Introduction to Three Primary NOK Rod Seals for Hydraulic Cylinders

NOK Corporation, a leading Japanese seal manufacturer, is renowned for its high-performance and reliable hydraulic components. Among its extensive product line, certain rod seals stand out as industry standards for durability and performance. Below is an introduction to three of the most frequently specified NOK rod seals.

1. NOK S-Type Rod Seal (Standard Duty)

The NOK S-Type is a versatile and widely used rod seal, designed for general hydraulic applications. It is characterized by its single-acting lip seal design, which provides excellent sealing performance and low friction.

• Material: Typically made from Nitrile Rubber (NBR) or Polyurethane (AU).

• Temperature Range: Approximately -30°C to +100°C (NBR) / -20°C to +110°C (AU).

• Pressure Range: Suitable for working pressures up to 40 MPa.

• Key Features & Application:

  • Offers excellent resistance to wear and extrusion.

  • Ideal for a broad range of industrial machinery, construction equipment, and machine tools.

  • A reliable, cost-effective solution for standard hydraulic cylinders.

2. NOK DKB Series Rod Seal (Heavy Duty & High Pressure)

The NOK DKB seal is a heavy-duty, single-acting rod seal engineered for demanding applications with high pressure and potential pressure shocks. Its robust design includes an integrated anti-extrusion ring for superior performance.

• Material: The sealing element is typically made of Polyurethane (AU).

• Temperature Range: Standard range from -20°C to +110°C.

• Pressure Range: Capable of handling very high pressures, often up to 60 MPa or more.

• Key Features & Application:

  • Excellent resistance to high pressure and extrusion, thanks to its reinforced design.

  • Superior stability under pulsating pressure conditions.

  • Primarily used in heavy construction machinery like excavators, presses, and other high-pressure hydraulic systems.

3. NOK U-Type Packing (General Purpose U-Ring)

The NOK U-Packing is a classic, double-acting seal suitable for both rod and piston applications. Its simple U-shaped design allows for effective sealing in two directions, making it a versatile choice.

• Material: Commonly available in Nitrile Rubber (NBR) or Polyurethane (AU).

• Temperature Range: Approximately -30°C to +100°C (NBR) / -20°C to +110°C (AU).

• Pressure Range: Generally used for pressures up to 40 MPa.

• Key Features & Application:

  • Provides effective sealing on both inward and outward strokes.

  • Easy to install and replace.

  • Used in various hydraulic equipment, agricultural machinery, and as a secondary seal in conjunction with primary rod seals.