DODGE RAM 2001 Service Repair Manual

PRESSURE
Pressure (Fig. 189) is nothing more than force
(lbs.) divided by area (in or ft.), or force per unit
area. Given a 100 lb. block and an area of 100 sq. in.
on the floor, the pressure exerted by the block is: 100
lbs. 100 in or 1 pound per square inch, or PSI as it is
commonly referred to.
PRESSURE ON A CONFINED FLUID
Pressure is exerted on a confined fluid (Fig. 190)
by applying a force to some given area in contact
with the fluid. A good example of this is a cylinder
filled with fluid and equipped with a piston that is
closely fitted to the cylinder wall. If a force is applied
to the piston, pressure will be developed in the fluid.
Of course, no pressure will be created if the fluid is
not confined. It will simply ªleakº past the piston.
There must be a resistance to flow in order to create
pressure. Piston sealing is extremely important in
hydraulic operation. Several kinds of seals are used
to accomplish this within a transmission. These
include but are not limited to O-rings, D-rings, lip
seals, sealing rings, or extremely close tolerances
between the piston and the cylinder wall. The force
exerted is downward (gravity), however, the principle
remains the same no matter which direction is taken.
The pressure created in the fluid is equal to the force
applied, divided by the piston area. If the force is 100
lbs., and the piston area is 10 sq. in., then the pres-
sure created equals 10 PSI. Another interpretation of
Pascal's Law is that regardless of container shape or
size, the pressure will be maintained throughout, as
long as the fluid is confined. In other words, thepressure in the fluid is the same everywhere within
the container.
FORCE MULTIPLICATION
Using the 10 PSI example used in the illustration
(Fig. 191), a force of 1000 lbs. can be moved with a
force of only 100 lbs. The secret of force multiplica-
tion in hydraulic systems is the total fluid contact
area employed. The illustration, (Fig. 191), shows an
area that is ten times larger than the original area.
The pressure created with the smaller 100 lb. input
is 10 PSI. The concept ªpressure is the same every-
whereº means that the pressure underneath the
larger piston is also 10 PSI. Pressure is equal to the
force applied divided by the contact area. Therefore,
by means of simple algebra, the output force may be
found. This concept is extremely important, as it is
also used in the design and operation of all shift
valves and limiting valves in the valve body, as well
as the pistons, of the transmission, which activate
the clutches and bands. It is nothing more than
using a difference of area to create a difference in
pressure to move an object.
PISTON TRAVEL
The relationship between hydraulic lever and a
mechanical lever is the same. With a mechanical
lever it's a weight-to-distance output rather than a
pressure-to-area output. Using the same forces and
areas as in the previous example, the smaller piston
(Fig. 192) has to move ten times the distance
required to move the larger piston one inch. There-
fore, for every inch the larger piston moves, the
smaller piston moves ten inches. This principle is
true in other instances also. A common garage floor
jack is a good example. To raise a car weighing 2000
lbs., an effort of only 100 lbs. may be required. For
every inch the car moves upward, the input piston at
the jack handle must move 20 inches downward.
Fig. 189 Force and Pressure Relationship
Fig. 190 Pressure on a Confined Fluid
21 - 756 AUTOMATIC TRANSMISSION - 47REBR/BE
PISTONS (Continued)

PLANETARY GEARTRAIN/
OUTPUT SHAFT
DESCRIPTION
The planetary gearsets (Fig. 193) are designated as
the front, rear, and overdrive planetary gear assem-
blies and located in such order. A simple planetary
gearset consists of three main members:
²The sun gear which is at the center of the sys-
tem.
²The planet carrier with planet pinion gears
which are free to rotate on their own shafts and are
in mesh with the sun gear.²The annulus gear, which rotates around and is
in mesh with the planet pinion gears.
NOTE: The number of pinion gears does not affect
the gear ratio, only the duty rating.
OPERATION
With any given planetary gearset, several condi-
tions must be met for power to be able to flow:
²One member must be held.
²Another member must be driven or used as an
input.
²The third member may be used as an output for
power flow.
²For direct drive to occur, two gear members in
the front planetary gearset must be driven.
NOTE: Gear ratios are dependent on the number of
teeth on the annulus and sun gears.
DISASSEMBLY
(1) Remove planetary snap-ring from intermediate
shaft (Fig. 194). Discard snap-ring as it is not reus-
able.
(2) Remove front planetary gear and front annulus
gear as assembly (Fig. 195).
(3) Remove front planetary gear and thrust
washer from front annulus gear (Fig. 196). Note
thrust washer position for assembly reference.
(4) Remove tabbed thrust washer from driving
shell (Fig. 197). Note washer position for assembly
reference.
(5) Remove sun gear and driving shell as assembly
(Fig. 198).
Fig. 191 Force Multiplication
Fig. 192 Piston Travel
Fig. 193 Planetary Gearset
1 - ANNULUS GEAR
2 - SUN GEAR
3 - PLANET CARRIER
4 - PLANET PINIONS (4)
BR/BEAUTOMATIC TRANSMISSION - 47RE 21 - 757
PISTONS (Continued)

Fig. 194 Removing Planetary Snap-Ring
1 - PLANETARY SNAP-RING
Fig. 195 Removing Front Planetary And Annulus
Gears
1 - DRIVING SHELL
2 - FRONT ANNULUS GEAR
3 - FRONT PLANETARY GEAR
Fig. 196 Disassembling Front Planetary And
Annulus Gears
1 - FRONT PLANETARY GEAR
2 - TABBED THRUST WASHER
3 - FRONT ANNULUS GEAR
Fig. 197 Driving Shell Thrust Washer Removal
1 - DRIVING SHELL
2 - TABBED THRUST WASHER
3 - SUN GEAR
21 - 758 AUTOMATIC TRANSMISSION - 47REBR/BE
PLANETARY GEARTRAIN/OUTPUT SHAFT (Continued)

(6) Remove tabbed thrust washer from rear plane-
tary gear (Fig. 199). Note washer position on gear for
assembly reference.
(7) Remove rear planetary gear and rear annulus
gear from intermediate shaft (Fig. 200).
(8) Remove thrust plate from rear annulus gear
(Fig. 201).
Fig. 198 Sun Gear And Driving Shell Removal
1 - INTERMEDIATE SHAFT
2 - DRIVING SHELL
3 - SUN GEAR
Fig. 199 Rear Planetary Thrust Washer Removal
1 - SUN GEAR
2 - REAR PLANETARY THRUST WASHER
3 - DRIVING SHELL
Fig. 200 Rear Planetary And Annulus Gear Removal
1 - INTERMEDIATE SHAFT
2 - REAR ANNULUS GEAR
3 - REAR PLANETARY GEAR
Fig. 201 Rear Annulus Thrust Plate Removal
1 - REAR ANNULUS GEAR
2 - THRUST PLATE
BR/BEAUTOMATIC TRANSMISSION - 47RE 21 - 759
PLANETARY GEARTRAIN/OUTPUT SHAFT (Continued)

INSPECTION
Inspect the planetary gear sets and annulus gears.
The planetary pinions, shafts, washers, and retaining
pins are serviceable. However, if a pinion carrier is
damaged, the entire planetary gear set must be
replaced as an assembly.
Replace the annulus gears if the teeth are chipped,
broken, or worn, or the gear is cracked. Replace the
planetary thrust plates and the tabbed thrust wash-
ers if cracked, scored or worn.
Inspect the machined surfaces of the intermediate
shaft. Be sure the oil passages are open and clear.
Replace the shaft if scored, pitted, or damaged.
Inspect the sun gear and driving shell. If either
component is worn or damaged, remove the sun gear
rear retaining ring and separate the sun gear and
thrust plate from the driving shell. Then replace the
necessary component.
Replace the sun gear as an assembly if the gear
teeth are chipped or worn. Also replace the gear as
an assembly if the bushings are scored or worn. The
sun gear bushings are not serviceable. Replace the
thrust plate if worn, or severely scored. Replace the
driving shell if distorted, cracked, or damaged in any
way.
Replace all snap-rings during geartrain assembly.
Reusing snap-rings is not recommended.
ASSEMBLY
(1) Lubricate sun gear and planetary gears with
transmission fluid during assembly. Use petroleum
jelly to lubricate intermediate shaft bushing surfaces,
thrust washers and thrust plates and to hold these
parts in place during assembly.
(2) Install front snap-ring on sun gear and install
gear in driving shell. Then install thrust plate over
sun gear and against rear side of driving shell (Fig.
202). Install rear snap-ring to secure sun gear and
thrust plate in driving shell.
(3) Install rear annulus gear on intermediate shaft
(Fig. 203).
(4) Install thrust plate in annulus gear (Fig. 204).
Be sure plate is seated on shaft splines and against
gear.
Fig. 202 Sun Gear Installation
1 - DRIVING SHELL
2 - SUN GEAR
3 - THRUST PLATE
4 - SUN GEAR REAR RETAINING RING
Fig. 203 Installing Rear Annulus Gear On
Intermediate Shaft
1 - REAR ANNULUS GEAR
2 - OUTPUT SHAFT
21 - 760 AUTOMATIC TRANSMISSION - 47REBR/BE
PLANETARY GEARTRAIN/OUTPUT SHAFT (Continued)

(5) Install rear planetary gear in rear annulus
gear (Fig. 205). Be sure planetary carrier is seated
against annulus gear.
(6) Install tabbed thrust washer on front face of
rear planetary gear (Fig. 206). Seat washer tabs in
matching slots in face of gear carrier. Use extra
petroleum jelly to hold washer in place if desired.
(7) Lubricate sun gear bushings with petroleum
jelly or transmission fluid.
(8) Install sun gear and driving shell on interme-
diate shaft (Fig. 207). Seat shell against rear plane-
tary gear. Verify that thrust washer on planetary
gear was not displaced during installation.
(9) Install tabbed thrust washer in driving shell
(Fig. 208), be sure washer tabs are seated in tab slots
of driving shell. Use extra petroleum jelly to hold
washer in place if desired.
(10) Install tabbed thrust washer on front plane-
tary gear (Fig. 209). Seat washer tabs in matching
slots in face of gear carrier. Use extra petroleum jelly
to hold washer in place if desired.
Fig. 204 Installing Rear Annulus Thrust Plate
1 - REAR ANNULUS GEAR
2 - THRUST PLATE
Fig. 205 Installing Rear Planetary Gear
1 - REAR ANNULUS GEAR
2 - REAR PLANETARY GEAR
Fig. 206 Installing Rear Planetary Thrust Washer
1 - REAR PLANETARY GEAR
2 - TABBED THRUST WASHER
BR/BEAUTOMATIC TRANSMISSION - 47RE 21 - 761
PLANETARY GEARTRAIN/OUTPUT SHAFT (Continued)

(11) Install front annulus gear over and onto front
planetary gear (Fig. 210). Be sure gears are fully
meshed and seated.
(12) Install front planetary and annulus gear
assembly (Fig. 211). Hold gears together and slide
them onto shaft. Be sure planetary pinions are
seated on sun gear and that planetary carrier is
seated on intermediate shaft.
(13) Place geartrain in upright position. Rotate
gears to be sure all components are seated and prop-
erly assembled. Snap-ring groove at forward end of
intermediate shaft will be completely exposed when
components are assembled correctly.
(14) Install new planetary snap-ring in groove at
end of intermediate shaft (Fig. 212).
(15) Turn planetary geartrain over. Position wood
block under front end of intermediate shaft and sup-
port geartrain on shaft. Be sure all geartrain parts
have moved forward against planetary snap-ring.
This is important for accurate end play check.
(16) Check planetary geartrain end play with
feeler gauge (Fig. 213). Insert gauge between rear
annulus gear and shoulder on intermediate shaft as
shown. End play should be 0.15 to 1.22 mm (0.006 to
0.048 in.).
(17) If end play is incorrect, install thinner/thicker
planetary snap-ring as needed.
Fig. 207 Installing Sun Gear And Driving Shell
1 - OUTPUT SHAFT
2 - DRIVING SHELL
3 - REAR PLANETARY GEAR
4 - OUTPUT SHAFT
5 - SUN GEAR
Fig. 208 Installing Driving Shell Thrust Washer
1 - TAB SLOTS (3)
2 - DRIVING SHELL
3 - TABBED THRUST WASHER
Fig. 209 Installing Thrust Washer On Front
Planetary Gear
1 - TABBED THRUST WASHER
2 - FRONT PLANETARY GEAR
21 - 762 AUTOMATIC TRANSMISSION - 47REBR/BE
PLANETARY GEARTRAIN/OUTPUT SHAFT (Continued)

Fig. 210 Assembling Front Planetary And Annulus
Gears
1 - FRONT ANNULUS GEAR
2 - FRONT PLANETARY GEAR
Fig. 211 Installing Front Planetary And Annulus
Gear Assembly
1 - DRIVING SHELL
2 - ASSEMBLED FRONT PLANETARY AND ANNULUS GEARS
Fig. 212 Installing Planetary Snap-Ring
1 - SNAP-RING PLIERS
2 - PLANETARY SNAP-RING
Fig. 213 Checking Planetary Geartrain End Play
1 - OUTPUT SHAFT
2 - REAR ANNULUS GEAR
3 - FEELER GAUGE
BR/BEAUTOMATIC TRANSMISSION - 47RE 21 - 763
PLANETARY GEARTRAIN/OUTPUT SHAFT (Continued)

REAR CLUTCH
DESCRIPTION
The rear clutch assembly (Fig. 214) is composed of
the rear clutch retainer, pressure plate, clutch plates,
driving discs, piston, Belleville spring, and snap-
rings. The Belleville spring acts as a lever to multi-
ply the force applied on to it by the apply piston. The
increased apply force on the rear clutch pack, in com-
parison to the front clutch pack, is needed to hold
against the greater torque load imposed onto the rear
pack. The rear clutch is directly behind the front
clutch and is considered a driving component.
NOTE: The number of discs and plates may vary
with each engine and vehicle combination.
OPERATION
To apply the clutch, pressure is applied between
the clutch retainer and piston. The fluid pressure is
provided by the oil pump, transferred through the
control valves and passageways, and enters theclutch through the hub of the reaction shaft support.
With pressure applied between the clutch retainer
and piston, the piston moves away from the clutch
retainer and compresses the clutch pack. This action
applies the clutch pack, allowing torque to flow
through the input shaft into the driving discs, and
into the clutch plates and pressure plate that are
lugged to the clutch retainer. The waved spring is
used to cushion the application of the clutch pack.
The snap-ring is selective and used to adjust clutch
pack clearance.
When pressure is released from the piston, the
spring returns the piston to its fully released position
and disengages the clutch. The release spring also
helps to cushion the application of the clutch assem-
bly. When the clutch is in the process of being
released by the release spring, fluid flows through a
vent and one-way ball-check-valve located in the pis-
ton. The check-valve is needed to eliminate the pos-
sibility of plate drag caused by centrifugal force
acting on the residual fluid trapped in the clutch pis-
ton retainer.
Fig. 214 Rear Clutch Components
1 - REAR CLUTCH RETAINER 11 - REACTION PLATE
2 - TORLONŸ SEAL RINGS 12 - CLUTCH PLATES
3 - INPUT SHAFT 13 - WAVE SPRING
4 - PISTON RETAINER 14 - SPACER RING
5 - OUTPUT SHAFT THRUST WASHER 15 - PISTON
6 - INNER PISTON SEAL 16 - OUTER PISTON SEAL
7 - PISTON SPRING 17 - REAR SEAL RING
8 - PRESSURE PLATE 18 - FIBER THRUST WASHER
9 - CLUTCH DISCS 19 - RETAINING RING
10 - SNAP-RING (SELECTIVE)
21 - 764 AUTOMATIC TRANSMISSION - 47REBR/BE

DISASSEMBLY
(1) Remove fiber thrust washer from forward side
of clutch retainer.
(2) Remove input shaft front and rear seal rings.
(3) Remove selective clutch pack snap-ring (Fig.
215).
(4) Remove the reaction plate, clutch discs, steel
plates, pressure plate, wave spring, spacer ring, and
piston spring (Fig. 215).
(5) Remove clutch piston with rotating motion.
(6) Remove and discard piston seals.
(7) Remove input shaft retaining ring. It may be
necessary to press the input shaft in slightly to
relieve tension on the retaining ring
(8) Press input shaft out of retainer with shop
press and suitable size press tool. Use a suitably
sized press tool to support the retainer as close to the
input shaft as possible.
CLEANING
Clean the clutch components with solvent and dry
them with compressed air. Do not use rags or shoptowels to dry any of the clutch parts. Lint from such
materials will adhere to component surfaces and
could restrict or block fluid passages after assembly.
INSPECTION
Replace the clutch discs if warped, worn, scored,
burned/charred, the lugs are damaged, or if the fac-
ing is flaking off. Replace the top and bottom pres-
sure plates if scored, warped, or cracked. Be sure the
driving lugs on the pressure and clutch plates are
also in good condition. The lugs must not be bent,
cracked or damaged in any way.
Replace the piston spring and wave spring if either
part is distorted, warped or broken.
Check the lug grooves in the clutch retainer. The
clutch and pressure plates should slide freely in the
slots. Replace the retainer if the grooves are worn or
damaged. Also check action of the check balls in the
retainer and piston. Each check ball must move
freely and not stick.
Replace the retainer bushing if worn, scored, or
doubt exists about bushing condition.
Fig. 215 Rear Clutch Components
1 - REAR CLUTCH RETAINER 11 - REACTION PLATE
2 - TORLONŸ SEAL RINGS 12 - CLUTCH PLATES
3 - INPUT SHAFT 13 - WAVE SPRING
4 - PISTON RETAINER 14 - SPACER RING
5 - OUTPUT SHAFT THRUST WASHER 15 - PISTON
6 - INNER PISTON SEAL 16 - OUTER PISTON SEAL
7 - PISTON SPRING 17 - REAR SEAL RING
8 - PRESSURE PLATE 18 - FIBER THRUST WASHER
9 - CLUTCH DISCS 19 - RETAINING RING
10 - SNAP-RING (SELECTIVE)
BR/BEAUTOMATIC TRANSMISSION - 47RE 21 - 765
REAR CLUTCH (Continued)