GMNS61921ETAP4Super Precision Deep Groove Ball Bearing – 105 mm ID, 145 mm OD, 20 mm Width, Open, P4, Phenolic Cage, Light Preload

Product Description

What this part is

GMN S61921ETAP4, a super precision deep groove ball bearing from GMN’s spindle bearing range. Bore: 105 mm. Outside diameter: 145 mm. Width: 20 mm. Series: 619, the extra-light ISO deep groove section. Bore form: straight, cylindrical. Closure: open. Manufacturer: GMN Paul Müller Industrie, Nuremberg. Country of origin: Germany.

Decoding the designation

S is GMN’s spindle bearing prefix. 61921 is the ISO base number: series 619, bore code 21, giving a 105 mm bore. TA is a fabric-base phenolic laminate cage. P4 is the precision class, ABEC 7.

Published specifications

Dynamic load rating: 54.5 kN (12,252 lbf). Static load rating: 56 kN (12,589 lbf). Limiting speed: 13,000 rpm. Precision class: P4 / ABEC 7. Preload: light. Cage type: outer-ring guided. Cage material: phenolic. Operating temperature range: -30 to 100 °C. Lubrication: oil. Material: chrome steel. Weight: 2.5 lb (1.13 kg).

What these specs mean in practice

The 619 section is the thinnest deep groove series at a 105 mm bore — 20 mm of radial section and 20 mm of width — which is what allows a large-diameter spindle quill to stay compact. A deep groove geometry takes radial load with axial load in both directions equally, so a single bearing locates a shaft in both directions without a matched partner.

Cage and precision

The phenolic cage is guided on the outer ring land rather than by the balls. Outer-ring-land guidance stabilises the cage at speed and lets the phenolic act as an oil reservoir, which together are what carry the 13,000 rpm figure. Phenolic runs quieter and lighter than brass at the cost of a 100 °C temperature ceiling. P4 to ABEC 7 sets running accuracy: tighter radial and axial runout, so the tool or workpiece holds position at speed.

Quantity and configuration

One bearing per unit of sale. Open on both faces, light preload.

Interchange guidance

Same envelope, same type: SKF 61921, FAG 61921 and NSK 6921 share 105 x 145 x 20 mm as standard-class deep groove bearings, so they match on size while this part carries the P4 super precision class and phenolic spindle cage. 71921 appears on the carton and in the catalogue title as a search term; 71921 is the angular contact designation on the same 105 x 145 x 20 envelope, which makes it a related size with a different internal geometry rather than an interchange. SKF 71921 ACD/P4A is that angular contact part.