it should be possible run a handcar or trolley on DC between bumpers so is reverses when it strikes one. If you run a handcar it would require a diode bridge implanted in it so it reverses by polarity, but a reversing handcar would not be needed. A regular handcar would do.
You ought to be able to implant a small roller switch in each bumper , or even below the rails where the wheel flanges would actuate them A pair of #697 trips might work too. Then, you construct a circuit with a four pole relay. The first two poles of the relay would reverse the polarity of the track power to reverse the handcar. The third pole of the relay would be used to create a latching circuit for the relay. The roller switch at one end would be wired to feed a burst of power to the relay coil, thus reversing track polarity if it were struck. Once the relay were thrown, a connection through the n and no contacts of the third relay pole would continue to feed power to the relay coil, keeping the relay activated.. The roller switch at the other end of the track would be wired to interrupt power to the relay coil when struck. This would de energise the relay coil , because the latching circuit through the third relay pole would no longer feed it power. The track polarity would flip and the handcar would reverse again. The fourth relay pole could be used to alternately light one or the other bumper light, if you disconnect the bumper lights from the track. This type circuit could also be used in a DC - motorized accessory to limit and reverse motion of an eccentric arm or similar device. i will write this up in The Roundhouse if folks are interested. Tom Jarcho S-Trains list sponsor: http://www.americanflyertrains.com All the Flyer you desire...books and accessories too! To UNSUBSCRIBE from this list send a note to [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
