Transmission Description through Low and Reverse Drive System
DESCRIPTION AND OPERATIONTransmission Description The 4R100 features include:
- four speeds.
- fully automatic.
- electronically controlled.
- optional power take-off. The main operating components include:
- Torque converter clutch.
- Six multiple-disc friction clutches.
- One band.
- One Sprig one-way clutch.
- Two roller one-way clutches that provide for the desired function of three planetary gearsets.
Identification Tags
An identification tag is located on the left side of the transmission, rearward of the Transmission Range Digital (TR) sensor.
Range Selection
The transmission has six range positions: P, R, N, 0, 2 and 1.
Park
In the PARK position:
- there is no powerflow through the transmission.
- the parking pawl locks the output shaft to the case.
- the engine may be started.
- the ignition key may be removed.
Reverse
In the REVERSE position:
- the vehicle may be operated in a rearward direction, at a reduced gear ratio.
Neutral
In the NEUTRAL position:
- there is no powerflow through the transmission.
- the output shaft is not held and is free to turn.
- the engine may be started.
Overdrive
Overdrive is the normal position for most forward driving.
The OVERDRIVE position provides:
- automatic shifts.
- apply and release of the torque converter clutch.
- maximum fuel economy during normal operation.
Second Position-2nd Gear
This position provides:
- second gear start and hold.
- the torque converter clutch to apply and release.
- improved traction and engine baking on slippery roads.
First Position
If this position is selected at normal road speeds, the transmission will shift into second gear, then into first when the vehicle reaches a speed within 1st gear range. This position provides:
- first gear operation only.
- engine braking for descending steep grades.
Shift Patterns
Upshifts
NOTE: All gasoline vehicles will have new adaptive shift strategies. Whenever the vehicle's battery has been disconnected for any type of service or repair the strategy parameters that are stored in the Keep Alive Memory (KAM) will be lost. The strategy will start to relearn once the battery is reconnected and the vehicle is driven. This is a temporary condition and will return to normal operating condition once the Powertrain Control Module (PCM) relearns all the parameters from the driving conditions. There is no set time frame for this process. If a concern is present during downshifts or converter clutch apply, it is not the fault of the shift strategy and will require diagnosis.
The customer needs to be notified that they may experience slightly different upshifts either soft or firm and that this is a temporary condition and will eventually return to normal operating condition. Transmission upshifting is controlled by the (PCM). The PCM receives inputs from various engine or vehicle sensors and driver demands to control shift scheduling, shift feel and Torque Converter Clutch (TCC) operation.
Downshifts
Under certain conditions the transmission will downshift automatically to a lower gear range (without moving the transmission range selector lever). There are three categories of automatic downshifts; Coastdown, Torque Demand and Forced or Kickdown shifts.
Coastdown
The coastdown downshift occurs when the vehicle is coasting down to a stop.
Torque Demand
The torque demand downshift occurs (automatically) during part throttle acceleration when the demand for torque is greater than the engine can provide at that gear ratio.
Kickdown
For maximum acceleration, the driver can force a downshift by pressing the accelerator pedal to the floor. A forced downshift into a lower gear is possible below calibrated speeds. Specifications for downshift speeds are subject to variations due to tire size, engine and transmission calibration requirements.
Disassembled Views
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Item 53 - 99
Item 100 - 148
Item 149 - D
Item E - G
Transmission, Disassembled View
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Item 15 - 28
Bushings, Bearing and Thrust Washer Locator
Item 1 - 3
Item 4 - 33
Seals, Rings and Gasket Locator
Main Components and Functions
Item 1 - 14
Automatic Transmission-Sectional View
Torque Converter
The torque converter transmits and multiplies torque. The torque converter is a four-element device:
- Impeller assembly
- Turbine assembly
- Reactor assembly
- Clutch and damper assembly
The standard torque converter components operate as follows:
- Rotation of the converter housing and impeller set the fluid in motion.
- The turbine reacts to the fluid motion from the impeller, transferring rotation to the geartrain through the input shaft.
- The reactor redirects fluid going back into the impeller, providing for torque multiplication.
- The clutch and damper assembly dampens powertrain torsional vibration and provides a direct mechanical connection for improved efficiency.
- Power is transmitted from the torque converter to the planetary gearsets and other components through the input shaft.
Geartrain
Power is transmitted from the torque converter to the geartrain components through the input shaft and forward clutch cylinder.
- By holding or driving certain members of the gearset, four forward ratios and one reverse ratio are obtained and transmitted to the output shaft. The ratios are as follows:
Gear Ratio
Input Shaft
The input shaft is supported by two bushings in the stator support. End positioning of the input shaft is controlled by the splines in the converter turbine and the overdrive planet assembly.
Output Shaft
The output shaft is supported by two bushings in the case and by the slip-yoke and bushing in the extension housing. End positioning is controlled by the parking pawl gear and snap ring or shoulder and by the reverse ring gear hub and snap ring.
Overdrive System
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Item 14 - 16
The overdrive planetary system consists of the overdrive planet assembly, overdrive sun gear, overdrive ring gear, coast clutch cylinder, overdrive one-way clutch assembly and the center shaft, as shown in the following illustration. The overdrive planet assembly is spliced to the input shaft. The overdrive sun gear is centered by a bushing on the input shaft and held in place laterally by needle bearings on the reactor support and the overdrive planet assembly. The overdrive sun gear is splined to the coast clutch cylinder, which in turn is splined to the overdrive one-way clutch inner race.
The outer race of the one-way clutch is splined to the overdrive ring gear, which is splined to the center shaft. The center shaft is centered by the forward planetary assembly and is laterally held by needle bearings on the center support and the overdrive planet assembly. The center shaft is splined into the forward clutch cylinder.
Two friction clutches are assembled in the overdrive planet assembly. The coast clutch is splined between the coast clutch cylinder and the overdrive ring gear. The coast clutch is activated to carry out engine braking in MANUAL 1, MANUAL 2 and third gear with the transmission control switch engaged.
The overdrive clutch is splined between the case and the coast clutch cylinder. The overdrive clutch holds the coast clutch cylinder and, in turn, the overdrive sun gear, to permit the planet assembly to overdrive the ring gear.
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Item 13 - 22
Center Support and Intermediate/Overdrive Clutch Cylinder
The center support provides a pilot for the forward clutch and direct clutch cylinders. It also provides fluid for clutch application and lube flow. The center support is held radially and laterally by the case. Fluid supply enters through feed bolts into the center support and supplies the forward clutch and the intermediate lube circuits. The direct clutch is fed by the center support.
The intermediate/overdrive clutch cylinder is radially supported by the case. Laterally, the cylinder is held in the case by a snap ring. The overdrive circuit is fed through a feed bolt into the cylinder. The intermediate clutch circuit is fed through nearby orifices.
Forward Drive System
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Item 12 - 39
Forward Drive System Components
The forward drive system consists of the forward clutch cylinder, intermediate brake drum, intermediate one-way clutch, input shell, forward ring gear, forward ring gear hub, forward/reverse sun gear and the forward planetary carrier and forward planetary gears.
The forward clutch cylinder is splined on the center shaft. The forward ring gear is piloted on the forward ring gear hub. Thrust bearings on the forward planet assembly and forward clutch cylinder hold the forward ring gear hub in place.
The intermediate brake drum is radially supported by bushings on the center support and is laterally controlled by a thrust washer on the forward clutch cylinder and center support. The intermediate brake drum has the inner race of the intermediate one-way clutch press-fitted on it's pilot. The intermediate one-way clutch's outer race is splined to the intermediate friction clutch, which is spliced to the case. The intermediate brake drum has lugs that are slotted into the input shell to form a mechanical connection. The input shell is splined into the forward/reverse sun gear. The forward/reverse sun gear is common to two planetary gearsets. The forward planet is splined to the output shaft and is laterally positioned by needle bearings on the sun gear and on the forward clutch cylinder, as shown in the following illustration.
Two friction clutch assemblies, the direct clutch and the forward clutch, are shown with the forward planetary assembly. The direct clutch assembly splines the forward clutch cylinder to the intermediate brake drum. The forward clutch assembly splines the forward clutch cylinder to the forward ring gear. The forward clutch is activated during all forward gears. While in third or fourth gear, both the direct and forward clutches are applied to hold the forward planetary assembly and enable it to act as a solid shaft.
In second gear, the intermediate clutch assembly holds the forward/reverse sun gears. It is applied, along with the intermediate one-way clutch, to hold the intermediate brake drum, input shell and forward/reverse sun gear. In higher gears, the one-way clutch overruns.
Low and Reverse Drive System
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Item 11 - 12
The reverse planetary assembly consists of the reverse planetary carrier, reverse planet gears, the reverse ring gear, the reverse ring gear hub, the reverse clutch hub and the low-reverse one-way clutch assembly.
The reverse ring gear hub is splined to the output shaft and to the reverse ring gear. The reverse ring gear hub is laterally held by a needle bearing on the inner race of the low-reverse one-way clutch and a snap ring on the output shaft. The reverse planet assembly is splined to the low-reverse clutch hub. The low-reverse clutch hub is connected by the reverse clutch to the case. The inner race of the one-way clutch is bolted to the case.
The reverse clutch assembly is activated in REVERSE gear and in MANUAL 1.The reverse clutch bypasses the reverse one-way clutch during coast and MANUAL 1. The reverse clutch holds the reverse planet assembly in REVERSE gear to enable the sun gear to drive the reverse ring gear in the opposite direction.