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  • 20x28x4mm Nitrile Rubber Rotary Shaft Oil Seal R21 / SC
  • 20x28x4mm Nitrile Rubber Rotary Shaft Oil Seal R21 / SC
20x28x4mm 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: 4mm
Shaft Size not Inside Diameter (d)
=
20mm
Outside Diameter (D)
=
28mm
Width (b)
=
4mm
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.

Construction
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

  • Jaime Rohan, United Kingdom 19/12/2019

    5 of 5 Stars!
    Your range is great, managed to find just what i was looking for

  • Donovan Steele, United Kingdom 01/10/2019

    5 of 5 Stars!
    Top-quality oil seals at budget prices. Customer service spot on and the goods were delivered quicker than expected. 10/10

  • Scott Trace, United Kingdom 08/03/2018

    5 of 5 Stars!
    quality seals

  • Jair Sebastian, United Kingdom 25/11/2015

    5 of 5 Stars!
    THANKS FOR THE GREAT SERVICE VERY IMPRESSED

  • Jasper Sandoval, United Kingdom 16/10/2015

    5 of 5 Stars!
    VERY GOOD QUALITY OIL SEALS AT RIGHT PRICE THANKS

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20x28x4mm Nitrile Rubber Rotary Shaft Oil Seal R21 / SC
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Brands

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
WN7 3XJ
United kingdom

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