Company Profile

U-Cup Seal Supplier: Sourcing U-Cup Seals for Hydraulic and Pneumatic Cylinders

Quick Answer: CORASEALS is a U-cup seal supplier for hydraulic cylinders, pneumatic cylinders, rod sealing, and piston sealing applications. We quote U-cup seals based on the seal profile, material, ID, OD, groove dimensions, pressure, speed, fluid, and operating temperature. Send us your drawing, sample photo, or measured dimensions for a U-cup seal quotation.

U-cup seals are lip-type seals with a U-shaped cross section. They are used mainly in reciprocating hydraulic and pneumatic cylinders. The U-cup design uses system pressure to press the sealing lips against the rod or bore and the groove sidewall. The U-cup design allows the seal to work in low and high pressure conditions when the seal profile and groove match correctly.

U-Cup Seal Profiles and Material Options

CORASEALS can quote U-cup seals based on your existing part number, sample, drawing, or measured dimensions. Common profile codes include UN, UHS, UPH, and DH, but these codes are not treated as automatic interchange signals. Different catalogs define these codes differently. CORASEALS confirms the lip geometry, cross section, ID, OD, groove width, and material before quoting.

Common U-cup seal materials include the following.

• Polyurethane and TPU: high wear resistance, good for hydraulic cylinders, but limited by temperature and water compatibility depending on the grade.
• NBR: good mineral oil compatibility, widely used in hydraulic systems.
• FKM: higher temperature and chemical resistance than NBR, suitable for demanding hydraulic fluids and some chemical exposure.
• HNBR: better heat and wear resistance than NBR, used in mobile hydraulic and high temperature oil applications.

Material selection depends on the hydraulic fluid, temperature range, pressure cycle, and surface finish of the rod or bore. CORASEALS does not assign a fixed temperature or pressure rating without checking the material grade and groove design.

How to Specify a U-Cup Seal

U-cup seal dimensions are usually stated as inside diameter, outside diameter, and groove width or seal height. Some customers provide rod diameter, bore diameter, and groove dimensions from the cylinder drawing. Others provide an existing part number, sample photo, or measured seal dimensions. Both methods are acceptable.

Dimensions can be given in millimeters or inches. CORASEALS works with both metric and inch U-cup seal sizes. Always state the unit next to each measurement.

To get accurate pricing, include these details.

• Seal profile or part number, such as UN or UHS, if available.
• Rod diameter and bore diameter for rod or piston sealing.
• Groove ID, groove OD, groove width, and groove depth.
• Operating pressure and pressure spikes.
• Rod or cylinder speed in m/s.
• Hydraulic fluid or pneumatic medium, including any additives.
• Operating temperature and ambient temperature.
• Seal material preference, hardness, and color if color matters.
• Required quantity, sample availability, and drawing or photo.

Send us the rod diameter, bore diameter, groove dimensions, pressure, speed, hydraulic fluid, and seal profile. If you have a drawing or sample photo, include that with your inquiry.

Applications for U-Cup Seals

U-cup seals are common in mobile and industrial hydraulic cylinders. Typical equipment includes excavators, loaders, agricultural machinery, forklifts, presses, lifting platforms, and pneumatic actuators. The seal position can be a rod seal or a piston seal. U-cup seals can also be used in some pneumatic cylinders when the material and groove design suit compressed air and lubricating conditions.

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