Railroad switch

The frog end of the switched crossing, despite still having a gap in one rail, is less problematic in this regard.


Purely mechanical interlockings were eventually developed into integrated systems with electric control. The outer rail is still continuous, the wing rail the part that turns out, after the frog gap provides a gradual transition, and the check rail avoids the possibility of points splitting.

Because plate switches can only be used by double-flanged wheels and at extremely low speeds, they are typically only found on hand-worked narrow gauge lines. Patent , , Oct.

In North American English, the arrangement may also be called a double switch , or more colloquially, a puzzle switch. An advantage over an inside slip switch is that trains can pass the slips with higher speeds. If the switch fails to do this, the governing signal is kept at red stop. Trains approaching on one of the two crossing tracks can either continue over the crossing, or switch tracks to the other line. Julian—Gregorian uncertainty Articles containing German-language text Articles needing additional references from April All articles needing additional references Wikipedia articles needing clarification from December All articles with unsourced statements Articles with unsourced statements from February All articles with vague or ambiguous time Vague or ambiguous time from February Articles with unsourced statements from February Articles containing Italian-language text Articles containing Dutch-language text Commons category link is on Wikidata Wikipedia articles with NDL identifiers Articles containing video clips.

In these cases, vehicles would otherwise roll onto and foul obstruct the main line and cause a collision. They are used to prevent runaway vehicles colliding with another train further down the slope. A railroad switch AE , turnout , or [ set of ] points BE is a mechanical installation enabling railway trains to be guided from one track to another, such as at a railway junction or where a spur or siding branches off.

In areas with very low speeds, like depots, and on railroads that had to be built very cheaply, like logging railroads, three-way switches were sometimes built as stub switches. Wye switches are usually used where space is at a premium. The sideways action of the point rails pushes snow to the side, instead of packing the snow between the points and the rail in a more modern design.

Railway platform Side platform Island platform Bay platform Split platform Terminal station Balloon loop Spanish solution Cross-platform interchange Interchange station. Electrical operation of the switches Note: Eventually, mechanical systems known as interlockings were introduced to make sure that a signal could only be set to allow a train to proceed over points when it was safe to do so.

A straight track is not always present; for example, both tracks may curve, one to the left and one to the right such as for a wye switch , or both tracks may curve, with differing radii , while still in the same direction.

If the right point is connected, the right wheel's flange will be guided along the rail of that point, and the train will continue along the straight track. This both allows for remote control and for stiffer, strong switches that would be too difficult to move by hand, yet allow for higher speeds. The rails leading up to a stub switch are not secured to the sleepers for several feet, and rail alignment across the gap is not positively enforced.

Clic on picture to enlarge. On lines with heavy use the casting may be treated with explosive shock hardening to increase service life. New York: Assembly completed!

You see the result on both pictures on the right. The heaters need time to melt the ice, so if service frequency is high, there may not be enough time to melt the ice before the next train arrives, disrupting services. A separate switch machine is required to operate the movable-point frog switch. On most motors referrals, there is an inverter controlled by the movement.