As a core tool in industrial maintenance and assembly, the pneumatic wrench is susceptible to damage if its internal parts wear down and are not replaced or repaired promptly. This can lead to unstable torque output, sluggish operation, or even complete failure. The replacement and repair process must follow a logical chain of "diagnosis first, disassembly second, replacement third, and final debugging" to ensure precise and controllable operation at each step.
When the pneumatic wrench exhibits torque decay, abnormal noise, or discontinuous operation, high-wear areas should be prioritized for inspection. The blades, as the power core of the pneumatic wrench, are prone to edge wear, delamination, and even breakage due to long-term friction with the cylinder wall. This can be checked visually for burrs on the blade edges and thinning, or by using a feeler gauge to measure the gap between the blades and the cylinder wall to see if it exceeds the standard value. Bearing wear manifests as periodic abnormal noise during operation; this can be checked by disassembling and rotating the bearing to feel for any sticking or wobble. Cylinder wall wear can cause air leakage; this can be checked by injecting a small amount of compressed air into the cylinder to observe for leaks.
Before disassembling the pneumatic wrench, prepare specialized tools such as an Allen wrench, snap ring pliers, and a rubber mallet to avoid damaging the outer casing or internal parts with ordinary tools. First, disconnect the air supply and release any residual pressure to prevent parts from suddenly popping out during disassembly. Disassemble in an "outside-in" order: first remove external accessories such as the intake port and pressure regulating valve, then remove the outer casing fixing screws and gently tap the edges of the casing with a rubber mallet to separate them. Mark the locations of parts during disassembly, especially easily confused small parts such as springs and snap rings, to avoid subsequent reassembly errors.
When replacing blades, select models that are exactly the same as the original specifications. The material is usually high-strength alloy steel or nylon composite material. After removing the old blades, thoroughly clean the cylinder inner wall and rotor slots with a cleaning agent to remove oil and metal debris. When installing new blades, ensure that the fit between the blade and the rotor slot is uniform; too tight a fit will cause jamming, while too loose a fit can easily lead to blade breakage. When replacing bearings, distinguish between deep groove ball bearings and thrust bearings. Apply an appropriate amount of high-temperature grease before installation to reduce friction during operation. When the cylinder inner wall is severely worn, chrome plating can be used to restore surface hardness, or the cylinder can be replaced directly.
The assembly process must follow the "reverse disassembly" principle, installing parts one by one according to the marked positions. When installing blades, a special pressing tool can be used to ensure that the blades are completely fitted to the rotor slots. After assembly, preliminary debugging is required: connect the air source, adjust the pressure regulating valve to the standard working pressure, and touch the cylinder shell to check for local overheating. If abnormal temperature rise is found, the machine must be stopped immediately for inspection, which may be caused by overly tight bearing installation or blade jamming.
Functional testing should simulate actual working conditions, using a torque tester to check whether the output torque reaches the nominal value. Low-pressure testing can verify the stability of the pneumatic wrench under edge conditions, and continuous operation testing can check heat dissipation performance. If torque fluctuations exceed ±5% during testing, the blade balance or bearing clearance must be rechecked.
Routine maintenance is key to extending the service life of the pneumatic wrench. After each use, the inlet and outlet ports should be cleaned with compressed air to prevent impurities from entering the interior. Regularly apply specialized pneumatic tool oil to the air inlet to lubricate the blades and bearings, reducing wear. Store vertically to avoid deformation caused by heavy pressure.
Replacing and repairing internal parts of a pneumatic wrench is a systematic project requiring a plan tailored to the tool's structural characteristics, wear mechanism, and actual operating conditions. From accurate diagnosis to standardized disassembly, from parts selection to meticulous assembly, and rigorous testing, every step demands a professional approach.
