No need to stop a hydro unit to change speed, adjust it on the fly to suit conditions.

Looks like the same setup I had on my old Huskee. Push the lever forward and you go forward. The farther you push, the faster you go. There's a neutral position for the lever, and you go in reverse by pushing back on the lever. I seem to remember you had to disengage the blades to go into reverse.

OP - yes that machine has a typical hydro tranny with a fender-mounted control lever. After starting the engine and releasing the clutch pedal, you can slowly move the lever either forward or backward slowly. The further you move the lever, the faster the machine will move (in the direction selected). No need to clutch/declutch each time a change is speed direction is desired.

Here is a link that might be useful: 28852 manual