McK&H.Aust wrote: Nice find with the video. Apparently that teardrop was a Westinghouse, the one at Orange also sounds different and the gong actually has a rounder shape, so maybe they changed the gongs on the newer ones. The wording around the Westinghouse logo on the bell at Orange is also different, it reads "Westinghouse Brake & Signal Co. Pty Ltd" while all of the other ones I have seen read "Westinghouse McKenzie Holland Pty Ltd".
The teardrops that read "Westinghouse Brake & Signal Co. Pty Ltd" are the newest teardrop bells, most likely made in the early 80's.