Product Description
What this part is
NTN 78225/78551 inch-series single-row tapered roller bearing set: 78225 cone (inner ring with rollers and cage) and 78551 cup (outer ring). Bore Diameter: 2.2500 in (57.150 mm). Outside Diameter: 5.5130 in (140.030 mm). Total Width: 1.4375 in (36.512 mm) assembled. Cone Width: 1.3085 in (33.236 mm). Cup Width: 0.9260 in (23.520 mm). Rolling Elements: Tapered Roller. Bearing Material: Case carburized steel. Closure Type: Open.
Decoding the designation
78225 — NTN cone number, 2.2500 in bore.
78551 — NTN cup number, 5.5130 in OD, the matching outer ring for the 78225 cone.
What these specs mean in practice
Dynamic Load Rating: 171,000 N. Static Load Rating: 212,000 N. Limiting Speed: 2,600 rpm grease. Item Weight: 2.680 kg (5.909 lb). Axial load factor e: 0.87. Axial load factor Y2: 0.69. The steep roller angle gives high thrust capacity alongside radial load; the bearing locates in one direction and is normally paired with a second opposed bearing on the shaft.
Mounting data
Effective load centre a: 8.4 mm (0.33 in). Cone fillet radius r: 2.3 mm. Cup fillet radius R: 3.5 mm. Shaft abutment diameters: 83.0 mm and 77.0 mm. Housing abutment diameters: 132.0 mm and 117.0 mm.
Quantity and configuration
Unit Quantity: 2 Pcs. One 78225 cone and one 78551 cup forming a complete bearing.
Interchange guidance
Cross-Reference: Timken 78225/78551 uses the same ABMA inch cone and cup numbers and envelope.