PDF Technical Manual Hitachi ZX27U Hydraulic Excavator - 1 MB
Dive deep into the mechanics of your Hitachi ZX27U Hydraulic Excavator with this comprehensive technical manual.
This guide is designed for service technicians, providing in-depth information on testing, adjusting, and troubleshooting all major systems.
It includes hydraulic and electrical schematics, specifications, and disassembly/assembly procedures.
This manual is essential for performing advanced diagnostics and repairs.
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--- Page 1 ---
INTRODUCTION
TO THE READER
• This manual is written for an experienced technician • If you have any questions or comments, at if you
to provide technical information needed to maintain found any errors regarding the contents of this
and repair this machine. manual, please contact using “Service Manual
Revision Request Form” at the end of this man-
• Be sure to thoroughly read this manual for correct ual.
product information and service procedures. (Note: Do not tear off the form. Copy it for usage.):
Publications Marketing & Product Support
Hitachi Construction Machinery Co. Ltd.
TEL: 81-298-32-7173
FAX: 81-298-31-1162
ADDITIONAL REFERENCES
• Please refer to the materials listed below in addition • Operation Manual of the Engine
to this manual. • Parts Catalog of the Engine
• Hitachi Training Material
• The Operator’s Manual
• The Parts Catalog
MANUAL COMPOSITION
• This manual consists of two portions:
the Technical Manual and the Workshop Manual.
Use the manuals according to purpose.
• Information included in the Technical Manual: • Information included in the Workshop Manual:
technical information needed for redelivery and technical information needed for maintenance and
delivery, operation and activation of all devices repair of the machine, tools and devices needed
and systems, operational performance tests, and for maintenance and repair, maintenance stan-
troubleshooting procedures. dards, and removal/installation and assem-
ble/disassemble procedures.
PAGE NUMBER
• Each page has a number, located on the center
lower part of the page, and each number contains
the following information:
Example : T 1-3-5
Consecutive Page Number for Each Group
Group Number
Section Number
T: Technical Manual W: Workshop Manual
IN-01
--- Page 3 ---
SAFETY
DRIVE MACHINE SAFELY
• Before driving the machine, always confirm that the
travel levers/pedals direction corresponds to the di-
rection you wish to drive.
• Be sure to detour around any obstructions.
• Avoid traveling over obstructions. Soil, fragments
of rocks, and/or metal pieces may scatter around
the machine. Don’t allow personnel to stay around
the machine while traveling.
SA-663
• Driving on a slope may cause the machine to slip or
overturn, possibly resulting in serious injury or death.
• When driving up or down a slope, keep the bucket
facing the direction of travel, approximately 200 to
300 mm (A) above the ground.
• If the machine starts to skid or becomes unstable,
immediately lower the bucket to the ground and
stop traveling.
SA-664
• Driving across the face of a slope or steering on a
slope may cause the machine to skid or turnover.
If the direction must be changed, move the ma-
chine to level ground, then, change the direction
SA-441
to ensure sage operation.
019-E01D-0492
SA-589
SA-9
--- Page 4 ---
SAFETY
PREVENT PARTS FROM FLYING
• Grease in the track adjuster is under high pressure.
Failure to follow the precautions below may result in
serious injury, blindness, or death.
• Do not attempt to remove GREASE FITTING or
VALVE ASSEMBLY.
• As pieces may fly off, be sure to keep body and
face away from valve.
• Travel reduction gears are under pressure.
SA-344
• As pieces may fly off, be sure to keep body and
face away from AIR RELEASE PLUG to avoid
injury. GEAR OIL is hot.
• Wait for GEAR OIL to cool, then gradually loosen
AIR RELEASE PLUG to release pressure.
503-E01B-0344
STORE ATTACHMENTS SAFELY
• Stored attachments such as buckets, hydraulic
hammers, and blades can fall and cause serious
injury or death.
• Securely store attachments and implements to
prevent falling. Keep children and bystanders
away from storage areas.
SA-034
504-E01A-0034
USE TOOLS PROPERLY
• Use tools appropriate for the work to be done.
• Makeshift tools, parts, and procedures can create
safety hazards.
• For loosening and tightening hardware, use the
correct size tools to avoid injury caused by
slipping wrenches.
• Use only recommended replacement parts.
(See the parts catalog.)
SA-040
S522-E01A-0040
SA-19
--- Page 5 ---
SECTION AND GROUP SECTION 1 GENERAL
CONTENTS Group 1 Specification
Group 2 Component Layout
Group 3 Component Specifications
SECTION 2 SYSTEM
Group 1 Hydraulic System
TECHNICAL MANUAL Group 2 Electrical System
SECTION 3 COMPONENT OPERATION
Group 1 Pump Device
Group 2 Swing Device
Group 3 Control Valve
Group 4 Pilot Valve
Group 5 Travel Device
Group 6 Others (Upperstructure)
Group 7 Others (Undercarriage)
SECTION 4 OPERATIONAL PER-
FORMANCE TEST
Group 1 Introduction
Group 2 Standard
Group 3 Engine Test
Group 4 Excavator Test
Group 5 Component Test
All information, illustrations and speci-
fications in this manual are based on SECTION 5 TROUBLESHOOTING
the latest product information available
at the time of publication. The right is Group 1 Diagnosing Procedure
reserved to make changes at any time
without notice. Group 2 Troubleshooting A
Group 3 Troubleshooting B
Group 4 Electrical System Inspection
COPYRIGHT(C)2002
Hitachi Construction Machinery Co., Ltd.
Tokyo, Japan
All rights reserved
--- Page 6 ---
GENERAL / Component Layout
MAIN COMPONENTS
2
1
4
3
5
6
7
8
9
21
10
20 11
12
19
18
17
13
16 14
15
T1LA-01-02-001
1- Bucket Cylinder 7 - Solenoid Valve 12 - Engine 17 - Swing Device
2- Arm Cylinder 8 - Hydraulic Oil Tank 13 - Center Joint 18 - Blade Cylinder
3- Boom Cylinder 9 - Control Valve 14 - Pump Device 19 - Boom Swing Cylinder
4- Front Attachment / Swing 10 - Oil Cooler 15 - Travel Device 20 - Travel Pilot Valve
Pilot Valve
5 - Blade Pilot Valve 11 - Radiator 16 - Fuel Tank 21 - Boom Swing Pilot Valve
6 - Pilot Filter
T1-2-1
--- Page 7 ---
GENERAL / Component Specifications
SWING MOTOR
27U
Model ............................................................. MSG-27P-16
Type ............................................................... Swash-Plate Type, Fixed Displacement Axial Plunger Motor
30U
Model ............................................................. MSG-27P-16
Type ............................................................... Swash-Plate Type, Fixed Displacement Axial Plunger Motor
35U
Model ............................................................. MSG-27P-16
Type ............................................................... Swash-Plate Type, Fixed Displacement Axial Plunger Motor
SWING VALVE UNIT
27U
Type ............................................................... Non Counterbalance Valve Type
Relief Set-Pressure........................................ 19.5 MPa (200 kgf/cm2, 2840 psi) at 16 L/min
30U
Type ............................................................... Non Counterbalance Valve Type
Relief Set-Pressure........................................ 13.7 MPa (140 kgf/cm2, 1990 psi) at 26 L/min
35U
Type ............................................................... Non Counterbalance Valve Type
Relief Set-Pressure........................................ 16.2 MPa (165 kgf/cm2, 2350 psi) at 26 L/min
SWING PARKING BRAKE
27U
Type ............................................................... Single-Disc-Wet Negative Type
Release Pressure (Full Stroke)...................... 1.5 to 2.3 MPa (12 to 23 kgf/cm2, 170 to 327 psi)
30U
Type ............................................................... Single -Disc-Wet Negative Type
Release Pressure (Full Stroke)...................... 1.5 to 2.3 MPa (12 to 23 kgf/cm2, 170 to 327 psi)
35U
Type ............................................................... Single -Disc-Wet Negative Type
Release Pressure (Full Stroke)...................... 1.5 to 2.3 MPa (12 to 23 kgf/cm2, 170 to 327 psi)
T1-3-7
--- Page 8 ---
SYSTEM / Hydraulic System
OUTLINE
The hydraulic system consists of the main circuit and
pilot circuit.
Pilot Circuit:
Supplies pressure oil from the pilot pump into the op-
eration circuit, valve control circuit and travel speed
changeover circuit.
Main Circuit:
Controls pressure oil from the main pump by the con-
trol valve to actuate the cylinders and motors.
T2-1-1
--- Page 9 ---
SYSTEM / Electrical System
OUTLINE
The electrical system is roughly classified into the The main functions and construction of the main circuit
main circuit and the monitor circuit. are outlined here:
• Main Circuit • Power Circuit: Supplies electrical power to all
Operates the engine and accessory circuits. electrical systems on the machine.
(including key switch, battery, fuse box and fusible
• Monitor Circuit links)
Consists of the monitors, sensors, and switches to
display machine operating conditions. • Indicator Light Check Circuit: Checks for burned
monitor indicators.
(including key switch, fuse box and controller)
• Accessory Circuit: Works with the key switch ON.
(including key switch and fuse box)
• Preheating Circuit: Helps start the engine in cold
weather.
(including key switch, QOS sensor, glow timer, glow
relay and glow plugs)
• Engine Starting Circuit: Starts the engine.
(including key switch, starter and starter relay 1)
• Charging Circuit: Supplies all electric power to
onboard systems and recharges the batteries.
(including alternator and battery)
• Engine Stop Circuit: Stops the engine with the stop
solenoid.
(including stop solenoid and alternator)
T2-2-1
--- Page 10 ---
SYSTEM / Electrical System
ENGINE STOP CIRCUIT
(KEY SWITCH OFF)
1. When the key switch is turned from the ON NOTE: Surge voltage to be developed when
position to the OFF position, key switch terminal stopping the engine doesn’t arise because
B is disconnected from terminals BR, R2 and the alternator generation circuit is directly
ACC in the key switch. connected to the battery. (The batteries
2. Current to the accessories from key switch function as a condenser.)
terminal R2 and ACC is stopped.
3. Current to the holding side of the stop solenoid
from key switch terminal BR is stopped,
deactivating the stop solenoid. Then, the fuel cut
lever is moved by spring force to the fuel cut
position. Therefore, the fuel isn’t supplied,
causing the engine to stop.
Key Switch
Fuse Box
To Each Accessory
Battery
Alternator
Stop Solenoid
T1LA-02-02-006
Holding Side
T2-2-11
--- Page 11 ---
COMPONENT OPERATION / Pump Device
PILOT PUMP (P4) (27U)
The inner rotor is splined to the shaft, and engages the The rotational center of outer rotor is eccentric to the
outer rotor. rotation center of the shaft.
The engine rotation drives the shaft directly, and it ro- Thereby, the hydraulic oil from the suction port fills the
tates the inner rotor. When the inner rotor rotates, the spaces between the rotors, then discharges through
outer rotor also rotates. the delivery ports.
Pilot Pump (P4)
Rotation Direction T574-03-01-001
Outer Rotor
Shaft
Inner Rotor
Suction Port Delivery Port
Rotation Center of Shaft
Rotation Center of Outer Rotor
T571-03-01-004
T3-1-5
--- Page 12 ---
COMPONENT OPERATION / Swing Device
• 30U, 35U
The swing reduction gear is a two-stage planetary-
gear reduction type.
The swing motor rotation force is transmitted to the
first stage sun gear.
The rotation of first stage sun gear is reduced by the
first stage planetary gear and the ring gear and is
transmitted to the second stage sun gear via the first
stage holder.
The rotation of the second stage sun gear is re-
duced by the second stage planetary gear and ring
gear and rotates the shaft via the second stage
holder.
First Stage Sun Gear
First Stage Holder
First Stage
Planetary Gear
Second Stage
Planetary Gear
Second Stage
Holder
Ring Gear
Second Stage
Sun Gear
Shaft
T575-03-02-001
T3-2-7
--- Page 13 ---
COMPONENT OPERATION / Control Valve
Section L (Boom) Section K-K
2
4
3
T1LA-03-03-023
T1LA-03-03-022
Section M (Bucket)
23
1
T1LA-03-03-024
T3-3-9
--- Page 14 ---
COMPONENT OPERATION / Control Valve
Flow Combiner Valve in Neutral
Passage (E) Passage (G)
From Main Pump P3
T577-03-03-003
Flow Combiner Valve When Operated
Passage (E) Passage (G)
From Main Pump P3
Pilot Signal
Pressure
T577-03-03-004
Flow Combiner Valve Spool
T3-3-19
--- Page 16 ---
COMPONENT OPERATION / Pilot Valve
1 1
2 2
6
3 3 Port T
4 4 7
5 5 Port P
6 Output Port
6
Port T Port T
7 Port P 7 Port P
Output Port T183-03-04-002
Output Port T183-03-04-004
1 - Cam 3 - Spring Guide 5 - Return Spring 7 - Hole
2 - Pusher 4 - Balance Spring 6 - Spool
T3-4-5
--- Page 17 ---
COMPONENT OPERATION / Travel Device
TRAVEL BRAKE VALVE
27U:
The travel brake valve consists of counterbalance
valve, and travel speed changeover valve.
The counterbalance valve has two functions; one is to
start and stop the travel smoothly, and the other is to
prevent the machine from running away while
descending slopes.
The travel speed changeover valve is switched by
pressure oil from the travel speed changeover
solenoid valve. It switches the travel speed by the
control piston.
Travel Brake Valve
T574-03-05-001
Section of Brake Valve Counterbalance Valve
Travel Speed
Changeover Valve
T571-03-05-006
T3-5-3
--- Page 18 ---
COMPONENT OPERATION / Travel Device
At Slow Speed:
Spool
P1 P2
Travel Speed Plunger Surface (b)
Changeover
Solenoid Valve Ball
A B
Surface (a) Control
Piston T565-03-05-005
At Fast Speed: Spool
P1 P2
Notch
Travel Speed
Changeover Plunger Surface (b)
Solenoid Valve
Ball
A B
Surface (a) Control
Piston T565-03-05-006
T3-5-13
--- Page 19 ---
SECTION 4
OPERATIONAL PERFORMANCE TEST
CONTENTS
Group 1 Introduction Group 5 Component Test
Operational Performance Test.................... T4-1-1 Primary Pilot Pressure ..................................T4-5-1
Preparation for Performance Tests ............. T4-1-2 Secondary Pilot Pressure .............................T4-5-2
Main Relief Valve Set Pressure ....................T4-5-4
Group 2 Standard Overload Relief Valve Set Pressure .............T4-5-8
Operational Performance Standard ............. T4-2-1 Pump Driving Torque ..................................T4-5-10
Swing Motor Drainage ................................T4-5-12
Group 3 Engine Test Travel Motor Drainage ................................T4-5-14
Engine Speed ............................................... T4-3-1
Engine Compression Pressure..................... T4-3-2
Valve Clearance ........................................... T4-3-3
Nozzle Check ............................................... T4-3-4
Injection Timing............................................. T4-3-6
Group 4 Excavator Test
Travel Speed ................................................ T4-4-1
Track Revolution Speed ............................... T4-4-2
Mistrack Check ............................................. T4-4-3
Travel Motor Leakage................................... T4-4-4
Swing Speed ................................................ T4-4-5
Swing Function Drift Check .......................... T4-4-6
Swing Motor Leakage................................... T4-4-7
Maximum Swingable Slant Angle................. T4-4-8
Swing Bearing Play ...................................... T4-4-9
Hydraulic Cylinder Cycle Time ................... T4-4-10
Dig Function Drift........................................ T4-4-12
Control Lever Operating Force................... T4-4-13
Control Lever Stroke................................... T4-4-14
1LAT-4-1
--- Page 20 ---
OPERATIONAL PERFORMANCE TEST / Engine Test
VALVE CLEARANCE
Summary:
1. Perform the measurement when the engine is
cold.
2. Before removing the head cover, clean the area
around the head cover to prevent the entry of Mark Groove
dust into the engine.
Preparation:
1. Remove the head cover.
2. Locate the top dead center (TDC) in the com-
pression stroke. Align "Mark Groove" on crank
pulley with "TDC Mark" on timing gear case
cover. Crank Pulley
In this position, cylinder No.1 is at the top dead TDC Mark
center in the compression stroke.
NOTE: The flywheel can be easily turned after the
glow plugs are removed. T533-06-02-001
Measurement:
1. Measure the valve clearance between the rocker
arm and valve.
2. When the measurement is started from cylinder
No.1, measure the clearances of valves marked Valve
({) in the table below. Clearance
Cylinder No. 1 2 3
Valve I E I E I E
Cylinder No.1 at top dead center { { { {
Cylinder No.1 at overlap × ×
3. Turn flywheel 360°, then measure the valve
clearances marked (×) in the above table.
T532-06-02-001
Evaluation:
Refer to T4-2 Operational Performance Standard.
Adjustment:
If the measured value is not within specification,
loosen the lock nut and adjust valve clearance by
turning the adjusting bolt, then tighten lock nut.
T4-3-3
--- Page 21 ---
OPERATIONAL PERFORMANCE TEST / Excavator Test
SWING MOTOR LEAKAGE
Summary:
To check swing parking brake performance, meas-
ure the upperstructure drift after parking the machine
on a slope with the upperstructure positioned 90° to
the slope.
(Mechanical brake for swing parking is installed on
swing device.)
Preparation:
1. Check the lubrication of swing gear and swing
bearing.
2. Load the bucket with either soil or a weight
equivalent to the weight standard.
With: 27U: 120 kg (265 lb)
30U: 120 kg (298 lb)
35U: 165 kg (364 lb)
3. With the arm rolled out and bucket rolled in, hold
the bucket so that the height of bucket pin is even
with the boom foot pin.
4. Park the machine on a flat slope with a gradient of
15±1°.
5. Climb the slope, then swing the upperstructure
90°toward the slope. Make aligning marks on
the swing bearing circumference and track frame.
6. Maintain the hydraulic oil temperature at 50±5 °C
(122±9 °F). T570-06-03-006
Measurement:
1. Start the engine and maintain engine speed at
idle speed. After 5 minutes, measure the differ-
ence between the marks on the swing bearing
circumference and the track frame.
2. Perform the measurement under the following Measure the arc length along the swing
bearing circumference.
two conditions:
⋅When the brake is applied(with the pilot control
shut-off lever in the LOCK position).
⋅When the brake is released(with the pilot control
shut-off lever in the UNLOCK position).
3. Perform the measurement on both right and left
Mark on the track frame
swing directions.
4. Perform the measurement three times in each di-
rection and calculate the average values. Mark on the swing bearing
T105-06-03-010
Evaluation:
Refer to T4-2 Operational Performance Standard.
Remedy:
Refer to T5-2 "Troubleshooting A".
T4-4-7
--- Page 22 ---
OPERATIONAL PERFORMANCE TEST / Component Test
PRIMARY PILOT PRESSURE
Hose (PF3/8)
Preparation:
1. Stop the engine. Pilot Filter
2. Turn the filling cap on hydraulic oil tank to bleed
air. Relief Valve
3. Disconnect the hose (PF 3/8) at the pilot filter. In-
stall pressure gauge assembly (ST 6932) with tee
(ST 6639) and adapter (ST 6069) to the pilot filter. 2-Unit Sole-
noid Valve
: 22 mm
4. Start the engine and check for oil leakage from
the gauge connection.
5. Maintain the hydraulic oil temperature at 50±5 °C
(122±9 °F).
Measurement:
1. Run engine at fastidle speed.
2. Measure the pressure without load. T1LA-04-04-001
3. Perform the measurement three times and calcu-
late the average value. Adjusting Screw
Lock Nut
Evaluation:
Refer to T4-2 Operational Performance Standard.
Adjustment:
Adjustment the relief valve on 2-unit solenoid valve
if necessary.
1. Loosen the lock nut.
2. Turn the adjusting screw to adjust the pressure.
: 5 mm
3. Tighten the lock nut.
: 17 mm
: 20 to 29 N⋅m (2 to 3 kgf⋅m, 14 to 22 lbf⋅ft) T574-03-06-002
4. After completing the adjustment, recheck the set
pressure.
NOTE: Standard change in pressure.
Screw Turns 1/4 1/2 3/4 1
Change in kPa 147 294 441 588
Relief (kgf/cm ) 2
(1.5) (3) (4.5) (6)
Pressure
(psi) (21) (43) (64) (85)
T4-5-1
--- Page 23 ---
OPERATIONAL PERFORMANCE TEST / Component Test
(Blank)
T4-5-11
--- Page 24 ---
TROUBLESHOOTING / Diagnosing Procedure
INTRODUCTION
Troubleshooting charts shown in this section indicate
the orderly procedures for inspecting and finding out
the cause(s) of problems in the machine.
This section is comprised of three groups:
Troubleshooting A (diagnosis of machine by symptom),