dc motor brake problem
dc motor brake problem
(OP)
Hi Guys
I have a problem I'm trying to understand. I haven’t had a great of experience regarding dc motors and control so I'm hoping someone can help. I have been trying to understand an old amusement ride. It has cars powered by a 110V dc motor. Its a fairly simple pick up power from a rail and it go's straight to the motor. It is very old and I believe the motor is a neco. The motor has 3 wires black, red and grey. The black and red are connected together and wired to the ground and the grey is wired to the +110V. Now the motor works ok and drives around the track, but part of the track go's up a slope. If there is a power loss, the cars can roll back at speed. The cars have a diode connected between the +110v and ground with the anode to ground so it’s reversed bias. As I understand it, this blocks the +110V shorting to ground during normal operation. When the power is lost and the car go's backwards and the motor acts as a generator and reverses the polarity. The diode then is forward biased and completes the circuit. This causes the motor to act as a brake and slow the car down. Am I correct with my theory or is the diode just to prevent spikes? I have a couple of cars that dont slow down if rolling backwards! I have checked the diodes and connecting wire which are good, so I believe the problem is in the motors. Any help greatly appreciated.
I have a problem I'm trying to understand. I haven’t had a great of experience regarding dc motors and control so I'm hoping someone can help. I have been trying to understand an old amusement ride. It has cars powered by a 110V dc motor. Its a fairly simple pick up power from a rail and it go's straight to the motor. It is very old and I believe the motor is a neco. The motor has 3 wires black, red and grey. The black and red are connected together and wired to the ground and the grey is wired to the +110V. Now the motor works ok and drives around the track, but part of the track go's up a slope. If there is a power loss, the cars can roll back at speed. The cars have a diode connected between the +110v and ground with the anode to ground so it’s reversed bias. As I understand it, this blocks the +110V shorting to ground during normal operation. When the power is lost and the car go's backwards and the motor acts as a generator and reverses the polarity. The diode then is forward biased and completes the circuit. This causes the motor to act as a brake and slow the car down. Am I correct with my theory or is the diode just to prevent spikes? I have a couple of cars that dont slow down if rolling backwards! I have checked the diodes and connecting wire which are good, so I believe the problem is in the motors. Any help greatly appreciated.





RE: dc motor brake problem
RE: dc motor brake problem
Thanks for the reply. the resistance
Grey to red is 1.4 ohms
Grey to black is 189 ohms
Red to Black is 190 ohms
So I guess the Grey to red is the armature and Grey to black is the feild? These measurements are from a good motor that does slow down. The only slight differance on a bad motor that dose not slow was the Grey to red was 4.7 ohms. Thats what made me suspect the motor. I checked the brushes which seem ok.
RE: dc motor brake problem
Just how vintage is this? Is the diode a modern type or one of the flat plate selenium types?
RE: dc motor brake problem
RE: dc motor brake problem
RE: dc motor brake problem
Bill
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