CAT 307-4821 BUSHING

CAT 307-4821 is a Caterpillar genuine straight-tube steel wear-resistant bushing, suitable for heavy-duty hinged parts such as the stick and bucket connection pins of Cat 320D/323D excavators and the boom linkage pins of 950GC loaders. It is used to reduce friction and wear between the pin and the pin hole and absorb impact vibration. It weighs approximately 0.85 kg. The following is professional structured information:

Core Technical Parameters (Professional Version)

Item Details
Basic Attributes
Model 307-4821 Straight-tube bushing, material is 4140 alloy steel (chromium-molybdenum steel), integrally hardened (HRC 55-60, hardened layer 1.5-2.0 mm), inner diameter φ50 mm, outer diameter φ65 mm, total length 80 mm, single weight 0.85 kg, with axial lubrication groove + 2 radial oil injection holes, suitable for pin diameter φ50 mm, rated load 120 kN, operating temperature – Operating temperature: 25℃ to +120℃, corrosion resistance rating: IP65

Key Dimensions: Inner diameter tolerance +0.01/-0.005 mm, outer diameter tolerance +0.02/-0.01 mm, length tolerance ±0.1 mm, inner hole surface roughness Ra≤0.8 μm, outer diameter Ra≤1.6 μm, lubrication groove width 3 mm, depth 2 mm, oil injection hole diameter φ4 mm, chamfers at both ends 1×45°

Material and Manufacturing Process: Forged and precision machined from 4140 alloy steel, induction hardened to improve surface hardness and wear resistance. The lubrication groove and oil injection hole are connected for even distribution of grease (NLGI 2 lithium-based grease). No flange design; interference fit installation with an interference amount of 0.02-0.03 mm ensures no loosening after installation.

Compatible Models: Cat 320D/320D2/323D/326D excavator sticks This product is suitable for the following applications: bucket articulation, boom-rocker connecting pin of 950GC/966GC loader, scraper linkage pin of 140M grader, and accessory drive shaft support of some Cat C13 engines.

Assembly fit: Interference fit with mounting seat (0.02-0.03 mm). Installation requires a hydraulic press (pressure ≥ 5 t). After press-fitting, the inner hole and pin clearance should be 0.05-0.08 mm, coaxiality ≤ 0.05 mm, and end face runout ≤ 0.03 mm.

Installation and maintenance points: Before installation, clean the mounting seat hole and bushing surface. Check the bushing for cracks and deformation, and ensure the lubrication groove and oil filling hole are not blocked. During installation, align the oil filling hole with the mounting seat oil passage and press smoothly with a hydraulic press. Do not hammer and damage the bushing surface.

After installation, check that the bushing end face is flush with the mounting base plane (deviation ≤ 0.1 mm). The pin should rotate freely without jamming after installation. The initial grease injection volume should be 1/3 of the bushing’s capacity. Subsequent grease injections should be performed every 500 hours, injecting until a small amount of grease overflows from both ends of the bushing each time.

Maintenance cycle: Check bushing wear every 1000 hours. Replace the bushing when the inner diameter wear exceeds 0.2 mm or when scratches/peeling appear on the surface. For long-term operation in dusty/muddy conditions, shorten the maintenance cycle to once every 300 hours.