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(5) Different tightening conditions
The tightening torque may vary in accordance with bolt torque coefficient (dependent on manufacturing and
finishing processes, and specified by bolt manufacturers), bolt grade and bolt length, even though the
dimensions of the bolts are the same. Tightening torque may also vary depending on the surface finishing
state of tightening materials (steel, aluminum, etc.) and materials to be tightened. In addition, if there is a seal
packing or a clearance between tightening materials, the tightening torque is decreased.
(6) Wear and looseness of the socket
With extended use, the hexagonal portion of the socket which is fitted to the head of the bolt and the
hexagonal portion which is fitted onto the anvil in the main body will become worn and loose. Wear and
looseness will cause a proportionate loss of tightening torque. In addition, use of an incorrect size socket will
also result in decreased torque.
(7) Bolt and nut rotate together
Tightening torque that can be achieved will be considerably decreased if the bolt and the nut rotate together
during the tightening operation. The customer should be advised to carefully observe the operation and
ensure this does not occur.
7-4. Temperature Rise
If the Model WR 14VB is used for tightening bolts which require long time to be tightened continuously, it will
cause temperature rise of the motor and burnout subsequently. Advise the customer to perform no-load operation
for several minutes to cool the motor if the outside of the main body becomes hot.
8. OTHER PRECAUTIONS
(1) Check for cracks or other damage on the socket
Cracks or any other faults on the socket are very hazardous and decrease the tightening torque. Advise the
customer to ensure that there are no abnormalities on the socket before operation.
(2) Socket dimensions
Without fail, utilize an appropriate socket which matches the bolt dimensions. If the clearance between the
socket and the nut is large, it will not only cause insufficient tightening torque but could also easily cause
damage to the socket. Please refer to Para. 5-2 for appropriate socket dimensions.
(3) Hammering section lubrication
Grease (Doubrex 251, optional accessory) is utilized in the hammering section.
Frequent or continuous use of the tool will cause excessive temperature rise of the hammering section,
resulting in depletion of the grease and subsequent increased wear of components which will, in turn, cause
loss of tightening efficiency. Accordingly, it is necessary to periodically replenish the grease in the hammering
section to ensure proper lubrication of moving and sliding components.
