PDF Training Text Manual Hitachi LX70-7 LX80-7 Wheel Loader - 902 KB
Dive deep into the mechanics of your Hitachi wheel loader with this Operational Principle Training Text Manual for the LX70-7 and LX80-7 models.
This manual goes beyond standard operation, explaining the 'why' behind the machine's systems, including hydraulics and electronics.
It is an excellent resource for technicians seeking a thorough understanding of the equipment's design and function.
Enhance your diagnostic skills and technical knowledge with this in-depth guide.
PDF Viewer
Viewer loads when you scroll here
SHARE THIS MANUAL
Download the PDF Manual
PDF viewer loading area
Text Preview from This Manual
The text below was extracted from the visible preview pages to help you confirm the manual contents before download.
--- Page 3 ---
0. SPECIFICATIONS
LX70-7 LX80-7
Rear overhang angle ° 32 33
Min. ground clearance, center hinge pin mm [in.] 365 [14.4] 375 [14.8]
Bucket hinge pin height mm [in.] 3515 [138.4] 3615 [142.3]
Dumping height, at 45° discharge angle mm [in.] 2710 [106.7] 2750 [108.3]
Reach, at 45° discharge angle mm [in.] 1020 [40.2] 1040 [40.9]
Bucket roll angle, in carry position ° 48 48
Bucket dumping angle,
bucket fully raised ° 48 48
Towing pin height mm [in.] 980 [38.6] 1070 [42.1]
Weight
Weight of the loader kg [lbs] 6625 [14610] 8215 [18110]
-4-
--- Page 4 ---
1. ENGINE AND RELATED COMPONENTS
1.5 INTAKE AND EXHAUST SYSTEM
LX70-7 (BB-4BG1T) LX80-7 (DD-4BG1T)
Air cleaner Cyclone filter paper type (8”) ←
Muffler Porous separators ←
Turbocharger
Name TD04HL TD04H
Turbocharging Exhaust turbocharger ←
Lubrication Forced circulation, oil cooled ←
1. General Description
The intake system of the engine is designed so that the outside open air is drawn through the air
cleaner into the inlet manifold. The air cleaner is equipped with a dust indicator. The element needs to
be cleaned when the warning light comes on.
The exhaust system is designed so that the exhaust gas from the exhaust manifold is passed through
the muffler where the pressure and temperature of the exhaust gas are lowered, and discharged through
the tail pipe into the atmosphere.
Be careful not to touch the muffler or exhaust manifold since they are hot when the engine is
running or for a while after it is shut off; otherwise you might burn your hand.
Turbocharger
It is possible to attain high engine output by sending highly compressed air into the cylinders on the
intake stroke to increase air supply, thus increasing the quantity of fuel to be injected. To achieve this
purpose, the L13-2 and L16-2 are equipped with an exhaust-driven turbocharger.
The turbocharger’s exhaust gas inlet is connected to the exhaust manifold. The exhaust gas rotates
the turbine wheel at a high speed, before being routed through the exhaust gas outlet into the muffler.
Therefore, the impeller, mounted on the opposite end of the same shaft as the turbine, also rotates at
a high speed to compress the air drawn through the air cleaner and sends it to the intake manifold.
- 14 -
--- Page 5 ---
2. POWER TRAIN
2. Hydrostatic Transmission (HST)
The operating principle of the general hydrostatic transmission (HST) which uses a variable capacity
axial piston pump and motor for the HST pump and HST motor, respectively is given below.
(1) Operation of HST Pump
1. When the sliding surface of the swash plate is flat and positioned vertically, the system stands
neutral and no oil is discharged. Even if the drive shaft rotates, the suction and discharge of oil is
not performed, despite the rotation of the cylinder block.
Low-pressure oil PISTON
KIDNEY B
DRIVE SHAFT
PORT B
PORT A
TRUNNION
CYLINDER BLOCK MOVABLE SWASH PLATE
KIDNEY A
Fig. 2.4 Neutral
2. When the swash plate angle control lever is shifted to the left, the cylinder block turns enough to
pass beyond the kidney B to draw oil into the piston holes. When the cylinder block turns to pass
beyond the kidney A, pressure oil is discharged from the piston holes. When the cylinder block
turns continuously, oil is sucked through port B leading to the kidneys, being discharged through
port A.
3. The volume of oil to be sucked and discharged depends upon the piston stroke or the tilting angle
of the swash plate. The discharge volume of oil is reduced by reducing the tilting angle of the
swash plate and is increased by increasing the tilting angle.
Low-pressure oil SWASH PLATE ANGLE CONTROL LEVER
High-pressure oil
PISTON
KIDNEY B
DRIVE SHAFT
PORT B
INLET
OUTLET
PORT A
TRUNNION
CYLINDER BLOCK MOVABLE SWASH PLATE
KIDNEY A
Fig. 2.5 Pump Operation (1)
- 24 -
--- Page 6 ---
2. POWER TRAIN
INCHING BRAKE
PEDAL
to HST MOTOR
to HST MOTOR
HST PUMP
1. PUMP COMBINATION VALVE 1 10. from HST CHARGING PUMP 19. CHARGE PORT (from PUMP
2. CUT-OFF VALVE 11. PUMP SELF-DISCHARGE CASING)
3. from MAIN STEERING CIRCUIT PRESSURE PORT (to PUMP 20. CHARGE RELIEF VALVE
4. PUMP SELF-DISCHARGE COMBINATION VALVE 1) 21. DRAIN PORT (to HST
PRESSURE PORT (from PUMP 12. PUMP COMBINATION MOTOR)
COMBINATION VALVE 2) VALVE 2 22. CHARGE PORT ( to NEUTRAL
5. INCHING VALVE 13. NEUTRAL DAMP VALVE DAMP SOL VALVE)
6. CONTROL PRESSURE 14. RELIEF VALVE (FOR REV) 23. PUMP TILT-ROLLING
BYPASS VALVE 15. RELIEF VALVE (FOR FWD) CONTROL PRESSURE PORT
7. FNR SOLENOID VALVE 16. PORT B (FOR REV)
8. PUMP TILT-ROLLING SPEED 17. PORT A 24. PUMP TILT-ROLLING
CONTROL VALVE 18. NEUTRAL DAMP CONTROL PRESSURE PORT
9. REGULATOR SOLENOID VALVE (FOR FWD)
Fig. 2.16 HST Pump (Circuit Diagram)
- 34 -
--- Page 7 ---
2. POWER TRAIN
CIRCUIT B
CUT-OFF VALVE
MAIN CIRCUIT PRESS
CIRCUIT A
FWD TRAVELING
PRESSURE
HST CHARGING PUMP
HST MOTOR
HST MOTOR
FWD TRAVELING
CUT-OFF VALVE PRESS
CIRCUIT A CIRCUIT B
MAIN CIRCUIT
PRESS
SPOOL PIN
Fig. 2.29 Control by Cut-off Valve
- 44 -
--- Page 8 ---
2. POWER TRAIN
2.3 HST MOTOR
LX70 -7 LX70-7
Model A6V86HA A6V115HA
Type Variable delivery piston motor ←
(inclined shaft type)
Discharge (suction) 33.5 – 86.3 cc/rev 38.0 – 114.7 cc/rev
[0.00885 – 0.0228 gal/rev] [0.01004 – 0.0303 gal/rev]
Control HA (high-pressure dependent, ←
constant pressure control)
Weight 46 kg [101 lbs] 49 kg [108 lbs]
Note: Mating surfaces: LOCTITE #5127 or 515
1. HST MOTOR
2. (TRANSMISSION)
Fig. 2.39 HST Motor
- 54 -
--- Page 9 ---
2. POWER TRAIN
2.3.5 STOCK-PILE & SNOW (S&S) MODE (OPTION FOR LX80-7)
The fact that the engine output is constant means
that the force available for lifting booms becomes
MOTOR TILT-
smaller when a great traveling power is used. By ROLLING ANGLE S&S SOL
VALVE OFF
contrast, the boom lifting force available becomes
greater when the traveling power is small. The S&S SOL
VALVE ON
traveling power and the bucket break-out force are well
matched. The S&S mode is activated by turning the
S&S mode switch on with the Hi-Lo switch at the Lo HYDRAULIC
PRESS
position.
When the S&S mode is turned on, the maximum
traveling power is suppressed to 75% of that obtained
when the S&S mode is OFF. Therefore, with the S&S
mode turned on, the boom lifting force in digging Fig. 2.49 Relationship of Tilt-rolling Angle
operation (composite operation of scooping and and Hydraulic Pressure in S&S mode
traveling) becomes greater than that obtained when the S&S mode is off.
For this reason, the scooping is easier to do when the S&S mode is off. In addition, since the maximum
traveling power is suppressed to 75%, snow removal operation can also be performed and easily and
efficiently.
Operation
1. When the HST motor working pressure is more than 26.5 ± 0.5 MPa {270 ± 5 kgf/ cm2} [3844 ± 73
psi], the hydraulic pressure overcomes the regulator spring force to push down the pilot piston.
This allows the ports A and B to connect to each other so that the motor hydraulic oil flows,
passing through the port B, into the large-diameter chamber of the servo piston. The HST motor
hydraulic oil also flows, passing through the port C, to the small-diameter chambers of the servo
piston and control piston. Since there is a difference in area between the large-diameter chamber
and the small-diameter chamber of the servo pistons, the servo pistons move upward.
2. When the Hi-Lo switch is in the Lo position, the Hi-Lo solenoid valve relay is energized by the
controller to energize the Hi-Lo solenoid valve, thus letting the loader traveling at low speed.
When the S&S mode switch is turned on, the S&S mode relay is energized by the controller to
energize the S&S mode solenoid valve.
3. As the S&S solenoid valve spool is moved, the port C is connected to the port D so that the working
pressure of the motor acting on the regulator pilot piston flows, passing through the ports C and D,
into the large-diameter chamber of the control piston.
The area differential between the large-diameter chamber and the small-diameter chamber of the
control piston forces the control piston downward.
4. When the control piston moves down, it serves as a stopper for the servo piston. When the servo
piston moves upward, the tilt-rolling amount of the motor becomes larger. However, with the control
piston down, the servo piston comes in contact with the control piston and stops there. Therefore,
the traveling motor’s maximum tilt-rolling angle is suppressed to 75% to suppress the traveling
power.
- 64 -
--- Page 10 ---
2. POWER TRAIN
Hi CLUTCH Lo CLUTCH
HST
MOTOR
SELECTOR VALVE
ACCUMULATOR
Hi-Lo SELECTOR
THROTTLE SOLENOID VALVE (ON)
TRANSMISSION
CHARGING/BRAKE
PUMP RELIEF VALVE
Hi-Lo TRANSMISSION
Fig. 2.60 Low Speed
Hi CLUTCH Lo CLUTCH
HST
MOTOR
SELECTOR VALVE
ACCUMULATOR
Hi-Lo SELECTOR
THROTTLE SOLENOID VALVE (OFF)
TRANSMISSION
CHARGING/BRAKE
PUMP RELIEF VALVE
Hi-Lo TRANSMISSION
Fig. 2.61 High Speed
- 74 -
--- Page 12 ---
2. POWER TRAIN
Brake piping ports (2)
Note: 88 N-m {9 kgf-m} [64.9 lbf-ft], Threaded area: LOCTITE #262
225 N-m {23 kgf-m} [166.0 lbf-ft], Threaded area: LOCTITE #262
Threaded area: LOCTITE #572
Lip: Grease
Mating surfaces: LOCTITE FMD-127
1. OIL SEAL 6. AXLE TUBE 11. BLEEDER
2. AXLE SHAFT 7. RING GEAR 12. OIL DIPSTICK
3. DIFFERENTIAL BODY 8. PIN 13. PLUG (CHECK PORT)
4. DIFFERENTIAL 9. BREATHER 14. DRAIN PLUG
5. FINAL REDUCTION GEAR 10. COVER
ASSEMBLY
Note: The sketches show the rear axle of the LX70-7. The rear axle of the LX80-7 has the same structure
as that of the LX70-7.
Fig. 2.69 Rear Axle
- 84 -
--- Page 13 ---
3. BRAKE SYSTEM
to TRANSMISSION
CONTROL VALVE
1. TRANSMISSION 5. BRAKE PEDAL 11. FILTER
2. STRAINER 6. BRAKE VALVE 12. PARKING BRAKE
3. TRANSMISSION 7. BRAKE OIL TANK SOL VALVE
CHARGING PUMP 8. PRESSURE SWITCH 13. PARKING BRAKE
4. TRANSMISSION 9. DISK BRAKE (FRONT) 14. RELIEF VALVE
INLINE FILTER 10. DISK BRAKE (REAR)
Fig. 3.2 Brake Oil Pressure Circuit Diagram
- 94 -
--- Page 14 ---
3. BRAKE SYSTEM
3.2.1 GENERAL DESCRIPTION (BRAKE LINE)
The parking brake is an internal expansion drum brake and installed on the transmission output shaft.
The parking brake is operated with the parking brake switch in the operator’s compartment.
SPRING PISTON
BRAKE
DRUM
BRAKE SHOE
PARKING BRAKE
PARKING BRAKE SW
(RELEASE POSITION)
TRANSMISSION PARKING BRAKE SOL
CHARGING/ VALVE (ON POSITION)
BRAKE PUMP
Hi-Lo TRANSMISSION
Position Name Use Specification
Pressure switch Transmission clutch OFF: 0.64 MPa {6.5 kgf/cm 2} [92.8 psi]
(parking brake cut-off and “parking ON: 0.27 MPa {2.8 kgf/cm 2} [39.2 psi]
switch) brake” indication light The switch is turned on at atmospheric pressure.
Fig. 3.13 Parking Brake Line
- 104 -
--- Page 15 ---
4. STEERING SYSTEM
The steering mechanism is orbitrol type (full-hydraulic power steering) which does not use any linkage
mechanism, but operates on hydraulic power alone.
The steering system consists of the steering wheel unit, orbitrol, priority valve, cushion valve (LX80-7
only), steering cylinders and hydraulic piping.
If the pressure oil is not supplied from the pump for any reason such as when the engine stalls,
the orbitrol acts as a manual steering system, thus making it possible to steer the loader. However,
note that steering operation is considerably harder than usual.
STEERING WHEEL
STEERING WHEEL UNIT
PRIORITY VALVE
CUSHION VALVE
(LX80 -7 only)
ORBITROL
STEERING CYLINDER
Note: The above sketch does not illustrate the hydraulic piping.
For the hydraulic piping, refer to “6. HYDRAULIC SYSTEM.”
Fig. 4.2 Steering System
- 114 -
--- Page 16 ---
4. STEERING SYSTEM
(2) Steering wheel in neutral (engine running)
1. The pressure oil from the main pump flows, passing through the priority valve P port, CF port, into
the orbitrol. The oil then flows, passing through the internal throttle C0 and T port, back into the oil
tank.
2. At this time, the pressure differential produced across the internal throttle C0 of the orbitrol is also
transmitted to both the pressure chambers (A) and (B) so that the spool (1) moves to the right in the
figure.
3. Therefore, the priority valve’ EF port is fully closed while the CF port is slightly opened. This lets
almost all portion of the oil discharged from the main pump flow to the control valve for operating
the load handling system.
ORBITROL
PRIORITY VALVE
Fig. 4.14 Steering Wheel in Neutral (engine running)
- 124 -
--- Page 17 ---
5. FRAME AND COCKPIT
Upper hinge section
Detail of area A
Lower hinge section
Note: Inner surface: Grease (before installing pin)
34.3 ± 2.9 N-m {3.5 ± 0.3 kgf-m} [25.3 ± 2.14 lbf-ft]
548.8 ± 39.2 N-m {56.0 ± 4.0 kgf-m} [404.8 ± 28.9 lbf-ft]
Threaded area: LOCTITE #262
1. UPPER HINGE PIN 6. COLLAR 11. CAP
2. BUSHING 7. SHIM 12. BUSHING
3. BUSHING 8. FLANGE 13. COLLAR
4. GREASE FITTING 9. U-NUT 14. RUBBER
5. LOWER HINGE PIN 10. DUST SEAL
Fig. 5.3 Center Hinge Pin (LX70-7)
- 134 -
--- Page 18 ---
6. HYDRAULIC SYSTEM
8 8 8 stroke (mm)
8 8 stroke (mm)
Parallel circuit
Note: (2 points) 64.7 N-m
{6.6 kgf-m} [47.7 lbf-ft]
101 N-m {10.3 kgf-m}
[74.49 lbf-ft]
1. MAIN RELIEF VALVE
2. INLET SECTION
3. PORT RELIEF VALVE
4. SPOOL SECTION (BUCKET)
5. OUTLET SECTION
6. SPOOL SECTION (BOOM)
Fig. 6.5 Control Valve
- 144 -
--- Page 19 ---
6. HYDRAULIC SYSTEM
Z
1
8
1 9 10 2
17
2 11 12
2
13
3 Z
18
4 19
14 15
16
5
6
7
Note: Threaded area: LOCTITE #262
Before assembly, apply grease.
1. KNOB 8. CONTROL LEVER 15. SPRING
2. BOOT 9. BUSHING 16. HANDLE (LEVER STOPPER)
3. COVER 10. PIN 17. BALL LINK
4. CONTROL BOX 11. BUSHING 18. CABLE (FOR BUCKET)
5. PLATE 12. BOSS 19. CABLE (FOR BOOM)
6. CONTROL VALVE 13. BRACKET
7. BRACKET 14. STOPPER LINK
Fig. 6.21 Valve Controls
- 154 -
--- Page 20 ---
7. LOAD HANDLING SYSTEM
7.2 CYLINDERS
LX70 -7 LX80-7
Boom cylinder
Type Double-acting piston ←
Q’ty 2 ←
Inner diameter 90 mm [3.54 in.] 110 mm [4.33 in.]
Cylinder rod diameter 55 mm [2.17 in.] 60 mm [2.36 in.]
Cylinder stroke 760 mm [29.9 in.] 681 mm [26.8 in.]
Weight (per cylinder) 53 kg [117 lbs] 75 kg [165 lbs]
Bucket cylinder
Type Double-acting piston ←
Q’ty 1 ←
Inner diameter 110 mm [4.33 in.] 130 mm [5.12 in.]
Cylinder rod diameter 60 mm [2.36 in.] 70 mm [2.76 in.]
Cylinder stroke 421 mm [16.6 in.] 431 mm [17.0 in.]
Weight 56 kg [123 lbs] 88 kg [194 lbs]
7.2.1 BOOM CYLINDER
Two double-acting piston type boom cylinders are used. When the boom cylinders are extended or
retracted, the booms are raised or lowered, rocking around the connecting pin at each cylinder tail.
The boom cylinder consists of a cylinder tube, cylinder head, piston rod, piston and packings.
7.2.2 BUCKET CYLINDER
The bucket cylinder is a double-acting piston type. As the bucket cylinder is extended or retracted,
the bucket is dumped or rolled back through the bell crank and push rod.
The bucket cylinder consists of a cylinder tube, cylinder head, piston rod, piston and packings.
- 164 -