Narex ESR 20-5, Original Operating Manual, Page: 13 / 32

English
13
Technical data
Impact wrench
Type ESR 20-5
Voltage 230–240 V
Frequency 50–60 Hz
Rated power 450 W
Blows under load 2 300 min
-1
Scope of use M12–M20*
Tightening torque max. 280 Nm
Tool clamping ½”
Weight 2.75 kg
Protection class II /
* With the use of torsion rods bolts from M8 size may be tightened
Changing the direction of rotation
The rotation direction switch (3) may be used to change the direc-
tion of rotation.
Change the direction of rotation at rest only!
Tool clamping
Impact wrench is fitted with a dedicated ½” square chuck (5) for
clamping of all standard tools (extensions, heads etc.).
Head (8) is secured from accidental release by means of a safety
pin (6) and safety rubber ring (7) inserted into the head groove (8).
Instructions for use
Apply the machine on the nut or screw only if not running.
The torque (tightening torque) depends on the duration of im-
pacts. Maximum torque is reached following 6–10 seconds of im-
pact action. Then the tightening torque increases a little but the
head is heated significantly.
Such an excessive heat may result in intensive wear and tear of all
impact components and higher consumption of lubricant grease.
The duration of impact action must be determined for each tight-
ening torque. The actual tightening torque must be constantly
checked by torque spanner.
For the purposes of application we distinguish between two
characteristic joints:
Firm joint:
Screwing of two or more usually metal parts with no spring effect
or deformation due to tightening pressure.
Soft joint:
Screwing of two or more parts with at least one of such material
or design that causes deformation or spring effect as a result of
tightening pressure.
With a firm joint, using solid screws and nuts, the following
tightening torque (Nm) can be achieved using the impact
wrench:
The required time of tightening may be estimated according to the
following scheme:
Strength class*
Thread diameter
4.8 5.6 5.8 6.8 8.8 10.9 12.9
M12 40 38 50 60 80 113 135
M14 65 60 79 95 130 180 ×
M16 98 92 122 147 196 × ×
M18 135 126 168 202 270 × ×
M20 190 178 238 286 × × ×
* Strength classes of screws and nuts according to ISO 898-1 stand-
ard
Control elements
1 ...........Stay-down key
2 ...........Switch
3 ...........Rotation direction switch
4 ...........Air vents
5 ...........Tool clamping
6 ...........Safety pin
7 ...........Safety rubber ring
8 ...........Tool
The displayed and/ or described accessories may not be included
in the scope of delivery.
Double insulation
To ensure maximum safety of the user, our tools are designed and
built to satisfy applicable European standards (EN standards). Tools
with double insulation are marked by the international symbol of
a double square. These tools must not be grounded and a two-wire
cable is sufficient to supply them with power. Tools are shielded in
accordance with EN 50114.
Application
Cord hand-held impact wrench is designed for easy tightening and
loosening of hexagonal screws and nuts even the rusty ones.
Because of low weight the wrench is easy to operate which makes
it ideal tool for use on assembly lines, in assembly workshops, con-
struction sites etc.
Use for other than intended purposes shall be a sole liability of the
user.
Function principle
Tool clamping (5) with a tool (8) is driven by electric motor through
a gearing and impact mechanism.
Work process can be divided into two phases:
1. Screwing;
2. Tightening.
The impact mechanism starts only after the screw joint is tight - the
motor is under load.
The impact mechanism changes the motor power to even rotating
impacts. While loosening the screw joints, this process is reversed.
Putting into operation and use
Check whether the type plate data comply with the actual voltage
of power source. Check whether the socket type complies with
the plug type. Tools designed for 230 V may be connected also to
220 / 240 V.
Switching on/ off
By pressing the switch button (2) the machine is activated. It stops
immediately when the switch button is released.
Continual running
Press the switch button (2) and also the stay-down key (1).
By pressing the switch button (2) again and releasing the continual
running mode is terminated.