Model Railroading > HO Sector Plate - My Experience

When I first read of a sector plate I liked the idea and decided to build one for my planned HO railroad. I designed and built one 84 inches long. It pivots at a point 70 inches in and rolls on 5 non-swiveling 2 inch casters. Electric contacts show its track setting at the control panel and allow for powering only the selected track of 5. It was positioned near the edge of the railroad and clearly visible.

About the time it was installed a move to a different home came up and I salvaged this item while planning a new railroad. I added IRDOT infra-red sensors to show track occupancy. The new design precluded the sector plate from being close at hand and instead it had to be out of sight and 3 feet away. NOT a good thing.

After much work it is apparent that uncontrollable temperature changes cause slight track mis-alignment so that at any given time 1 or 2 tracks are off by just 1/32 of an inch, enough to cause a derailment in a place that is not going to be very accessible once the scenery is in place. If you correct either the track location or the aluminum plate for the locking steel pin a different track will be off by the next day. Perhaps if I were a machinist with a milling machine, using only metal and no wood, all would work fine but I have decided to replace all this with a small single end 3 track yard. I will loose 2 tracks but gain a derailment free zone.

My recommendation is to use a sector plate only where you have immediate access to watch that the “points” are perfectly aligned and you don’t have to rely on anything less.

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Looks like an old Ulrich drop bottom gondola on the left and a Silver Streak SP caboose. Can't identify the loco???

Interesting.

I have a swing up section of double track mainlines
spanning a 36" doorway on my layout - hinged on one end.

I made it using 1/2" exterior plywood.
Its basically 36-1/2" across the span by 2 feet wide.

Here in the So Cal coastal valleys we have dry winds that come off the Mojave desert
on some days and moist on-shore breeses on other days.

I get + or - 1/8" of gap changes on the non hinged end of the lift section -
During several days of dry windy weather the railhead gaps are <1/8> wider than on moist
on shore breese or rainy days where the gap in railheads are a line to line fit

Combine that with the wood framed shop my layout is built in and that the swing up section is mounted to makes for some interesting end play gaps on the section of track.

Bottom line is wood expanes and contracts along with the humidity index - Big time-

Gary



Edited 1 time(s). Last edit at 03/14/13 15:02 by P5r24.

You are right on the first two. Locomotive is a 4-6-0 by Roundhouse with a brass headlight correctly lowered for SP.

boejoe Wrote:
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> Looks like an old Ulrich drop bottom gondola on
> the left and a Silver Streak SP caboose. Can't
> identify the loco???

Where alignment is critical use any material EXCEPT wood, it is too vulnerable to humidity swings.

A sector plate made with aluminum channel and styrofoam would probably work like a champ for years.

NZ