Tightening Torque Inspection Prior To Operation; Tightening Torque Variation - Hitachi WR 16SA Technical Data And Service Manual

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For U.S.A. and Canada
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For China

7-2. Tightening Torque Inspection Prior to Operation

The output tightening torque of the Model WR 16SA is higher than the rated tightening torque of certain bolts.
Accordingly, if the tightening time is prolonged for such bolts, it could cause damage to their threads or, in the
worst case, cause them to be sheared off. (This phenomenon is common to all existing impact wrenches.) The
customer should be advised to carry out several bolt tightening operations and adjust the tightening time as
necessary by measuring the tightening torque before commencing continuous operation.

7-3. Tightening Torque Variation

The tightening torque of an impact wrench may vary slightly in accordance with the factors described below.
Salespersons are requested to advise the customer to confirm that appropriate tightening torque is obtained by
measuring the torque at the beginning of the tightening operations, and as necessary during tightening
operations. In addition, the torque values shown in Para. 6-2, 6-3 and 6-4 above are useful as a handy reference,
and may be utilized as tentative standards.
(1) Voltage
The tightening torque of an impact wrench is influenced by voltage. For example, the tightening torque will be
reduced to about 90% if the Model WR 16SA is operated with 90% of the rated voltage. The line voltage may be
reduced by the use of a long extension cord depending on the work sites. Take the following countermeasures
against voltage reduction caused by the resistance of an extension cord and the load current.
Decrease the resistance of an extension cord.
Use an extension cord which is as short as possible and has a thick core.
Compensate for reduction of the voltage by using a step up transformer.
At this time, prevent the plug voltage of the main body from exceeding the rated voltage.
Advise the customer to use an extension cord which is as thick as possible (cross sectional area of the core of the
extension cord: 1.25 mm
recommend the customer to use a step up transformer to step up the voltage by the amount of reduction
previously.
2 or larger) if it is unavoidable to use a long extension cord on a building site. In addition,
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