Working Advice; Maintenance And Service; Maintenance And Cleaning - Bosch Professional GBH 3-28 DRE Original Instructions Manual

OBJ_BUCH-873-008.book Page 11 Thursday, December 21, 2017 7:56 AM
Reversing the rotational direction
The rotational direction switch 13 is used to reverse the rota-
tional direction of the machine.
 Actuate the rotational direction switch 13 only when
the machine is at a standstill.
Right rotation: Turn the rotational direction switch 13 to
the stop in position .
Left rotation: Turn the rotational direction switch 13 to
the stop in position .
Set the direction of rotation for hammer drilling, drilling and
chiselling always to right rotation.
Switching On and Off
– To start the machine, press the On/Off switch 7.
– To switch off the machine, release the On/Off switch 7.
Setting the Speed/Impact Rate
The speed/impact rate of the switched on power tool can be
variably adjusted, depending on how far the On/Off switch 7
is pressed.
Light pressure on the On/Off switch 7 results in low speed/im-
pact rate. Further pressure on the switch increases the
speed/impact rate.
Overload Clutch
 If the tool insert becomes caught or jammed, the drive
to the drill spindle is interrupted. Because of the forces
that occur, always hold the power tool firmly with both
hands and provide for a secure stance.
 If the power tool jams, switch the machine off and loos-
en the tool insert. When switching the machine on with
the drilling tool jammed, high reaction torques can oc-
cur.

Working Advice

 Before any work on the machine itself, pull the mains
plug.
Changing the Chiselling Position (Vario-Lock)
The chisel can be locked in 36 positions. In this manner, the
optimum working position can be set for each application.
– Insert the chisel into the tool holder.
– Turn the mode selector switch 9 to the "Vario-Lock" posi-
tion (see "Setting the operating mode", page 10).
– Turn the tool holder to the desired chiselling position.
– Turn the mode selector switch 9 to the "chiselling" posi-
tion. The tool holder is now locked.
– For chiselling, set the rotation direction to right rotation.
Inserting Screwdriver Bits (see figure L)
 Apply the power tool to the screw/nut only when it is
switched off. Rotating tool inserts can slip off.
To work with screwdriver bits, a universal bit holder 28 with
SDS-plus shank (accessory) is required.
– Clean the shank end of the adapter shank and apply a light
coat of grease.
– Insert the universal bit holder with a turning motion into
the tool holder until it automatically locks.
– Check the locking effect by pulling the universal bit holder.
Bosch Power Tools
– Insert a screwdriver bit into the universal bit holder. Use
only screwdriver bits that match the screw head.
– Turn the mode selector switch 9 to the "drilling" position.
– To remove the universal bit holder, pull the locking sleeve
5 toward the rear and remove the universal bit holder 28
out of the tool holder.

Maintenance and Service

Maintenance and Cleaning

 Before any work on the machine itself, pull the mains
plug.
 For safe and proper working, always keep the machine
and ventilation slots clean.
 A damaged dust protection cap should be changed im-
mediately. We recommend having this carried out by
an after-sales service.
– Clean the tool holder 3 each time after using.
If the replacement of the supply cord is necessary, this has to
be done by Bosch or an authorized Bosch service agent in or-
der to avoid a safety hazard.
After-sales Service and Application Service
Our after-sales service responds to your questions concern-
ing maintenance and repair of your product as well as spare
parts. Exploded views and information on spare parts can al-
so be found under:
www.bosch-pt.com
Bosch's application service team will gladly answer questions
concerning our products and their accessories.
In all correspondence and spare parts orders, please always
include the 10-digit article number given on the nameplate of
the product.
Cambodia
Robert Bosch (Cambodia) Co., Ltd
Unit 8BC, GT Tower, 08th Floor, Street 169,
Czechoslovakia Blvd, Sangkat Veal Vong
Khan 7 Makara, Phnom Penh
VAT TIN: 100 169 511
Tel.: +855 23 900 685
Tel.: +855 23 900 660
www.bosch.com.kh
People's Republic of China
China Mainland
Bosch Power Tools (China) Co., Ltd.
567, Bin Kang Road
Bin Jiang District 310052
Hangzhou, P.R.China
Tel.: 4008268484
Fax: (0571) 87774502
E-Mail: contact.ptcn@cn.bosch.com
www.bosch-pt.com.cn
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