My, How time fly's!

[Ed Valentine]

Here's some industry history my son just sent to me:

Patents by Inventor Edward R. Valentine

Edward R. Valentine has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

• Vacuum power booster with automatic waste liquid discharge for a water vacuum extraction apparatus
  
  Patent number: 4800612
  
  Abstract: A vacuum power booster with automatic waste liquid discharge for a water vacuum extraction apparatus. A first vacuum source is coupled to a first waste liquid storage tank in a main housing, typically vehicle mounted. A second, auxilliary vacuum source is mounted in a mobile housing remotely located from the first housing which contains a second auxilliary waste liquid storage tank. A vacuum pickup implement is coupled to the mobile waste liquid storage tank for extracting and transmitting dirty liquid from the surface being cleaned to the second waste liquid storage tank. The liquid in the second waste liquid storage tank is automatically discharged and transmitted to the first waste liquid storage tank when the level of such liquid reaches a predetermined height or level within the second waste liquid storage tank.
  
  Type: Grant
  
  Filed: November 23, 1987
  
  Date of Patent: January 31, 1989
  
  Assignee: Cross American Corporation
  
  Inventor: Edward R. Valentine

 

[John LaBarbera]

We researched that patent. Ed You abandon the patent a few years after filing. Why?