Installing a trailer turntable bearing correctly is a critical process that ensures the safety and longevity of your trailer. It’s a complex task that requires attention to detail and following the manufacturer’s specific instructions. However, there are some general best practices that apply to most installations.
Trailer Turntable Bearing Installation
1. Preparation and Inspection
Inspect the mounting surface: Before you begin, the mounting surface on both the A-frame and the trailer chassis must be completely flat, rigid, and free of any debris, burrs, or paint thicker than 50 mm. Any unevenness (max. 1 mm) can be corrected with shims or plastic metal.
Check the bearing: Ensure the new bearing is the correct type and size for your trailer and that it’s in good condition. The bearing may have a “soft zone” marked with an “S.” This soft zone should be positioned in a non-load or non-constant load area during installation.
Gather your tools: You’ll need high-tensile bolts (grade 8.8 or higher), a torque wrench, and potentially a special tool for pressing in cups or seals, depending on the bearing type.
2. Mounting the Bearing
Never weld the bearing: The turntable bearing itself should never be welded to the trailer frame or A-frame. Welding can damage the bearing and compromise its integrity.
Positioning: The lower ring of the turntable is typically bolted to the A-frame, and the upper ring is bolted to the trailer chassis.
Bolting: Use a minimum of 8 high-tensile bolts per flange. For smaller bearings, 4 to 6 bolts may be sufficient. The mounting bolts should be tightened in a crosswise pattern to ensure even pressure.
Torque: Tighten the bolts to the manufacturer’s specified torque. The pre-tensioning force on the bolts should be approximately 70% of the bolt material’s yield limit. Using a leveling washer is recommended, and spring washers should be avoided.
Shear load: To relieve shear load on the mounting bolts, it’s recommended to weld at least four blocks immediately next to each flange.
3. Lubrication
Pre-lubrication: Many new turntable bearings are supplied with a base coating of lubricant, but they must be thoroughly re-lubricated before the trailer is put into operation for the first time.
Grease type: Use a high-quality ball bearing grease, typically a lithium-saponified grease of NLGI class 2.
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