Idling control system for an automatic transmission providing anti roll back action

An idling control system for an automatic transmission system for a vehicle equipped with an engine and a braking system, said automatic transmission system comprising a gear transmission mechanism which comprises:

• a power output shaft, a forward clutch which is engaged when said gear transmission mechanism is engaged to a forward speed stage, a one way clutch which in cooperation with said forward clutch provides a first speed stage by means of rotation prevention, and a brake which, when engaged, in cooperation with said one way clutch prevents said power output shaft of said gear transmission mechanism from rotating in the direction to allow reverse motion of said vehicle, comprising:
• a first means for engaging said forward clutch selectively either to a maximum amount or to an intermediate amount substantially lower than said maximum amount;
• a second means for engaging said brake, when said forward clutch is thus engaged to said intermediate amount by said first means;
• and
• a third means for:
• when said automatic transmission is being operated in a forward driving mode, said vehicle is substantially stationary, said engine is in substantially idling condition, and said braking system is applied, starting the actuation of said first means to engage said forward clutch to said intermediate amount and of said second means to engage said brake;
• and for:
• thereafter, as long as said automatic transmission is being operated in a forward driving mode, said vehicle is substantially stationary, and said engine is in substantially idling condition, continuing the actuation of said first means to engage said forward clutch to said intermediate amount and of said second means to engage said brake, even if said application of said braking system is terminated;
• and for:
• when thereafter either said automatic transmission ceases to be operated in a forward driving mode, or said vehicle ceases to be substantially stationary, or said engine ceases to be in substantially idling condition, starting the actuation of said first means to engage said forward clutch to said maximum amount and of said second means to disengage said brake.