View From the Head End

Recently a Youtube channel appeared called View From The Head End, that was posting complete head end cab videos from Amtrak trains. These were not the more typical "reversed" videos taken from a rear facing window, but legit head end videos that documented both signals and signaling. More significantly the videos were up to date, likely all recorded within the last couple of years. My first thought was that someone had recently retired because since the early 2000's Amtrak (and I assume most railroads) have been somewhat anal about employees moonlighting as content creators. Well, I guess they hadn't retired because if you haven't noticed the link is broken and the entire channel is gone.

While the practice of workers recording head end videos to feed Youtube channels seems to be quite common in Europe (where I should add its practically impossible to fire railway workers), there are surprisingly few full-line inside-the-cab videos from North America. Up through the early 2000's there was a cottage industry head end videos being sold at "Train Shows" on either VHS or DVD. Some of these were professionally produced by outfits like Pantex, while others were made by AV savvy employees with access to a Hi-8 camera and a capture card. Unfortunately the rise of The Internet brought this wildcat era of video to an end as the speed of information made it easier for previously underground works to become known by regulators, the media and lawyers.

In the early years of Youtube, spotty internet connections and the more ephemeral nature of online data encouraged folks to save off important video content like head end videos. This practiced has decreased as the internet became more reliable overall, however when you find something that seems too good to last, you might want to leap into action and save off a local copy. In a sliver of good news I was able to watch some of the videos before they vanished and resolve some outstanding signal questions I had.

Meanwhile if you'd like something similar to watch I can provide two pairs of videos from the late 2000's covering an Acela trip from Boston to NYP (head end) and the Former Conrail Chicago Line between Buffalo and Albany (rear facing). Intended for Train Show (tm) sale both had been scrubbed of ambient cab sounds and the Chicago Line also being video reversed (which I was able to undo). Although mostly silent, the Chicago Line video in particular captures the NYC/Conrail signaling immediately before its complete replacement ~2010.

Caltrain EMU Cab Video Signal Survey

After the loss of the Caltrain gallery car railfan window I wasn't holding out much hope for having anything worthwhile to do on the Caltrain system as European spec rolling stock typically come with bulkhead style cab doors. However videos have been appearing showing that front facing views are present. This have the added benefit of providing a southbound signaling survey as previously such photos and videos were only possible facing northbound. 

I have already covered changes between San Jose and Tamien and can now confirm that the remaining Southern Pacific style signals in the terminal area have been replaced. The good news is that the few SP target type signals on the north end near the tunnels are still in place although unfortunately the triple unilens stacks at CP-COMMON were replaced by a standard LED modular type in a three virtual head configuration. Another note is how bad the sight lines for some of the wayside mast signals have become. This makes clear the advantage for position lights and cab signals in electrified territory. Although the freight spec PTC system Caltrain uses is kinda like a cab signal, moving to a Rule 562 coded track circuit arrangement might save them a lot of trouble. 

You can watch the video for yourself, but despite the hype the weekend and daytime local service is still highly underwhelming with little in the way of interesting signaling or routing. Although faster than diesel, the speeds are still slow compared to a limited stop run and unfortunately these have been largely curtailed with the fastest peak period trains still 3 or 4 minutes slower than the famed 4 or 5 stop Baby Bullets of the 2004-2024 time period.

Inside the US&S A-5 Switch-Point Machine

This blog devotes a lot of coverage to the plight of the pneumatic switch-point machine and its long decline since its heyday between 1930 and 1955, but apart from the ka-chug--woosh sound, what makes them distinctive? Well its actually their simplicity compared to their electric counterparts and its that simplicity that made them so competitive with electric point machines despite the overhead of making and distributing compressed air. 

Above we see a Union Switch and Signal model A-5 pneumatic point machine. (An earlier A-1 model also existed and you can tell them in photos because the housing looks like a miniature Quonset hut.) At one end we see the double acting air piston, at the other we see a connection for the control circuits and a blind tube without an air piston, and in the middle we have a fairly plain looking box.

Next lets quickly go over a standard power operated switch layout using some casual terminology. Moving away from the camera we have a stretcher bar that provides rigidity. Next is the throw mechanism that transmits force from the point machine to the points via a rod. This uses a slack coupling so the point mechanism can begin to move and break the static friction. Finally we have the detection rods that accurately detect if the points are hard against the stock rail and communicate that state to the signaling system.

Exposed US&S A-5 pneumatic point machine.

The mechanism can be set up for operation from either side.

Here we see a naked A-5 without its cover on showing off the simplicity of the action. The air piston connects to an action bar which runs through a crank mechanism that transmits force to the point rodding and also its positional state to the circuit controller.

The crank (left) and circuit controller (right).

The coupling between the air piston and the action bar.

The air piston, these came in 3 inch and 5 inch diameter models.

The throw rod couples to the crank assembly. In the photo below this connection is the bolt hole on the stubby arm below the pivot pin. The detection rods sit under the circuit controller have the golden coated nuts on them.

The circuit controller pulls double duty, detecting both the position of the points for the signaling system and also the position of the action bar / air piston, which is sent to the style CP air value unit to cut the flow of air and dump the pressure in the piston. We can see the hind end of the action bar that is given room to push outward under the covering.

The upper two rods provide the actual point detection while I believe the lower rod that extends through the mechanism provides a physical locking function in conjunction with the action bar. When this technology was new that rod would serve the role of the familiar facing point lock.

The goal of the mechanism is to lock the switch point securely against the stock rail even when air pressure in the cylinder has been exhausted, but allow smooth movement of the action bar and points when air is admitted to move the piston. A similar concept is present in firearms where the bolt is locked against moving rearward by the force of gases in the chamber, but is able to be easily unlocked via motion in a different axis.

While I have personally captured video of an A-5 point machine performing a throw cycle, it only showed the points moving along with the admittedly cool sound. However I recently came across a different video from a UK rail museum that has their own flavor of a US&S A-series set up for live demonstrations. Still popular on the London Underground, these instances are commonly used without the protective cover which allows visitors to actually see how the mechanism functions. This flavor of Westinghouse point machine is intended to be set between the rails and has the throw rods moving through the mechanism. The extra circuit controller on the back provides feedback to the pneumatic value.