I can take photos of it later today... it's a series of exterior friction plates to hold the linkage arm that is tied to the foot petal at a certain "speed" (The farther you push it forward, the more petal is press down). You can set it at any position and it stays in that spot.
If you push both brake pedals, it cancels (disconnects) the cruise control (returns the HST petal to the neutral position). If you take the lock off the brake pedals to separate them, you can use the hand lever to "drive" (control motion) and use either the left or right brake to turn (steer) quicker. Or you can just steer / drive like normal without using the brakes.
Does not work in "reverse" only forward. Pulling the lever all the way back until it stops, puts the HST petal back in neutral.
I'm not sure about these small tractors, but at work with larger John Deere, with 4x4 engaged, the tractor still wanted to drive straight. It would bind up the transmission, it seems... I'll get mine out sometime today and test it out in 4x4 and try steering with the brakes and see if it works....