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SKF 31177 shaft seal, transparent nitrile rubber ring, 3.125 by 4.125 by .375 in

SKF

SKF 31177 Shaft Seal 3.125 x 4.125 x .375 in CRW1 Nitrile

SKU CH-PQT8-HYF9E

Rotary shaft seal with 3.125 in bore, 4.125 in OD and .375 in width, nitrile lip rated to 10 psi and 2,340 RPM

  • ColorTransparent
  • Width3/8"
  • Seals 10 psi pressure with nitrile lip
  • Handles 340 RPM shaft speed reliably
  • Resists oil, fuel and hot water
  • Fits 3.125 in bore and 4.125 in housing
  • .375 in width installs in standard groove

SKF 31177 Shaft Seal for Rotating Equipment

This SKF rotary shaft seal fits shafts with a 3.125 in inside diameter and a 4.125 in outside diameter. The CRW1 design uses a single nitrile rubber lip with a carbon steel spring to retain lubricants and exclude contaminants. It suits maintenance teams repairing gearboxes, pumps or motors where the original seal has hardened or leaked.

Replaces Worn CRW1 Seals in Inch-Sized Bores

The seal upgrades a hardened, leaking or grooved lip that no longer holds 10 psi at the rated 2,340 RPM. The jump is worth it when the shaft surface is still within spec but the old nitrile has lost elasticity or the spring has unseated. It is not for applications exceeding 9.71 mps surface speed or pressures above the rated limit.

Press-Fit Install with Standard Driver Tools

Installation requires a clean bore, light oil on the lip and even pressure from a seal driver to avoid cocking the acrylic-coated case. The most common error is damaging the single lip during insertion or seating the seal past the chamfer, which creates an immediate leak path. No special tooling beyond a correct-size driver is needed.

Highlights

  • Seals 10 psi pressure with nitrile lip
  • Handles 340 RPM shaft speed reliably
  • Resists oil, fuel and hot water
  • Fits 3.125 in bore and 4.125 in housing
  • .375 in width installs in standard groove

Specifications

BrandSKF
ColorTransparent
Width3/8"

Questions about this item

What bore size does the 3.125 in inside diameter shaft seal require for installation?

The seal fits a 4.125 in bore with a 3/8 in width; ensure the housing is clean and free of burrs before pressing the seal in squarely.

Which step is most often missed when pressing in the CRW1 nitrile shaft seal?

Installers frequently forget to lubricate the nitrile lip with clean oil or grease before pressing the seal, causing lip damage and early leakage.

When should the SKF 31177 seal be replaced under normal operating conditions?

Replace the seal if the nitrile lip shows hardening, cracking, or if leakage appears, especially after sustained runs near the 2,340 RPM limit.

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