Metric U-cup seals are essential for preventing leaks and reducing friction in hydraulic systems, including floor jacks, pistons, and hydraulic cylinders. This guide highlights five reliable metric U-cup seals that fit common sizes and applications, helping you compare compatibility, operating temperature ranges, and extrusion resistance. Whether you are restoring a Sears 328-series jack or upgrading a CNC hydraulic actuator, these selections cover a range of common ID/OD dimensions and lip configurations to maintain smooth operation.
| Product | Brand | Type | ID x OD x Height | |
|---|---|---|---|---|
| Hydraulic U-Cup Seal for Sears Floor Jack Repair | Camoo | Twin Lips U-Cup | 22 x 40 x 12 mm | Floor jack piston seal, multiple Sears/ASTRO models |
| RAParts JIC-D36970 U Cup Symmetrical Seal | Reliable Aftermarket Parts | U-Cup Symmetrical Seal | 1.75 x 2.25 x 0.375 in | Case IH and similar hydraulic components |
| 3/4″ X 1″ X 1/8″ Piston/Rod Loaded U-Cup Seal | Mr O-Ring | Square Straight Lip U-Cup | 0.75 x 1.0 x 0.125 in | Piston/rod seal in compact assemblies |
| 2 3/4″ X 3 1/4″ X 1/4″ Piston/Rod Loaded U-Cup Seal | Mr O-Ring | Square Straight Lip U-Cup | 2.75 x 3.25 x 0.25 in | Medium-to-large hydraulic rods |
| 1 1/8″ X 1 1/2″ X 3/16″ Piston/Rod Loaded U-Cup Seal | Mr O-Ring | Square Straight Lip U-Cup | 1.125 x 1.5 x 0.187 in | Smaller hydraulic pistons and rods |
Below is a closer look at each selected product, with image, quick spec notes, and how it may fit typical hydraulic systems and jacks in American applications.
Hydraulic U-Cup Seal for Sears Floor Jack Repair
Brand: Camoo. This metric seal measures 22x40x12 mm and is described as a dual-lip rod seal that fits Sears 328-series floor jacks and related ASTRO-AM models. Its design aims to prevent liquid and small solids from leaking into the piston, reducing friction and preserving air pressure. The listed applications include various model numbers and years, emphasizing broad compatibility with common hydraulic jacks and repair kits.
RAParts JIC-D36970 U Cup Symmetrical Seal
Brand: Reliable Aftermarket Parts. This U-seal is described as a single replacement with a 1.75″ ID, 2.25″ OD, and 0.375″ height. Temperature ratings span -40 to 195 F, with extrusion resistance specified at various pressures. The listing provides detailed performance data, including extrusion gaps and PSI ratings, suitable for hydraulic components subject to varying loads and temperatures.
3/4″ X 1″ X 1/8″ Piston/Rod U-Cup Seal
Brand: Mr O-Ring. Size: 0.75″ ID x 1.0″ OD x 0.125″ height. This piston/rod loaded U-Cup features a square straight lip and is built from TPU with a 95 Duro inner material, offering a compact seal option for small to mid-size hydraulic components where space is at a premium.
2 3/4″ X 3 1/4″ X 1/4″ U-Cup Seal
Brand: Mr O-Ring. Size: 2.75″ ID x 3.25″ OD x 0.25″ height. The listing highlights piston/rod loaded U-Cup seals with a square straight lip and a TPU shell. This size range suits mid-to-large hydraulic cylinders and jacks needing robust seal surfaces for greater fluid containment and lip stability under load.
1 1/8″ X 1 1/2″ X 3/16″ U-Cup Seal
Brand: Mr O-Ring. Size: 1.125″ ID x 1.5″ OD x 0.187″ height. This piston/rod loaded U-Cup features a square straight lip and a TPU shell with a 70 Duro O-ring, offering a balance of flexibility and sealing strength for compact hydraulic assemblies and rod passages where precise lip geometry is required for reliable sealing performance.
Buying Guide
Key purchase considerations for metric U-cup seals include size compatibility, lip design, material, and operating environment. Size accuracy matters most: verify ID, OD, and height against the hydraulic component’s piston or rod dimensions to avoid interference or leakage. Lip geometry (square straight, twin lips) affects how well the seal handles friction, pressure, and extrusion under load. Materials such as TPU and 70–95 Duro O-rings influence flexibility, wear resistance, and temperature tolerance. Consider the operating temperature range, chemical compatibility with hydraulic fluids, and the expected pressure cycling in your system. For jacks and compact cylinders, smaller, square straight lip seals can offer reliable sealing with easy installation, while larger sizes may require more robust TPU formulations to withstand extrusion and wear. When possible, match seals to OEM or proven aftermarket equivalents to ensure compatibility with existing housings and gasket interfaces. Finally, confirm that the seal type (piston/rod loaded U-cup) aligns with your piston rod diameter and stroke to maintain consistent sealing performance over time.