CAT 388-7494 Camshaft Main Bearing

CAT 388-7494 is a steel-backed bronze straight sleeve bearing (sleeve) for the lug end of Caterpillar hydraulic cylinders. It is suitable for the cylinder articulation points of equipment such as 336D2/349D excavators, 980M loaders, and D8T bulldozers. It is used to bear radial loads, reduce journal wear, and assist in lubrication. It is suitable for medium and heavy load, oscillating, and low-speed rotation conditions. It is often used in conjunction with Cat® Parts such as 364-9897 sleeve and 477-2023 bearing cap. The following is structured technical and application information:

Core Technical Parameters

Item Details
Basic Attributes
Model 388-7494, Straight Sleeve Bearing (Sleeve), Material: Steel-backed bronze (steel back + tin bronze ZCuSn10Pb10 liner, oil-containing self-lubricating, hardness HB85-95, wear-resistant and impact-resistant), Surface graphite inlay (friction coefficient 0.08-0.12), Operating temperature -40℃ to +120℃, Single weight approximately 0.6 kg, Suitable for medium and heavy loads, oscillating and low-speed rotation conditions, Used for radial support, friction reduction, and auxiliary lubrication of hydraulic cylinder hinge points

Key Dimensions
Inner diameter 75 mm (tolerance 0/-0.015 mm), Outer diameter 95 mm (tolerance +0.015/0 mm), Total length 45 mm, Wall thickness 10 mm, Inner hole surface roughness Ra≤0.4 μm, Fitting tolerance inner ring h6 (0/-0.015 mm), outer ring H7 (+0.030/0 mm), journal fillet radius ≤1.0 mm, coaxiality ≤0.02 mm. Compatible models: Cat 336D2/349D excavators (boom cylinder lug end), 980M loaders (bucket cylinder piston rod end), D8T bulldozers (bottom hinge point of the pusher cylinder), 966M loaders (upper hinge point of the boom cylinder). Uses 364-9897 sleeves, 477-2023 bearing caps, and 191-2569 bearing assemblies. Assembly fit: Inner bore and journal transition fit (clearance 0.005-0.020 mm), outer ring and bearing housing interference fit (interference 0.008-0.015 mm). Compatible with 75 mm diameter shafts. Journals require heat treatment (HB220-250) and grinding (Ra≤0.8). **Bearing housing bore must be bored (Ra≤1.6 μm)**

**Installation and Maintenance Points:**
Before installation, clean the inner and outer surfaces of the bearing, the journal, and the bearing housing bore. Check for scratches, porosity, and cracks. Measure the dimensions of the journal and outer ring bore to ensure the fit meets requirements. The journal fillet radius should be ≤1.0 mm to avoid stress concentration.

Use the cold-press installation method. Use a special press to press the bearing into the bearing housing. Do not directly strike the end face to prevent deformation. After installation, check for axial movement ≤0.05 mm to ensure there is no jamming.

**Lubrication and Maintenance:** Before assembly, apply Cat Moly Grease (filling amount: 20-30% of the bearing’s internal space). Check for wear every 500 hours. If the inner bore wear exceeds 0.15 mm or scoring occurs, replace immediately. It is recommended to replace the bearing along with the sleeve and bearing cap.