INA81240-MAxial Cylindrical Roller Thrust Bearing – 200 mm Bore, 280 mm OD, 62 mm Height, Machined Brass Cage, Single Direction

Product Description

What this part is

INA 81240-M single-direction axial cylindrical roller thrust bearing, complete with both washers. Bore: 200 mm. Outside Diameter: 280 mm. Overall Height: 62 mm. Series: 812. Base Number: 81240. Rolling Elements: Cylindrical rollers. Cage Material: Machined brass. Number Of Rows: 1. Direction: Single. Dynamic Axial Load Rating: 900 kN. Static Axial Load Rating: 3,150 kN. Limiting Speed: 1,200 rpm. Reference Speed: 450 rpm. Item weight: 12.2 kg (26.9 lb). Design Units: Metric. Unit Quantity: 1 Pc.

Decoding the designation

812 — the heavy axial cylindrical roller thrust series, a taller section than the 811 series at the same bore.

40 — bore code, 40 x 5 mm, giving a 200 mm bore.

M — machined brass cage.

WS and GS — the housing washer and shaft washer that make up the complete bearing with the cage-and-roller assembly.

What these specs mean in practice

Static Axial Load Rating: 3,150 kN. That is 320 tonnes of axial capacity in a 280 mm circle, and it is why the 812 series is used on press rams, screw-down gear, extruder thrust positions, crane hooks and hydraulic swivels. Cylindrical rollers give line contact across the washer face, so the load is spread along the roller length instead of concentrating at a point as it does in a thrust ball bearing. Dynamic Axial Load Rating: 900 kN. Static well above dynamic is the normal relationship on this type: line contact resists permanent indentation far better than it resists rolling fatigue, and these bearings usually work under high slow-moving or intermittent load rather than continuous rotation. Limiting Speed: 1,200 rpm. Reference Speed: 450 rpm. Cage Material: machined brass, which holds its form at load and temperature and tolerates marginal lubrication better than a polymer cage. Item weight: 12.2 kg.

Mounting data

Bore: 200 mm at the shaft washer. Outside Diameter: 280 mm at the housing washer. Overall Height: 62 mm assembled. The bearing takes axial load in one direction, with an opposing location carrying reverse thrust. Both washers seat flat, square and fully supported across their whole face; a partly supported washer deflects and concentrates the roller line contact at one end, which is the usual cause of early failure on a thrust bearing this size. Lubricant: grease or oil. At this diameter and load an oil bath or circulating oil feed is the common arrangement.

Quantity and configuration

Unit Quantity: 1 Pc. Complete bearing: shaft washer (GS), housing washer (WS) and the K81240-M cage-and-roller assembly together as one unit.

Interchange guidance

81240 is an ISO boundary size for axial cylindrical roller thrust bearings, 200 x 280 x 62 mm. Cross-References: SKF 81240 M, FAG 81240-M, NSK 81240, Koyo 81240, NTN 81240. The K81240-M is the cage-and-roller assembly alone, and GS81240 and WS81240 are the individual washers, so all three are components of this bearing rather than substitutes for it. The 81140-M shares the 200 mm bore in the lighter 811 section, making it a related size rather than an interchange. Searchable variants of the manufacturer part number: 81240M, 81240-M, 81240 M, 81240, 81240M WS GS.