Hitachi NR 90AC2 Manual

POWER TOOLS
TECHNICAL DATA
AND
SERVICE MANUAL
STRIP NAILER
NR 90AC2
SPECIFICATIONS AND PARTS ARE SUBJECT TO CHANGE FOR IMPROVEMENT
LIST No. E002 Sep. 2001
N
MODEL
NR 90AC2

REMARK:
Throughout this TECHNICAL DATA AND SERVICE MANUAL, a symbol(s)
is(are) used in the place of company name(s) and model name(s) of our
competitor(s). The symbol(s) utilized here is(are) as follows:
Symbols Utilized
Competitors
Company Name Model Name
P SENCO SN65C
Q Paslode F-350SRH

1. PRODUCT NAME ........................................................................................................................... 1
2. MARKETING OBJECTIVE ............................................................................................................. 1
3. APPLICATIONS .............................................................................................................................. 1
4. SELLING POINTS .......................................................................................................................... 1
5. SPECIFICATIONS .......................................................................................................................... 2
5-1. Specifications .................................................................................................................................. 2
5-2. Nail Selection .................................................................................................................................. 3
5-3. Nail Driving Force ........................................................................................................................... 3
5-4. Optional Accessories ...................................................................................................................... 4
6. COMPARISONS WITH SIMILAR PRODUCTS .............................................................................. 5
7. PRECAUTIONS IN SALES PROMOTION ..................................................................................... 6
7-1. Instruction Manual .......................................................................................................................... 6
7-2. Warning Label ................................................................................................................................. 6
7-3. Related Laws and Regulations ....................................................................................................... 7
8. MECHANISM AND OPERATION PRINCIPLE ............................................................................... 8
8-1. Mechanism ..................................................................................................................................... 8
8-2. Interchangeability ............................................................................................................................ 9
8-3. Operation Principle ........................................................................................................................ 11
9. TROUBLESHOOTING GUIDE ..................................................................................................... 13
9-1. Troubleshooting and Correction .................................................................................................... 13
9-2. Possible Causes and Corrections of Air Leakage ......................................................................... 16
10. DISASSEMBLY AND REASSEMBLY ........................................................................................ 18
10-1. General Precautions in Disassembly and Reassembly .............................................................. 18
10-2. Disassembly and Reassembly of the Output Section ................................................................. 19
10-3. Disassembly and Reassembly of the Control Valve Section (See Fig. 12.) ............................... 21
10-4. Disassembly and Reassembly of the Driving Section (See Fig. 16.) .......................................... 24
10-5. Disassembly and Reassembly of the Cap and the Magazine Section ....................................... 25
11. INSPECTION AND CONFIRMATION AFTER REASSEMBLY .................................................. 28
12. STANDARD REPAIR TIME (UNIT) SCHEDULES ..................................................................... 29
Assembly Diagram for NR 90AC2
CONTENTS
Page

--- 1 ---
1. PRODUCT NAME
Hitachi 90 mm (3-12") Strip Nailer, Model NR 90AC2
2. MARKETING OBJECTIVE
The Model NR 90AC2 strip nailer is an upgraded version of the current Model NR 90AC, equipped with the
demands for improvement but remained its powerful driving force capable of driving round-head nails. We are
confident that your sales will increase with the new Model NR 90AC2. Primary improvements made to the Model
NR 90AC2 are described below.
(1) The magazine section is simplified:
The material of the magazine is changed from nylon (constructed of two parts) to extruded aluminum in order
to increase the strength and to reduce parts count (NR 90AC: 27 parts NR 90AC2: 20 parts).
(2) A dust filter is added to the air inlet to prevent dust from getting in the machine.
(3) The grip tape is changed to the long-life grip rubber.
(4) The piston ring is changed to the O-ring.
(5) The material of the O-ring used in the head valve section is changed to swell-resistant material.
(6) The shape of the pushing lever spring is changed to prevent settling.
3. APPLICATIONS
Floor and wall framing
Truss build-up, window build-up
Subflooring and roof decking
Wall sheathing
Mobile home and modular housing construction
4. SELLING POINTS
Equipped with a rubber grip
Rear loading type
Equipped with a
pushing lever stopper
(idling protector)
Simple and high-strength
aluminum magazine
(NR 90AC: nylon magazinne)
Equipped with a dust filter

--- 2 ---
Optional accessories
Nail capacity
4.0 kg (8.9 lbs.)
2.7 ltr/cycle at 7 kgf/cm2(0.095 ft3/cycle at 100 psi) (2.7 ltr/cycle at 6.9 bar)
Corrugated cardboard box
3 pcs./sec.
Driving speed
503 mm x 353 mm x 121 mm
(19-13/16" x 13-7/8" x 4-3/4")
50 to 60 nails (2 strips)
Dimensions
(Length x Height x Width)
Nail feed system
3/8 NPT thread
Standard accessories
Weight
Spiral spring
Air consumption
Air inlet
Package dimensions
(Length x Height x Width)
Packaging
587 mm x 398 mm x 136 mm
(23-1/8" x 15-21/32" x 5-11/32")
Nose cap (Code No. 881968) ................................................................... 1
Hex. bar wrench for M5 screw (Code No. 944458) .................................... 1
Hex. bar wrench for M6 screw (Code No. 944459) .................................... 1
Hex. bar wrench for M8 screw (Code No. 872422) .................................... 1
Eye protector (Code No. 875769).............................................................. 1
Sequential fire parts set (Code No. 881973)
Pneumatic tool lubricant (1 oz oil feeder) (Code No. 877153)
Pneumatic tool lubricant (4 oz oil feeder) (Code No. 874042)
Pneumatic tool lubricant (1 quart can) (Code No. 876212)
Grease (ATTOLUB No. 2) (500 g (1.1 lbs.)) (Code No. 317918)
Case (Code No. 878898)
5. SPECIFICATIONS
5-1. Specifications
Reciprocating piston type
Model
Driving system
NR 90AC2
Operating pressure 5 --- 8.5 kgf/cm2 (70 --- 120 psi, 4.9 --- 8.3 bar) (Gauge pressure)

--- 3 ---
7 mm
(0.286")
60 mm (2-3/8")
Minimum
Plastic-collated strip nails full-head nails
Maximum
8.3 mm
(0.327")
90 mm (3-1/2")
4.1 mm
(0.162")
20 deg. Min. 13 mm
(0.5") Max. 41 mm
(1.6")
5-2. Nail Selection
The Model NR 90AC2 utilizes round-head nails collated with plastic resin into bands of 25 to 30 pieces.
Applicable nail dimensions are shown below.
CAUTION: Ensure that nails are as specified in Fig. 1. Other nails will cause clogging of nails and
subsequent damage to the nailer.
Fig. 1 Dimensions of nails
5-3. Nail Driving Force
Fig. 2 shows by type of wood and nail, the nailer output energy provided by the supply pressure and the nailing
energy required for driving the nail flush. Air pressure which exceeds the intersecting point between the nailer
output energy and the required nailing energy required for driving the nail allows the nail to be fully driven.
For example, when driving a nail of 4.1 mm dia. by 90 mm length (0.162" x 3-1/2") into a workpiece of hemlock
spruce with he Model NR 90AC2, a pressure of about 6.4 bar (6.5 kgf/cm2, 92 psi) allows the nailer to drive the
nail flush to the wood surface. A pressure beyond this value causes the nail head to be driven below the wood
surface. Fig. 2 should be used as reference data because those values vary depending on the type, moisture
content, and grain of wood.
2.9 mm
(0.113")

--- 4 ---
Fig. 2 Required nailing energy and nailer output energy
5-4. Optional Accessories
Sequential fire parts set:
The Sequential Fire Parts Set is provided as an optional accessory for the Model NR 90AC2. By using this
optional accessory, a nail is driven by pressing the push lever first against a workpiece and then pulling the trigger,
and no nail is driven when pulling the trigger first and then pressing the push lever against a workpiece (single-
shot operation). Please recommend the sequential fire parts set to the customers who want to use it.
Salespersons must instruct the customers to read the Handling Instructions attached to the sequential fire parts
set and also the Handling Instructions of the Model NR 90AC2 thoroughly for correct use.
Hemlock spruce
NR 90AC
NR90AC2
P
Q
Air pressure setting to drive nail flush
with NR 90AC2

--- 5 ---
6. COMPARISONS WITH SIMILAR PRODUCTS
Maker HITACHI
Air consumption at
7 kgf/cm2(100 psi)
Operating pressure
Magazine type
Weight
Dimensions
(L x H x W)
Model
Nail capacity
(3-1/2 x .162")
5 -- 8.5 kgf/cm2
(70 -- 120 psi)
503 x 353 x 121 mm
(19-13/16 x 13-7/8 x 4-3/4")
NR 90AC2
2.7 ltr/cycle
(.095 ft3/cycle)
50
Rear loading
(Aluminum)
4.0 kg (8.9 lbs.)
5 -- 8.5 kgf/cm2
(70 -- 120 psi)
548 x 353 x 121 mm
(21-9/16 x 13-7/8 x 4-3/4")
NR 90AC
2.7 ltr/cycle
(.095 ft3/cycle)
50
Top loading
(Plastic)
4.3 kg (9.5 lbs.)
5 -- 8.5 kgf/cm2
(70 --120 psi)
501 x 343 x 111 mm
(19-3/4 x 13-5/8 x 4-3/8")
2.3 ltr/cycle
(.081 ft3/cycle)
50
Rear loading
(Aluminum)
3.7 kg (8.2 lbs.)
With wrench
P
Driving depth
adjustment mechanism
Tool not required Tool not required With wrench
Idling protector Provided Not provided Provided
Direction change
of exhaust air
Handle grip
Applicable
nails Length
Dia.
Tool not required
Rubber
60 -- 90 mm
(2-3/8 -- 3-1/2")
2.9 -- 4.1 mm
(0.113 -- 0.162")
Tool not required
Racket grip
60 -- 90 mm
(2-3/8 -- 3-1/2")
2.9 --4.1 mm
(0.113 --0.162")
Leather
60 -- 90 mm
(2-3/8 -- 3-1/2")
2.9 -- 4.1 mm
(0.113 -- 0.162")
With wrench
5.6 -- 8.5 kgf/cm2
(80 ---120 psi)
569 x 332 x 130 mm
(22-13/32 x 13-1/16 x 5-1/ 8")
2.4 ltr/cycle
(.085 ft3/cycle)
50
Top loading
(Aluminum)
3.9 kg (8.6 lbs.)
With wrench
Q
Not provided
Rubber
50 -- 90 mm
(2 -- 3-1/2")
2.9 -- 4.1 mm
(0.113 -- 0.162")
Note:
The Model NR 90AC2 is equipped with a pushing
lever stopper as an idling protector. The Pushing
Lever Stopper [72] is placed over Pushing Lever (B)
[33] to prevent Pushing Lever (B) [33] from being
pushed up when no nail is loaded in the magazine
or the number of nails remained in the magazine is
five or less (depending on the types of nails).
(See Fig. 3.)
Fig. 3
5
Pushing lever (B) [33]
Pushing Lever Stopper [72]

--- 6 ---
7. PRECAUTIONS IN SALES PROMOTION
In the interest of promoting the safest and most efficient use of the Model NR 90AC2 Nailer by all of our
customers, it is very important that at the time of sale the salesperson carefully ensures that the buyer seriously
recognizes the importance of the contents of the Instruction Manual, and fully understands the meaning of the
precautions listed on the Warning Label attached to each tool.
The Model NR 90AC2 Nailer is designed for continuous nail driving (however, some of the Model NR 90AC2 are
designed for single-shot operation only for some destinations). At time of sale, the salesperson must inform the
customer that the sequential trip mechanism kit which can change the Model NR 90AC2 to a single-shot nailer is
optionally available, and recommend it to the customers who want to use it. Refer to the leaflet attached together
with the Instruction Manual for details.
7-1. Instruction Manual
Although every effort is made in each step of design, manufacture, and inspection to provide protection against
safety hazards, the dangers inherent in the use of any pneumatic tool cannot be completely eliminated.
Accordingly, general precautions and suggestions for use of pneumatic tools, and specific precautions and
suggestions for the use of the pneumatic nailer are listed in the Instruction Manual to enhance the safe, efficient
use of the tool by the customer.
Salespersons must be thoroughly familiar with the contents of the Instruction Manual to be able to offer
appropriate guidance to the customers during sales promotion.
7-2. Warning Label
Each Model NR 90AC2 unit is provided with a Warning Label (illustrated below) which lists basic safety
precautions in its use. Carefully ensure that customers fully understand and follow these precautions before using
the tool.

--- 7 ---
7-3. Related Laws and Regulations
As nailers and staplers are designed to instantaneously drive nails and staples, there is an ever-present danger of
misfiring and subsequent possible serious injury. Accordingly, close attention in handling is absolutely necessary
at all times. Carefully ensure that the customer is fully aware of the precautions listed in the Instruction Manual
provided with each unit.
While there are no specific safety regulations, there are related items in various general safety regulations with
which the salespersons should be familiar in order to properly advise the customer. Please check your national
and/or local regulations for applicable items. Some applicable items are outlined below.
The U.S.A:
OSHA 1926.102 Eye and face protection
1926.302 Power-operated hand tools
ANSI SNT-101-1993 Portable, Compressed-Air-Actuated,
Fastener Driving Tools-Safety Requirements for
The following label is adhered to the Model NR 90AC2 for Europe to prohibit the use of the Model NR 90AC2
standing on a stepladder. Carefully ensure that customers fully understand and follow the precaution before using
the tool.

--- 8 ---
8. MECHANISM AND OPERATION PRINCIPLE
8-1. Mechanism
As illustrated in Fig. 4, the Model NR 90AC2 can be generally divided into four sections:
output section, control valve section, driving section and magazine section.
The magazine section has been newly designed though its basic construction is the same as that of the Model
NR 90AC. Features of the main parts are described below.
Output section ................. Most parts are common to the Model NR 90AC except the following parts.
The dust filter is added to the cap. Owing to this addition, gasket (B) is changed.
The piston ring is changed to the O-ring.
The O-ring used in the head valve section is changed to swell-resistant type.
The rubber handle grip is adopted at the body ass'y.
Control valve section ....... The valve construction is similar to the Model NR 90AC.
Driving section ................ The nose and pushing lever (B) have been newly designed.
Magazine section ............ All the parts have been newly designed. The rear-loading type magazine is made
of aluminum and equipped with an idling protector.
Fig. 4 Construction
Exhaust vent
Adjuster (A) [ 34 ]
Cylinder [17]
Piston [19]
Piston Bumper (A)
[24]
Trigger (A) [46]
Dust Filter [41]
Exhaust Cover [5]
, O-Ring
Body [22]
Cap [42]
Nail feeder ass'y Magazine section
Rubber
Driving section Output section
Top Cover [3]
Exhaust Valve
Rubber [7]
Head Valve [10]
Accumulator
Piston Bumper (B)
[25]
Nose [30]
Pushing Lever (B)
[33]
Pushing Lever (A)
[37]
Control valve
section
Plunger Spring [57]
Plunger (A) [58]
Valve Piston (B) [54]
Valve
Bushing (B) [51]
Valve Bushing (A) [60]
Control valve section

--- 9 ---
8-2. Interchangeability
The magazine section is not interchangeable between the Model NR 90AC2 and the NR 90AC because this
section of the Model NR 90AC2 have been newly designed. The output section, the driving section and the
control valve section are interchangeable except the following parts.
Cylinder O-Ring (B) [9]
Cylinder O-Ring [11]
O-Ring [18]
Piston [19]
Body [22]
Gasket (B) [40]
Dust Filter [41]
Part NR 90AC2 NR 90AC
Dust filter is provided and
the shape of gasket (B) is
different from the Model
NR 90AC.
Grip rubber
The grooves made
to the O-ring are
different from the
Model NR 90AC.
O-Ring
O-Ring Piston ring
Piston ring
O-Ring
Grip tape
Material: Fluororubber
(The size is the same as the Model NR 90AC.)
Material: Fluororubber
(The size is the same as the Model NR 90AC.)
Material: Nitrile rubber
Material: Nitrile rubber

--- 10 ---
Nose [30]
Guard [28]
Collar (B) [29]
Part NR 90AC2 NR 90AC
Collar
Protruded
NR 90AC: 13.3 mm (0.524")
NR 90AC: 10 mm (0.394")
Spring [32]
Pushing Lever (B) [33]
Idling protector
NR 90AC2: 7 mm (0.276")
NR 90AC: 4.5 mm (0.177")
NR 90AC2: 8 mm (0.315")
NR 90AC: 12 mm (0.472")

--- 11 ---
8-3. Operation Principle
(1) Before nailing (See Fig. 5 and Fig. 6.)
1) When compressed air is fed to the main body, it
fills the accumulator ( portion).
2) At the same time, the compressed air flows into
the valve piston lower chamber of the control valve
section and forces Valve Piston (B) [54] upward.
Compressed air is then fed through the air supply
vent and air passage to the head valve chamber.
As a result, the Head Valve Spring [8] is pushed
down to seal the Head Valve [10] and Cylinder
[17].
(2) When nailing (See Fig. 4 and Fig. 5.)
1) When Pushing Lever (A) [37] and Trigger (A) [46]
are operated together and Plunger (A) [58] is
pushed upward, the compressed air in the valve
piston lower chamber is discharged from the
bottom of Plunger (A) [58]. As a result, the
compressed air in the accumulator ( portion)
pushes down Valve Piston (B) [54], blocking the air
supply vent and opening the exhaust valve.
2) When the exhaust valve opens, the compressed
air in the head valve chamber is discharged into
the atmosphere through the air passage.
3) When the air pressure on the bottom surface of the
Head Valve [10] overcomes the strength of the
Head Valve Spring [8], the Head Valve [10] is
pushed upward. At this time, the Head Valve [10]
seals with the Exhaust Valve Rubber [7], blocking
the passage to the exhaust vent.
4) When the Head Valve [10] goes up, the
compressed air in the accumulator flows rapidly
into the Cylinder [17], forcing the Piston [19]
downward to strike the nail. When the Piston [19]
passes the cylinder hole, the compressed air flows
into the return air chamber and is accumulated
there.
Fig. 6 Control valve section
Fig. 5
Head valve chamber
Nail
Air passage
Control
valve
section
Cylinder hole
Head Valve
Spring [8]
Exhaust vent
Exhaust Valve Rubber [7]
Head Valve [10]
Cylinder [17]
Return air
chamber
Pushing Lever (A) [37]
Piston [19]
Accumulator
Trigger (A) [46]
To the head valve chamber
Plunger (A) [58]
Valve Piston (B)
[54]
Valve piston lower chamber
Exhaust
valve
Air passage
Accumulator
Air supply vent

--- 12 ---
(3) During return (See Fig. 7 and Fig. 8.)
1) When either Pushing Lever (A) [37] or Trigger (A)
[46] is released, Plunger (A) [58] goes down and
the compressed air in the accumulator flows into
the valve piston lower chamber.
2) As the air pressure in the valve piston lower
chamber increases to overcome the air pressure
applied on the upper portion of Valve Piston (B)
[54], Valve Piston (B) [54] is forced upward. When
this occurs, the exhaust valve is closed and the air
supply vent is opened.
3) When the air supply vent opens, the compressed
air in the accumulator ( portion) passes
through the air passage and flows into the head
valve chamber to push down the Head Valve [10].
As a result, the Head Valve [10] and the Cylinder
[17] are sealed and , at the same time, the Head
Valve [10] and the Exhaust Valve Rubber [7]
separate to open the exhaust vent.
4) The compressed air above the Piston [19] is
discharged into the atmosphere through the
exhaust vent. In this way, the air pressure above
the Piston [19] is reduced, and the greater
pressure of the air accumulated in the return air
chamber pushes the Piston [19] upward.
5) If the air pressure below the Piston [19] is higher
than that of the atmosphere after the Piston [19]
has fully returned, the excess air pressure is
discharged into the atmosphere through the
clearance between Piston Bumper (B) [25] and
the driver blade. Fig. 8 Control valve section
Fig. 7
Head valve chamber
Air passage
Control
valve
section
Piston Bumper
(A) [24]
Head Valve [10]
Exhaust vent
Exhaust Valve Rubber [7]
Return air
chamber
Piston Bumper
(B) [25]
Driver blade
Pushing Lever (A)
[37]
Piston [19]
Accumulator
Trigger (A) [46]
To the head valve chamber
Plunger (A) [58]
Valve
Piston (B) [54]
Valve piston
lower chamber
Exhaust
valve
Air passage
Accumulator
Air supply vent
Cylinder [17]

--- 13 ---
<Magazine>
Magazine is abnormal
(deformed or damaged).
Nail feeder is abnormal
(deformed or damaged).
Ribbon spring is abnormal
(deformed or damaged).
Nail rail is abnormal
(deformed, burrs, damaged
or fatigued).
Adhesive fragments are on
the nail rail or they need oil.
Foreign matter is found on
the guide face of the nail
feeder.
<Nails>
Magazine is not loaded with
specified genuine nails.
Problem Possible cause Inspection method Remedy
9. TROUBLESHOOTING GUIDE
9-1. Troubleshooting and Correction
1) Nails cannot
be driven. Check if the magazine is
normally loaded with
specified nails.
Check if nails (one strip) are
fed smoothly into the nail
injection port of the nose.
Use specified nails.
Magazine is loaded with
abnormal nails (bent nails,
large or small round-head
nails, abnormal collation,
etc.).
Nail or collating band clogs.
Collating band is deformed
or torn.
Remove the abnormal nails
and load the magazine with
normal nails.
<Nose>
Nail inlet groove of the nose
is abnormal (deformed,
burrs or damaged).
Adhesive fragments are in
the nail inlet groove.
Repair or replace the
defective part.
Remove the adhesive
fragments and apply oil to
the nail feeder, ribbon spring
and the nail rail.
Repair or replace the
defective part.
Remove the adhesive
fragments.
Check if the nail feeder
operates smoothly in the
magazine.
Check if nails (one strip)
move smoothly in the
magazine.

--- 14 ---
Plunger (A), valve piston (B),
valve bushing (A) or valve
bushing (B) is abnormal
(galled or damaged).
O-ring is worn or oiling is
needed.
Air pressure is too low.
Piston O-ring is worn or
damaged.
Piston bumper is abnormal
(dislocated, deformed or
damaged).
O-ring of the cylinder is
abnormal (dislocated,
deformed or damaged).
Driver blade is abnormal
(deformed, burrs, damaged
or fatigued).
Cylinder's internal surface is
abnormal (deposits of dirt or
worn).
Head valve sliding surface is
abnormal (galled, damaged
or needs oil).
Head valve spring is
abnormal (fatigued or
damaged).
Problem Possible cause Inspection method Remedy
Pull the nail feeder
backward and perform idle
driving. Check if the driver
blade has returned.
Check if nails can be driven
at 5 kgf/cm2.
While operating the nailer
without nails, check if the
drivng operation is
performed.
After operating the nailer
without nails, check if the
driver blade is kept in the
down position.
After making idle driving,
check if the driver blade is
kept in the down position.
Disassemble the control
valve and check the O-ring.
Adjust for 5 to 8.5 kgf/cm2.
Replace the piston ring.
Replace the piston bumper.
Reassemble or replace.
Repair or replace.
Remove the dirt and apply
oil, or replace.
Replace the defective part.
Apply grease.
Replace the head valve
spring.
Replace the defective part.
Apply grease, or replace.
<Output section>
<Control valve section>

--- 15 ---
Problem Possible cause Inspection method Remedy
For short nails, the adjuster
is raised too high.
Nails are not fully fed into
the injection port.
Unspecified nails are used.
Driver blade is worn.
Workpiece is very hard.
2) Nails are bent
when being
driven.
Check if the adjuster is
raised too high.
See item 1).
Check if the driver blade tip
is abnormally worn.
Drive a nail into soft wood
workpiece and check if the
nail is bent.
Turn the adjuster to the
lower position to decrease
the pressure.
See item 1).
Replace the driver blade.
Do not use unspecified
workpieces.
Adjust the adjuster to the
proper position.
Adjust for 5 to 8.5 kgf/cm2.
Do not use unspecified
workpieces.
Replace the drive blade.
Replace the defective part.
Adjuster is improperly
adjusted.
Air pressure is too low.
Workpiece is very hard.
Driver blade is worn.
Piston ring is abnormal
(worn or damaged).
Cylinder's internal surface is
abnormal (worn or rough).
3) Head of a nail
driven into a
workpiece
protrudes
from the wood
surface.
Turn the adjuster to the
lowest position and drive a
nail.
Drive a nail into soft wood
workpiece and check if the
head protrudes from the
wood surface.
Operate the nailer without
nails and check if the driver
blade is projected from the
nose tip.
Disassemble the output
section and check the
piston ring, O-ring and the
inner/outer surfaces of the
cylinder for abnormal
condition.

--- 16 ---
Repair procedure
(1) Check the points of the following parts marked by an
asterisk * for abnormal condition.
(2) Next, check the seal parts marked with a double
circle for wear, flaw and damage.
(3) And then, check other places.
9-2. Possible Causes and Corrections of Air Leakage
Air leakage repair location
a
b
d
c
e
f
Air leakage point Possible cause
With control valve OFF With control valve ON
Cylinder O-ring (B) [9] of the Head Valve
[10] is abnormal or its sliding surface a is
worn, deformed or flawed.
The Head Valve Rubber [12] is abnormal or
the sealing surface b of the Cylinder [17]
is worn or flawed.
The Exhaust Valve Rubber [7] is abnormal
or the sliding surface c of the Head Valve
[10] is worn or flawed.
A) Exhaust port
B) Exhaust cover The Hex. Socket Hd. Bolt (W/Flange)
M6 x 35 [4] is loose.
Gasket (A) [6] is damaged.
Seal surface of the Body [22] or the
Exhaust Cover [5] is abnormal.
(A)
(B)
(C)
(D)
(G)
Control valve section

--- 17 ---
The upper O-ring (I.D. 8.8) [55] of Valve
Piston (B) [54] is abnormal (worn, broken or
flawed).
The Head Valve O-ring (I.D. 16.8) [50] of
Valve Bushing (B) [51] is abnormal (broken
or flawed).
The upper surface f of the valve cavity of
the Body [22] is abnormal.
The O-ring (I.D. 11) [56] of Valve Piston (B)
[54] is abnormal (worn, broken or flawed).
The lower O-ring (I.D. 8.8) [55] of Valve
Piston (B) [54] is abnormal (worn, broken or
flawed).
The O-ring (S-18) [52] of Valve Bushing (B)
[51] is abnormal (broken or flawed).
The internal surface e of the valve cavity
of the Body [22] is abnormal.
C) Nose 1
The O-ring (S-95) [14] of the Cylinder Plate
[13] or the O-ring (I.D. 59.6/W2.4) [15] of
the Cylinder [17] is abnormal (broken or
flawed).
Air leakage point Possible cause
With control valve OFF With control valve ON
The Cylinder O-ring [26] of the Body [22] or
the groove is abnormal (broken or flawed).
The Hex. Socket Hd. Bolt M8 x 30 [61] is
loose.
Piston Bumper (A) [24] is abnormal
(portion d is damaged, deformed or
cracked).
The Piston [19] is abnormal (driver blade is
deformed or seal surface is deformed).
The O-ring (I.D. 1.8) [59] of Plunger (A)
[58] is abnormal (worn, broken or flawed).
Valve Bushing (A) [60] is abnormal (sliding
surface of Plunger (A) [58] is deformed or
flawed).
The O-ring (S-4) [53] of Valve Piston (B)
[54] is abnormal (worn, broken or flowed).
Valve Piston (B) [54] is abnormal (sliding
surface of Plunger (A) [58] is deformed or
flawed).
D) Nose 2
E) Control Valve 1
F) Control Valve 2
Gasket (B) [40] is damaged.
The Hex. Socket Hd. Bolt M5 x 16 [43] is loose.
Seal surface of the Body [22] or the Cap [42] is abnormal (damaged, deformed or flawed).
G) Cap