Acura RL. Manual - part 230

control valve moves to the right side.

The manual valve is moved to P, and line pressure (1) becomes line pressure (3) at the manual valve. Line
pressure (3) passes through the reverse control valve, and becomes line pressure (3A), then flows to the servo
valve. Line pressure (3A) pushes the servo valve to the reverse position. Line pressure (3) flows to the manual
valve via the reverse CPC valve and shift valve A, and stops at the manual valve. Hydraulic pressure is not
applied the clutches.

Fig. 58: Hydraulic Pressure Flow Diagram (P Position)
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Lock-up System

The lock-up mechanism of the torque converter clutch operates in D (2nd, 3rd, 4th, and 5th), and D3 (2nd and
3rd). 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 the hydraulic control, the PCM optimizes the
timing and amount 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. The A/T clutch pressure control
solenoid valve C, the lock-up control valve, and lock-up timing valve control the amount of lock-up.

NOTE:

When used, "left" or "right" indicates direction on the hydraulic circuit.

2007 Acura RL

2005-08 TRANSMISSION Automatic Transmission - RL

Friday, June 05, 2009 1:18:11 PM

Page 91

Torque Converter Clutch Lock-up ON (Engaging Torque Converter Clutch)

Fluid in the chamber between the torque converter cover and the torque converter clutch piston is drained off,
and fluid entering from the chamber between the pump and stator exerts pressure through the torque converter
clutch piston against the torque converter cover. The torque converter clutch piston engages with the torque
converter cover; torque converter clutch lock-up ON, and the mainshaft rotates at the same speed as the engine.

Fig. 59: Power Flow Diagram (Torque Converter Clutch Lock-Up On /Engaging Torque Converter
Clutch)
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Torque Converter Clutch Lock-up OFF (Disengaging Torque Converter Clutch)

Fluid entered from the chamber between the torque converter cover and the torque converter clutch piston
passes through the torque converter and goes out from the chambers between the turbine and the stator, and
between the pump and the stator. As a result, the torque converter clutch piston moves away from the torque
converter cover, and the torque converter clutch lock-up is released; torque converter clutch lock-up OFF.

Fig. 60: Power Flow Diagram (Torque Converter Clutch Lock-Up Off /Disengaging Torque Converter
Clutch)
Courtesy of AMERICAN HONDA MOTOR CO., INC.

No Lock-up

2007 Acura RL

2005-08 TRANSMISSION Automatic Transmission - RL

Friday, June 05, 2009 1:18:11 PM

Page 92

The PCM commands shift solenoid valve D to remain OFF, and shift solenoid valve D covers the port of shift
solenoid valve D pressure (SD) to the lock-up shift valve. The lock-up shift valve is in the right side, and
uncover the port leading torque converter pressure (92) to the left side of the torque converter. Torque converter
pressure (92) from regulator valve becomes torque converter pressure (94) at the lock-up shift valve, and enters
into the left side of the torque converter to disengage the torque converter clutch. The torque converter clutch is
OFF.

Fig. 61: Power Flow Diagram (No Lock-Up)
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Partial Lock-up

As the speed of the vehicle reaches the programmed value, PCM turns shift solenoid valve D ON, and shift
solenoid valve D uncovers the port of shift solenoid valve D pressure (SD) to the lock-up shift valve. The lock-
up shift valve is moved to the left side to uncover the port of torque converter pressure (91) leading to the right
side of the torque converter to engage the torque converter clutch. The PCM also actuates A/T clutch pressure
control solenoid valve C, and A/T clutch pressure control solenoid valve C pressure (58) is applied to the lock-

NOTE:

When used, "left" or "right" indicates direction on the hydraulic circuit.

2007 Acura RL

2005-08 TRANSMISSION Automatic Transmission - RL

Friday, June 05, 2009 1:18:11 PM

Page 93

up control valve and lock-up timing valve. When A/T clutch pressure control solenoid valve C pressure (58) is
low, torque converter pressure (91) from the lock-up timing valve is low. The torque converter clutch is
engaged partially. A/T clutch pressure control solenoid valve C pressure (58) increases, and the lock-up timing
valve is moved to the left side to uncover the port leading torque converter pressure to high. Under this
condition, the torque converter clutch is engaged by pressure from the right side of the torque converter; this
condition is partial lock-up.

Fig. 62: Power Flow Diagram (Partial Lock-Up)
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Full Lock-up

When the vehicle speed further increases, the PCM actuates A/T clutch pressure control solenoid valve C to
increase A/T clutch pressure control solenoid valve C pressure (58). A/T clutch pressure control solenoid valve
C pressure (58) is applied to the lock-up control valve and lock-up timing valve, and the lock-up control valve
and lock-up timing valve are moved to the left side. Torque converter pressure (94) from the left side of the
torque converter releases at the lock-up control valve, and lock-up timing valve uncovers the port of torque

NOTE:

When used, "left" or "right" indicates direction on the hydraulic circuit.

2007 Acura RL

2005-08 TRANSMISSION Automatic Transmission - RL

Friday, June 05, 2009 1:18:11 PM

Page 94

Content .. 228 229 230 231 ..