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  • 17x25x4mm Nitrile Rubber Rotary Shaft Oil Seal R21 / SC
  • 17x25x4mm Nitrile Rubber Rotary Shaft Oil Seal R21 / SC
17x25x4mm 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: 17mm
Outside Diameter: 25mm
Width: 4mm
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

  • Liam Walsh, United Kingdom 30/12/2019

    5 of 5 Stars!
    I called at your trade counter to source some replacement oil seals which were very badly damaged.

  • Raiden Rafael, United Kingdom 18/12/2019

    5 of 5 Stars!
    Amazing oil seals, top quality!

  • Ty Hurley, United Kingdom 30/09/2019

    5 of 5 Stars!
    Very pleased with the trade counter staff, they couldn't do enough for me when I called in for these oil seals, which were superb quality by the way. I'll definitely be back. Highly recommended.

  • Roy Dominique, United Kingdom 04/07/2016

    5 of 5 Stars!
    Good quality seals delivered super quick. Will be sure to come back and order more from you very soon. Found the whole experience of ordering with you a pleasure. Your website was really easy to navigate

  • Jocelyn Compton, United Kingdom 01/07/2015

    5 of 5 Stars!
    Seal was cheap as chips in comparison to manufacturer prices, got a bit confused between SC and TC but was explained the difference by a lady in your customer service department. A great shopping experience created via yourself. Pat on the back

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17x25x4mm 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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