Hitachi NR 90AC3 Manual

TECHNICAL DATA
AND
SERVICE MANUAL
STRIP NAILER
NR 90AC3
SPECIFICATIONS AND PARTS ARE SUBJECT TO CHANGE FOR IMPROVEMENT
LIST No. E013 Sep. 2003
N
MODEL
NR 90AC3
Hitachi 
Power Tools

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

CONTENTS
Page
1. PRODUCT NAME.............................................................................................................................. 1
2. MARKETING OBJECTIVE ................................................................................................................ 1
3. APPLICATIONS................................................................................................................................. 1
4. SELLING POINTS ............................................................................................................................. 1
5. SPECIFICATIONS ............................................................................................................................. 2
5-1. Specifications......................................................................................................................................2
5-2. Explanation of the Nailing Action ........................................................................................................3
5-3. Nail Selection......................................................................................................................................4
5-4. Nail Driving Force ...............................................................................................................................4
5-5. Optional Accessories ..........................................................................................................................5
6. COMPARISONS WITH SIMILAR PRODUCTS ................................................................................. 6
7. PRECAUTIONS IN SALES PROMOTION ........................................................................................ 7
7-1. Handling Instructions ..........................................................................................................................7
7-2. Warning Label.....................................................................................................................................7
7-3. Related Laws and Regulations ...........................................................................................................8
8. MECHANISM AND OPERATION PRINCIPLE .................................................................................. 9
8-1. Mechanism .........................................................................................................................................9
8-2. Interchangeability..............................................................................................................................10
8-3. Operation Principle ...........................................................................................................................12
9. TROUBLESHOOTING GUIDE ........................................................................................................15
9-1. Troubleshooting and Correction........................................................................................................15
9-2. Possible Causes and Correction of Air Leakage ..............................................................................18
10. DISASSEMBLY AND REASSEMBLY ........................................................................................... 20
10-1. General Precautions in Disassembly and Reassembly ..................................................................20
10-2. Disassembly and Reassembly of the Output Section.....................................................................21
10-3. Disassembly and Reassembly of the Control Valve Section ..........................................................23
10-4. Disassembly and Reassembly of the Driving Section ....................................................................26
10-5. Disassembly and Reassembly of the Cap and the Magazine Section ...........................................27
11. INSPECTION AND CONFIRMATION AFTER REASSEMBLY ..................................................... 30
12. STANDARD REPAIR TIME (UNIT) SCHEDULES ........................................................................ 31
Assembly Diagram for NR 90AC3

--- 1 ---
1. PRODUCT NAME
Hitachi 90 mm (3-1/2") Strip Nailer, Model NR 90AC3
2. MARKETING OBJECTIVE
The new Model NR 90AC3 strip nailer is a minor-changed version of the current Model NR 90AC2. Owing to the
modification of the ANSI standard, the current Model NR 90AC2 has gone out of production since the 1st of May
2003. To correspond to this, the switching device (change knob) was added to select the nailer operation
between "single actuation (single sequential actuation)" and "contact actuation" (the current Model NR 90AC2 is
provided with the contact actuation mechanism only).
Except the above, the construction is common to the current Model NR 90AC2 as well as the features such as
driving response and balance.
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
With "single actuation/
contact actuation selector

--- 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
Safety glasses (Code No. 875769)............................................................ 1
Full sequential actuation mechanism kit (Code No. 884142)
(Sequential trip mechanism kit)
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 90AC3
Operating pressure 5 --- 8.5 kgf/cm2 (70 --- 120 psi, 4.9 --- 8.3 bar) (Gauge pressure)

--- 3 ---
5-2. Explanation of the Nailing Action
To meet the requirements of "ANSI SNT-101-2002", the Model NR 90AC3 is equipped with a nailing operation
switching device at the valve portion as shown in the figures below. Use SINGLE ACTUATION MECHANISM
(SINGLE SEQUENTIALACTUATION MECHANISM) or CONTACT ACTUATION MECHANISM in accordance with
the work to be performed. A FULL SEQUENTIALACTUATION MECHANISM KIT (SEQUENTIAL TRIP
MECHANISM KIT) is also available as an option. Each nailing operation is as follows.
SINGLE ACTUATION MECHANISM (SINGLE SEQUENTIALACTUATION MECHANISM):
First, press the pushing lever against the wood; next, pull the trigger to drive the nail. First, pull the trigger;
next, press the pushing lever against the wood to drive the nail. After nailing once, nailing will not be possible
again until the trigger is released and pressed again.
CONTACT ACTUATION MECHANISM:
First, press the pushing lever against the wood; next, pull the trigger to drive the nail. First, pull the trigger;
next, press the pushing lever against the wood to drive the nail. If the trigger is held back, a nail will be driven
each time the pushing lever is pressed against the wood.
FULL SEQUENTIALACTUATION MECHANISM:
First, press the pushing lever against the wood; next, pull the trigger to drive the nail. Follow the same
sequence to continue driving nails.

--- 4 ---
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")
5-3. Nail Selection
The Model NR 90AC3 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
5-4. Nail Driving Force
Figure 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 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 the Model NR 90AC3, 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. Figure 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")

--- 5 ---
Fig. 2 Required nailing energy and nailer output energy
5-5. Optional Accessories
Full sequential actuation mechanism kit (Sequential trip mechanism kit) (Code No. 884142)
Full sequential actuation mechanism kit (Sequential trip mechanism kit) is provided as an optional accessory for
the Model NR 90AC3. By using this optional accessory, a nail is driven by pressing the pushing lever first against
a workpiece and then pulling the trigger, and no nail is driven when pulling the trigger first and then pressing the
pushing lever against a workpiece (single actuation). 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 90AC3 thoroughly for
correct use.
Hemlock spruce
NR 90AC2
NR 90AC3
P
Q
Air pressure setting to drive nail flush
with NR 90AC3

--- 6 ---
2.9 --4.1 mm
(0.113" --0.162")
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 90AC3
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 90AC2
2.7 ltr/cycle
(.095 ft3/cycle)
50
Rear loading
(Aluminum)
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 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
Rubber
60 -- 90 mm
(2-3/8" -- 3-1/2")
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 90AC3 is equipped with a pushing lever stopper as an idling protector. The Pushing Lever Stopper
[74] 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 [74]
Not provided
Single actuation/
contact actuation
selector Provided Not provided Not provided

--- 7 ---
7. PRECAUTIONS IN SALES PROMOTION
In the interest of promoting the safest and most efficient use of the Model NR 90AC3 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 Handling Instructions, and fully understands the meaning of the
precautions listed on the Warning Label attached to each tool.
The Model NR 90AC3 Nailer is designed for continuous nail driving (however, some of the Model NR 90AC3 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 90AC3 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. Handling Instructions
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 Handling Instructions to enhance the safe, efficient
use of the tool by the customer.
Salespersons must be thoroughly familiar with the contents of the Handling Instructions to be able to offer
appropriate guidance to the customers during sales promotion.
7-2. Warning Label
Each Model NR 90AC3 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.