What is the maximum operating pressure for this 50x70x10mm T-shaped sealing ring?

The maximum operating pressure depends on the groove design and whether a backup ring is used. Without a backup ring, the NBR 70 Shore A T-ring can handle up to 16 MPa in static applications and 10 MPa in dynamic applications. With a PTFE backup ring installed on the low-pressure side, the pressure rating increases to 25 MPa for dynamic service. For pressures above 25 MPa, we recommend the PU 90 Shore A version or a combination with a anti-extrusion ring. Always ensure the groove dimensions meet ISO 7425-1 standards for T-seals to avoid extrusion gaps exceeding 0.2mm at 25 MPa.

How do I install the T-shaped sealing ring without damaging the lips?

Installation requires careful handling to avoid cutting the lips on sharp edges. First, deburr the shaft and housing bore, and chamfer the bore entry to at least 15 degrees. Lubricate the seal and groove with the system fluid or a compatible grease. For the 50mm ID ring, use a tapered installation sleeve to slide the inner lip over the shaft. Press the seal evenly into the groove by hand or with a flat plate—never use a screwdriver. After installation, verify that the seal rotates freely without twisting. For reciprocating applications, cycle the shaft slowly 10 times to seat the lips before applying full pressure.

What is the expected service life of this NBR T-ring in a hydraulic pump?

In a clean hydraulic pump operating at 15 MPa and 60°C with a shaft speed of 1500 rpm, the NBR 70 Shore A T-ring typically lasts 3000 to 5000 hours. Service life depends on fluid cleanliness (ISO 4406 18/16/13 or better), shaft surface roughness (Ra 0.2-0.4 µm), and proper alignment. Contamination above 20 mg/100ml or shaft runout exceeding 0.3mm can reduce life by 50%. We recommend inspecting the seal every 1000 hours and replacing it if the lip wear exceeds 0.5mm or if leakage increases. Using a backup ring and maintaining oil temperature below 80°C will maximize service life.

Can this T-shaped sealing ring be used with biodegradable hydraulic fluids?

The NBR compound is compatible with most biodegradable hydraulic fluids based on synthetic esters and polyglycols, but not with those based on vegetable oils (e.g., rapeseed oil) because the fatty acids can cause excessive swelling. For synthetic ester fluids (e.g., Mobil EAL 224H), the NBR seal swells less than 15% after 1000 hours at 80°C, which is acceptable. However, for polyglycol fluids (e.g., Shell Naturelle HF-E), we recommend FKM seals because NBR may harden and crack. Always check the fluid manufacturer's seal compatibility chart. If in doubt, perform a 500-hour bench test with the actual fluid before production use.

T-Shaped Sealing Ring

T-Shaped Sealing Ring – 50mm ID x 70mm OD, NBR 70 Shore A for Rotary & Reciprocating Shafts

The T-shaped sealing ring is a double-acting elastomeric seal featuring a T-shaped cross-section that provides two sealing lips: one for the primary dynamic surface and one for secondary retention. This specific ring measures 50mm inner diameter, 70mm outer diameter, and 10mm width, molded from NBR (nitrile butadiene rubber) with a hardness of 70 Shore A.

Material

NBR (Nitrile Butadiene Rubber)

Inner Diameter

50 mm

Outer Diameter

70 mm

Width

10 mm

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How Does the T-Shaped Sealing Ring Perform in High-Pressure Hydraulic Systems?

The T-shaped sealing ring with 50mm ID, 70mm OD, and 10mm width is a precision-molded NBR seal designed for dynamic applications where both pressure and contamination must be controlled. The T-cross-section creates two distinct sealing lips: the outer lip contacts the housing bore, while the inner lip seals against the shaft. This geometry maintains contact even under eccentricity or shaft deflection up to 0.3mm, which is common in hydraulic pumps and motors. The 70 Shore A hardness provides a balance between flexibility for easy installation and rigidity to resist extrusion at pressures up to 25 MPa when used with a proper backup ring. The NBR compound offers excellent resistance to petroleum-based hydraulic oils, making it suitable for gear pumps, vane motors, and rotary actuators in mobile and industrial machinery.

Typical applications include sealing rotating shafts in gearboxes, reciprocating rods in pneumatic cylinders, and oscillating joints in steering systems. The 50mm shaft diameter is a standard size in many European and Asian hydraulic pumps, such as those from Bosch Rexroth, Parker, and Yuken. The T-shape's dual-lip design addresses a common pain point: single-lip seals often leak when the shaft has slight runout or when pressure fluctuates. By providing a secondary sealing edge, the T-ring reduces leakage risk by up to 40% compared to O-rings in similar grooves. Additionally, the solid T-section prevents the seal from rolling in the groove during reciprocating motion, which is a frequent failure mode for O-rings in dynamic service.

Compared to other sealing rings in the same series, this 50x70x10mm T-ring is optimized for medium-duty applications where space is limited but reliability is critical. Unlike standard O-rings, the T-shape allows for a smaller groove width (10mm) while maintaining two sealing points, saving axial space. The NBR material is also available in FKM for higher temperatures, but this NBR version offers superior oil resistance at a lower cost. For applications requiring higher pressure resistance, a polyurethane (PU) version with 90 Shore A is available, but the NBR 70 Shore A provides better conformability to rough surfaces. This makes the current ring ideal for retrofitting older equipment where shaft surfaces may not be perfectly smooth.

Dual-lip design reduces leakage by up to 40% compared to single-lip O-rings in dynamic tests.
NBR 70 Shore A compound resists mineral oil swelling by less than 10% after 168 hours at 100°C (ASTM D471).
Solid T-section prevents roll-out and extrusion at pressures up to 25 MPa with backup ring.

Core Technical Features and Quantified Advantages

STEP 1

Dual-Lip Sealing Geometry with 50mm ID and 70mm OD

The T-shaped cross-section provides two sealing lips: an outer lip (70mm OD) that seals against the housing bore and an inner lip (50mm ID) that seals against the shaft. This dual action maintains contact even under shaft misalignment up to 0.3mm, reducing leakage in dynamic applications. The 10mm width allows installation in grooves with a minimum depth of 8mm, saving axial space compared to two separate seals.

STEP 2

NBR 70 Shore A Compound for Oil and Water Resistance

The nitrile butadiene rubber (NBR) compound with 70 Shore A hardness offers excellent resistance to mineral oils, greases, and water-based fluids. It exhibits less than 10% volume swell after 168 hours immersion in IRM 903 oil at 100°C (ASTM D471). The material operates effectively from -30°C to +100°C, making it suitable for hydraulic systems in mobile machinery and industrial gearboxes.

STEP 3

Extrusion Resistance up to 25 MPa with Backup Ring

The solid T-section resists extrusion at pressures up to 25 MPa when paired with a PTFE backup ring, compared to 16 MPa for standard O-rings in the same groove. This allows the seal to be used in high-pressure hydraulic pumps and motors without frequent replacement. The T-shape also prevents roll-out during reciprocating motion, a common failure mode for O-rings in dynamic service.

STEP 4

Standard 50x70x10mm Size for Easy Retrofit

The 50mm inner diameter, 70mm outer diameter, and 10mm width match common metric shaft sizes used in European and Asian hydraulic equipment. This standard size allows direct replacement of worn seals in Bosch Rexroth, Parker, and Yuken pumps without machining. The simple groove design (rectangular cross-section) requires no special tools for installation, reducing downtime during maintenance.