How do they do it with subway cars? It's my understanding that when they put on the brakes on a subway car, they're actually charging UP batteries by using the motor as a generator.....wouldn't the motors just keep running when connected to the batteries? Matt ----- Original Message ----- From: "YK Chan" <[EMAIL PROTECTED]> To: "Richard Hallett" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Sunday, November 26, 2000 12:39 AM Subject: Re: [RCSE] brake/permanent magnet winch motor > Your solenoid normally comes with single pointer and single terminal for make > and break action only, will require to change into single pointer and one of > two terminals. This will enable one of two mode operation. When solenoid is > energized, it will select the battery +ve, or when de-energized will select a > loading resistor. The other end of the resistor will be terminated to the > motor -ve terminal (not the battery -ve terminal). In winch braking application > we want to drain the energy out of the spool as soon as possible and that calls > for highest possible of generator load (current) and therefore minimum > resistance value should meet that demand. The minimum resistance, however, > should not be any lower than the internal resistance in the winch battery under > load at zoom-launch. Eventually, we are talking resistance a copper wire may > provide, while a current rating of an solenoid that can handle about 500 amp. > > ROOT CAUSE: > The other less apparent cause is in the winch line. When the line is loaded up > with enough stretch, it will "shoot" back at the spool more than a spool can > take, thus enabling chance for entanglement. A non-stretch line and/or a > "giant" parachute should be considered. (However, that work against the > stretching line principle) A mechanically correct view is to omit the braking > assembly, instead, letting it free wheel after zoom and at the same time effect > drag in the winch line (starting from) in front of the spool through the > turn-around .... and up the O-ring end. That should address the problem at the > source. The number of ways to implement that is limited by our imagination. > Hope some of us will take it as an interesting new project. So keep us update > on your progress. > YK Chan > Seattle area. > > ----- Original Message ----- > From: Richard Hallett <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]> > Sent: Saturday, November 25, 2000 8:57 AM > Subject: [RCSE] brake/permanent magnet winch motor > > > > How do you make an electronic brake work on a permanent magnet winch motor. > > > > Some how or other you are supposed to turn it into a generator and run it > > into a heavy load. > > > > Thankyou. > > > > Rick > > > > RCSE-List facilities provided by Model Airplane News. Send "subscribe" and > "unsubscribe" requests to [EMAIL PROTECTED] > > > > RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] > RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
