Automatic transmission

An automatic transmission, providing five forward speeds and one reverse speed, comprising:

• a casing;
• first and second parallel transmission shafts rotatably mounted within said casing;
• a fluid coupling for transmitting engine power to said first shaft and a housing for said fluid coupling joined to said casing to form an integral casing unit;
• a main transmission mechanism mounted within said casing, coaxially with said fluid coupling on said first shaft, said main transmission mechanism providing three forward speeds and one reverse speed and including:
• a planetary gear train coupled to said fluid coupling;
• and
• an output unit connecting said planetary gear train and arranged between said planetary gear train and said fluid coupling;
• an auxiliary transmission mechanism mounted within said casing on said second shaft, said auxiliary transmission mechanism providing three forward speeds and including:
• a hollow output shaft mounted on said second shaft;
• a band brake which is engaged at 2nd speed of said auxiliary transmission mechanism;
• a multi-disc clutch which is engaged at 3rd speed of said auxiliary transmission mechanism and a first hydraulic servo for said multi-disc clutch including a first cylinder and a piston slidably mounted in said first cylinder, said multi-disc clutch and said first hydraulic servo being connected to said integral casing through said band brake, said band brake being arranged around the outer circumference of said first hydraulic servo;
• a multi-disc brake which is engaged at 1st speed of said auxiliary transmission mechanism and a second hydraulic servo for said multi-disc brake including a second cylinder and a piston slidably mounted in said second cylinder;
• a first planetary gear set comprising a first ring gear, connected to the output unit of said main transmission mechanism and serving as an input unit for said auxiliary transmission mechanism, a first carrier connected to said output shaft and a first sun gear engageable with said first carrier through said multi-disc clutch and said first hydraulic servo;
• and
• a second planetary gear set comprising a second ring gear connected to said output shaft, a second carrier engageable with said integral casing through said multi-disc clutch and a second sun gear connected to said first sun gear through said hydraulic servo for said multi-disc clutch.