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When the switch is set to L, the motor rotates counterclockwise to loosen the bolt. When the switch is released, the motor stops.

CAUTION

Be sure to turn the switch OFF and wait until the motor completely stops before changing the direction of wrench revolution. Switching while the motor is rotating will result in burning the motor.

2.Tightening and loosening bolts

A hex socket matching the bolt or nut must first be selected. Then mount the socket on the anvil, and grip the nut to be tightened with the hex socket. Holding the wrench in line with the bolt, press the power switch to impact the nut for several seconds. If the nut is only loosely fitted to the bolt, the bolt may turn with the nut, therefore preventing proper tightening. In this case, stop impact on the nut and hold the bolt head with a wrench before restarting impact, or manually tighten the bolt and nut to prevent them slipping.

OPERATIONAL CAUTIONS

1.Confirm the line voltage (Fig. 4)

The available tightening torque is influenced by line voltage. Reduced line voltage lowers the available tightening torque.

For example, if you use a 220 V type wrench on a 200 V line the available tightening torque will be reduced to 70 to 90 %. When extending the power cord, use an extension cord which is as short as possible. When the line voltage is low and a long extension cord is needed a step up transfomer should be used. The relation between the line voltage and the tightening torque are shown in the figures.

2.Do not touch the bumper or hammer case during continuous operation

The bumper and hammer case become hot during continuous screw tightening so be careful not to touch them at that time.

3.Work at a tightening torque suitable for the bolt under impact

The optimum tightening torque for nuts and bolts differs with material and size of the nuts and bolts. An excessively large tightening torque for a small bolt may strech or break the bolt. The tightening torque increases proportionally to the operating time. Use the correct operating time for the bolt.

4.Selecting the socket to be matched to the bolt Be sure to use a socket which is matched to the bolt to be tightened. Using an improper socket will result not only in insufficient tightening but also in damage to the socket or nut.

A worn or deformed hex or square-holed socket will not give an adequate tightness for fitting to the nut or anvil, consequently resulting in loss of tightening torque.

Pay attention to wear of socket holes, and replace before further wear developes. Matching socket and bolt sizes are shown in Table 1.

The numerical value of a socket designation denotes the side to side distance (S) of its hex hole.

5.Holding the tool

Hold the Impact Wrench firmly with both hands by the body handle and the side handle. In this case hold the wrench in line with the bolt.

It is not necessary to push the wrench very hard. Hold the wrench with a force just sufficient to counteract the impact force.

6.Confirm the tightening torque

The following factors contribute to a reduction of the tightening torque. So confirm the actual tightening torque needed by screwing up some bolts before the job with a hand torque wrench.

Factors affecting the tightening torque are as follows.

(1)Line voltage:

The tightening torque decreases when the line voltage becomes low (See Fig. 4).

(2)Operating time:

The tightening torque increases when the operating time increases. But the tightening torque does not increase above a certain value even if the tool is driven for a long time (See Fig. 4).

(3)Diameter of bolt:

The tightening torque differs with the diameter of the bolt as shown in Fig. 4. Generally a larger diameter bolt has a larger tightening torque.

(4)Tightening conditions:

The tightening torque differs according to the torque ratio; class, and length of bolts even when bolts with the same size threads are used. The tightening torque also differs according to the condition of the surface of metal through which the bolts are to be tightened.

(5)Using optional parts:

The tightening torque is reduced a little when an extension bar, universal joint or a long socket is used.

(6)Clearance of the socket:

A worn or deformed hex or a square-holed socket will not give an adequate tightness to the fitting between the nut or anvil, consequently resulting in loss of tightening torque.

Using an improper socket which does not match to the bolt will result in an insufficient tightening torque. Matching socket and bolt sizes are shown in Table 1.

MAINTENANCE AND INSPECTION

1.Inspecting the socket

A worn or deformed hex or a square-holed socket will not give an adequate tightness to the fitting between the nut or anvil, consequently resulting in loss of tightening torque. Pay attention to wear of socket holes periodically, and replace with a new one if needed.

2.Inspecting the mounting screws

Regularly inspect all mounting screws and ensure that they are properly tightened. Should any of the screws be loose, retighten them immediately. Failure to do so could result in serious hazard.

3.Maintenance of the motor

The motor unit winding is the very “heart” of the power tool.

Exercise due care to ensure the winding does not become damaged and/or wet with oil or water.

4.Inspecting the carbon brushes

For your continued safety and electrical shock protection, carbon brush inspection and replacement on this tool should ONLY be performed by a Hitachi Authorized Service Center.

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