I do not see another reason for the extra supports !!
Mart, there is only one (1) reason for the lateral arm “supports”, other than aesthetics of course, and that is to prevent the chair arm from “splitting” lengthwise.
When a person raises themselves out of an “arm” chair,
especially a “rocking” chair, they will usually “grab” hold of the “outside” front edges of the chair arms, and via
the palms of their hands they will apply SUFFICIENT downward PRESSURE on the chair arms to raise or assist in raising their body mass to a standing position. The heavier the persons is, the greater the pressure required.
With that PRESSURE being applied to
the outside edge of the arms, that “
lever” action puts extreme “stress” on the grain of the wood where the “hole” for the front legs have been drilled ..... which may eventually cause the wood to “split”. If the wood was Oak or the “holes” were in the center of the arms there would be no “pressing” (
pun intended) need of “lateral” supports,
OK !! So what do you think these are for ?? They do not extend farther than what you see,, just go in and out !!
Mart, I truly believe they are part of a “non-binding” latching mechanism or “compression” latch ….. that applies the same principle as this “spring-loaded” cabinet door latch, to wit:
See picture below for the following ……
What I denoted as the “escapement dog” is firmly attached to the end of the denoted “leaf spring” …. and functions the same as the “spring-loaded” roller-bearing in the above picture.
And you are correct, Mart, the spring loaded “escapement dog” ….. just goes in and out (
technically – up and down) of the mortised cavity on the underside of the arm.
And iffen it works the way I think it does, the arm “attachment”, whatever it is, will have a “projection”, ..... that when installed, ..... will compress the “escapement dog” and then the “dog” will hold it in place via a “hole” or “depression” in said “projection”. To remove the “attachment” it is just “pulled” away from the chair arm.
And it is extremely possible that I am
50% WRONG about what I stated above
…… so use your own best judgement.