This modifies the pressure in the main circuit according to the position of the tor and the speed of the vehicle. - The slide valves (Ist - 2nd and 2nd - 3rd) These directly control the front clutch and one of the brake bands according to the position of the accelerator and the speed of the vehicle. - The control slide valve for the rear servo : This makes possible progressive from 2nd to 3rd or from 3rd to 2nd, depending on vehicle speed.