The present subject matter relates to adjustable ground speed control devices, systems, and methods for walk-behind equipment. A variable speed control system for a machine can include a control system base, one or more control lever selectively movable with respect to the control system base between a first operating position and a second operating position, first and second speed adjustment actuators positioned on the control system base proximal to the one or more control lever, and a control unit configured for communication with the one or more control lever, the first and second speed adjustment actuators, and a machine component. In this configuration, the one or more control lever can be configured to control the machine component to operate between a minimum operating speed and a variable maximum operating speed, where the value of the variable maximum operating speed can be adjusted by the first and second speed adjustment actuators.