful to
keep the hole perpendicular to the wheel face and centered.
This will help avoid any wobble in the wheels when they are
mounted onto the axles. In some cases it may be necessary
to add a bushing inside the wheel center to make it fit
properly on the axle. K&S offers a large range of brass
tubing that can be used for this purpose.
Use a two part epoxy with a five minute set time, such as
JB Kwik Weld, to attach the wheels to the axles. Since
these motor blocks are being used for very light duty
purposes, gluing the wheels to the axles works well. Apply
the epoxy only to the outer end of the wheel hub to avoid
getting any epoxy near the area where the axles go through
the motor block housing. Set the assembly on a riser or
stand so that the wheels are not resting on anything.
After the epoxy has set up for 3 to 4 minutes you can
check for wheel wobble. You now have a two or three minute
window to make adjustments as needed. Hold the power block
so that the wheels are not touching anything and turn on
the power to spot any problems.
After allowing time for the epoxy to dry test the power
block by running it on the rails. If all is well, you may
want to make some modifications to the electrical system.
For example you can move the on/off switch to a different
location or add battery holders. Wiring for lights can also
be added at this time.
Mount your frame and body onto the motor block and go
railroading!
If you like some additional information on this subject,
order the DVD or Video “Simple Drive Train Projects” for
scratchbuilding and modeling ideas.

Alan Olson