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  • 20x28x5mm Nitrile Rubber Rotary Shaft Oil Seal R21 / SC
  • 20x28x5mm Nitrile Rubber Rotary Shaft Oil Seal R21 / SC
20x28x5mm Nitrile Rubber Rotary Shaft Oil Seal R21 / SC
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Oil Seals: Designed to aid trouble-free operation of your equipment, providing an excellent barrier against the escape of oils and greases and preventing the ingress of foreign matter.
Benefits: Excellent wear resistance, good running properties, high resistance to chemicals and petroleum based fuels including petrol, diesel and LPG.

Brand / Quality: Simply NBR Seals - High Quality
Inside Diameter: 20mm
Outside Diameter: 28mm
Width: 5mm
Shaft Size not Inside Diameter (d)
Outside Diameter (D)
Width (b)
Oil Seals
An oil seal normally consists of three basic components: The Sealing Element (the nitrile rubber part), the Metal Case, and the Spring. It is a widely used sealing component. The function of a seal is to prevent the leakage of medium along the moving parts. This is mainly achieved by the sealing element. Nitrile Rubber (NBR)
NBR is the most commonly used seal material. It has good heat resistance properties, good resistance to oils, salt solutions, hydraulic oils, and gasoline. Operation temperatures are recommended from -40deg C to 120deg C. It also functions well under dry environment, but only for intermittent periods.
R21 / SC design cross section

Cross section of an R21 / SC style oil seal.

This is a single sealing lip seal arrangement.

The seal cases are made from SAE 1008-1010 Carbon Steel and are often coated in a very thin layer of Nitrile rubber to assist sealing in the housing.
The principle function of the metal case is to impart rigidity and strength to the seal.
The spring is made from SAE 1050-1095 Carbon Spring Steel which has a protective zinc coating.
The principle function of the spring is to maintain an even gripping pressure around the shaft

Viton Chemical Resistance

  • Cayden Price, United Kingdom 19/12/2019

    5 of 5 Stars!
    Very friendly staff on the phone who helped deliver my oil seals next day!

  • Ezekiel Raphael, United Kingdom 01/10/2019

    5 of 5 Stars!
    Even though I have little knowledge of oil seals, I was assured and made confident in the oil seals I needed.

  • Larry Garner, United Kingdom 08/03/2018

    5 of 5 Stars!
    affordable pricing

  • Rogelio Carter, United Kingdom 07/02/2017

    4 of 5 Stars!
    Received with many thanks. Good quality at great price. Will be back to order from you for definitely should I need to order any more. Thank you

  • Muhammad Simmons, United Kingdom 06/02/2017

    4 of 5 Stars!
    Good quality seals delivered quickly. Just what I was after. Thank you. Will be back to order some more of you very soon.

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20x28x5mm Nitrile Rubber Rotary Shaft Oil Seal R21 / SC

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Simply bearings are the UK's largest online retailer of bearings, seals, belts, chains, sprockets, lubricants and other associated power transmission equipment.
Simply Bearings Ltd, Halton House, Greenfold Way, Leigh
Greater Manchester
United kingdom

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