Thanks for the great pictures of your Westinghouse. I am going to go through my ad collection. I believe I have something about that model. It is, I believe, 1930's. I'll get back to you.  

John

What I found were two references to what appears to be the same model (#RDA-3). One is a Crisco sweepstakes contest, which gave away 1,200 Westinghouse upright cleaners (!). This contest ad was dated April, 1938, and appeared in the Better Homes and Gardens magazine.

The second item is an article that appeared in The American Home magazine, dated May, 1939. I believe these are both the same model vacuums. A few interesting variations: This model looks like it has a side-clipped bag; the bag stretches across the front of the machine, tucked behind the motor housing. The bag has a clip in the lower right-hand corner of the bag that clips to the motor housing to hold the bag in place as it inflates; this feature appeared on some Eureka models, also, and on some Westinghouse models, especially in the 40's. I'm not sure if you can see this in the Crisco sweepstakes ad. Your cleaner, which apparently has a catalog number of RS-3, may have been a variation of this model RDA-3.

Here's the first, the Crisco ad: 

There's also a shot of the Hoover Model 26, and the General Electric DeLuxe, and a Cadillac upright.

As the cleaning article details, there is an indicator bar on the Westinghouse that warns you of problems with the bag. Does yours have anything like that? In the Crisco sweepstakes ad, it is called the Servi-Sentinel, a device that warns when the nozzle needs to be adjusted or the bag needs emptying.

On the Hoover 150 of the day, it was accomplished by a suction sensing valve that sensed when suction was being reduced, and it moved a red disk into a window to show that there was a problem.

I am not sure where that device would be located on the machine - maybe down on the motor housing near the wheels? I've never seen either model in person. Does anyone else have any knowledge of either model?