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Tapiola Parish Model Railway Club


Return loops

For the Lahti exhibition 16th-17th Nov 2002 we decided to build our modular layout in a row with return loops at both ends. The return loops were constructed following MIBA SPEZIAL 52 article. The surface of the loop is a three-part plywood board joined together with hinges. The board may be folded is so as to protect the trackwork. Due to too hastly design process the boards became slightly too small. The original order of the boards had to be resuffled, as the S-curve became just over the board joint. Now the board with track connection now becomes the innermost board while folded in. hence there is no chance to attach permanent module joint ange irons to the end. Another thing we learned the hard way was that the S-curve was too tight.

The project in it's beginnings. Note the vise at the end of the joint hoding the boards aligned. The 12mm (1/2in) plywood didn't hold straight.

The trackwork done, the S-curve is too tight!!!

The smaller inserts show that we needed to reinforce the joint with through bolts, big washers and a wingnut to keep the board edges plane!

The plywood sheets are bolted to 50mm (2in) sq. tubes that form the beams to keep the lot straight. the lot is then placed on steel leg units we purchased from Bauhaus.

The other loop has RocoLine 83 trackwork, the other has Peco/Roco code 100, The turnouts in both loops are Rocoline code 83.

The point motors are Biltema car relays, the polarity of the loop is changed with another relay. the relays are operated w. NE555 timer used as flip-flop. The flip-flop is controlled by having short insulated sections at both legs of the loop and feeding those through a opto-isolator LED (and antiparallel diode). The opto-isolators transistor fires the flip-flop. The initial deign was not successfull but a help was at hand from Model Electronics Railway Group.

[31th.Oct.2002]Yesterday we tested the return loops trackwork. The S-curve was too tight! We moved the turnout to a separate board, joined with removable splice plates and made the S-loop more gentle.

The turnout board from below. The PCB holds the NE555 and two 4N25 opto-isolators the white thing is the polarity relay and the black thing the car relay.

[2nd Nov. 2002] Today the trackwork was finished

The modified loop now has the extension boards

The loop as part of the the exhibition layout

Loops in use with Kauniainen-layout

The extension boards was attached to "kauniainen" frame system with additional corner plates



The loops needed to be rised as the rail level of Kauniainen is greater than that of the old layout Two examples of the method used for rising the loops


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