Nostalgia & History > Lower Quadrant Semaphores

This is for BCHellman or anyone else who has knowledge of lower quadrant semaphores. It is my understanding that the two-armed signal blades each had only two positions, horizontal or a downward angle, even though there were three roundels. Top blade roundels were red, red, and green and bottom roundels were yellow, yellow, and green. Thus displays were green over green, green over yellow, or red over yellow. For a signal that had only one blade, there appears to be red, yellow, and green roundels. If red was displayed when the blade was horizontal and green was displayed when the blade was at the most downward angle, was there a middle angle halfway between the two to display the yellow roundel?

Tom

Did anyone use three-position single-blade
lower quadrant semaphores?

timz Wrote:
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> Did anyone use three-position single-blade
> lower quadrant semaphores?

Some roads used them as Train Order signals.

UP3806 Wrote:
-------------------------------------------------------
> This is for BCHellman or anyone else who has
> knowledge of lower quadrant semaphores. It is my
> understanding that the two-armed signal blades
> each had only two positions, horizontal or a
> downward angle, even though there were three
> roundels. Top blade roundels were red, red, and
> green and bottom roundels were yellow, yellow, and
> green. Thus displays were green over green, green
> over yellow, or red over yellow.

Correct.

>For a signal that
> had only one blade, there appears to be red,
> yellow, and green roundels. If red was displayed
> when the blade was horizontal and green was
> displayed when the blade was at the most downward
> angle, was there a middle angle halfway between
> the two to display the yellow roundel?

Lower quadrant US&S Style-B single-arm blades had only two positions for all the railroads that I'm aware of (SP, UP, B&M, Lackawanna,etc). If it was a home signal the roundels would be red-red-green; if it was a distant signal it would be yellow-yellow-green. I'm not aware of any railroad the used the middle roundel in a US&S two position Style B lower quadrant as an indication. US&S did make a three position upper-quadrant Style-B for one-arm signals (like a Style-S), but that is for another discussion.

The purpose of the middle roundel in a lower-quadrant Style-B spectacle casting was two fold (according to US&S literature of the period).

1. Continously-lit signal. When the signal changes position the lighted indication does not go momentarily dark as the spectacle casting is moving from the lower to upper position (or from upper to lower position).

2. Should the signal while changing position to its most restrictive indication not be able complete its travel (due to foreign material binding the rod, ice interfering with the spec casting, or the dash-pot preventing travel), the indication would be stuck in the most restrictive position. That's why the railroads chose to use a red-red-green pattern as opposed to a red-green-green pattern.

timz Wrote:
-------------------------------------------------------
> Did anyone use three-position single-blade
> lower quadrant semaphores?


For automatic line-side block signals, I'm not aware of any. But there were some bizarre signals at the turn of the last century.

That being said, I do seem to recall that N&W had a type of signal that was lower quadrant that may have given three indications. I would have to look through some mimeographed Railway Signal Engineer.

>This is for BCHellman or anyone else who has knowledge of lower quadrant semaphores. It is my understanding that the two-armed signal blades each had only two positions, horizontal or a downward angle, even though there were three roundels.

Assuming you're thinking about the SP style B's, correct,

>Top blade roundels were red, red, and green and bottom roundels were yellow, yellow, and green. Thus displays were green over green, green over yellow, or red over yellow.

Yes, but when there are more than one blade on a mast, the red, square-ended blade is "read" in conjunction with the yellow fish tailed blade below it. If there is another red blade below that, it doesn't figure in. They weren't two separate signal heads like a double searchlight signal.

>For a signal that had only one blade, there appears to be red, yellow, and green roundels.

The reason for the two red (and yellow) lenses is to give the most restrictive nighttime indication in cases where the blade doesn't operate fully to it's clear position.

>Did anyone use three-position single-blade lower quadrant semaphores?

No such thing as a 3-position LQ semaphore because when "down" (clear) the blade must be visible from a distance, which means it can't be straight down because it would be obscured by the signal mast. And if the blade can't be seen, then it must be taken as a stop signal. In order to be seen, "down" is actually an angle of about 75 degrees below the horizontal. The problem with using 45 deg for yellow in this situation is that from a distance, you can't really tell whether the blade is down at 45 deg below the horizontal or 75 degrees. UQ semaphores don't have this problem.

There were four types of semaphores: lower right-hand quadrant (like the SP had), upper right-hand quadrant (AT&SF), and the same thing for the left hand side of the mast, although these were used mostly by electric lines so the blades would project inside the pole lines and be visible from a distance.

Prior to about 1920, there were a lot of what we would consider bizarre signals (not counting Nachod and US Electric).

Early morning on the old SP north of Carrizozo, New Mexico. December 23, 1996 Fuji Provia 100
tom biery



Edited 1 time(s). Last edit at 09/30/14 07:32 by TrackOne.

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Is it true that a short coming with the lower quadrant semaphore is that it could give a false clear aspect if the signal blade fell unintentionally, and that was the reason why the upper quadrant came in favor? (Therefore, if the upper quadrant signal failed, it would give the most restrictive aspect.) Has anyone ever heard of a lower quadrant semaphore failing in such a manor?

So if the single-blade lower quadrant signal could only display a 'clear' or 'stop' indication, how was an 'approach' indication displayed?

Tom

wabash2800 Wrote:
-------------------------------------------------------
> Is it true that a short coming with the lower
> quadrant semaphore is that it could give a false
> clear aspect if the signal blade fell
> unintentionally, and that was the reason why the
> upper quadrant came in favor? (Therefore, if the
> upper quadrant signal failed, it would give the
> most restrictive aspect.) Has anyone ever heard of
> a lower quadrant semaphore failing in such a
> manor?

If you can think of a way that any device could conceivably fail, sure enough sooner or later it will if it hasn't already. So yes, I'm sure it did.

However, LQ semaphores were designed that the weight of the mechanism running up the inside of the poles shaft would overbalance the semaphore arm causing it to fail-safe in the horizontal position - unless the push rod itself broke.

-John

UP3806 Wrote:
-------------------------------------------------------
> So if the single-blade lower quadrant signal could
> only display a 'clear' or 'stop' indication, how
> was an 'approach' indication displayed?
>
> Tom


It couldn't. That why two blade signals were used - the top blade was home, the lower blade distant for approach.

-John

> > So if the single-blade lower quadrant signal
> could only display a 'clear' or 'stop' indication, how
> > was an 'approach' indication displayed?

> It couldn't.

Hello all,

I can's tell for sure, but it sure looks like the middle lens on signal 14414 is yellow in the photos above. If so, that contradicts what's been said here. If not yellow, then the signal can show only clear & stop indications, no approach?

Take care,

Mark

Not much question that an SP single-blade
lower-quadrant semaphore can only show
two aspects-- lots of people have the
1930-1943-1951-1960 SP rulebooks that
show no single-blade approach.

Was N&W the only one with those lower-quad
blades that turned thru 90 deg?

>Is it true that a short coming with the lower quadrant semaphore is that it could give a false clear aspect if the signal blade fell unintentionally,

Any signal is capable of giving a false clear, it's just that the manufacturers and signal circuit designers go to great lengths to prevent this.

>and that was the reason why the upper quadrant came in favor?

No. Which ever type a RR used was up to its discretion. The SP and AT&SF never changed semaphore types; it's a matter of cost. Some of the SP's LQ style Bs are still in service, although precious few these days.

>Therefore, if the upper quadrant signal failed, it would give the most restrictive aspect.

If the operating mechanism became jammed, it couldn't do anything, but this stuff was intentionally overdesigned and overbuilt so that the possibility of this ever happening would be vanishingly small (which isn't to say it absolutely never happened, just that it's virtually unheard of).

All semaphores were designed with counterweights: that heavy cast iron part of the display which holds the color lenses. If the latch ("slot" as it was called) lost power, it released the semaphore's operating mechanism, and the counterweight used gravity to pull the display, the blade, to display the most restrictive indication.

>So if the single-blade lower quadrant signal could only display a 'clear' or 'stop' indication, how was an 'approach' indication displayed?

By the yellow, fishtail-ended blade on the distant signal which preceded it. In the facing view of the double-bladed signal (pic #2), the home signal for the block just beyond the signal is the upper red, square-ended blade. The yellow, fish-tailed blade below it is the distant signal for the next home signal, further down the tract at the entrance to the next block. If this was a searchlight or colorlight signal, it would be displaying yellow. On the W Div of the SP, this signal would be called out as "one down".

>I can's tell for sure, but it sure looks like the middle lens on signal 14414 is yellow in the photos above.

This is an effect of viewing the red lens against the blue background of the sky (and the way your graphics card and monitor display colors for you). Semaphore lenses were illuminated by kerosene flames, and their colors are tinted to compensate for the orange-ness of the flame. This is the reason why you see so many "blue" lenses for sale on ebay which aren't the dark, cobalt blue used for blue lights (nor the very pale blue of lunar lenses). These are actually green ones, tinted and off-green in order to look green when viewing a kero flame. Tungsten filaments have a similar orange cast to the light they give off, particularly if you run them on a reduced voltage the way the RRs do.

If you ever watch old film of a US&S style B lower quad. semaphore in operation, you'll notice as the signal transitions from clear to stop, there is an initial 'snap' as the blade lifts. However, the final movement of the blade to the stop position smooths out for a slow rise to the fully horizontal position. As has been pointed out, by having two red spectacles (or yellow for the distant), a train crew will receive the intended 'stop' indication throughout this final slow transition to horizontal.
Generally speaking, double headed semaphores would be found approaching either end of a siding (hence the distant signal) and at either switch.

Posted from iPhone

As far as showing a green aspect, let me tell you, those counter weights weigh a lot. The SP Style Bs had a small motor for each blade. On that motor were some reducing gears connected to a piece of roller chain. This roller chain had short stubs sticking out of both sides. There were two short forks on either side of the chain. Those forks were connected to a shot coil and were held in a position to catch the chain rollers when the motor started. The chain would hook the forks and lift them until the bracket would hit a contact and stop the motor. At that time another contact would lower the juice to the forks but still keep them locked, holding the rod that went up the pipe. This rod was connected to a fitting that went through the pipe, outside, and there was a square piece that the blade and counter weight were mounted to. It would stay like that as long as those little forks had power to them. When a train hit the circuit, the power to the forks would be cut off. The forks would snap back and the weight of the blade and rod would allow gravity to lower the rod down to its stop. There was an air buffer pot connected to this bracket that controlled the rod so it didn't just bang down which would have shortened the life of the motor, gears and other equipment.

If the signal had two blades, it would have two motors, chains, etc. mounted on one plate. If you look at any "B" style case, the upper door always held that equipment. If the upper case had been converted to a light type signal, you will find a couple piece's of wood that would have held some new relays in the conversion. Pry up those boards and you will see 3 threaded holes in the steel where the motors, etc. were bolted down. I never understood why they used lower quadrant blades myself. I know the indications were too close together to safely see the indications. Back then most light behind them were kerosene and they would get blown out, etc. As long as you could see the position of the blades, it was okay. In those short degrees mistakes could be easily made. Upper quadrant there is no mistake. Straight up is green, at a 45 degree, yellow and at 90 degrees red. One motor, 3 indications. Simple.

As far as the SP went,as you went over the road and were coming up to a siding, they had an approach, bottom blade up, top blade down. That was a yellow. The next signal, both blades would be up, showing a red. The trouble with this was you used to be working on a green, come to the next signal and it would be red. There was only one blade on most of the intermediate signals so it had to show either a red or green aspect. Yes, it was a pain in the ass but that's the way they did it back then. Well the FRA got a burr up butt and discovered this (what had they been doing for the 20 years) and wanted the SP to change everything and install yellow indications on all their style "B"s. Well, the expense was going to be over the top. Parts were not available for the existing system so they started a campaign to replace everything with a light type signal. On the Siskiyous, CORP was able to bribe someone and they allowed them to pull out everything by the roots from Weed to Ashland.

In the desert they had converted a lot of places to CTC. Some of these still had Style "B"s. They added a small, single indication to the mast below the yellow blade in order to show a diverging route indication.

I only had 1 problem with a Style B signal and it was on the race track between Hilt and Hornbrook, just over the Calif. border. I was on west helper on the SLW, cut in with 5 stoves and 4 on the point. We were going down the hill and the head end had made a set so we were pushing a bit to keep our speed at 20. We came around the curve and the signal was down, showing green. The head end had passed and it never dropped. I called the caboose and asked them to check it when they went by. It was still in the clear position. We called the Branch Dispatcher and told them and it was changed out to a search light type that day but was unable to find out what caused it.


Nudge



Edited 1 time(s). Last edit at 09/30/14 16:12 by spnudge.

That may be true for the SP and Santa Fe, but I know the Wabash converted from lower to upper quadrant, (except for a few train order signals). Based on photographs, it does seem that more roads had the lower quadrant in the old days versus the later days. And when the change was made, it was made system-wide.

EtoinShrdlu Wrote:
> >and that was the reason why the upper quadrant
> came in favor?
>
> No. Which ever type a RR used was up to its
> discretion. The SP and AT&SF never changed
> semaphore types; it's a matter of cost. Some of
> the SP's LQ style Bs are still in service,
> although precious few these days.

wabash2800 Wrote:
-------------------------------------------------------
> Is it true that a short coming with the lower
> quadrant semaphore is that it could give a false
> clear aspect if the signal blade fell
> unintentionally, and that was the reason why the
> upper quadrant came in favor? (Therefore, if the
> upper quadrant signal failed, it would give the
> most restrictive aspect.) Has anyone ever heard of
> a lower quadrant semaphore failing in such a
> manor?

I've heard it said that the EP&SW preferred upper-quadrant semaphores on its Eastern Line in high altitude because ice build-up on a lower-quadrant blade could possibly hold it in the clear position when it should be in the stop position. Years ago I talked to some old-timers in the area and they heard the same, but I've never seen anything official written to confirm it. The SP eventually converted the Hall upper-quad Model Ks to lower-quadrant Style Bs, so obviously they didn't have problems.

EtoinShrdlu Wrote:
-------------------------------------------------------
> >Is it true that a short coming with the lower
> The SP and AT&SF never changed
> semaphore types;

Not so. Santa Fe owned the first lower quadrant Style-B and later moved to the upper-quadrant Style-S. The SP installed upper-quadrant two-position Style-S on the South Line (in order to conform to signals installed on the EP&SW).

> Some of
> the SP's LQ style Bs are still in service,
> although precious few these days.

None are in service.
>
> >So if the single-blade lower quadrant signal
> could only display a 'clear' or 'stop' indication,
> how was an 'approach' indication displayed?
>
> By the yellow, fishtail-ended blade on the distant
> signal which preceded it. In the facing view of
> the double-bladed signal (pic #2), the home signal
> for the block just beyond the signal is the upper
> red, square-ended blade. The yellow, fish-tailed
> blade below it is the distant signal for the next
> home signal, further down the tract at the
> entrance to the next block.

Depends on how the distant blade (DG) is wired. The distant block may extend well beyond the next home signal all the way to the next siding.

>Not so. Santa Fe owned the first lower quadrant Style-B and later moved to the upper-quadrant Style-S. The SP installed upper-quadrant two-position Style-S on the South Line (in order to conform to signals installed on the EP&SW).

First I've heard of this, but then I haven't made a point out of keeping abreast of the arcane details of SP and AT&SF signal history (although I do have a set of AT&SF WA and WB plans). What I have studied is the circuitry and principles of that era in general.

>The distant block may extend well beyond the next home signal all the way to the next siding.

This makes no sense because a distant signal has no block of its own, which is the reason why it has no red indication. If it did, then it would be a home signal for the block (and have a red indication).

On the other hand, it might be wired so that it gives warning for the next two home signals, but that isn't a "distant block", because the distant signal itself has no block.