Interesting Railroad Stuff


I know there used to be "sprung switches", where the mainline was like a regular frog, but the rail on the frog end of the siding was forced against the stock side of the frog by heavy springs. The flanges would "pick" the frog, forcing it over to permit passage. Not sure how a train took the siding from the point ends. It may be that it couldn't, and was only supposed to exit the siding this way.
 
I know there used to be "sprung switches", where the mainline was like a regular frog, but the rail on the frog end of the siding was forced against the stock side of the frog by heavy springs. The flanges would "pick" the frog, forcing it over to permit passage. Not sure how a train took the siding from the point ends. It may be that it couldn't, and was only supposed to exit the siding this way.

A spring switch can still be thrown normally with a switch stand like any other switch.

The springs allow a train to run through the trailing end of the switch even when the switch is thrown against it without causing any damage. (The train must not stop and reverse on the switch though for obvious reasons.)

My railroad was a regional railway with a 300 mile main line and a 26 mile branch line that came off roughly in the middle. After the 1980s the junction switch was a spring switch, normally set for the main line, so most normal movements could travel through it without stopping. A train heading out onto the branch would have to stop, through the switch run forward and then have the tail end crew close the switch again - like any hand-thrown switch. However returning into the yard they could run right in without stopping for the switch since it was sprung.
 
At a power station where I once worked, we had a spring switch that allowed empty hoppers to come out of the dumper, through the spring switch, up a steep ramp, then down through the spring switch and into a siding. Only issue was the bozo that let a full hopper go through and hit an empty on the way down the ramp. Guess who had to shovel the coal spilled around and in between the tracks??
 
I only remember seeing one spring switch while working on the RR and that was at Oak Point yard on the NH. It had a big SS sign to let you know you could run through it and it would spring back. You could run through a normal yard switch with out a problem but maybe be on the ground on way back over it.

George
 
Spring switches were quite common at different places. On the PRR and PC, they were listed in the timetable, including the normal direction of the switch points, and were generally marked by a white Disk with SS on it.

There were other switches known as Semi - automatic switches, that allowed trailing movements through it regardless of alignment. The general rule was to make a complete movement through the switch and manually realign the switch for the intended track, before proceeding through it.

Conrail's Engineering Department took a dim view of spring switches and semi-automatic switches, and eventually removed most of them, for traditional hand operated switches.

In HO, Kato #6 manual control switches can be set up for use as a spring switch. Most commonly at the end of a passing siding.

Boris
 



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