More on hankscraft switch motor problemgreenspun.com : LUSENET : Wiring for DCC : One Thread
This is a follow up to my previous email regarding "relaxation". I power the Switchcraft motors from a DC power supply via a switch on the control panel. The switch obviously stays in the same position when I power down, and in theory when I power up the motors should be energised in the same position. However, only by switching the the turnout blades do the microswitches become depressed. The switch itself is in the right position, but the microswitches are not energised. Obviously this results in a short when running a loco over the switch. It seems I am the only person with this problem. I preume its a mechanical problem. I wouls have thought that others would have the same problem. By the way the whole railway is DCC controlled. Robert Bradley
-- Robert Bradley (firstname.lastname@example.org), March 02, 2005
I understand now. I've seen this problem.
I assume you are using resistors in series with your motor. Your problem is that you don't have enough current to power your motors when you start up. It may be indeed that your micro switches have too strong a spring for the resistors you are using. Either decrease the value of your resistors or increase the voltage of your DC power supply.
I started out with 1200 ohm resistors on my layout and had to decrease to 680 for reliable operation.
-- Allan Gartner (email@example.com), March 02, 2005.
The problem is mechanical. When you run the motor to throw the turnout a significant rotating inertia helps you slam it home at the end of the throw. When you turn power off spring tension in the mechanism relaxes a little which allows your microswitch for frog power to 'unclick'. When you re-apply power the motor is not strong enough to start up again and run tightly into the end stop and it does not have the slam-it-home help of the inertia that was present when you first threw the switch. You need to 'exercise' the turnout upon power up (as provided by NCE switch-its) OR do that manualy OR re-adjust you microswitches to 'click' closer to mid-throw.
-- Don Vollrath (firstname.lastname@example.org), March 02, 2005.