61948-NSK bearing: complete specifications & equivalents

Specification table

Source: catalog reference (NSK Rolling Bearings E1103 Part C) · extracted 2026-09-24

Cross references & equivalents

Interchange levels: full standard interchange · partial verify parameters · verify manual confirmation required. Links resolve to the equivalent model's specification page where available.

How the 61948-NSK model number is decoded

In the 61900-series (diameter series 9 of ISO 15) the last two digits encode the bore: 61948 carries bore code 48 = 240 mm. Outside diameter 320 mm and width 38 mm come from the ISO 15 boundary-dimensions general plan. With no seal suffix the bearing is open: no shields or seals are fitted and lubrication is supplied by the application. For normal-load mounting with a rotating inner ring on a 240 mm shaft, typical catalogue practice is a m6 shaft seat with an H7 housing bore — verify against the actual load direction and magnitude. In the NSK catalogue this open execution carries the bare designation; protected variants are ordered separately with suffixes ZZ (steel shields), VV (non-contact rubber seals) and DDU (contact rubber seals).

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• Mount this 240 mm bore bearing by heating the inner ring (induction heater, max 120 °C) — never drive it home through the outer ring or balls, that brinells the raceways.
• The 619xx thin section (40.0 mm section height at 240 mm bore) trades load capacity for compactness; stiff, accurately aligned seats are essential or edge loading will spall the raceway early.
• The open 61948-NSK has no lubricant retention: grease escapes and contaminants migrate straight into the 240×320×38 mm raceway, so specify a sealed arrangement for dusty or washdown duty.
• Storage matters for open bearings: 61948-NSK leaves the factory with rust preventive only, so clean it and apply the service grease at assembly even if the rings look oily from the wrapper.
• Never mix components between two 61948-NSK units: rings, cage and balls are factory-matched and are not field-interchangeable, even between identical designations.
• Measure the shaft, do not trust the drawing: a 240 mm nominal journal worn by even 0.02 mm turns an interference seat into a creeping fit that frets the bore of 61948-NSK.
• The open 61948 has no integral sealing; in the NSK E1103 catalogue the protected variants carry suffixes ZZ (non-contact steel shields), VV (non-contact rubber seals) and DDU (contact rubber seals). NSK does not offer a low-torque contact seal equivalent to NTN's LLH in this catalogue — for high-speed sealed duty specify the VV non-contact seal and an external housing labyrinth.
• The 240 mm bore places 61948 at the upper end of NSK's single-row deep-groove catalogue for the E1103 Part C extract; this is a heavy-engineering bearing where centrifugal force and cage inertia dominate the design envelope. NSK supplies a machined brass cage (suffix M) and expects oil lubrication with a defined relubrication interval — do not use catalogue grease speed figures for this size without an NSK engineering review.
• NSK rates 61948 at 170 kN dynamic (C) and 190 kN static (C0); this heavy-load rating is at the upper end of the E1103 Part C single-row deep-groove extract — NSK supplies a machined brass cage (suffix M) and expects an application review, because catalogue L10 life alone does not capture shock and misalignment loads at this rating.
• At 8490 g (8.5 kg), 61948 is a heavy NSK bearing that requires a crane or hoist for handling; induction-heat the inner ring (max 120 °C) and use a mechanical puller for removal — never apply heat directly to the balls or cage.
• The 240×320×38 mm envelope of 61948 gives a D/d ratio of 1.33 and only 40.0 mm radial section height — this is an ultra-thin section in NSK's E1103 catalogue where shaft deflection and housing ovality directly load the ball-raceway contact; verify shaft stiffness (target deflection under 0.05 mm) before specifying it over a 62-series.
• The 170/190 kN load ratings, mass 8490 g here are NSK Rolling Bearings E1103 Part C catalogue figures for 6948 on the 240×320×38 mm ISO 15 envelope; internal geometry and ratings legitimately differ between brands, so re-verify before substituting another manufacturer's 61948 in a rated drive. NSK does not tabulate reference or limiting speeds in the E1103 Part C dimension tables used for this page — consult NSK's separate speed-rating tables before high-speed service.
• When replacing a failed unit, inspect the shaft and housing seats before fitting the new 61948 — a new bearing pressed onto a worn or oval seat reproduces the original failure mode in a fraction of its expected life.
• NSK's VV non-contact seal keeps frictional torque close to the open 61948; in motor duty where heat build-up matters, VV is the usual compromise between debris protection and speed capability.