Hi All
I have a question for the experts out there, this type of truck was on a boxcar of the New Haven RR.
The truck looks like a Fox Pressed Steel type truck, that has been mortified with different side frames.
My question to you is this If it a Fox Pressed Steel Truck or some other type of truck, ??
If so Who Made It, What company? As always Thank you, Pat.

Would I be correct in believing that all of these fabricated plate trucks were discontinued because they were liable to work loose at the joints and fail?

I believe the problem with these Fox trucks was in the design.

The sideframe, riveted directly to the truck bolster, fails to allow sufficient equalization of load between the two journals on the same side.

As I recall, they came to be seen as a notorious risk for hotboxes, explaining their unusually short service life.

They may have had a short service life but the Burlington Northern still had a old MOW car with Fox trucks in the 1980's. Yes it was being scraped when I saw it but that was in the 80's.

Interestingly enough. Australia's Puffing Billy Railway makes extensive use of Fox trucks and has had new side frames manufactured within the last two or three years. "Puff" is one of the busiest tourist railways in the world, carrying half a million passengers annually prior to COVID-19.

I can't say what it is, but this looks nothing like a Fox truck, AFAIK. Fox trucks that I've seen always have a single pressed steel outside frame. The frame shown here is clearly made from standard steel channel with cast pedestals riveted to each end. Standard channel is made in an extrusion process. The Fox trucks that I've seen (for all of my 60 years of seeing) have a dog bone shaped pressed steel frame that is clearly made in a press between two dies, thus the name "pressed steel truck". The Fox frame is continuous from front end to back, with the pedestal elements (apparently) riveted between a sandwich of inner and outer pressed steel frames.

Perhaps this is an alternate Fox design that I've never seen, but I've been watching for a looong time, and never seen any other than what I describe here. The B&M had Fox trucks on many of their smaller locomotive tenders, on eight-wheelers and Moguls, and probably others; photos of them are easily found. Good luck in your research.

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I think of all these plate-fabricated trucks as being analogous to British steam use of plate rather than bar or fabricated frames. The designs all hinge on the implicit cheap presence of rolled Bessemer steel. Weren't at least some of the Fox trucks stamped or pressed with an external box section, not just a plate with webs?

The truck in question, in fact, is implicitly 'British' in its reliance on individually sprung journals running in pedestals to get even running and a level of cross-articulation. Very quickly you run into the usual problems with pedestal wedge and liner fit, critical lubrication, etc. -- all things that a cheaper three-piece truck with the same wheels and journal-box construction style simply doesn't have.

An interesting exercise is to approximate three-piece truck sideframe geometry using either fabricated or pressed-steel sideframes, compared to the advantages and disadvantages of a fabricated archbar truck with similar plate in strips used for the construction. Then compare with a good cast three-piece frame and see how quickly increasing car weight doesn't scale well... it looks to me as if this approach is to get 'battleship' kind of construction for loads a conventional three-piece truck of its time isn't expected to provide, or perhaps brake effectiveness a three-piece is relatively less well suited to provide.

...this even before we start addressing how to handle the joint between bolster and sideframes, an issue not quite comparable to the methods used (sometimes defectively) in, say, an Ohio tender truck arrangement. Look how heavy it is on the example Pat provided -- side-bearing area looks like an actual casting and there are LOTS of rivets; note also the doubled lower web thickness.