Recently I found a layout in a March 2005 MRR (the plan was the Central RR Company of New Jersey) that could finally fit in my available space, with some modifications for wider curves and larger yard. One of my plan adaptations was to replace the turnout at the bottom of the yard ladder with a double slip turnout to make a yard lead for switching.
The only problem is that I have never worked with a double slip. I was looking at some pictures of one in the Walthers book, and I was wondering if you can also use a double slip as a crossover too. If anyone can help me it is greatly appreciated.
A double slip can be used as a diamond crossing. Just be aware that if the blades are set correctly that you can only travel one path at a time. You cannot for example have a train running over the straight and immediately afterwards have one take the crossing path without changing one of the switches
I have always taken it that a double-slip switch allows either a diverging and turn onto parallel adjacent track, or a crossing over to the track beyond that. So, in a way it is a crossing, but it also allows a crossing over to a third track.
Looked at schematically, a double slip switch is equivalent to two ordinary turnouts installed with their points facing one another.
Looked at operationally it is a flat crossing with four sets of switch points crammed into the space between the acute-angle frogs.
Looked at as a way to allow an approaching train to take either of the available routes out the other end of the diamond, it is almost a standard turnout. The, “Almost,” is the need to align the points at the far end of the diamond to allow free passage onto the chosen route - which is exactly equivalent to crossing a trailing-point switch.
Control-wise, the points at one end of the diamond have to be able to operate independently of the points at the opposite end, which means two point actuators and two panel controls. This is exactly what would be needed if there were two turnouts installed point-to-point.
So, why use a double slip? Two reasons:
Eliminate S-curves for trains passing through.
Shorten the specialwork by the length of one switch, adding track capacity or reducing yard/station throat length. The higher the frog number, the greater the saving in length.
thanks guys, after dicussing the plan with my father last night though he said “I dont like haveing the yard on a curve”, go figure, now I dont need a double slip, although I am planing an exstention to a much larger city, and the station could probably use some double slips.
How do you use double slips in a station configuration?
A yard on a curve isn’t really an issue if the radius is large enough (and if the operators are on the inside of the curve they’ll do less walking when running the yard).
The Bear Creek yard on my previous layout was on a curve, but the radii in it started at around 36" and went up. My crews didn’t have problems with coupling and uncoupling. If you’re looking at tight curves in your yard then you could have problems but if you can allow a few car lengths of straight track after the ladder track turnouts it might be workable anyway (as long as you do your coupling/uncoupling on the straight tracks).
Incidently this yard also had double slip in its throat - using the dbl-slip let me add 2 car lengths (at least) to each track in the yard. Mine was scratch built and had 12 points in it (the crossing frogs had movable points). The only problem with it were the linkages to get all those points thrown (and training the operators how to set a route through it. A dbl slip isn’t called a puzzle switch for nuthing!
I used Wayne Rodericks write up of his double slip switch at Malfunction Junction on his Teton Short Line to help me with the mechanics of operating the double slip. However, to the best of my knowledge there are no pre-fab double slip switches with 12 points, only 8 pointers, so you won’t be likely to
For an exhaustive discussion of this subject, find a copy of of John Armstrong’s book, Track Planning For Realistic Operation. Lots of other good info on a variety of layout planning subjects.
Nobody’s asked how you wire these devils but, having experienced an epiphany of sorts with the 5 I use at my depot throat, I’ll jump in anyway (I use Shinoharas but I expect this will work with any pre-fab).
For propulsion power (analog DC in my case) I simply wire each switch and immediately adjacent track as a single block. Four of my DSlips require cab access to 2 road cabs, the depot switcher cab and the hostler so I use rotory switches on them. The remaining switch needs only to access 2 cabs so I use a dpdt toggle there.
The trick is in route selection. If you picture your control panel schematic w/ a simple sideways X representing the DSlip, you will need a DPDT toggle wired as a reversing switch mounted in each crotch of the X. The trick is that the toggle in the left crotch controls the points for the right side of the DSlip and vice-versa. This way to run from the lower left to the upper right on the schematic you want the left toggle to be down and the right to be up. To change the routing of the switch to run from lower left to lower righ you throw the right toggle to down but it’s the left points that move. This probably sounds clear as mud, but if you lay a DSlip on a table and manually work the points, it will become clear (I hope).
I don’t like yards on a curve, well, like your dad says about it, but its not impossible.My layout to be is forced to do it due to lack of space. I just plan right to have uncoupling and coupling spots situated right that I do that on a straight section, and try to NOT do that on the curve. In my switching duties I prolly will avoid pushing cars thru the curve and leave them there a la delayed kadee. But if it takes the 5 fingered hook to solve a problem, oh well…
I have built double slips, huge space savers, but cutting back on its needs unless…needed…
