July, 2017, CTT motor question

0 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    December 2001
  • From: Austin, TX
  • 10,036 posts
July, 2017, CTT motor question
Posted by lionelsoni on Saturday, May 27, 2017 4:44 PM

On page 18, the answer to a fellow trying to reverse a 1940 model with a universal motor is to swap the brush wires, which will do the job.  However, the answer also asserts that the brushes and the field are wired in parallel.  I think CTT got this wrong, for two reasons:

o  Shunt-wound motors, whether AC or DC, tend to run at a nearly constant speed, very unsuitable for prototype or model trains.

o  Shunt-wound AC motors have the further problem that the currents in the field and armature can be substantially out of phase, reducing the torque produced.

In a series-wound motor, the same current flows through the field and through the armature, so there can be no phase difference between the two parts of the motor.

A series-wound motor also works well over a wide speed range.  That is why both prototype and model locomotives have traditionally used series-wound motors, whether with DC voltage or, as laminated universal motors, with AC voltage.



Bob Nelson

Join our Community!

Our community is FREE to join. To participate you must either login or register for an account.

Search the Community


Get the Classic Toy Trains newsletter delivered to your inbox twice a month