There is an entire language that you need to understand when talking about
motors. Current draw, turns, winds and even timing can be confusing. When each
is taken one at a time, this complicating lingo can be easily understood. Because
some of the motors we may use come from the R/C car-truck world, I have included this
information as a reference.
Armature Turns & Winds
Number of turns
The number of turns, usually 6 to 20 for
modified & always 27 for stock, refers to how many times the wire is wrapped around
each of the three (or more) poles of the armature. The number of turns will let you
determine how many rpm's one motor will have compared to another.
The lower number of turns will mean more
rpm's (less wire on each pole = less resistance). It will also mean the motor will
let the current pass through it faster & drain your battery much quicker.
Low turn motors would be a better choice for planning hulls, deep Vee's for example.
High RPM motors are a good candidate for a gear drive system if used in a scale
A motor with more turns will have more
resistance & turn less rpm's but will produce more torque. Higher turn motors
are easier on batteries and will allow you to use a large propeller before having to use a
gear drive system. High turn motors work better for scale ships and work type
Number of winds
The number of winds refers to the number of
strands of wire wound around each pole on the armature. A typical stock motor is
wound with a single piece of 22 gauge wire. To make the motor faster with the same
number of turns you can go to a bigger gauge wire like 21 or 20 gauge, or use 2, 3, or
more pieces of smaller gauge wire all wound at the same time. As an example,
if you were to unwind a triple armature you would find 3 pieces of wire on each
pole. Using multiple pieces of wire decreases the resistance thus making it turn
faster. A motor with more winds will have less resistance & turn more rpm's but
produce less torque. Higher wind motors will need to use some type of a gear drive
to turn the motors torque into usable rpm's.
Silver - offer the highest
performance by producing the most rpm & power but require the commentator to be trued
more often. Use with higher turn motors 14 to 17 turn modified and all Stock
motors. Silver compound is for serious boat racers only because of the wear they
will cause to the comm.
Standard or Copper - offer
good performance for general purpose and racing applications. This compound is
easier on the commentator than softer silver compounds. The standard brush lasts
longer than silver brushes also.
Laydown - This is what is
used in most new stock motors. This brush is wider than it is tall for greater brush
wrap around the commutator. This makes the motor produce more rpm.
Normal - This is what comes
in modified motors. This brush is taller than it is wide.
Dual - This brush is
designed to be used in either application above.
Smooth / Full-Face - has a
smooth face with no grooves in it. Takes longer to break in. For use if you
want to cut your own brushes.
Serrated - has small grooves
molded into it to break in almost instantly.
H-Cut - have the face of the
brush cut into the shape of an H.
There are many different brush face
types. Each manufacturer will tell you that their brush face cut will be the
best. As a general rule the more material that is cut away from the face of the
brush the more rpm the motor will gain. However as the motor gains rpm in this
manner the torque of the motor is fading away at the same rate.