CAT 7U-7013 276mm Inner Diameter Hitch Bushing

CAT 7U-7013 is a Caterpillar original equipment manufacturer (OEM) heavy-duty articulated truck hinge bushing (bimetallic composite structure). It is compatible with the frame articulation pins of Cat 730, D250B/E, and D300B/E articulated trucks. Its core function is to absorb impact and vibration at the articulation point, reduce friction and wear between the pin and the lug, and ensure steering flexibility and structural stability. The following is a professional technical and application guide:

Core Technical Parameters (Professional Version)

Item Details
Basic Attributes
Model 7U-7013, Type: Bimetallic Composite Hinge Bushing (Steel Backing + Bronze Alloy Wear-Resistant Layer + Graphite Lubrication Holes), Compatible with Cat 730, D250B/D/E, and D300B/D/E Articulated Truck Frame Articulation Pins, Material: Steel Backing (Q345B/SAE 1045, HB 180-220) + Bronze Alloy (CuSn10Pb10, HB…) 80-100) + Embedded graphite lubrication points (6 evenly distributed), inner diameter 276 mm (10.87 inches, tolerance 0/-0.05 mm), outer diameter 315 mm (12.4 inches, tolerance 0/-0.06 mm), length 100 mm (3.94 inches, tolerance ±0.2 mm), unit weight approximately 28.5 kg, rated radial load ≥800 kN, operating temperature -40℃ to +120℃, lubrication method is graphite self-lubrication + periodic grease lubrication (NLGI 2 lithium-based grease), wear layer thickness 5 mm (tolerance ±0.1 mm), coefficient of friction ≤0.12 (dry friction) / ≤0.08 (grease lubrication)

Key dimensions: Chamfer r=3 mm (tolerance ±0.3 mm), inner diameter cylindricity ≤0.03 mm, outer diameter cylindricity ≤0.04 mm, parallelism of both end faces ≤0.05 mm, lubrication hole diameter φ6 mm (6 evenly distributed around the circumference, 3 mm hole depth), steel backing thickness 8 mm, bronze alloy layer hardness HB 80-100, graphite particle size φ3 mm, embedding depth 2 mm.

Material and Manufacturing Process: The steel backing is sandblasted and rust-removed + electrostatically sprayed with primer. The bronze alloy layer is metallurgically bonded to the steel backing using centrifugal casting (bonding strength ≥200 MPa). The graphite lubrication points are press-fitted. The bushing outer diameter is precision machined (Ra≤1.6 μm), and the inner hole is precision bored (Ra≤0.8 μm). The surface is free of defects such as porosity and slag inclusions. Salt spray resistance ≥200 hours.

Compatible Models: Cat 730, D250B, D250D, D250E, D300B, D300D, D300E The articulated truck frame hinge pin is designed for low-friction support at the hinge point, absorbing steering shocks and vibrations, preventing direct wear between the pin and the lug plate, and is suitable for heavy-duty, dusty, and frequent steering conditions, ensuring the structural strength and steering accuracy of the frame hinge point.

Assembly Fit: Clearance fit with the pin (0.15-0.25 mm); interference fit with the hinge lug plate (0.10-0.18 mm, cold fitting/hydraulic press fitting). After installation, axial positioning uses a retaining ring + shoulder combination, with radial runout ≤0.1 mm. After installation, the gap between the bushing and lug plate should be ≤0.05 mm when measured with a feeler gauge.

Installation and Maintenance Points: Before installation, clean the outer diameter of the bushing, the surface of the pin, and the holes in the hinge lug plate. Check the bushing for cracks, deformation, and peeling of the wear-resistant layer. Ensure the measured dimensions and tolerances meet requirements, and that the lubrication holes are not blocked.

During assembly, use a hydraulic press to smoothly press the bushing into the ear plate hole (pressing force ≤ 500 kN, pressing speed ≤ 5 mm/s). After pressing, check that the bushing end face is flush with the ear plate plane and there is no misalignment. Install the retaining ring to fix it. Finally, add lithium-based grease through the lubrication hole until it overflows.

Maintenance Recommendations: Check the bushing wear and lubrication condition every 500 hours. Replenish grease every 1000 hours. Replace immediately when the inner diameter wear is > 0.3 mm or when bronze layer peeling occurs to prevent abnormal wear of the pin and ear plate.