How to Correct Equipment and Protect Reverse Support
Source: China Bearing Network | Time: 2014-06-26
When handling and storing reverse supports, it's essential to follow proper procedures to ensure their longevity and performance. Before leaving the factory, reverse supports are coated with anti-rust oil and wrapped in protective film, which typically remains effective for 3 to 6 months. To maintain this protection, store them at a temperature of 20±10°C with a relative humidity not exceeding 60%. After the expiration period, they should be re-protected. It is recommended to fill the bearing inventory with smooth grease after one year and check its flexibility. Reverse supports are usually fixed on trays or packaged in single or group formats. During transportation and storage, they must be kept level to avoid damage from bumps or pressure. They should also be protected from rain and stored on flat surfaces. A barrier should be placed between each support to prevent contact and potential damage. Most reverse supports are equipped with lifting holes, allowing them to be safely lifted using an eye bolt. When opening the package, always check the certificate and markings to confirm the correct type of reverse support is being used. The equipment surface should be clean, free of paint residue, weld spatter, and burrs. Avoid using solvents that could damage internal components or the seal. Ensure the surface roughness is no greater than Ra=12.5 μm, and correct any circumferential or radial errors. The flatness tolerance should match the raceway specifications, with radial tolerances set at half the circumferential value. To prevent deformation or overloading, the circumferential flatness error should only be corrected once within a 180-degree range, ensuring a gradual change. The rigidity requirements for reverse bearings vary depending on whether they are standard or zero-gap types. For example: | Raceway Diameter (mm) | Ball Type Allowable Deformation (mm) | Roller Type Allowable Deformation (mm) | |------------------------|---------------------------------------|----------------------------------------| | 250 | 0.31 | 0.24 | | 500 | 0.40 | 0.30 | | 750 | 0.53 | 0.36 | | 1000 | 0.60 | 0.41 | | 1500 | 0.80 | 0.53 | | 2000 | 1.0 | 0.60 | | 2500 | 1.2 | 0.68 | | 3500 | 1.5 | 0.90 | For zero-gap reverse supports, the allowable deformation is slightly less, as shown in the table above. Positioning reverse bearings have soft bands on both the inner and outer raceways, which should be placed on either side of the main load plane, offset by 90 degrees. These soft bands are often marked with a blockage or "S" symbol. Additionally, ensure the reverse bearing is compatible with the equipment surface. Use a feeler gauge for checking accuracy, and fill in any gaps if necessary. Avoid welding on the support during installation. When selecting bolts, use standard bolts, washers, and nuts with the appropriate strength grade. Avoid full-threaded bolts, old fasteners, or open washers like spring washers. For bolts larger than M27, it's recommended to use hydraulic tightening tools, with pre-tightening force not exceeding 85% of the yield strength. Apply a small amount of oil to the bolt threads to ensure even friction resistance. Do not use thread-locking glue. Tighten the bolts in three steps: 30%, 80%, and 100% of the final torque. When adjusting gear backlash, it's crucial to do so correctly. Use a feeler gauge at the highest point of radial runout or lead wire for measurement. If the gap is out of specification, adjust the pinion spacing accordingly. Rotate the bearing fully to check for any other tooth jump points and recheck the backlash after securing the bearing. Before initial use, apply smooth grease to the raceway as specified in the product documentation. Ensure all grease nipples are filled, and apply grease until it begins to extrude from the seal. For gears, ensure the tooth surfaces are clean and apply grease using a soft brush. After the first 100 operating hours, check the bolt pre-tightening torque. If more than 10% of the bolts are loose, recheck after the next 100 hours. From then on, inspect every 500 hours. In harsh conditions, shorten the inspection interval. After 2000 hours of operation, if any bolt is loose to less than 80% of the rated torque, replace that bolt and the two adjacent ones. If 20% of the bolts are loose, replace all of them. After 14,000 hours, replace all bolts. For high-speed or frequently operated equipment, add grease every 100 hours. In poor working conditions, further reduce the interval.
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