Ford ATX Transaxle


Ford ATX Transaxle

The Ford ATX is a 3-speed automatic transaxle that uses a Ravigneaus planetary gear train. The gear-type oil pump is driven indirectly by the torque converter. Because the oil pump is located at the opposite end of the transaxle, as is the torque converter, a drive shaft is used to rotate the oil pump.

The transaxle has been continuously updated and modified to fit different applications. The most obvious changes made to the transaxle are the torque converter. The ATX has been available with three different designs of torque converters: the conventional three-element converter, a converter with centrifugal lock-up, and a split-torque converter.

The original ATX transaxles were equipped with a splitter gear torque converter. This unit contained a planetary gearset that divided the delivery of input torque. Part of the torque is transmitted mechanically and the remainder by fluid force on the torque converter's turbine. In second gear, 62 percent of the torque is transmitted mechanically, while in third gear 93 percent is mechanically transmitted. In low gear and reverse, full engine torque is transmitted by normal converter fluid flow.

The split-torque converter is used in Escort and Lynx ATX transaxles and in the transaxles of 1984-86 Tempo and Topaz models. The ATX used in the Taurus and Sable models used a centrifugally locking torque converter. By 1988, all ATX transaxles used in the Tempo, Topaz, Taurus, and Sable models were equipped with a conventional fluid-linked torque converter.

The small sun gear of the ATX gear train is called the reverse sun gear and is meshed with the short pinion gears. The short pinion gears serve as idler gears between the reverse sun gear and the long pinion gears. The large sun gear is called the forward sun gear and it meshes with the long planetary pinion gears. The short pinion gears are meshed with the long gears and both sets of pinions can rotate on their own shafts held by the carrier. The planetary carrier serves as the output for the gear train. The ring gear surrounds the other members of the planetary gearset. The long pinions are in constant mesh with the short pinions, the forward sun gear, and the ring gear.

The ATX is equipped with three multiple-disc clutches, one band, and a one-way roller clutch. The parking gear is located on the output gear of the final drive assembly.

Refer to the clutch and band application chart given at below.

Gear Selector Position

Operating Gear

Front Band

Top-Gear Clutch

2nd Gear Clutch

Reverse Clutch

One-Way Clutch

P-Park None         x
R-Reverse Reverse   x   x x
N-Neutral None         x

D-Drive

1st gear

x

 

 

 

x

 

2nd gear

x

 

x

 

 

 

3rd gear

 

x

x

 

 

2-Second

1st gear

x

 

 

 

x

 

2nd gear

x

 

x

 

 

1-Man. 2nd

1st gear

x

x

 

 

x

Power Flow In Neutral When the gear selector is placed into neutral or park, the one-way clutch locks the input from the torque converter's turbine shaft to the sun gear. Since no other clutch or band is applied, power does not flow through the gear train. When the gear selector is in park, the parking gear is locked to the transaxle case by the parking pawl.

Power Flow in First Gear The one-way roller clutch locks and allows the reverse sun gear to be driven by the turbine shaft. The reverse sun gear drives the short pinion gears in a counterclockwise direction. The short pinions, in turn, drive the long pinion gears in a clockwise direction. The long pinions walk around the forward sun gear, which is held stationary by the front brake band and drive the planet carrier and final drive clockwise. The top gear clutch is applied in manual low to provide for engine braking.

Power Flow in Second Gear Engine torque is transmitted through the planet carrier to the applied second gear clutch, which locks the intermediate shaft to the ring gear. The front brake band is also applied and holds the forward sun gear. The turning of the ring gear causes the long pinion gears to rotate clockwise and walk around the forward sun gear. This action drives the planetary carrier and final drive clockwise.

Power Flow in Third Gear When operating in third gear, the second gear clutch of the ATX remains applied and locks the intermediate shaft to the ring gear. The top gear clutch is also applied and locks the reverse sun gear to the turbine shaft. Since the planetary gear train has two inputs, direct drive results. By allowing input on both the reverse sun gear and the ring gear, the long and short pinion gears are trapped between the ring gear and reverse sun gear. The planetary carrier is the output.

Power Flow in Reverse while operating in reverse gear, the ATX applies the reverse clutch, which holds the ring gear. The applied top gear clutch and one-way clutch lock the reverse sun gear to the turbine shaft. The clockwise rotation of the sun gear causes the short pinion gears to rotate in a counterclockwise direction. The short pinion gears drive the long pinion gears in a clockwise direction; however, since the ring gear is held, the planetary carrier is forced to rotate in a counterclockwise direction. The carrier drives the final drive and the vehicle moves in reverse.

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