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Turnout operating unit - initial work up.

Posted by RichardW1 , 27 January 2013 · 1,338 views

Standard TOUs are many and various. I doubt that there is anything truly original in this, but it is offered for interest's sake.

The baseboards for Maxstoke are of a low profile, so a reasonably discreet unit is required. Eventually the design will incorporate mountings for frog switching microswitches, but this is a trial unit to test the system. Firstly I wanted the unit to be as simple as possible. the points were originally made with my standard moving sleeper tie bar, which has pivoted arms soldered to the switchblades, and a hole in the centre of the tie bar for an operating wire which passes through the baseboard from below.

The TOU has a base, milled from 3mm ABS sheet. this guides a pin guide made from 1.5mm thick fibreglass circuit board cut into 4mm wide strips. A cover plate screwed to the base plate holds the pin guide in place.

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The main componants are here. The base plate has 4 holes, one in each corner, to fix the unit to the underside of the trackbed.

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This picure shows the pin guide in the baseplate slot.

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This shows the assembled unit. The pin is free to slide side to side. You may see a point between the two 10BA screwheads, this is to be drilled and tapped for a pivot screw, about which will be a lever, one end engaging in the guide pin, the other connected to (in my case) a servo motor. space exists for a micro-switch to be mounted on an adjustable plate to switch the frog.

Attached Image
The topside picture shows the TOU base plate orientated with the trackbed. It will of course be fitted below the turnout with the guide pin engaging in the hole discernable in the turnout tie-bar.

A trial with the unit clamped in place has been sucessful, and work will now start on completing the pivot/lever arm whilst await delivery of the servos.
  • Like x 2





Richard this looks nice and simple with plenty of scope for microswitches.  i hope you do not mind me copying  the idea

 

Nige

Richard this looks nice and simple with plenty of scope for microswitches.  i hope you do not mind me copying  the idea

 

Nige

Nige

Can't stop you!

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whinge-n-moan
Jan 28 2013 00:01

Neat! Are the switch blades still pivoted on the tie-bar? I was thinking you could easily adapt the design to use the twin dropper-and-tube method, a la Ian Rice, to avoid stresses on the blades.

Neat! Are the switch blades still pivoted on the tie-bar? I was thinking you could easily adapt the design to use the twin dropper-and-tube method, a la Ian Rice, to avoid stresses on the blades.

Neat indeed. However, I think that there needs to some allowance for the small rotation that occurs at the rail/tiebar joint... 

Neat! Are the switch blades still pivoted on the tie-bar? I was thinking you could easily adapt the design to use the twin dropper-and-tube method, a la Ian Rice, to avoid stresses on the blades.

The turnout tie-bar is jig drilled to accept a small pin at each switch blade. Each pin is bent through 90 degrees to lie horizontally, and the switch blade is soldered to the pin. The pin head prevents the outer end of the switch blade from rising. The eagle-eyed amongst you will not the the tie bar is installed copper side down, thus avoiding the possibility of the switchblade being soldered to the tie bar! It follows therefore that the gap in the copper on the underside must be generous to avoid the operating pin from below shorting across the copper.- (You can guess the hours of fun I had tracing that short circuit!)
 
The TOU certainly can be adapted for a twin tube version- perhaps on another layout.

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queensquare
Jan 29 2013 23:54

Neat indeed. However, I think that there needs to some allowance for the small rotation that occurs at the rail/tiebar joint... 

 

The stresses this exerts is over emphasised - certainly in 2mm with code 40 rail. I soldered the rail directly to the tie bars on Highbury, beefing up the joint with a small square of brass next to the rail (etch waste). The track has now been in use for about fifteen years, done around seventy shows plus regular use at home - still waiting for it to cause a problem!

 

Jerry

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