This model has a floating chassis under the tuning capacitor with rubber grommets. What was the intention here?

Yes, indeed...and they are lots of fun to work on as a result. My guess is that since that's where they placed the radio's "front end" with the tuned circuits, oscillator, etc, that they wanted to help enhance frequency stability. The grommets I think were supposed to act as shock absorbers somehow, with the surrounding main chassis taking the brunt of any jarring of whatever surface the set was placed on. Philco had a whole run of sets in that era that were built that way. To each his own, but if I am doing a "rebuild" of one of the big ones(38-2,etc), I find I have an easier time if I first separate the two chassis, do the work, then re-join 'em.
Jim

Brian,
You'll also notice that the tuning condenser is isolated both mechanically and electrically with the grommets, but a separate wire (usually flat braided copper) is soldered to the condenser frame near the brass/copper spring that remains in contact with the rotating plates, and a common RF ground point under the chassis. Make certain you return these 2 connections to their original location when the tuning condenser is returned to it's mount. Flat braid is important in this application, because it contributes very little inductance to the remaining circuitry.

marv

:
:This model has a floating chassis under the tuning capacitor with rubber grommets. What was the intention here?

Brian,
In addition to my earlier post, I believe the rubber grommets served to isolate mechanical vibration of the the tuning mechanism, and prevent microphonic tubes from translating vibrating elements into audio noise.

marv

:
:This model has a floating chassis under the tuning capacitor with rubber grommets. What was the intention here?

Brian: I believe Marv is correct. Vibration from speaker could cause feedback. I, too, have a Philco with this set up and it is a bear to work on. My Zenith chassis sits on four springs within the cabinet for the same purpose. Mark from Kalamazoo

The elecrolytic capacitor in this radio is of 3 values in one can, all have been bridged with replacements. It looks like one bridged replacement is non-polarized, and I'll guess no later than 1940s vintage. WOuld they have had such non-polarized electrolytics at that time?

:
:This model has a floating chassis under the tuning capacitor with rubber grommets. What was the intention here?