CAT 388-4771 Articulating Hitch Cap

CAT 388-4771 is a genuine Caterpillar articulated joint cover, compatible with the articulated parts of Cat 24M graders, 992K loaders, and other models. It seals and protects the articulated pins and bearings, preventing dust and mud intrusion and assisting in positioning, ensuring long-term stable operation of the articulated mechanism. The following is professional structured information:

Core Technical Parameters (Professional Version)

Item Details
Basic Attributes
Model 388-4771, Material: Ductile iron (QT500-7), Surface: Electrophoretic primer + yellow topcoat (film thickness ≥50 μm), Outer diameter: φ209 mm (8.23 in), Inner diameter: φ90 mm (3.55 in), Height: 25.4 mm (1.00 in), Single weight: Approximately 1.8 kg, Fits M12×1.75 bolts (torque 85-95 N・m), with 6 evenly distributed mounting holes (hole spacing φ180 mm, hole diameter φ13 mm). 5 mm wide and 2 mm deep sealing groove, compatible with O-rings (φ100×3.5 mm, material NBR 70)

Key Dimensions: Inner diameter tolerance +0.02/-0.01 mm, outer diameter tolerance +0.03/-0.02 mm, height tolerance ±0.1 mm, mounting hole position accuracy ≤0.1 mm, end face runout ≤0.05 mm, sealing groove coaxiality ≤0.03 mm, edge chamfer 2×45°

Material and Process: Ductile iron QT500-7, precision machined after casting, tensile strength ≥500 MPa, elongation ≥7%, surface coating corrosion protection level IP65, sealing groove and O-ring achieve static sealing, mounting surface flatness ≤0.05 mm, compatible with NLGI 2 lithium-based grease (containing EP additive)

Compatible Models: Cat 24M grader articulated steering knuckle cover, 992K This product is used for end caps at the hinge joint between the loader’s front frame and boom, and as a hinge connection cover for the scraper drive linkage of a 140M grader. It is compatible with hinge mechanisms with a pin diameter of φ90 mm and is also used for the lower hinge cover mounting position on the Cat 24H grader.

Assembly and Fit: The cover should be installed flush with the hinge seat plane. O-ring compression should be 0.5-0.8 mm. The rear end face should be flush with the hinge seat plane (deviation ≤0.1 mm). Bolts must be tightened symmetrically and crosswise. After installation, the coaxiality should be ≤0.05 mm.

Installation and Maintenance Points: Before installation, clean the mounting surface and sealing groove, checking for cracks, deformation, and damage to the O-ring. During installation, apply a small amount of grease to the O-ring, align it with the mounting hole, and tighten the bolts with a torque wrench. Do not exceed the torque limit, as this may deform the cover.

After installation, check for leaks at the seal and ensure the hinge moves freely without jamming. Inspect every 1500 hours. Replace immediately if coating peeling, O-ring aging, or bolt loosening is found.

When disassembling, loosen the bolts in a diagonal sequence to avoid damaging the mounting surface by prying. When replacing, check the wear of the hinge pin (≤0.05 mm). If it exceeds the standard, it needs to be repaired before installing the new cover.