Transaxle Power Flow

Reverse Gear

Fig 1: Reverse Clutch, Low/Reverse Clutch & Low Clutch

Courtesy of AUDI OF AMERICA, LLC

In reverse, the reverse clutch (1) is applied to provide input torque. The reverse clutch drives the front sun gear. The low/reverse clutch (2) is applied to hold the front carrier/rear annulus assembly. The rear carrier/front annulus assembly rotates as an output member in reverse with a reduction gear ratio of 2.21:1.

Power from the main centerline transfers to the underdrive compounder annulus by way of the transfer gears and the underdrive shaft. The low clutch (3) is applied to hold the underdrive compounder sun gear. With the sun gear held, the annulus drives the underdrive compounder carrier, and a reduction gear ratio of 1.45:1 is achieved.

The main centerline ratio of 2.21:1 is multiplied by the underdrive compounder centerline ratio of 1.45:1. As a result, the ratio through the entire gear train to the final drive in reverse is 3.215:1.

First Gear

Fig 2: Underdrive Clutch, Low/Reverse Clutch & Low Clutch

Courtesy of AUDI OF AMERICA, LLC

In first gear, the underdrive clutch (1) is applied to provide input torque. The UD hub is splined to the rear sun gear. When the UD clutch is applied, the UD hub and rear sun gear are driven. The low/reverse clutch (2) is applied to hold the front carrier/rear annulus assembly. By doing so, the rear planet gears are forced to rotate around the inside of the stationary rear annulus. The rear carrier/front annulus assembly rotates as an output member with a reduction gear ratio of 2.84:1.

Power from the main centerline transfers to the underdrive compounder annulus by way of the transfer gears and the underdrive shaft. The overrunning clutch holds the underdrive sun gear. The low clutch (3) is also applied during coast in first gear. With the sun gear held, the annulus drives the underdrive compounder carrier, and a reduction gear ratio of 1.45:1 is achieved by the underdrive compounder gear set.

The main centerline ratio of 2.84:1 is multiplied by the underdrive compounder centerline ratio of 1.45:1. As a result, the ratio through the entire gear train to the final drive in first gear is 4.127:1.

Second Gear

Fig 3: Underdrive Clutch, Low/Reverse Clutch & Direct Clutch

Courtesy of AUDI OF AMERICA, LLC

In second gear, the underdrive clutch (1) is applied to provide input torque. The UD hub is splined to the rear sun gear. When the UD clutch is applied, the UD hub and rear sun gear are driven. The low/reverse clutch (2) is applied to hold the front carrier/rear annulus assembly. By doing so, the rear planet gears are forced to rotate around the inside of the stationary rear annulus. The rear carrier/front annulus assembly rotates as an output member with a reduction gear ratio of 2.84:1.

Power from the main centerline transfers to the underdrive compounder gear set annulus by way of the transfer gears and the underdrive shaft. The direct clutch (3) is applied to drive the underdrive compounder sun gear at the same speed as the underdrive annulus. With two members driven, the underdrive compounder gear set operates in direct, or 1:1.

The main centerline ratio of 2.84:1 is multiplied by the underdrive compounder centerline ratio of 1:1. As a result, the ratio through the entire gear train to the final drive in second gear is 2.84:1.

Third Gear

Fig 4: Underdrive Clutch, 2/4 Clutch, Overrunning Clutch & The Low Clutch

Courtesy of AUDI OF AMERICA, LLC

In third gear, the underdrive clutch (1) is applied to drive the rear sun gear. The UD hub is splined to the rear sun gear. When the UD clutch is applied, the UD hub and rear sun gear are driven. The 2/4 clutch (2) is applied to hold the front sun gear. The rear carrier/front annulus rotates as an output member with a reduction gear ratio of 1.573:1.

Power from the main centerline transfers to the underdrive compounder annulus by way of the transfer gears and the underdrive shaft. The overrunning clutch (4) holds the underdrive sun gear. The low clutch (3) is also applied during coast in first gear. With the sun gear held, the annulus drives the underdrive compounder carrier, and a reduction gear ratio of 1.45:1 is achieved by the underdrive compounder gear set.

The main centerline ratio of 1.57:1 is multiplied by the underdrive compounder centerline ratio of 1.45:1. As a result, the ratio through the entire gear train to the final drive in Third gear is 2.28:1.

Third gear is also the default (limp-in) gear position.

Fourth Gear Prime

Fig 5: Underdrive Clutch & 2/4 Clutch, Direct Clutch

Courtesy of AUDI OF AMERICA, LLC

In fourth gear prime, the underdrive clutch (1) is applied to drive the rear sun gear. The UD hub is splined to the rear sun gear. When the UD clutch is applied, the UD hub and rear sun gear are driven. The 2/4 clutch (2) is applied to hold the front sun gear. The rear carrier/front annulus rotates as an output member with a reduction gear ratio of 1.57:1.

The main centerline ratio of 1.57:1 is multiplied by the underdrive compounder centerline ratio of 1:1. As a result, the ratio through the entire gear train to the final drive in fourth prime is 1.573:1.

Fourth Gear

Fig 6: Underdrive Clutch, Overdrive Clutch & Low Clutch

Courtesy of AUDI OF AMERICA, LLC

In fourth gear, the underdrive clutch (1) and the overdrive clutch (2) are applied to provide input torque. The UD hub is splined to the rear sun gear. When the UD clutch is applied, the UD hub and rear sun gear are driven. The OD hub assembly is splined to the front carrier/rear annulus assembly. When the OD clutch is applied, the OD hub and front carrier/rear annulus assembly are also driven. With the rear sun gear and the rear annulus driven at the same speed and in the same direction, the entire front/rear planetary gear train is locked and rotating as one unit. The rear carrier/front annulus rotates as an output member in direct, or 1:1.

The main centerline ratio of 1:1 is multiplied by the underdrive compounder centerline ratio of 1:45. As a result, the ratio through the entire gear train to the final drive in fourth gear is 1.45:1.

Fifth Gear

Fig 7: Underdrive Clutch, Overdrive Clutch & Direct Clutch

Courtesy of AUDI OF AMERICA, LLC

In fifth gear, the underdrive clutch (1) and the overdrive clutch (2) are applied to provide input torque. The UD hub is splined to the rear sun gear. When the UD clutch is applied, the UD hub and rear sun gear are driven. The OD hub assembly is splined to the front carrier/rear annulus assembly. When the OD clutch is applied, the OD hub and front carrier/rear annulus assembly are also driven. With the rear sun gear and the rear annulus driven at the same speed and in the same direction, the entire planetary gear set is locked and rotating as one unit. The rear carrier/front annulus assembly rotates as an output member in direct drive, or 1:1.

The main centerline ratio of 1:1 is multiplied by the underdrive compounder centerline ratio of 1:1. As a result, the ratio through the entire gear train to the final drive in fifth gear is 1.00:1.

Sixth Gear

Fig 8: Overdrive Clutch, 2/4 Clutch & Direct Clutch

Courtesy of AUDI OF AMERICA, LLC

In sixth gear, the overdrive clutch (1) is applied to drive the front carrier/rear annulus assembly. The OD hub is splined to the front carrier/rear annulus assembly. When the OD clutch is applied, the OD hub and front carrier/rear annulus assembly are driven. The 2/4 clutch (2) is applied to hold the front sun gear. Overdrive can be achieved using the front gear set. The rear carrier/front ring gear/annulus rotates as an output member with an overdrive gear ratio of 0.69:1.

Power from the main centerline transfers to the underdrive compounder annulus by way of the transfer gears and the underdrive shaft. The direct clutch (3) is applied to drive the underdrive compounder sun gear at the same speed as the underdrive annulus. With two members driven, the underdrive compounder carrier rotates with a direct drive.

The main centerline ratio of 0.69:1 is multiplied by the underdrive compounder centerline ratio of 1:1. As a result, the ratio through the entire gear train to the final drive in Sixth gear is 0.69:1.