Speed control for a utility vehicle

A method of controlling the speed of a utility vehicle, said vehicle having an engine driving a hydrostatic transmission, said hydrostatic transmission driving a drive train, said drive train including at least one gear and a driven wheel, comprising the steps of:

• continuously sensing a rotational speed of a rotating part in the drive train;
• operating said vehicle at a desired vehicle speed;
• at the desired vehicle speed, selecting the rotational speed as a set speed and saving said set speed in memory;
• thereafter, if the rotational speed of the rotating part differs from the set speed, changing the hydrostatic transmission output to diminish the difference;
• and
• providing a manual step of changing said set speed by incremental amounts and activating said manual step to change the set speed by an amount that is a function of the set speed, said amount being lesser for a range of lesser set speeds and greater for a range of greater set speeds.

A speed control system for a utility vehicle, comprising:

• a controller having an input for receiving a selectable set speed signal;
• an input device responsive to an operator command to select said selectable set speed signal, said input device signal-connected to said input;
• a drivetrain responsive to said controller to increase or decrease ground speed of said vehicle;
• a ground speed sensor arranged to sense ground speed of said vehicle, said sensor signal-connected to said controller to send a ground speed signal to said controller;
• said controller controlling said drivetrain with a control signal, said control signal adjustable to increase or decrease ground speed in response to a difference calculated by said controller between said ground speed signal and the set speed signal;
• and
• an incremental speed switch signal-connected to said controller, each activation of said incremental speed switch causing said controller to increase said set speed signal by an amount that is a function to said set speed signal, said amount being lesser for a range of lesser set speed signals and greater for a arrange of greater set speed signals.