CAT 544-4648 100mm Outer Diameter Upper Bushing

CAT 544-4648 is a Caterpillar steel-backed, copper-based alloy straight-tube upper bushing. It is primarily used in the boom, stick, and other connection parts of excavators, loaders, and other equipment. It is suitable for medium- and heavy-duty, medium- and low-speed swinging conditions and features wear resistance, anti-galling, and high strength to ensure stable rotation between components and extend equipment life (Cat® Parts). The following is structured technical and application information:

Core Technical Parameters
Item Details
Basic Attributes
Model 544-4648, Type: Straight cylindrical upper bushing (fixed bushing type), Material: Low carbon alloy steel backing + tin bronze alloy (alloy layer thickness 0.8-1.0 mm, hardness HB 80-95), steel backing thickness 2.2 mm (quenching hardness HRC 30-35), single weight approximately 0.42 kg, operating temperature -30℃ to +160℃, lubrication method: oil lubrication/grease lubrication, design life ≥8000 hours (normal operating conditions), suitable for heavy-duty, medium-low speed (≤1200 r/min), reciprocating oscillating conditions Cat® Parts

Key Dimensions
Inner diameter 50.8 mm (tolerance 0/+0.008 mm), outer diameter 63.5 mm (tolerance 0/-0.012 mm), total length 38.1 mm (tolerance 0/-0.12 mm) The bearing housing has a chamfer of r1.0 mm, a radial clearance of 0.07-0.09 mm (cold state), and an interference fit (0.02-0.03 mm interference between the bearing housing bore and the outer diameter). The journal clearance is 0.06-0.08 mm. Compatible Machines and Parts: Suitable for boom and stick connections on Cat 320D2 and 323D2 excavators, 950H and 966K loaders, etc. It comes with 103-8329 elastic retaining rings and 5P-0960 extreme pressure lithium-based grease. It is suitable for connections with a pin diameter of 50.8 mm and can be used with 544-4649 lower bushings. Performance Parameters: Basic rated dynamic load 32 kN, basic rated static load 55 kN, allowable radial load ≥22 kN, coefficient of friction ≤0.003 (oil lubrication), impact load ≥10. kN, recommended grease filling rate 0.8-1.2 g/cm³, recommended operating speed ≤1000 r/min (oil lubrication), ≤600 r/min (grease lubrication)

Structural and Performance Advantages: Steel backing + copper-based alloy composite structure. The steel backing provides high-strength support, while the copper-based alloy layer offers excellent wear resistance and anti-galling properties, suitable for heavy-load, frequent start-stop conditions in engineering machinery, reducing component wear.

Straight cylindrical design and precise dimensional tolerances ensure stable fit with pins and bearing housings, effectively absorbing vibration, reducing operating noise, and adapting to the reciprocating swing requirements of booms, sticks, and other components.

Suitable for multiple lubrication methods. The copper-based alloy layer can store lubricating oil, providing temporary lubrication when insufficient, improving the reliability of the bushing under harsh conditions.

Installation and Maintenance Points:
**Before installation, clean the bushing, pin, and bearing housing bore, checking for burrs, rust, or alloy layer peeling. Use a dedicated pressing tool to press the bushing into the housing bore. Do not strike, as this may damage the alloy layer. After pressing, check the fit between the bushing end face and the housing bore to ensure there is no misalignment.**

After installation, add appropriate grease to ensure sufficient lubrication. Install the elastic retaining ring to secure the bushing and prevent axial movement. Before operation, perform a no-load test run to check for abnormal noises or jamming, ensuring smooth rotation.

Maintenance: Check the lubrication and bushing wear every 600 hours. If excessive clearance, abnormal noise, or oil leakage is found, repair immediately. When replacing the bushing, if the journal wear exceeds 0.04 mm, the pin must also be replaced. Do not mix bushings of different models or brands.