61848-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 61848-NSK model number is decoded

In the 61800-series (diameter series 8 of ISO 15) the last two digits encode the bore: 61848 carries bore code 48 = 240 mm. Outside diameter 300 mm and width 28 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

• At 240 mm bore the ring mass is significant: heat 61848 on an induction heater (max 120 °C), never over an open flame, and plan puller access or a withdrawal sleeve now for the day it has to come off again.
• The 618xx thin section at 240 mm bore has only a 30.0 mm radial section height: it saves space but is highly sensitive to misalignment, shaft deflection and shock loads — verify shaft stiffness before choosing it over a 6248.
• Storage matters for open bearings: 61848-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.
• Open bearings tolerate the highest speeds in the 61800-series but need a defined regreasing interval; run-to-failure lubrication is the dominant cause of early failure in open 61848 units.
• Vibration during standstill brinells the raceways of a 240 mm bearing at ball spacing; if the machine sits idle next to running equipment, turn the shaft over periodically or isolate the arrangement.
• Grease compatibility is not guaranteed between fills: mixing lithium and polyurea thickeners in a 61800-series position can soften the mixture and leak — clean out the old fill before switching grease types.
• The open 61848 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 61848 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.
• At 108 kN dynamic load rating (C) and 137 kN static (C0), 61848 is a heavy-load NSK bearing for industrial gearboxes and large conveyors; NSK expects a machined brass cage (suffix M) at this rating for shock duty, and the static C0 must be checked against any mounting or lifting loads.
• At 4480 g (4.5 kg), 61848 needs mechanical handling for mounting; NSK recommends induction heating the inner ring (max 120 °C) rather than pressing cold, and a lifting eye if the housing is pre-assembled.
• The 240×300×28 mm envelope of 61848 gives a D/d ratio of 1.25 and only 30.0 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 108/137 kN load ratings, mass 4480 g here are NSK Rolling Bearings E1103 Part C catalogue figures for 6848 on the 240×300×28 mm ISO 15 envelope; internal geometry and ratings legitimately differ between brands, so re-verify before substituting another manufacturer's 61848 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.
• NSK supplies its sealed units pre-greased for general duty between roughly -10 and +110 °C; low-temperature, food-grade and high-temperature fills are special executions — ask at order time, because DDU/VV units are not designed to be opened and repacked.
• Keep NSK bearings in the original packaging until fitting: the wrapper carries the production lot, and the unopened shelf life of greased sealed units is typically quoted at three to five years in dry, vibration-free storage.