Most self-propelled machines now have a continuously variable drive speed so
the difficulty of speed adjustment is pretty well eliminated and it's easy
to slow down quickly or to propel in short lunges.

SJF

What you are referring to is a hydrostatic transmission and would
include reverse. You say most machines have one? Can you could give
even one example?

I own 4 self propelled mowers and only one of them has such a drive.
It is a $2100 walk behind brush mower. Any mower having such a feature
would have at least a 32 inch deck and be considerd a commercial mower.
17 inches is the typical deck size for a residential walk behind
mower. Here is a link to show you an example of my mower:

http://www.snapper.com/field_brush.html

My own search for such mowers can be found at this link:

http://www.google.com/search?hl=en&l...& btnG=Search

My search confirms my personal experience that front-wheel drive 17"
mowers have but one speed. 17 inch rear drive mowers often have
multiple speeds but apparently never do they have a hydrostatic
transmission. The smallest mower with such a feature has a 32 inch
deck and runs into the thousands of dollars.

I would be happy for you to prove me wrong so that I can go out an buy
such a mower.