Proto MAX(TM) metal knuckle couplers

[Toolbelt]

My recently purchased Walter's Proto 23,000 gallon tank car (UTLX #641639) came with Proto MAX(TM) metal knuckle couplers, which I think are Walter's version of Kadee #5's. I noticed the knuckle spring had fallen out of one of them, so I replaced it with a Kadee #148 whisker. I recently noticed the remaining Proto Max coupler wasn't centering properly. I inspected it and was going to reinstall it but forgot to note whether the brass spring plate goes on first, or after the coupler is installed. I'm out of #148's but have #118 (shelf couplers). Would that prototype have used shelf couplers? So my options are to reinstall the Proto Max and check if it's working now (if I can figure out the spring plate position), or put the 118's on it, or get some 148's. These Proto Max's seem problematic in my limited experience, or maybe the factory messed up and installed the spring plates upside down (if that's possible?

 

[bnsf971]

Tank cars would have used shelf-type couplers.

 

[Toolbelt]

Tank cars would have used shelf-type couplers.

Would that apply to older tanks (prior to 1995?) when rules were changed? Were older units required to retrofit to newer standards? I'm not sure when this prototype was produced, not that it would matter if retrofitting was required. I'm loosely trying to model the 70's to 90's era.

 

[bnsf971]

Type F couplers began being used around 1947 or so, and became a recommended alternate about 1955. They became used on nearly all tank cars by the mid 1970s.

 

[Toolbelt]

Type F couplers began being used around 1947 or so, and became a recommended alternate about 1955. They became used on nearly all tank cars by the mid 1970s.

I'm reading that type F couplers interlock in a way that limits vertical movement? My limited understanding is that shelf couplers (type E) appear to have a vertical protrusion that prevents one coupler from sliding over or under another coupler in the event there is vertical movement? A double shelf coupler has a protrusion top and bottom? Again, this is from my novice experience. I also purchased 2 Rapido's and one Athearn Genesis tank car of similar era/type/design but only the Genesis had what I would consider a "shelf" coupler similar to this pic.

Are there other variations considered as "shelf couplers" that don't have those vertical lug/lugs? The three tank cars appear to just be similar to Kadee #5/#148 although my eyes are terrible.

 

[bnsf971]

You can really get into the weeds, but the two major varieties are the single shelf, and double shelf. I haven't installed any lately, but I think Kadee 118 and 119 are representations of those.

 

[Toolbelt]

You can really get into the weeds, but the two major varieties are the single shelf, and double shelf. I haven't installed any lately, but I think Kadee 118 and 119 are representations of those.

I think manufacturers stick with the coupler that was in use at the date the originals were manufactured and these units were built over a 3+ decade period so its entirely possible they didn't use "shelf" type couplers (per the pic) when built, so it's up to the user to upgrade when necessary depending on the era they're modelling. At least that's their excuse? lol I think I'm like you in the sense that tank cars look better with the shelf type coupler, so I think I will upgrade this Proto unit regardless. Perhaps many tank cars upgraded before the rules changed in 1995 voluntarily. I'm not a stickler for tiny details but if I have to upgrade from the ProtoMax couplers in any case, I wanted to try to be prototypical.