910193 - Hydraulic Impact Wrench
Phone: (262) 637-9681
4.2021 Rev 2.1
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Torque Information
Note: This impact wrench is not a torque wrench.
If the torque setting of a particular fastener type is critical, the wrench should be set as close to the desired
torque as possible and a calibrated torque wrench used to verify or check the fastener torque periodically.
Factors that Affect Torque
An impact wrench is a rotary hammer that impacts the head of a bolt or nut.
It does not apply a slow steady torque as a standard torque wrench. Therefore, several factors affect the
result of torque when using impact wrenches:
Long Bolts
Long bolts having high-friction threads with lubrication under the bolt head or associated nut can twist
when impacted, then untwist before the next impact.
This will especially happen if there is low friction between the bolt head or nut and the mating surface.
Heavy, Loose or Multiple Adapters
Heavy, loose, or multiple adapters between the wrench and socket can dissipate the intensity of the
impact to the bolt head or nut.
Amount of Impact
Maximum torque results can be obtained by allowing continuous impacting of the socket against the
bolt head or nut for at least 10 seconds.
Hydraulic Flow Rate
If the flow rate to the tool is too low, the hammer (or impact) speed is reduced.
If the flow is correct, a change in the relief pressure does not affect the imp
act force.
Poorly designed hydraulic circuits can result in lower flow rates and reduced impact speeds when
pressure is required during impacting.
Bolt Grade and Thread Recommendations
Allowable bolt torque is limited by both bolt thread diameter and grade of steel in the bolt. The
Hydraulic Impact Wrench is recommended for use on the following bolt grade and thread sizes:
SAE Grade 2
1-1/8 to 1-7/8 inch [28.5 - 47.6 mm]
SAE Grade 5
1 to 1-5/8 inch [25.4 - 41.2 mm]
SAE Grade 8
7/8 to 1-3/8 inch [22.2 – 35 mm]
Sockets not designed to be used with impact wrenches can break
apart causing injury to operator or bystanders.