Time to Empty Signal

[briankirbyclass]

On today's Pic of the Day,,,,on the Hoover 150 Cleaning Ensamble,,the ad mentions a "Time to Empty Signal",,,what?,when?, where?, how?

Ive never heard of this,,,did it really work? Does a whistle blow or something, what exactly is a "Time to Empty Signal" on a Hoover upright? What triggers it? How does it work?
Please tell!

 

[briankirbyclass]

Ok, i see where the ad says that the "Time to Empty Signal" is a red dot (im assuming red light) that flashes. Where on the cleaner is this red dot?
How does it know when to flash,,or how does it know when the bag needs emptying?

 

[vintagehoover]

This feature...

...was discussed at length just the other week! Marty Kaplan provided photos of the mechanism, and demonstrated how it works.

Use this link and scroll down to the middle of the thread:

http://www.vacuumland.org/TD/THREADS/VINTAGE/3962x59.htm