I thought we just discussed this recently, but found it was on the Plastic Building forum. The discussion also covered top-operating uncoupling levers. This is updated from that discussion:
In the AAR Code of Rules that I have for 1947 it states on pg 18 as part of Rule 3:
"(c)(8) Coupler operating levers of the rotating type handle ... are required on all cars built new or rebuilt on or after August 1, 1933. From owners. Note: It is recommended that when cars built prior to August 1, 1933, receive Class I general repairs and new couplers are applied, that the rotating type handle of uncoupling levers be applied."
So far I have not found anything about banning them outright, only that they could not be applied to new or rebuilt cars after that date. Although if I recall, wasn't there a rule banning a car from interchange if it (or maybe its underframe) was more than 40 years old? If so, then that would eliminate them from interchange by 1973.
As for top operates uncoupling levers, if they were prohibited it was after the extent of my current library. Somebody with access to the AAR Code of Rules for the ‘50s or ‘60s will have to look into that. But here's what I do have readily available:
In the 1945 edition of the AAR US Safety Appliances it states: "UNCOUPLING LEVERS: Number - Two (2). Uncoupling levers may be either single of double, and of any efficient design ... Handles of uncoupling levers of the "rocking" or "pushdown" type shall be not less than eighteen (18) inches from top of rail when lockblock has released knuckle..."
There is no indication of any type that is not allowed, whether it be "push type" or top- or bottom-operated. Only an extensive list of dimensions (which can be useful to modelers): Handles should be no more than 6 inches from the side of the car, except Plate B types (see examples in the other post), which could be not more than 12, but preferably 9 inches from the side of the car. Center lift arms not less than 7 inches long with the center of the eye at the end of the lift arm no more than 3 1/2 inches beyond center of uncoupling pin when horn of coupler is against the buffer block. Ends of the handles not less than 4 inches below bottom of end sill, or constructed to give a minimum of 2 inches clearance around the handle. Minimum drop of the handles is 12 inches, maximum 15 inches overall. The 1945 issue does not have a diagram of a bottom-operated coupler. Note that the type of coupler is not addressed at all in the Safety Appliance Guide.
An interesting comment on pg 787 of the 1949/1951 Car Builder’s Cyclopedia is, “The Standard E coupler is so designed that any coupler may be fitted for either top or rotary operation. The top operates type is well adapted for service where this form is required, but the operation of the rotary type requires much less force at the operating rod handle. The uncoupling rod is simplified and may be readily located in a position that assures easy coupler operation by trainmen. These important features of coupler service make the rotary operated coupler the preferred form for general use.” This is also the first Cyclopedia without a diagram of the Plate B top operating uncoupler lever. The 1940 and 1946 both have pictures and diagrams.
Modeling the New Haven Railroad 1946-1954 | https//:blog.newbritainstation.com