What is a puzzle switch?
Gabe
A double slip switch (in Great British – simply a “double slip”; in North America often simply a “double switch,” or colloquially, a “puzzle switch”) is a narrow-angled diagonal flat crossing of two lines (“AB” and “CD”) combined with four pairs of points in such a way as to allow trains, as well as going straight across, also to pass from “A” to “D” and “C” to “B”, and vice versa. Although there is thus the possibility of setting four routes, the whole assembly normally has just two positions: either straight-across or “curved” and thus could be worked by one lever or point machine with all eight point blades co-acting.
These types of insanity are used only where a normal switch will not fit into the space available - such as passenger terminal throats. As you may suspect, Mudchicken will not like these machines.
…That photo sure shows a wild arrangement of trackage…! Don’t know that I’ve ever seen it’s equal. I wonder what is able to “track” across these sharp radius curves…Is it just for commuter type vehicles that have 2 or 3 axle trucks…or are the curves magnified in the photo via a telephoto lens shot…?
One more thing…The trackage is in beautiful alignment…parallel and tangent, etc…
looks like caltrain’s san francisco terminal. They have a million of these in a row serving 15-20 tracks.
Judging from the photo, yes, it was depth-of-field compressed with a telephoto lens. You can tell because the turnouts from front to back must occupy at least a couple hundred feet, yet there isn’t much of a difference in scale from front to back. I’d say the photographer was also quite a distance away when the shot was taken.
They have many of these in the throat of Chicago Union Station.
Hey, Smokey – I get this message when I click the link:
A dangerous page request was detected and logged in our system. This was due to Second-pass-normalization-failure. The site administrator will review the error logs and make adjustments to the security system as necessary.
…Wow, I imagine anyone guiding a unit through this maze would want to be at minumum speed…! Really hard to understand some of the curved rails in the “switches”…Are some of them spring loaded and activated {or moved}, by the train passing over them…? Then again, thinking about that last part…I doubt they could move with the train weight on them…
As memtioned above, these are most often found at the throat of passenger train terminals. The Illinois Central Randolph Street Station (now Metra Millenia) has several of these switches. Each set of points is moved by a switch machine and the interlocking logic of the control element assures that switch points are in correct allignment for any given move.
I would guess that these are built for the tightest turnout of any switch made and probably have speed limits of 10 mph or less. Mudchicken and other track people might not like the a mount of attention required by these switches but hey, not all of life is a walk in the park.
Jay
Double slips are not too bad if you have a good light on them. A few extra points on the ones in the photo:
There is one switch motor at each end and it controls all four points at that end. Because of this, only one of the four routes can be set at a time. It’s like having two turnouts point to point, but jamming them together. Some model slips are set up with two oprating units at each end and are set for both diagonal roads or both slip (curved) roads; I think Fleischman and Marklin.
Where the diamond crossing is in the middle, there is another pair of switched points. This frustrates the tendancy of wheels to do their own slip at the diamond when the angle is shallow.
The slips at Toronto Union Station can be negotiated by full-length passenger cars at Limited Speed with a bit of sway if you’re on the top floor.
Must be their firewall. Tried to post the page and it wouldn’t go either…
The switches in that picture do look well aligned, it looks like it was taken in Germany judging by those dwarf signals with striped backs sides. Puzzle switches are more commun in Europe where space is more tight. There used to be one puzzle switch in Buffalo NY on the CN line just after it crossed harbour draw in front of the customs building. But like mentioned earlier these switches are rare outside large terminals in big cities, presumably busy places with limited space. I wonder what the highest track speed puzzle switches in use is? I think the term “puzzle switch” can also be used for any hand throw switch that is a puzzle to figure out, like a 3 way switch where the points overlap etc.
It maybe due to your link is thru another site first and this sets off warnings when you direct to from this web address. The link below will get you there. http://www.rrpicturearchives.net/showPicture.aspx?id=415567 You will have to cut and paste as I have been unable to post a working link with our new forum system. I’m not as proficient anymore.
Here in the we have plenty of these puzzle switches, not only at the big stations. We call them “hele engelsman” (whole englishman or double slip) or “halve engelsman” if they have half the number of points (half englishman or single slip), maybe they were introduced by an englishman to our country? Speed is 40 kph. Try leaving your seat while moving through them at that speed! For maintance reasons they are replaced with two normal switches where possible.
By the way, this is a special version with the points outside whereas the “englishman” has the points inside. It is called Bauart (type) Baeseler. The one in these pictures was replaced by two normal switches soon after being photographed on 13 may 1993. Photographs taken by Thomas Becker.
greetings,
(1) You go through these rascals at relatively low speed because of the geometry.
(2) They are a pain because of non-standard parts (like compound frogs) compared to a conventional split switch (when something breaks, you usually lose 4 -6 options on congested tracks that require some strange moves to bypass, further tying up the plant.
(3) Signal has bigger headaches than the track people get. Tolerances and voltage drops across insulated sections are easy to screw up, resulting in track lights and whining towermen and dispatchers.
(Was glad that the puzzle switches at LAUPT were Amtrak’s problem and not Santa Fe mission Tower’s responsibility)…Inattentive operating crews can cause havoc in a plant with several of these switches…
…Great black and white photos of complicated trackage in the Netherlands…! What a maze…
The only place I know that only has one double slip is the Seashore Trolley Museum in Maine.
I know Toronto has two double ladders of double slips – one headed left and the other right so that there is backup. This creates a number of double crossovers which have 4 slips and a diamond. They also keep a full switch off to the side – can’t remember if it’s assempled or parts.
A correction: while we have enough complicated trackage in the Netherlands, the black and white pictures were taken in Dresden-Friedrichstadt in Germany. I forgot to mention that.
greetings,
Marc Immeker