Transmission mechanisms with three planetary gear sets and one fixed interconnection

A family of transmissions wherein each family member comprises:

• an input shaft;
• an output shaft;
• first, second and third planetary gear sets each having first, second and third members;
• said input shaft being continuously interconnected with at least one member of said planetary gear sets, said output shaft being continuously interconnected with another member of said planetary gear sets;
• said first member of said first planetary gear set being continuously connected with said first member of said second planetary gear set through an interconnecting member;
• a first torque-transmitting mechanism selectively interconnecting a member of said first planetary gear set with a member of said second or third planetary gear set;
• a second torque-transmitting mechanism selectively interconnecting a member of said second planetary gear set with a member of said first or third planetary gear set;
• a third torque-transmitting mechanism selectively interconnecting a member of said third planetary gear set with a member of said first or second planetary gear set;
• a fourth torque-transmitting mechanism selectively interconnecting a member of said first, second or third planetary gear set with another member of said first, second or third planetary gear set;
• a fifth torque-transmitting mechanism selectively interconnecting a member of said first, second or third planetary gear set with a stationary member;
• and
• a sixth torque-transmitting mechanism selectively interconnecting said interconnecting member or a member of the first, second or third planetary gear set with said stationary member;
• said torque-transmitting mechanism being engaged in combinations of four to establish at least seven forward speed ratios and a reverse speed ratio between said input shaft and said output shaft.