Controls and Gauges on the Ventrac 4000 series tractor. Summary of the controls and gauges on the tractor, including the SDLA Lever 1.The S..D..L..A. is the primary control for the tractor and consists of two parts: The front, taller lever is the primary lever and controls the travel Speed, Direction and front lift of the tractor. The shorter, rear lever is the secondary lever and controls the auxiliary hydraulic circuit through the front quick couplers. To operate Speed and Direction the selector/park lever must be in the middle or up position and the operator must be seated in the seat. 2.The distance the lever is moved forward or backward determines the ground speed of the tractor and the direction it travels. 3.Moving the primary lever to the left raises the front hitch, to the right lowers the hitch. Hitch flotation is obtained by continuing the movement to the right until the detent locks the lever in the float position. This allows the front attachment to move up and down independently of the tractor, when mowing, blading or when this function is desired.