Rod seals, double-acting, Type SD 02– SD 03

Double-acting rod seals of the types SD 02 (without notches) and SD 03 (with notches) are ideally suited for use in hydraulic systems and promise stick-slip-free running as well as good dry-running properties. The media used in these applications range from mineral oil-based hydraulic liquids, environment-friendly bio-oils and water to flame-resistant hydraulic liquids and air.

While the PTFE profile ring seals dynamically against the cylinder surface, the elastic O-ring ensures uniform contact pressure of the PTFE profile ring onto the cylinder surface and at the same time for a static sealing between profile ring and groove base.

Even with low pressures, the piston seal shows good sealing effect due to the inherent preloading of the PTFE profile ring and the contact force of the preloaded O-ring. At higher system pressures, the medium pressurizes the O-ring causing it to press the PTFE seal with enhanced force against the cylinder surface.

With different material combinations, the piston seal can be used reliably across the whole pressure, speed and temperature range.

Notches

To ensure that the preload on the seal is maintained under sudden changes in pressure and in direction of motion, it can be provided with two radial notches on both sides (Typ SD 03).

Application media

  • Mineral oil-based hydraulic liquids
  • Water
  • Air
  • Environment-friendly bio-oils
  • Flame-resistant hydraulic liquids
  • Other media, depending on the O-ring material

Application range

Pressure: up to 40 Mpa (400 bar)

Speed: approx. up to 15m/s

Temperature: -30°C to +200 °C (depending on the O-ring material)

Surface finish

Roughness depth Ra Rt
Running surface ≤ 0,3 µm ≤ 3,0 µm
Groove base ≤ 1,6 µm ≤ 16,0 µm
Groove flank ≤ 1,6 µm ≤ 16,0 µm

Installation dimensions

Rods ø D Gap size S
Heavy
Design
Standard
Design
Light
Design
Groove base ø D Groove width
L +0,2
Radius
R
10 Mpa
max.
20 Mpa
max.
40 Mpa
max.
O-ring
line
ø
8,0 – 18,9 ø d + 4,9 2,2 0,4 0,3 0,2 0,15 1,78
8,0 – 18,9 19,0 – 37,9 ø d + 7,3 3,2 0,6 0,4 0,25 0,15 2,62
8,0 – 18,9 19,0 – 37,9 38,0 – 199,9 ø d + 10,7 4,2 1,0 0,4 0,25 0,2 3,53
19,0 – 37,9 38,0 – 199,9 200,0 – 255,9 ø d + 15,1 6,3 1,3 0,5 0,3 0,2 5,33
38,0 – 199,9 200,0 – 255,9 256,0 – 649,9 ø d + 20,5 8,1 1,8 0,6 0,35 0,25 7,0
200,0 – 255,9 256,0 – 649,9 650,0 – 900,0 ø d + 24,0 8,1 1,8 0,6 0,35 0,25 7,0
256,0 – 649,9 650,0 – 900,0 ø d + 27,3 9,5 2,5 0,7 0,5 0,3 8,4

PTFE profile ring material

PTFE + bronze

The standard for hydraulic applications, good gliding behavior, particularly pressure and abrasion resistant, cannot be used in aqueous solutions or acids

PTFE + Glass-MoS2

particularly good resistance to wear and abrasion, application is possible even with poor lubricating pressure fluids, in water and in water-oil emulsions

PTFE + carbon

Exceptional resistance to abrasion and extrusion, can be used in water-hydraulics

For other possible materials see our overview of PTFE materials in the technical information section.

O-ring material

Nitrile rubber NBR: Temperature range − 30 °C to + 120 °C
Fluororubber FPM: Temperature range − 25 °C to + 200 °C

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