Good Afternoon,
 I have A 20 Hosepower Toro Riding Mower,with A "TRAC VAC" Model 462
Grass Clipping Catcher (44 Gal.) Mounted on to the Rear of the Rider.
This "TRAC VAC"
Unit is Power By a 5.5 Horsepower Motor.
I am Looking to Find Out if There is Anyone that Makes Any Type of
Mechanical or Electrical Indicator to Inform you When the Container is
Full of Grass Clippings. The Reason for this Request, is to eliminate
having to Get Off the Rider, Shut Off the 5.5 Horsepower Motor on the
Catcher, and Open the Cover to
Check the Amount of Grass in the Container.

Make one out of a fish scale, cardboard base for the bottom of the the
trashcan, and a rope.  When it gets to the weight of full, whatever
you find that to be, get off and dump it.

Not sure if your question was answered but I found this one site that
has some interesting lawn articles. Check it out <a
href="http://www.lawnmowersite.info">Lawn Mower</a> Site.

You may want to ask this question in a forum. The one that comes to
mind is lawn cafe.

http://www.lawncafe.com