Gantlet/Gauntlet Track in the USA

[Grovenor]

Trailable facing point locks have been available for many years and are pretty well the standard for points in Germany and Switzerland, the basic principle is that the two switch blades move independently, the application of drive moves the points in 3 steps, first the open blade starts movement and unlocks the closed blade, then both blades move over together until the new closed blade reaches the stockrail, the last part of the movement locks the closed blade whilst moving the open blade a bit further. There are several different mechanical arrangements that will do this. The German "hook lock" was the basis of the design of the BR clamplock, but to satisfy the HMRI requirement for stretcher bars between the switches the trailable feature had to be designed out.  When trailed it is the movement of the open switch under pressure from the wheels that unlocks the closed switch in time for the flanges to pass through.

Diagrams of the mechanics are plentiful in the literature, probably on line as well with a bit of searching.

 

For Gauntlet track installed for clearance purposes in an otherwise double line, it makes far more sense than a single line with two points no matter what kind of points they have to operate for almost every train and will require a lot of maintenance not needed by the gauntlet arrangement. Also the single line will need rail replacement twice as often as it will be carrying double the tonnage, and when replacing rail there is no chance for single line working round the blockage. Al in all using a stretch of single line rather than a gauntlet makes no sense.

Keith

[martin_wynne]

Trailable facing point locks have been available for many years and are pretty well the standard for points in Germany and Switzerland

 

Hi Keith,

 

Thanks. So for a spring switch, i.e. one which reverts to the initial position after being trailed through, flange pressure on the heel of the open switch rail unlocks the FPL on the closed one? And a hydraulic spring restores both switch rails and applies the lock, after the last wheel has trailed through?

 

In Mike's picture there is a stretcher bar visible, so presumably it is not working that way?

 

regards,

 

Martin.

[The Stationmaster]

Hi Keith,

 

Thanks. So for a spring switch, i.e. one which reverts to the initial position after being trailed through, flange pressure on the heel of the open switch rail unlocks the FPL on the closed one? And a hydraulic spring restores both switch rails and applies the lock, after the last wheel has trailed through?

 

In Mike's picture there is a stretcher bar visible, so presumably it is not working that way?

 

regards,

 

Martin.

Some further delving reveals that they are actually hydro-pneumatic (not hydraulic) and there is no facing point lock in the traditional sense.  The action of a train trailing through the points creates pressure which is stored and then forces the switch back against the stock rail and holds it in that position.  The detection operates a signal (various types have been used including a position light with no red aspect or in some instances a single white light - these are called points indicators.

 

Train speed is limited to 15mph in both directions.  If the speed is greater than 15 mph facing point locks are required (I've just found out from further delving on the 'net)

[Grovenor]

The Australians are big users of trailable fpls on passing loops, a google will bring up quite a lot. As Mike has now advised the one in his pic is not an fpl at all just a sophisticated spring point.

Keith