(The spring and hydraulic housing of the mechanical switchman is toast .... and not cheap to replace. Those rascals rarely work right or can be repaired after being mangled. And they are getting harder to replace. (old tech))
Normal is which ever way the bulk of the traffic goes. Plenty of situations where there are left hand turnouts with right hand frogs, usually in yards, drill tracks and other low speed places ... fortunately rigid carbon frogs are less common than they used to be and railbound manganese (RBM) cast inserts are more plentiful along with cast self-guarded frogs in the yard that can handle either direction equally . The concern is more focused on the fit and wear of the stock rail and switch points in the reversed scenario - the turnout becomes more susceptible to "picked-switch" derailments because of the extra wear on the curved side will attack the thin edges of the points faster.
A variable switch will push over and stay there. Variable switch stands and self guarded frogs should not be found in main tracks as a general rule.
Lithonia Operator* * * Now let's say a spring switch is lined for the diverging route. A long train comes along the straight route. I've always imagined the points are shoved aside by each wheel, but the points keep "trying" to go back where they were, because of the spring. So, the points are moving back and forth the whole time. With a fast train, it would be almost a "flutter." (I'm beginning to think I'm wrong about this.) Are you saying that, no, once the first wheelset pushes the points to the straight mode, they stay there? But, if the switch were lined for the straight route, and a train came out of the diverging route, that with the spring always trying to pull the points back to straight mode, that in that case, the back-and-forth would occur? (Does "normal" always (or mostly) denote the straight mode?)
Now let's say a spring switch is lined for the diverging route. A long train comes along the straight route. I've always imagined the points are shoved aside by each wheel, but the points keep "trying" to go back where they were, because of the spring. So, the points are moving back and forth the whole time. With a fast train, it would be almost a "flutter." (I'm beginning to think I'm wrong about this.) Are you saying that, no, once the first wheelset pushes the points to the straight mode, they stay there?
But, if the switch were lined for the straight route, and a train came out of the diverging route, that with the spring always trying to pull the points back to straight mode, that in that case, the back-and-forth would occur?
(Does "normal" always (or mostly) denote the straight mode?)
Spring switches are designed to only 'spring' in one direction for a trailing movement. Normally, Spring Switches allow diverging movement to access the Main Track when departing other than Main Track.
IF a Spring Switch has been LINED to allow a FACING POINT movement from the Main to the other than Main Track and then a trailing point movement operates straight on the Main - it will damage the switch mechanism unless the switch operating mechanism is thrown to allow for Spring operation when trailing through the other than Main Track side.
Never too old to have a happy childhood!
mudchicken Run through (variable) switch leaves the points in the position of last movement. Spring switch ... returns point to normal position (if switch is lined diverging route, nothing happens because "mechanical switchman" hydraulic piston in the throw rod assembly only pushes in one direction
Run through (variable) switch leaves the points in the position of last movement. Spring switch ... returns point to normal position (if switch is lined diverging route, nothing happens because "mechanical switchman" hydraulic piston in the throw rod assembly only pushes in one direction
Please bear with me. Sorry. But I have a lot of trouble envisioning things I cannot see.
I assume all of this discussion involves trailing-point movements, correct?
I get the part about the run-thru/variable switch, I think: Train comes off of diverging track onto straight track. The switch had been lined for the the straight track, but the train's wheels shoved the points to the diverging postion. After train is gone, the points remain lined for the diverging route. Right?
* * *
zugmannAll switches are run-through switches. Some just be run-though more than once. Next you need to look into different types of frogs (regular, spring, powered). It's a switchpoint's little brother.
Next you need to look into different types of frogs (regular, spring, powered). It's a switchpoint's little brother.
Some you can 'run through' in accordance with the rules.
Running through others will have you run off by the rules.
All switches are run-through switches. Some just be run-though more than once.
It's been fun. But it isn't much fun anymore. Signing off for now.
The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.t fun any
Lithonia OperatorWhat's the difference between a run-through switch and a spring switch?
Designated Spring Switches, only spring in one direction, they are 'solid' in the other direction. On the B&O many of the directional sidings on their double track 'current of traffic signaled' had Spring Switches on the leaving end of the siding. Movement, with the current of traffic, was normally governed by a Dwarf CPL signal. If it was desired to enter the siding when moving against the current of traffic, the switch mechanism had to be accessed and the switch thrown so the points would line into the siding. After the move was completed, the switch mechanism had to be accessed again to permit the switch to act as a Spring Switch again.
In some yards, some carriers installed Racor - trail through switches - when the switches were trailed through - on either side, the switch would stay in that position until it was either trailed through from the 'other' side or the switch was manually lined for a facing point movement to the 'other' track.
[quote user="mudchicken"]
Run through (variable) switch leaves the points in the position of last movement. Spring switch (or spring derail (alligator) returns point to normal position (if switch is lined diverging route, nothing happens because "mechanical switchman" hydraulic piston in the throw rod assembly only pushes in one direction, ....don't you dare back-up.)
In a variable switch, the springs are in the switch stand housing and cushion the force of pushing the switch points over. Big falsehood is that people think all low/ground switches are spring switches. NOT TRUE. All main track switches are supposed to be rigid - saw plenty of #3 and #5 hub switches destroyed by that wive's tail. (Running through a power switch results in serious damage to the clockwork innards and can be a five figure repair cost.
[/quote]Yes, the "SS" sign has real meaning. If it is not present, do not act though it were.
Johnny
What's the difference between a run-through switch and a spring switch?
Jeff, if the crossover switches in Wesson, Missisissippi, were typical on the IC, the IC also did not have any indication of how such points were set. Of course, the switches were linked to the ABS system, so if one were reversed, signals in both directions would be at stop.
zugmann mudchicken and then there are the track bumpers and wheel stops which aren't supposed to be touched.... Nah, all bumpers need to have a 30-day test. Or you know, maybe add 2' of track so I don't have to be within 2" of the bumper to spot your car? Esp. on your downhill track?
mudchicken and then there are the track bumpers and wheel stops which aren't supposed to be touched....
Nah, all bumpers need to have a 30-day test.
Or you know, maybe add 2' of track so I don't have to be within 2" of the bumper to spot your car? Esp. on your downhill track?
Las Vegas, NM (now gone) Mantana de Fibre fiberboard plant. Roadswitcher dropped a boxcar for loading into a warehouse building down 1000' of 2% grade into a level building. Last vertical curve ended 60 ft. from the building. Boxcar went in one side and out the other of the brand new building. The building only had a rail door on one side. To this day, I have no idea how the brakie survived as he rode the car to rest.
Old heads (those from the CNW days who hired out in the 1970s) told me that the CNW didn't have switch targets on some of the main track crossovers. I guess they figured block signal protection (and the restricted speed condition an open switch would cause) was protection enough. Of course moving against the current of traffic there would be no signal protection. Maybe they figured a crossover would only be used by a train crew or protected by a switch tender during planned single tracking. The few pictures I've seen of such crossovers all had switch targets.
Speaking of looking at the points. We have a switch flag test. Small reflectorized metal flags that are placed at the switch points of hand throw switches on other than main tracks. (One manager questioned if they could even test on main track switches when restricted speed would be required. I've not heard of it being done under such conditions, so I'm guessing the answer was no.) In most places, it's an easy test to pass. You have to stop before passing the clearance point and call for the manager in charge. The point of the test is to see if crewmembers are watching the switch points instead of depending on the switch target. Unless the test is being done at night on a switch around a tight curve, those test flags are visible long before the points actually are. The times I've been so tested, the reason I stopped wasn't because I was looking at the points and saw those flags, it's because I saw two red flags on track I was moving on near a switch.
Jeff
SD70DudeAnother crew decided to spot a downhill customer with all the cars they could take, while also keeping 20 or 30 other cars between the spotters and the unit, and tried stopping with just the independent brake.... .....you can guess how that turned out.
Or they stop at he block, then kick off the automatic.
That's when you lunge for the anglethingie.
zugmann Or you know, maybe add 2' of track so I don't have to be within 2" of the bumper to spot your car? Esp. on your downhill track?
We have a bunch like that too.
One day an inexperienced crew left the car about 6 feet from the block. The customer wouldn't unload it there, so I had to go back in the next day and shove it 5 feet further.
Another crew decided to spot a downhill customer with all the cars they could take, while also keeping 20 or 30 other cars between the spotters and the unit, and tried stopping with just the independent brake.... .....you can guess how that turned out.
Greetings from Alberta
-an Articulate Malcontent
South of the Canadian border, typically run-through switches have a "V" for variable or the tops painted yellow (or both). The shape thing is totally dependent on railroad and rule book. What would a canuck think of a 16" green or red circular disk?
Train crews have a bad habit of thinking all switches are run-through. In major teminals, that means lots of destroyed rigid switch stands, switch rods, elephant ears pt. (clips), #1 & #2 rods and torqued switch points... and then there are the track bumpers and wheel stops which aren't supposed to be touched....
The Canadian Rail Operating Rules say ALL hand operated switches must have a target.
Red for reverse on main track, green for normal.
Yellow for reverse on non main track, green for normal.
Run through, semi auto switches MUST have a diamond shaped target.
Any other hand operated switch can have any shape target, expect diamond.
Spring switches must have SS on the switch stand.
CTC switches and power switches in yards that are controlled by a switch tender/operator are exempt and do not need a target. In our yard, when switch tender controlled switches in the yard are placed on ground control (meaning the train crew can line them by push button) there is a yellow or green light to indicate which way the switch is lined and locked for.
10000 feet and no dynamics? Today is going to be a good day ...
Haven't seen too many targets or vanes on any power switch. (different story on the hydraulic). In yards, the targets are more of an indicator of which way the switch is lined for normal and which track is what number in the computer database. BNSF also tags the headblock ties with the CLIC numbers. (Targets get snagged or destroyed by chains, tie-downs, dunnage and god knows what else (wheel trucks, derailed cars, construction equipment, you name it)....Switch stands tend to outlive the rail (really tough piece of hardware), but replacement parts are hard to find, especially when repairing ground switches and the staffs that hold the switch targets. Lighted switch targets got replaced by more effective yard lighting.
Pennsylvania used to require a lighted switch lamp if more than a certain number (three if I remember correctly, but I may not) of moves were made over the switch in darkness. Almost all the switches in the B&O's yards had them. Inspectors would come around occasionally and then all the burned out bulbs or dead batteries would be replaced.
Mark Vinski
Thank you very much!
connorc10I am wondering if railroads require a target switch stand at a CTC control point. I see them in yards and spurs but not usually on mainlines with signalled interlocks to show switch position, is this because the signals already do so?
The signal indications at Control Points perform the function of visible switch stands. I don't believe, and I could be wrong, that visible switch stands are 'required' on any switch. They are provided in yards as a assist to improve efficienty of crews in yard situations.
Even where switch stands are used the rules require employees operating the switches to observe that the switch points are properly in position for the intended movement. There are detectors and electronic logic circuits that perform this function in the Dispatcher controlled power switches at Control Points.
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