Judging by the number of small companies which have recently formed to offer servo controllers aimed at the model railroading market, the present situation may be in for a major shift.
Since the output of a servo is a controlled shaft
rotation, this movement could be used directly or can be
converted to a controlled linear movement by means of
either a wheel or an arm affixed to the servo output shaft.
It is the combination of different size servos and the variety
of available controller modules which gives us hobbyists the
tools we need. In addition to the servo, each application
will need a controller which is one of three types:
(1) A manually operated controller, usually a rotary
( 2) A controller triggered by an external magnetic or
( 3) A controller which self-triggers.
So now, let’s imagine ways in which the controlled
motion of the servo can be put to good use in making a
model railroad layout more lifelike. Here is a gallery of 12
servo-based applications where the servo is used to create
a realistic true-to-life function which previously did not or
could not be accomplished.
SERVO 05.2014 59
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SERVO LINKED TO SWITCH MECHANISM
TRACK SWITCH MECHANISM
A mechanized steam shovel is not so
complicated and is more of a simple fun project. In
order to get the shovel’s boom to move up and
down on command, what better way than to mount
a servo in the cab and tie a line from the boom to
the servo arm. When the servo is manually activated
(controller type 1), the boom can be raised or
lowered to any position. This setup would work for
crane booms, as well.
Track switches are an essential component in model
railroad layouts. They provide the method by which trains can
be routed according to a plan. There are many types of track
switches, but all are operated by a linear movement which
can easily be provided by a servo activated by a controller
programmed with two servo positions. In a track switch
direction control setup, selecting one of the two controller
signals to the servo will set the track switch for the desired
direction. Besides switches, there is one other direct track
control arrangement — the engine transfer track — which is
2. Mechanized Steam Shovel
1. Track Switch Direction Control