The November, 1978 issue of Model Railroader had an article by the late John Porter (a fellow S-scale modeler) called "Scratchbuild a Wartime Hopper Car". Although it is not a PRR GLa he was building, it did have a fantastic drawing of the KC and AB brake systems, which I have copied here (without permission from MR). My plan is to put AB brakes on two of the three cars I am making, and the K brakes on the third one. I usually don't study the details until I get to that phase of the construction. As I studied available prototype photos that show brake system component of this hopper, I found that they seemed vary all over the place. Since the parts are under the hopper, they are usually very dark and details are hard to make out. K brakes have two major components, while AB brakes have three; that is one telltale sign. It also seems like the parts were kind of placed however and wherever it was convenient with a lot of custom welding work to make supports for them. Note that in the diagram below, the angled braces of the car run from the center sill to the outside corners of the car, while on the GLa they run in the opposite direction, which makes the placement of the parts more challenging.
In my excitement of finding the brake system and the ability to take such close-up photos, I neglected to take a photo of the whole car itself, so I have no idea what prototype this car is. Nevertheless, I decided to base my modeling installation of the AB brake system components on the photos I took of this car. It was the best view I had (the photos I have received of the one prototype GLa in New York seemed to either be with the K brakes, which would be odd, or brake components are missing from it, which is more likely). So, what follows is my installation of the AB brake components in one of the cars. If you are strict prototype modeler, you may take my construction with a grain of salt, but I am happy with the way it came out. Note that this part of the project slowed it down to a near glacial pace! There are a lot of custom parts that need to be hand-made and custom-fitted. Also, I made a good number of compromises here in order to keep my sanity!
This is a composite of three photos I took of the work I did to the air reservoir part (I am using Grandt Line parts). The single strip of styrene (right side in the photo) is used to connect the part to the side sill of the car. The U-shaped part was made from a slice off of a square tube of styrene strip with one of its four sides cut off. Two tiny pieces of strip styrene were cut and glued to the ends to represent mounting brackets to attach the reservoir to the back vertical wall of the car. All sizes were based on what it took to get the part to sit correctly in its position on the car.
Before installation I determined which wire I was going to use for the piping and drilled out the holes of the part. It was then a matter of holding the part in place and applying glue to the joints. I did have to flatten the back of the reservoir part a bit to make it fit in the space. That also became another hidden glue point.
I glued the brake cylinder to a piece of styrene sheet. The cylinder was sanded smooth on the bottom, and the styrene sheet was glued flush with the side of the cylinder that is in the back in the photo below. I also filed down the back of the cylinder part so that it sits flush against the back vertical plate. A pipe is normally attached to the back of the cylinder, but from the prototype photo above I gathered that the pipe went into the vertical plate, and, I presume, it then wrapped around and entered the back of the cylinder right where it attached to the vertical plate. In the model, of course, I didn't need to model that last part. Note also that I cut off the shaft that comes out of the cylinder on the front. This was because there was no way that it would fit under the hopper as it is, and the "turn-buckle" is in the wrong direction for a hopper.
I then glued the styrene base plate to the center sill. Note that I glued it on top of the bottom angle of the center sill. The back of the cylinder was also glued to the vertical plate, for additional strength.
Next up is the triple valve. I cleaned up some flash on the part, and then drilled out the three holes for the piping that I intend to install.
I then glued a thin sheet of clear styrene on top of the center sill to act as the base for the triple valve. I used clear "glass" styrene, because that was the absolute thinnest material I could find in my supplies. I then cut and formed a piece of music wire (the closest match to the diameter I had in my stash), and installed it between the air reservoir and the triple valve.
A lot has happened since the previous photo was taken. That was mostly because I was concentrating on how to do the work, and forgetting about the camera. First, I added two more pipes; another one between the air reservoir and the triple valve; another from the triple valve to the vertical back wall plate, to simulate it going to the back of the brake cylinder. Next, to be able to attach the components that connect to the front end of the cylinder, I needed to install the vertical hopper "pillars". I was going to use a scale 4-inch wide L-shaped angle strip styrene, but discovered I didn't have enough to do all three of my cars. So, instead, I decided to use 4-inch C-channel strip styrene. These were shaped to fit under the hopper and long enough to be glued to the inside of the end sill. Before installing them, I made a rough estimate as to the overall size of the gusset plate used to hold them to the hopper. I settled on a piece 15 inches square, which seemed to match the look compared to prototype photos. Three inches down from the top of the gusset, I cut a chamfer which left 9 inches flat at the bottom. I had to mark the center of the gusset plate and the center of the location of the two vertical C-channels (approximately above where the wheels of the car sit), because the gusset plate has to be attached first before the C-channels could be glued in place. All very delicate and patience-testing work.
The most difficult work of this entire project was coming up next. I dreaded working on it, which delayed my progress even more. I needed to hook a vertical cam shaft to the brake cylinder. I gather from the prototype photos that the cam shaft was fixed at the top, and the brake cylinder moving in and out caused this to part the move. I found a brass cam shaft in my spare parts box. A similar one can be made from a piece of strip styrene just as well. I glued the turn-buckle I had cut off from the brake cylinder part to it, and made its shaft as short as possible, because the whole assembly will need to sit very close to the brake cylinder to fit in the model. I then cut a strip of styrene which I glued to the brass part using super glue. Its end was filed at a chamfer to make it fit to the hopper's underside. Over a period of three modeling sessions I worked on trying to get this assembly to then sit at the correct position using my two hands, so that my third hand could apply the glue (or at least that is what it felt like when I finally got it in position, using self-closing tweezers). I used styrene glue to glue the part to the vertical C-channel part, and to the back of the hopper. I then used superglue to re-attach the brake cylinder part. Extreme care must be taken not to knock the parts loose from their delicate position when applying the glue to the joints. I did one joint and then walked away from it, to come back later to do another joint.
Here's the view from the other angle. The car itself was held in place with some metal weights, so that it wouldn't turn around as I was working on this part.
Up next is the vertical brake wheel. I used the same music wire I used for the brake system piping. From prototype drawings, I determined that it should be about 3-1/2 feet from the left side of the hopper. I drilled a hole into the end sill and attached the brake wheel (can be done later as well). I used some scrap pieces of styrene to hold the staff parallel to the end of the hopper, and then applied superglue to where the wire passes through the end sill.
The prototype photo shows two brackets that hold the brake wheel staff away from the body. I used a pair of scissors to cut some really thin brass sheet into a long strip. The strip curls, but it is easy enough to bend into the shape shown in the photo. I used a piece of the same music wire to form the wrap. The hardest part is to get the two end strips to be even with each other.
Here's a test on a sheet of glass.
I could then slip them over the brake wheel staff, and use superglue to attach them to the hopper body. The top one is just a bit below the top of the hopper. The bottom one sits above the brake wheel platform, so some coordination there is needed. At first I attached the bracket first and then adjusted the position of the platform, but I now prefer to install the platform first.
The platform is just a piece of styrene cut to a scale 3'3"x1'. From the prototype photos I determined that the brake wheel staff doesn't pass through the platform in its center, so it is offset a bit. I then used some tiny strips of styrene to form the brackets used to attach the platform to the body. The angled parts of the brackets should be glued such that they follow the angle of the hopper body, but I wasn't able to do that because I had already glued the brass bracket to the brake wheel staff. Lesson learned.
At the bottom of the body, the brake wheel staff sticks out just a bit below the end sill, and there is a U-shaped bracket attached to the end sill to provide the support of the staff. I simulated that with a slice of a square piece of styrene strip, and then cut a gap in one of the four sides, which is hidden.
After drilling a hole for the music wire staff, it was trivial to glue it into place.
And after more than three weeks of calendar time, the brake system is finally finished. Two more cars to do! At least I now have a role model to follow. Note that in the prototype photos there appears to be a nut or something like that above the brake wheel, probably to hold it to the staff. I simulated that by simply having the staff stick out through the brake wheel center a bit. A tiny dab of superglue simulates that nut. Although I tried, I couldn't get the wheel to sit perfectly horizontal.
And here is proof that I really did three of them. It took me almost two months of calendar time to just do the brake systems on these three cars. However, there were a number of days where I did no work on these cars, and a lot of days where I only had time to attach one or two pieces. The brake system was definitely the most intricate part of this project, and quite frustrating at times. I count 30 individual pieces per car. The car on the left has some brass parts I had in my parts box, the center one has an attempt at K brakes, and the one on the right is the one I photographed in detail above.
Although not related to the brake system, this shows the vertical support beams installed on the A side of the cars.