Acura RL. Instruction — page 216

Fig. 13: Identifying Automatic Transmission System Components Location
Courtesy of AMERICAN HONDA MOTOR CO., INC.

SYSTEM DESCRIPTION

General Operation

The automatic transmission is a combination of a three-element torque converter and a four-shaft electronically
controlled unit which provides five forward speeds and one in reverse. The entire unit is positioned in line with
the engine.

2007 Acura RL

2005-08 TRANSMISSION Automatic Transmission — RL

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Torque Converter, Shafts, Gears, and Clutches

The torque converter consists of a pump, turbine, and stator assembly in a single unit. The converter housing
(pump) is connected to the engine crankshaft and turns as the engine turns. Around the outside of the torque
converter is a ring gear which meshes with the starter pinion when the engine is being started. The entire torque
converter assembly serves as a flywheel, transmitting power to the transmission mainshaft. The transmission
has four parallel shafts; the mainshaft, the countershaft, the secondary shaft, and the intermediary shaft. The
mainshaft is in line with the engine crankshaft. The mainshaft includes the 4th and 5th clutches, and gears for
3rd, 4th, 5th, and reverse (reverse gear is integral with 5th gear). The countershaft includes gears for the final
drive, 2nd, idler, 1st, 4th, 5th, and reverse (the final drive gear is integral with the countershaft). The secondary
shaft includes the 1st, 1st-hold, and 2nd clutches, and gears for park, 2nd, idler, and 1st. The intermediary shaft
includes the 3rd clutch, and gears for 3rd and 4th. The countershaft 5th gear and the countershaft reverse gear
can be locked to the countershaft at its left end, providing 5th gear or reverse, depending with which way the
selector is moved. The gears on the mainshaft, secondary shaft, and intermediary shaft are in constant mesh
with those on the countershaft. When certain conditions of gears in the transmission are engaged by the
clutches, power is transmitted through the mainshaft, and/or to the secondary shaft, intermediary shaft, then to
the countershaft to provide drive.

Electronic Control

The electronic control system consists of the powertrain control module (PCM), sensors, and seven solenoid
valves. Shifting and lock-up are electronically controlled for comfortable driving under all conditions. The
PCM is located behind the driver’s dashboard cover.

Hydraulic Control

The valve bodies include the main valve body, the regulator valve body, the secondary valve body, and the
accumulator body. They are bolted to the torque converter housing. The main valve body: ’05 model contains
the manual valve, the modulator valve, shift valves A, B, and E, CPC valve A, the servo control valve, the
lubrication check valve, the lubrication control valve, the torque converter check valve, the lock-up timing
valve, the relief valve, the lock-up shift valve, the cooler check valve, and the ATF pump gears; ’06-08 models
contain the manual valve, the modulator valve, shift valves A, B, and E, CPC valve A, the servo control valve,
the lubrication check valve, the lubrication control valve, the torque converter check valve, the lock-up timing
valve, the relief valve, the lock-up shift valve, and the ATF pump gears. The regulator valve body: ’05 model
contains the regulator valve, the lock-up control valve, the servo valve, and the 3rd accumulator; ’06-08 models
contain the regulator valve, the cooler check valve, the lock-up control valve, the servo valve, and the 3rd
accumulator. The secondary valve body contains shift valves C and D, CPC valves B and C, the reverse CPC
valve, and the reverse control valve. The accumulator body contains the 1st, 1st-hold, 2nd, 4th, and 5th
accumulators, shift solenoid valves A, B, C, and D. Fluid from the regulator valve passes through the manual
valve to the various control valves. All the clutch receive fluid from the internal hydraulic circuit.

Shift Control Mechanism

To shift gears, the PCM controls shift solenoid valves A, B, C, and D, and automatic transmission (A/T) clutch
pressure control solenoid valves A, B, and C, while receiving input signals from various sensors and switches
located throughout the vehicle. The shift solenoid valves shift the positions of the shift valves to switch the port
to send hydraulic pressure to the clutches. A/T clutch pressure control solenoid valves A, B, and C control CPC
valves A and B, and the reverse CPC valve to shift smoothly between lower and higher gears. This pressurizes a

2007 Acura RL

2005-08 TRANSMISSION Automatic Transmission — RL

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line to one of the clutches, engaging the clutch and its corresponding gear.

Lock-up Mechanism

The lock-up mechanism operates in 2nd, 3rd, 4th, and 5th gears in D, and in 2nd and 3rd gears in the D3. The
pressurized fluid is drained from the back of the torque converter through a fluid passage, causing the torque
converter clutch piston to be held against the torque converter cover. As this takes place, the mainshaft rotates at
the same speed as the engine crankshaft. Together with hydraulic control, the PCM optimizes the timing and
volume of the lock-up mechanism. When shift solenoid valve D is turned on by the PCM, shift solenoid valve D
pressure switches the lock-up shift valve lock-up on and off. A/T clutch pressure control solenoid valve C, the
lock-up control valve, and the lock-up timing valve control the amount of the lock-up conditions. Shift solenoid
valve D is located on the accumulator body in the transmission, and A/T clutch pressure control solenoid valve
C is mounted on the transmission housing.

Gear Selection

The shift lever has five positions; P: PARK, R: REVERSE, N: NEUTRAL, D: DRIVE 1st through 5th gear
range with automatic shift and sequential sport shift in M (sequential sport shift mode), and D3: DRIVE 1st
through 3rd gear range with automatic shift.

SHIFT LEVER POSITION

Position

Description

P: PARK

Front wheels locked; park pawl
engaged with park gear on
secondary shaft. All clutches are
released.

R: REVERSE

Reverse; reverse selector engaged
with countershaft reverse gear and
5th clutch engaged.

N: NEUTRAL

All clutches are released.

D: DRIVE (1st through 5th)

Automatic shift mode

General driving; starts off in 1st,
shifts automatically to 2nd, 3rd,
4th, then 5th, depending on vehicle
speed and accelerator pedal
position. Downshifts through 4th,
3rd, 2nd, and 1st on deceleration to
stop. The lock-up mechanism
operates in 2nd, 3rd, 4th, and 5th
gears.

M: Sequential sport shift mode

Manual gear shift driving; vehicle
can start off in 1st gear, and does
not upshift automatically. Vehicle
can also start off in 2nd gear, and
does not upshift and downshift
automatically. Downshifts
automatically to 1st on
deceleration to stop. The lock-up

2007 Acura RL

2005-08 TRANSMISSION Automatic Transmission — RL

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Starting is possible only in P and N because of a slide-type neutral-safety switch.

Automatic Transmission (A/T) Gear Position Indicator

The A/T gear position indicator in the gauge control module shows which shift lever position has been selected
without having look down at the console.

Shift Indicator and M indicator

When the shift lever is shifted into M (sequential sportshift mode), the M indicator next to the D indicator
comes on, and the shift indicator at the bottom of the tachometer displays the gear selected.

Transfer Assembly

The transfer assembly consists of the transfer drive gear on the differential, the transfer output shaft in the
transmission, the transfer drive gear (hypoid gear), the transfer shaft, the transfer output shaft (hypoid gear), and
the companion flange. The transfer assembly is on the rear side of the transmission, beside the differential. The
transfer drive gear on the differential drives the transfer output shaft in the transmission. The transfer output
shaft in the transmission is connected to the transfer drive gear (hypoid gear) by splines. Power is transmitted
from the transfer drive gear on the differential to the rear differential via the transfer assembly and the propeller
shaft.

Clutches and Gears

The five-speed automatic transmission uses hydraulically-actuated clutches to engage or disengage the
transmission gears. When hydraulic pressure is introduced into the clutch drum, the clutch piston moves. This
presses the friction discs and steel plates together, locking them so they don’t slip. Power is then transmitted
through the engaged clutch pack to its hub-mounted gear. Likewise, when the hydraulic pressure is bled from
the clutch pack, the piston releases the friction discs and the steel plates, and they are free to slide past each
other. This allows the gear to spin independently on its shaft, transmitting no power.

mechanism operates in 2nd, 3rd,
4th, and 5th gears.

D3: DRIVE (1st through 3rd)

Used for rapid acceleration at
highway speeds and general
driving, up-hill and down-hill
driving; starts off in 1st, shifts
automatically to 2nd, then 3rd,
depending on vehicle speed and
accelerator pedal position.
Downshifts through 2nd and 1st on
deceleration to stop. The lock-up
mechanism operates in 2nd and
3rd gears.

2007 Acura RL

2005-08 TRANSMISSION Automatic Transmission — RL

me

Friday, June 05, 2009 1:18:10 PM

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© 2005 Mitchell Repair Information Company, LLC.

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