Fluid Pressure Control

FLUID PRESSURE CONTROL
VALVE BODY

The valve body with built-in valves to control fluid pressure is located in the oil pan. These valves are connected through fluid passages.

VALVE FUNCTION
MANUAL VALVE

This valve switches the fluid passage. As it is connected with the shift lever at the driver's seat through a linkage, it selects a fluid passage corresponding to each range of "P", "R", "N", "D", "2" or "L" as selected by the shift lever.

PRIMARY REGULATOR VALVE

This valve adjusts the fluid pressure to each element automatically so that an optimum pressure is obtained based on the vehicle speed and engine load (throttle valve opening) then and unnecessary power loss by the pump is avoided.

SECONDARY REGULATOR VALVE

This valve adjusts the converter pressure, lubricating fluid pressure and cooler pressure so that an optimum pressure is obtained based on the vehicle speed and engine load (throttle valve opening) then.

INTERMEDIATE COAST MODULATOR VALVE

This valve adjusts the line pressure and operates the second coast brake piston so as to relieve a shock which occurs when the engine brake works in the "2" range second gear.

LOW COAST MODULATOR VALVE

This valve adjusts the line pressure applied to it in the "L" range to the low fluid pressure (low modulator pressure) which is then applied through the low coast shift valve to the reverse brake so that a shock is relieved.

REVERSE CLUTCH SEQUENCE VALVE

This valve, controlled by the line pressure which is applied to the direct clutch outer piston, relieves a shock which occurs when the shift lever is shifted to "R" range. In "R" range, the line pressure is applied to A and B passages simultaneously. However, it is not until the fluid pressure in the A passage which is applied to this valve, or the line pressure on the direct clutch piston, exceeds the valve spring force that the B passage opens. Thus, the direct clutch inner piston operates later than the direct clutch piston.

In the "D" range 3rd gear, only the outer piston operates because the B passage is closed by the manual valve.

CUT BACK VALVE

This valve adjusts the cut back pressure which is applied to the throttle valve. It is controlled by the line pressure from 1 -2 shift valve and throttle pressure. When the cut back pressure is applied to the throttle valve, the throttle pressure is reduced to prevent unnecessary power loss.

ACCUMULATOR

An accumulator is installed to the forward clutch, direct clutch and second brake to relieve a shock which occurs when each of them operates. There is an area difference between the working pressure side and the back pressure side of the accumulator piston, with the former larger. The line pressure is applied to the back pressure side all the time and the piston is pushed down. When the passage to the working pressure side piston opens and the line pressure is applied, the piston is pushed upward gradually to relieve the shock at the gear shift.

SHIFT SOLENOID VALVE A (#1) AND B (#2) (SOLENOID VALVE NO.1)

As the shift solenoid valve-A (#1) is turned ON and OFF, 2-3 gear shift takes place automatically.

As shift solenoid valve-B (#2) is turned ON and OFF, 1-2 and 3-4 gear shifts take place automatically.

THROTTLE VALVE

The throttle valve produces the throttle pressure which corresponds to the engine load, that is, how far the accelerator pedal is depressed. Movement of the accelerator pedal is transmitted through the throttle cable connected to the accelerator pedal to the throttle cam which pushes the down shift plug according to how far the pedal is depressed.
Then 2 springs in the front and rear are compressed to move the throttle valve. As the valve opens the line pressure passage, the throttle pressure occurs. As this throttle pressure also acts on the back of the valve, the throttle valve is pushed back by it and when the down shift plug comes to the position where the tension of two springs is balanced, the throttle valve closes the line pressure passage.
In this way, the throttle pressure causes rise of the fluid pressure corresponding to the throttle valve opening. This fluid pressure is applied to the primary regulator valve and secondary regulator valve to adjust the line pressure.

1-2 SHIFT VALVE

As the shift solenoid valve-B is turned ON and OFF, switching between the first gear and second gear is controlled automatically.
In the first gear, the shift solenoid valve-B is turned OFF and the line pressure in the A passage is applied to the valve to move so as to close the passage to the second brake. When the shift solenoid valve-B turns ON, the line pressure in the A passage is drained and the valve moves by the spring force to open the passage to the second brake, resulting in the second gear.
In "2" and "L" ranges, the line pressure is applied through the B passage and it acts on the second coast brake through the intermediate modulator valve only when the valve is in the second position to actuate the engine brake in the second gear. In "L" range, the line pressure is applied through the C passage and it acts on the reverse brake only when the valve is in the first gear position to actuate the engine brake in the first gear.

2-3 SHIFT VALVE

As the shift solenoid valve-A is turned ON and OFF, the gear change between the second gear and the third gear is controlled automatically.
In the second gear, the shift solenoid valve-A is turned ON and the line pressure in the A passage is drained and the passage to the direct clutch is closed.
When the shift solenoid valve-A is turned OFF, the line pressure from the A passage is applied to the valve to open the passage to the direct clutch, resulting in the third gear.

3-4 SHIFT VALVE

As the shift solenoid valve-B is turned ON and OFF, switching between the third gear and O/D gear is controlled automatically.
In the third gear, as the shift solenoid valve-B is turned ON and the line pressure in the A passage is drained, the passage to the O/D clutch is opened and the passage to the O/D brake is closed.
When the shift solenoid valve-B is turned OFF, the line pressure in the A passage is applied to the valve to move, thereby closing the O/D clutch passage and opening the O/D brake passage is opened, resulting in the O/D gear.
Also, in the first gear, the shift solenoid valve-B is turned OFF. As the line pressure is applied to the valve through the A passage as well as through the B passage, it is held stationary and thus the passage is not switched between the O/D clutch and the O/D brake.

FLUID PRESSURE OPERATION

1. "D" or "2" Range First Gear
The discharge pressure from the oil pump is regulated to the line pressure by the primary regulator valve and applied to the manual valve, throttle valve, each accumulator and TCC (lock-up) control valve.
The line pressure fed to the manual valve works on the accumulator to engage the forward clutch. On the other hand, the line pressure passes though the primary regulator valve and 3-4 shift valve to engage the O/D clutch.
The line pressure fed to the throttle valve is converted into the throttle pressure, works on the primary regulator valve again to adjust the pressure to the line pressure suitable for the throttle opening. Also, the throttle pressure fed to the secondary regulator valve is converted into the secondary regulator pressure, fed to the torque converter and used for lubrication.

2. "D" Range Second Gear

The discharge pressure from the oil pump is regulated to the line pressure by the primary regulator valve and applied to the manual valve, throttle valve, each accumulator and TCC (lock-up) control valve.
The line pressure fed to the manual valve works on the accumulator to engage the forward clutch. On the other hand, the line pressure passes through the primary regulator valve and 3-4 shift valve to engage the O/D clutch.
Also, the line pressure fed to the 1-2 shift valve is applied to the accumulator through the passage to the second brake which is opened when the shift solenoid valve B turns ON and the 1-2 shift valve moves to the left, to cause the second brake to be engaged.
The line pressure fed to the throttle valve is converted into the throttle pressure, applied to the primary regulator valve again and adjusted to the line pressure suitable to that throttle opening.
The throttle pressure fed to the secondary regulator valve is converted to the secondary regulator pressure, fed to the torque converter and used for lubrication.

3. "D" Range Third Gear

The discharge pressure from the oil pump is regulated to the line pressure by the primary regulator valve and applied to the manual valve, throttle valve, each accumulator and TCC (lock-up) control valve.
The line pressure fed to the manual valve works on the forward clutch accumulator to engage the forward clutch.
On the other hand, the line pressure passes from the primary regulator valve, through the 3-4 shift valve to engage the O/D clutch.
Also, the line pressure fed to the 1-2 shift valve passes through the passage to the second brake which is opened when the shift solenoid valve B is turned ON to cause the 1-2 shift valve to move to the left and is applied to the second brake accumulator to engage the second braked The line pressure fed to the 2-3 shift valve passes through the passage to the direct clutch which is opened when the shift solenoid valve A is turned OFF to cause the valve to move to the left and is applied to the direct clutch accumulator to engage the direct clutch.
The line pressure fed to the throttle valve is converted into the throttle pressure and applied to the primary regulator valve again and adjusted to the line pressure suitable to that throttle opening.
The throttle pressure fed to the secondary regulator valve is converted to the secondary regulator pressure, fed to the torque converter and used for lubrication.

4. "D" Range Fourth Gear (Over Drive)

The discharge pressure from the oil pump is regulated to the line pressure by the primary regulator valve and applied to the manual valve, throttle valve, each accumulator and TCC(lock-up) control valve.
The line pressure fed to the manual valve works on the forward clutch accumulator to engage the forward clutch.
On the other hand, the line pressure fed from the primary regulator valve to the 3-4 shift valve turns OFF the shift solenoid valve B. thereby the valve moves to open the passage to the O/D brake and thus the O/D brake is engaged. The line pressure fed to the 1-2 shift valve turns OFF the shift solenoid valve B but as the line pressure is also applied through the 2-3 shift valve to the valve from the left to the right, it does not move to the left.
Thus, the line pressure is applied to the second brake accumulator and the second brake gets engaged.
Also, the line pressure fed to the 2-3 shift valve is applied to the direct clutch accumulator to engage the direct clutch.
The line pressure fed to the throttle valve is converted in the throttle pressure and applied to the primary regulator valve and adjusted to the line pressure suitable to that throttle opening.
The throttle pressure fed to the secondary regulator valve is converted into the secondary regulator pressure, fed to the torque converter and used for lubrication.

5. "2" Range Second Gear

The discharge pressure from the oil pump is regulated to the line pressure by the primary regulator valve and applied to the manual valve, throttle valve, each accumulator and TCC (lock-up) control valve.
The line pressure fed to the manual valve works on the F/C accumulator engage the forward clutch. Similarly, the line pressure passes through the 1 -2 shift valve and works on the second brake accumulator to engage the second brake.
Also, the line pressure passes through the 2-3 shift valve, 1-2 shift valve and intermediate modulator valve to engage the second coast brake.
On the other hand, the line pressure from the primary regulator valve passes through the 3-4 shift valve to engage the O/D clutch.
The line pressure fed to the throttle valve is converted to the throttle pressure and applied again to the primary regulator valve and adjusted to the line pressure suitable for the throttle opening.
Also, the throttle pressure fed to the secondary regulator valve is converted into the secondary regulator pressure, fed to the torque converter and used for lubrication.

6. "L" Range

The discharge pressure from the oil pump is regulated to the line pressure by the primary regulator valve and applied to the manual valve, throttle valve, each accumulator and TCC (lock-up) control valve.
The line pressure fed to the manual valve works on the forward clutch accumulator to engage the forward clutch.
The same line pressure passes through the 2-3 shift valve, low coast modulator valve and 1-2 shift valve to engage the brake.
Furthermore, the line pressure from the primary regulator valve passes through the 3-4 shift valve to engage the over drive clutch.
The line pressure fed to the throttle valve is converted to the throttle pressure, applied again to the primary regulator valve and adjusted to the line pressure suitable for the throttle opening.
Also, the throttle pressure fed to the secondary regulator valve is converted into the secondary regulator pressure, fed to the torque converter and used for lubrication.

7. "R" Range

The discharge pressure from the oil pump is regulated to the line pressure by the primary regulator valve and applied to the manual valve, throttle valve, each accumulator and TCC (lock-up) control valve.
The line pressure fed to the manual valve passes through the 2-3 shift valve and works on the direct clutch accumulator and then to the inner piston side of the direct clutch.
On the other hand, the line pressure fed from the manual valve to the reverse clutch sequence valve is applied to the outer piston side of the direct clutch because the line pressure through the passage to the inner piston of the direct clutch moves to the right. At this point, as the reverse clutch sequence valve does not move till the inner piston of the direct clutch completes its operation, the outer piston operates later to relieve the shock. The line pressure from the manual valve passes through the 1-2 shift valve and engages the reverse brake. Also, the line pressure from the primary regulator valve passes through the 3-4 shift valve to engage the over drive clutch.
The line pressure fed to the throttle valve is converted into the throttle pressure and applied again to the primary regulator valve and adjusted to the line pressure suitable for the throttle opening.
Also, the throttle pressure fed to the secondary regulator valve is converted into the secondary regulator pressure, fed to the torque converter and used for lubrication.

8. "N" or "P" Range