Wrench Torque Information

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, sever- al factors affect the result of torque when using impact wrenches:

1.LONG BOLTS. Long bolts having high-friction threads with lubrication under the bolt head or as- sociated 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.

2.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.

3.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.

4.HYDRAULIC FLOW RATE. If the flow rate to the tool is too low, the hammer (or impact) speed is re- duced. If the flow is correct, a change in the relief pressure does not affect the impact 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 di- ameter and grade of steel in the bolt. The IW16 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

PREOPERATION PROCEDURES

CHECK POWER SOURCE

1.Using a calibrated flow meter and pressure gauge, check that the hydraulic power source develops a flow of 7–12 gpm / 20-45 lpm at 1000–2000 psi / 70–140 bar.

2.Make certain that the hydraulic power source is equipped with a relief valve set to open at 2100 psi/145 bar minimum.

3.Check that the hydraulic circuit matches the tool for open-center (OC) operation.

4.UNDERWATER MODELS ONLY. Make certain that the wrench impact mechanism is cleaned and greased with waterproof grease after each day’s use.

CONNECT HOSES

1.Wipe all hose couplers with a clean, lint-free cloth before making connections.

2.Connect hoses from the hydraulic power source to the tool fittings or quick disconnects. It is good prac- tice to connect the return hose first and disconnect it last to minimize or eliminate trapped pressure within the wrench.

3.Observe the flow indicators stamped on the main body assembly and the hose couplers to ensure that the flow is in the proper directions. The female couple on the tools “IN” port is the inlet (pressure) coupler.

NOTE:

If the uncoupled hoses are left in the sun, pressure increase within the hoses can make them difficult to connect. Whenever possible, connect the free ends of hoses together.

WRENCH OPERATION

The IW16 is designed for 1-inch square hex drive. The 1-inch drive configuration is used with drive sockets for high impact (500–2500 ft lb / 680–3400 Nm) installation and removal of fasteners.

During normal operation it is common to see some grease leakage from around the anvil during hard use. Refer to the IW16 Service Manual for the correct lubrica- tion procedures.

Use at the low end of the 500–2500 ft lb / 680–3400 Nm torque range during continuous use over long peri- ods of time (impact times exceeding 10 seconds). The high temperature generated in the impact mechanism can reduce steel part and lubricant durability within the wrench.

1.Observe all Safety Precautions.

2.Move the hydraulic circuit control valve to the “ON” position to operate the wrench.

10 ► IW16 User Manual