2004 ISUZU TF SERIES Workshop Manual

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ISUZU TF SERIES 2004 Workshop Manual CONSTRUCTION AND FUNCTION 7A1-7

TRANSMISSION CONTROL UNIT (TCM) PERIPHERAL CIRCUIT

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ISUZU TF SERIES 2004 Workshop Manual 7A1-8 CONSTRUCTION AND FUNCTION
STRUCTURE AND FUNCTION OF COMPONENT
TORQUE CONVERTER (WITH LOCK-UP FUNCTION)
The torque converter is a device for transmitting the engine torque to the transmissi

7A1-8 CONSTRUCTION AND FUNCTION
STRUCTURE AND FUNCTION OF COMPONENT
TORQUE CONVERTER (WITH LOCK-UP FUNCTION)
The torque converter is a device for transmitting the engine torque to the transmission. It transmits power
by means of oil when the lock-up is disengaged and by means of a lock-up piston when it is engaged.
The torque converter is of the symmetrical, three-element, single-stage, two-phase type.
As shown in the drawing, the symmetrical three-elements refer to three elements (components) consisting
of impeller (1), turbine (2) and stator (3) that are arranged symmetrically (figure 5).
"Single-stage" means that there is only one turbine as an output element; "two-phase" means that the
pump impeller acts as a torque converter when the turbine speed is comparatively low, and as a fluid
coupling when the speed is high.

1. Pump Impeller
2. Turbine Runner
3. Stator

1. Pump Impeller
2. Turbine Runner
3. Stator
4. Converter Cover
5. One-way Clutch
6. Lock-up Piston
7. Torsion Damper

Figure 5. Torque Converter
Figure 6. Construction of Torque Converter

Lock-up mechanism
"Lock-up" refers to a fixed state of the lock-up piston inside the torque converter and thus connects the
engine directly to the transmission.
The hydraulic pressure for the lock-up control is supplied from two circuits.

When the lock-up is disengaged (Figure 7)
When the lock-up is disengaged, the torque converter operating pressure is supplied from the oil passage
(A) to between the cover and the lock-up piston, and separates the lock-up piston clutch facing and
converter cover.
As a result, the engine drive power is transmitted from the converter cover to the pump impeller, the ATF
and to the turbine. The torque converter function as a fluid connector in this condition.
The torque converter operating pressure is supplied from the oil passage (A), passes through the oil
passage (B).

When the lock-up is engaged (Figure 8)
When the lock-up is engaged, the torque converter operating pressure is supplied from oil passage (B) to
the oil pump impeller, turbine, then to the stator side. The oil between the lock-up piston and converter
cover is drained.
Since the force acting on the right side of the lock-up piston is greater than force on the left side, it
connects the lock-up piston clutch facing with the converter cover, thereby increasing the transmission
efficiency.

Page 3955 of 4264

ISUZU TF SERIES 2004 Workshop Manual CONSTRUCTION AND FUNCTION 7A1-9

Figure 7. Lock-up Control (Disengaged) Figure 8. Lock-up Control (Engaged)
OIL PUMP
The oil pump generating oil pressure is a small-size trochoid gear t

Page 3956 of 4264

ISUZU TF SERIES 2004 Workshop Manual 7A1-10 CONSTRUCTION AND FUNCTION
INPUT SHAFT
The input shaft has some oil holes, through which lubricating ATF is supplied to the torque converter,
bearings, etc.
The input shaft is fitted t

7A1-10 CONSTRUCTION AND FUNCTION
INPUT SHAFT
The input shaft has some oil holes, through which lubricating ATF is supplied to the torque converter,
bearings, etc.
The input shaft is fitted the turbine runner in the torque converter, reverse & high clutch drum and rear sun
gear by means of the spline. Therefore, the engine driving force received by the torque converter is
transmitted to the reverse & high clutch drum and rear sun gear.

OUTPUT SHAFT
The output shaft has some oil holes, through which the lubricating ATF is supplied to the bearings,
planetary gear unit, etc.
The output shaft transmits the engine driving force from the planetary gear to the propeller shaft.
The front internal gear is fitted with the rear carrier assembly by spline. The parking gear is also fitted by
spline. By fixing this gear mechanically, the output shaft is fixed as required when parking the vehicle.

GEAR SHIFTING MECHANISM
The JR405E consists of two sets of planetary gears, three multiple plate clutches, two multiple plate
brakes and a one-way clutch. They are activated in different combinations in any of four forward and one
reverse gear positions.

Principle of gear shifting (Figure 12)
Planetary gears have the advantage of a compact configuration because of the way they are constructed
with a single central shaft.
Also, unlike the manual transmission gears that require changing of gear mesh, the gear ratio of the
planetary gears can be changed more easily by locking, releasing or rotating only some of their parts.
A planetary gear is made up of a sun gear (1) at its center and pinion gears (2) each of which rotates
about its own center and also along the sun gear, as shown. They are all called in the internal gear (3).
Also, since the pinion gears are further supported by the planetary carrier (4), they rotate as a unit in the
same direction and at the same rate.
As shown above, each planetary gears are constructed of three elements; a sun gear, pinion gears, and
internal gear and a planetary carrier. Gear shifting is achieved by conditioning two of the three elements
namely the sun gear, internal gear and the planetary carrier.
The planetary gears are locked by the clutch, brake and one-way clutch according to the gear shifting.

1. Sun Gear
2. Pinion Gear
3. Internal Gear
4. Planetary Carrier

Figure 12. Planetary Gear

Page 3957 of 4264

ISUZU TF SERIES 2004 Workshop Manual CONSTRUCTION AND FUNCTION 7A1-11

The JR405E consists of two sets of planetary gears, which are called front planetary gear and rear
planetary gear.
The sun gear of front planetary gear is f

CONSTRUCTION AND FUNCTION 7A1-11

The JR405E consists of two sets of planetary gears, which are called front planetary gear and rear
planetary gear.
The sun gear of front planetary gear is fixed to the drive plates of 2-4 brake and reverse clutch.
The planetary carrier of front planetary gear is fixed to the drum of low clutch, the drive plates of low &
reverse brake and the hub of high clutch.
The internal gear of front planetary gear and the planetary carrier of rear planetary gear are connected as
one, and they are fixed to output shaft.
The sun gear of rear planetary gear is fixed to input shaft.
The internal gear of rear planetary gear is fixed to the hub of low clutch.

Clutch and Brake
Basic structure of the clutch and brake is shown in the figures below.
In the figure A, the clutch plates (drive plate and driven plate) are in the fluid so that they slip against each
other transmitting no power.
Figure B shows the condition where the oil pressure is acting on the piston. The clutch plates are fitted
to each other under pressure transmitting the rotations of the clutch drum to the clutch hub.
When the oil pressure is removed from the piston, the clutch returns to the condition in the figure A by the
return spring.

Figure 13. Basic Construction of Clutch and Brake

Low Clutch, High Clutch and Reverse Clutch (Multi-Plate Clutch)
The multi-plate clutch is composed of drive plates and driven plates. By applying the oil pressure onto
the end surface of the plates, the clutch is engaged or disengaged. The oil pressure is adjusted with the
control valve according to the signal from the TCM.
All clutches use dish plates to prevent uncontrolled operation of the clutches when engaged, causing a
shock.
For the reverse clutch, a piston check ball is used to release the oil pressure for the purpose of preventing
the clutch drag due to oil pressure generated by residual ATF because of the centrifugal force while the
clutch is racing (under no oil pressure).
For the low clutch and high clutch, a centrifugal balance chamber always full of ATF is provided to offset
the excessive oil pressure, for the purpose of preventing the clutch drag due to oil pressure generated by
residual ATF because of the centrifugal force while the clutch is racing (under no oil pressure).
The solenoid in the control valve is driven based on the speed change signal from TCM and moves the
shift valve, thereby engaging the drive plate and driven plate through the piston of each clutch.
Resultantly, elements of the planetary gear unit are combined.
When the oil pressure is removed, the piston returns to the original position by the force of the return
spring.

Page 3958 of 4264

ISUZU TF SERIES 2004 Workshop Manual 7A1-12 CONSTRUCTION AND FUNCTION

Figure 14. Basic Construction of Low Clutch
and High Clutch Figure 15. Basic Construction of Reverse Clutch

Figure 16. Construction of Low Clutch Figure

Page 3959 of 4264

ISUZU TF SERIES 2004 Workshop Manual CONSTRUCTION AND FUNCTION 7A1-13

2-4 Brake and Low & Reverse Brake (Multi-Plate Brake)
The multi-plate brake is composed of drive plates and driven plates. By applying the oil pressure onto

Page 3960 of 4264

ISUZU TF SERIES 2004 Workshop Manual 7A1-14 CONSTRUCTION AND FUNCTION
CONTROL VALVE
Employing the direct electronic control (Direct Electronic Shift Control: DESC) for the clutch pressure has
simplified the oil pressure circuit, re

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