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Polyurethane U-Seal, 4.00 Inch OD, 3.25 Inch ID, 0.50 Inch Height

Description & Features

Rated for pressures up to 6,000 PSI and a temperature range of -65°F to 220°F, this polyurethane U-seal is built for demanding hydraulic piston applications. Manufactured by Hercules Sealing Products, the Polyurethane U-Seal, 4.00 Inch OD, 3.25 Inch ID, 0.50 Inch Height features a beveled lip design that promotes effective film breaking across the sealing surface. The urethane construction provides durability in high-pressure environments where resistance to wear and extrusion is critical.

With a 0.375-inch cross section and a height of 0.50 inches, this seal falls into the deep-type profile category, where height exceeds cross section. The 4.00-inch OD and 3.25-inch ID dimensions suit standard hydraulic cylinder bore configurations requiring a reliable piston seal.

SKU: U37-3.25-50B

Supplier Part Number (MPN): U37-3.25-50B

Alternate Part Numbers: C1DQ58, MI-01197984, MINO-00407X60337

Specifications

Cross Section 0.375 in	Brand Hercules Sealing Products	Brand Hercules Sealing Products	Pack Size 1.00	UOM EA	H 0.5 in	I.D. 3.25 in	O.D. 4 in	Supplier Part Number U37-3.25-50B	Alternate Part Numbers Alternate Part Number C1DQ58, Alternate Part Number MI-01197984, Alternate Part Number MINO-00407X60337	Product Weight 0.09 lbs

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Model Number	Cross Section	I.D.	O.D.	H
U12-0.62-25B Polyurethane U-Seal	0.125 in	0.625 in	0.875 in	0.25 in
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U18-1.25-SQB Polyurethane U-Seal	0.1875 in	1.25 in	1.625 in	0.1875 in
U18-1.75-37B Polyurethane U-Seal	0.1875 in	1.75 in	2.125 in	0.375 in
U18-2.12-SQB Polyurethane U-Seal	0.1875 in	2.125 in	2.5 in	0.1875 in
U18-2.50-31B Polyurethane U-Seal	0.1875 in	2.5 in	2.875 in	0.3125 in
U25-1.25-37B Polyurethane U-Seal	0.25 in	1.25 in	1.75 in	0.375 in
U25-1.50-37B Polyurethane U-Seal	0.25 in	1.5 in	2 in	0.375 in
U25-2.00-37B Polyurethane U-Seal	0.25 in	2 in	2.5 in	0.375 in
U25-2.50-37B Polyurethane U-Seal	0.25 in	2.5 in	3 in	0.375 in
U25-3.00 Polyurethane U-Seal	0.25 in	3 in	3.5 in	0.25 in
U25-3.00-37B Polyurethane U-Seal	0.25 in	3 in	3.5 in	0.375 in
U25-3.50-37B Polyurethane U-Seal	0.25 in	3.5 in	4 in	0.375 in
U25-4.00-SQB Polyurethane U-Seal	0.25 in	4 in	4.5 in	0.25 in
U25-4.50 Polyurethane U-Seal	0.25 in	4.5 in	5 in	0.25 in
U25-5.00 Polyurethane U-Seal	0.25 in	5 in	5.5 in	0.25 in
U12-0.18-25B Polyurethane U-Seal	0.125 in	0.1875 in	0.438 in	0.25 in
U12-0.25-25B Polyurethane U-Seal	0.125 in	0.25 in	0.5 in	0.25 in
U12-0.25-SQB Polyurethane U-Seal	0.125 in	0.25 in	0.5 in	0.125 in
U12-0.31-25B Polyurethane U-Seal	0.125 in	0.3125 in	0.563 in	0.25 in
U12-0.31-SQB Polyurethane U-Seal	0.125 in	0.3125 in	0.563 in	0.125 in
U12-0.37 Polyurethane U-Seal	0.125 in	0.375 in	0.625 in	0.125 in
U12-0.50-25B Polyurethane U-Seal	0.125 in	0.5 in	0.75 in	0.25 in
U12-0.50-SQB Polyurethane U-Seal	0.125 in	0.5 in	0.75 in	0.125 in
U12-0.56 Polyurethane U-Seal	0.125 in	0.625 in	0.938 in	0.125 in
U12-0.62-SQB Polyurethane U-Seal	0.125 in	0.625 in	0.875 in	0.125 in
U12-0.68 Polyurethane U-Seal	0.125 in	0.6875 in	0.938 in	0.125 in
U12-0.75-18B Polyurethane U-Seal	0.125 in	0.75 in	1 in	0.1875 in
U12-0.75-25B Polyurethane U-Seal	0.125 in	0.75 in	1 in	0.25 in
U12-0.75-SQB Polyurethane U-Seal	0.125 in	0.75 in	1 in	0.125 in
U12-0.81 Polyurethane U-Seal	0.125 in	0.8125 in	1.063 in	0.125 in
U12-0.87-25B Polyurethane U-Seal	0.125 in	0.875 in	1.125 in	0.25 in
U12-0.87-SQB Polyurethane U-Seal	0.125 in	0.875 in	1.125 in	0.125 in
U12-1.00-18B Polyurethane U-Seal	0.125 in	1 in	1.25 in	0.1875 in
U12-1.00-SQB Polyurethane U-Seal	0.125 in	1 in	1.25 in	0.125 in
U12-1.06-SQB Polyurethane U-Seal	0.125 in	1.0625 in	1.313 in	0.125 in
U12-1.12-25B Polyurethane U-Seal	0.125 in	1.0625 in	1.375 in	0.25 in
U12-1.12-SQB Polyurethane U-Seal	0.125 in	1.0625 in	1.375 in	0.125 in
U12-1.18 Polyurethane U-Seal	0.125 in	0.188 in	1.438 in	0.125 in
U12-1.18-18B Polyurethane U-Seal	0.125 in	0.188 in	1.438 in	0.1875 in
U12-1.18-25B Polyurethane U-Seal	0.125 in	0.188 in	1.438 in	0.25 in
U12-1.25-18B Polyurethane U-Seal	0.125 in	1.25 in	1.5 in	0.1875 in
U12-1.25-25B Polyurethane U-Seal	0.125 in	1.25 in	1.5 in	0.25 in
U12-1.37-25B Polyurethane U-Seal	0.125 in	1.375 in	1.625 in	0.25 in
U12-1.37-SQB Polyurethane U-Seal	0.125 in	1.375 in	1.625 in	0.125 in
U12-1.50-25B Polyurethane U-Seal	0.125 in	1.5 in	1.75 in	0.25 in
U12-1.50-SQB Polyurethane U-Seal	0.125 in	1.5 in	1.75 in	0.125 in
U12-1.62-SQB Polyurethane U-Seal	0.125 in	1.625 in	1.875 in	0.125 in
U12-1.75-SQB Polyurethane U-Seal	0.125 in	1.75 in	2 in	0.125 in
U12-2.00 Polyurethane U-Seal	0.125 in	2 in	2.25 in	0.125 in
U12-2.25 Polyurethane U-Seal	0.125 in	2.25 in	2.5 in	0.125 in
U12-2.75 Polyurethane U-Seal	0.125 in	2.75 in	3 in	0.125 in
U15-1.18 Polyurethane U-Seal	0.1563 in	0.188 in	1.5 in	0.1563 in
U15-1.25 Polyurethane U-Seal	0.1563 in	1.25 in	1.563 in	0.1563 in
U15-1.37 Polyurethane U-Seal	0.1563 in	1.375 in	1.688 in	0.1563 in
U18-0.50 Polyurethane U-Seal	0.1875 in	0.5 in	0.875 in	0.1875 in
U18-0.62-31B Polyurethane U-Seal	0.1875 in	0.625 in	1 in	0.3125 in
U18-0.62-SQB Polyurethane U-Seal	0.1875 in	0.625 in	1 in	0.1875 in
U18-0.75-31B Polyurethane U-Seal	0.1875 in	0.75 in	1.125 in	0.3125 in
U18-0.75-SQB Polyurethane U-Seal	0.1875 in	0.75 in	1.125 in	0.1875 in
U18-0.87-31B Polyurethane U-Seal	0.1875 in	0.875 in	1.25 in	0.3125 in
U18-0.87-SQB Polyurethane U-Seal	0.1875 in	0.875 in	1.25 in	0.1875 in
U18-1.00-25B Polyurethane U-Seal	0.1875 in	1 in	1.375 in	0.25 in
U18-1.00-31B Polyurethane U-Seal	0.1875 in	1 in	1.375 in	0.3125 in
U18-1.00-37B Polyurethane U-Seal	0.1875 in	1 in	1.375 in	0.375 in
U18-1.00-SQB Polyurethane U-Seal	0.1875 in	1 in	1.375 in	0.1875 in
U18-1.12-25B Polyurethane U-Seal	0.1875 in	1.0625 in	1.5 in	0.25 in
U18-1.12-31B Polyurethane U-Seal	0.1875 in	1.0625 in	1.5 in	0.3125 in
U18-1.12-SQB Polyurethane U-Seal	0.1875 in	1.0625 in	1.5 in	0.1875 in
U18-1.18 Polyurethane U-Seal	0.1875 in	0.188 in	1.563 in	0.1875 in
U18-1.25-25B Polyurethane U-Seal	0.1875 in	1.25 in	1.625 in	0.25 in
U18-1.25-31B Polyurethane U-Seal	0.1875 in	1.25 in	1.625 in	0.3125 in
U18-1.25-37B Polyurethane U-Seal	0.1875 in	1.25 in	1.625 in	0.375 in
U18-1.37-25B Polyurethane U-Seal	0.1875 in	1.375 in	1.75 in	0.25 in
U18-1.37-31B Polyurethane U-Seal	0.1875 in	1.375 in	1.75 in	0.3125 in
U18-1.37-37B Polyurethane U-Seal	0.1875 in	1.375 in	1.75 in	0.375 in
U18-1.37-SQB Polyurethane U-Seal	0.1875 in	1.375 in	1.75 in	0.1875 in
U18-1.50-25B Polyurethane U-Seal	0.1875 in	1.5 in	1.875 in	0.25 in
U18-1.50-31B Polyurethane U-Seal	0.1875 in	1.5 in	1.875 in	0.3125 in
U18-1.50-37B Polyurethane U-Seal	0.1875 in	1.5 in	1.875 in	0.375 in
U18-1.50-SQB Polyurethane U-Seal	0.1875 in	1.5 in	1.875 in	0.1875 in
U18-1.62 Polyurethane U-Seal	0.1875 in	1.625 in	2 in	0.1875 in
U18-1.62-25B Polyurethane U-Seal	0.1875 in	1.625 in	2 in	0.25 in
U18-1.62-31B Polyurethane U-Seal	0.1875 in	1.625 in	2 in	0.3125 in
U18-1.62-37B Polyurethane U-Seal	0.1875 in	1.625 in	2 in	0.375 in
U18-1.62-SQB Polyurethane U-Seal	0.1875 in	1.625 in	2 in	0.1875 in
U18-1.75-25B Polyurethane U-Seal	0.1875 in	1.75 in	2.125 in	0.25 in
U18-1.75-31B Polyurethane U-Seal	0.1875 in	1.75 in	2.125 in	0.3125 in
U18-1.75-SQB Polyurethane U-Seal	0.1875 in	1.75 in	2.125 in	0.1875 in
U18-1.87-37B Polyurethane U-Seal	0.1875 in	1.875 in	2.25 in	0.375 in
U18-1.87-SQB Polyurethane U-Seal	0.1875 in	1.875 in	2.25 in	0.1875 in
U18-2.00-31B Polyurethane U-Seal	0.1875 in	2 in	2.375 in	0.3125 in
U18-2.00-37B Polyurethane U-Seal	0.1875 in	2 in	2.375 in	0.375 in
U18-2.00-SQB Polyurethane U-Seal	0.1875 in	2 in	2.375 in	0.1875 in
U18-2.12-25B Polyurethane U-Seal	0.1875 in	2.125 in	2.5 in	0.25 in
U18-2.25-37B Polyurethane U-Seal	0.1875 in	2.25 in	2.625 in	0.375 in
U18-2.25-SQB Polyurethane U-Seal	0.1875 in	2.25 in	2.625 in	0.1875 in
U18-2.37-SQB Polyurethane U-Seal	0.1875 in	2.375 in	2.75 in	0.1875 in
U18-2.50-25B Polyurethane U-Seal	0.1875 in	2.5 in	2.875 in	0.25 in
U18-2.50-37B Polyurethane U-Seal	0.1875 in	2.5 in	2.875 in	0.375 in
U18-2.50-SQB Polyurethane U-Seal	0.1875 in	2.5 in	2.875 in	0.1875 in
U18-2.62-37B Polyurethane U-Seal	0.1875 in	2.625 in	3 in	0.375 in
U18-2.62-SQB Polyurethane U-Seal	0.1875 in	2.625 in	3 in	0.1875 in
U18-2.75-37B Polyurethane U-Seal	0.1875 in	2.75 in	3.125 in	0.375 in
U18-2.75-SQB Polyurethane U-Seal	0.1875 in	2.75 in	3.125 in	0.1875 in
U18-2.87 Polyurethane U-Seal	0.1875 in	2.875 in	3.25 in	0.1875 in
U18-3.00 Polyurethane U-Seal	0.1875 in	3 in	3.375 in	0.1875 in
U18-3.00-37B Polyurethane U-Seal	0.1875 in	3 in	3.375 in	0.375 in
U18-3.12-37B Polyurethane U-Seal	0.1875 in	3.125 in	3.5 in	0.375 in
U18-3.12-SQB Polyurethane U-Seal	0.1875 in	3.125 in	3.5 in	0.1875 in
U18-3.50-37B Polyurethane U-Seal	0.1875 in	3.5 in	3.875 in	0.375 in
U18-3.62-37B Polyurethane U-Seal	0.1875 in	3.625 in	4 in	0.375 in
U18-3.62-SQB Polyurethane U-Seal	0.1875 in	3.625 in	4 in	0.1875 in
U18-4.00-37B Polyurethane U-Seal	0.1875 in	4 in	4.375 in	0.375 in
U25-0.75 Polyurethane U-Seal	0.25 in	0.75 in	1.25 in	0.25 in
U25-0.93 Polyurethane U-Seal	0.25 in	0.8125 in	1.438 in	0.25 in
U25-1.00-37B Polyurethane U-Seal	0.25 in	1 in	1.5 in	0.375 in
U25-1.00-SQB Polyurethane U-Seal	0.25 in	1 in	1.5 in	0.25 in
U25-1.12 Polyurethane U-Seal	0.25 in	1.0625 in	1.625 in	0.25 in
U25-1.12-37B Polyurethane U-Seal	0.25 in	1.0625 in	1.625 in	0.375 in
U25-1.18 Polyurethane U-Seal	0.25 in	0.188 in	1.688 in	0.25 in
U25-1.25-SQB Polyurethane U-Seal	0.25 in	1.25 in	1.75 in	0.25 in
U25-1.37 Polyurethane U-Seal	0.25 in	1.375 in	1.875 in	0.25 in
U25-1.37-37B Polyurethane U-Seal	0.25 in	1.375 in	1.875 in	0.375 in
U25-1.50-31B Polyurethane U-Seal	0.25 in	1.5 in	2 in	0.3125 in
U25-1.50-SQB Polyurethane U-Seal	0.25 in	1.5 in	2 in	0.25 in
U25-1.75 Polyurethane U-Seal	0.25 in	1.75 in	2.25 in	0.25 in
U25-1.75-37B Polyurethane U-Seal	0.25 in	1.75 in	2.25 in	0.375 in
U25-1.87-37B Polyurethane U-Seal	0.25 in	1.875 in	2.375 in	0.375 in
U25-2.00-31B Polyurethane U-Seal	0.25 in	2 in	2.5 in	0.3125 in
U25-2.00-SQB Polyurethane U-Seal	0.25 in	2 in	2.5 in	0.25 in
U25-2.12-37B Polyurethane U-Seal	0.25 in	2.125 in	2.625 in	0.375 in
U25-2.25 Polyurethane U-Seal	0.25 in	2.25 in	2.75 in	0.25 in
U25-2.25-37B Polyurethane U-Seal	0.25 in	2.25 in	2.75 in	0.375 in
U25-2.37-37B Polyurethane U-Seal	0.25 in	2.375 in	2.875 in	0.375 in
U25-2.50-SQB Polyurethane U-Seal	0.25 in	2.5 in	3 in	0.25 in
U25-2.62-37B Polyurethane U-Seal	0.25 in	2.625 in	3.125 in	0.375 in
U25-2.75-37B Polyurethane U-Seal	0.25 in	2.75 in	3.25 in	0.375 in
U25-2.75-SQB Polyurethane U-Seal	0.25 in	2.75 in	3.25 in	0.25 in
U25-3.25-37B Polyurethane U-Seal	0.25 in	3.25 in	3.75 in	0.375 in
U25-3.50 Polyurethane U-Seal	0.25 in	3.5 in	4 in	0.25 in
U25-3.50-SQB Polyurethane U-Seal	0.25 in	3.5 in	4 in	0.25 in
U25-3.75-37B Polyurethane U-Seal	0.25 in	3.75 in	4.25 in	0.375 in
U25-3.75-SQB Polyurethane U-Seal	0.25 in	3.75 in	4.25 in	0.25 in
U25-4.00-37B Polyurethane U-Seal	0.25 in	4 in	4.5 in	0.375 in
U25-4.00-50D Polyurethane U-Seal	0.25 in	4 in	4.5 in	0.5 in
U25-4.00-56B Polyurethane U-Seal	0.25 in	4 in	4.5 in	0.5625 in
U25-4.50-37B Polyurethane U-Seal	0.25 in	4.5 in	5 in	0.375 in
U25-4.50-56B Polyurethane U-Seal	0.25 in	4.5 in	5 in	0.5625 in
U25-4.50-62B Polyurethane U-Seal	0.25 in	4.5 in	5 in	0.625 in
U25-5.00-37B Polyurethane U-Seal	0.25 in	5 in	5.5 in	0.375 in
U25-5.50 Polyurethane U-Seal	0.25 in	5.5 in	6 in	0.25 in
U25-5.50-37B Polyurethane U-Seal	0.25 in	5.5 in	6 in	0.375 in
U25-5.50-56B Polyurethane U-Seal	0.25 in	5.5 in	6 in	0.5625 in
U31-1.00-50B Polyurethane U-Seal	0.3125 in	1 in	1.625 in	0.5 in
U31-1.25 Polyurethane U-Seal	0.3125 in	1.25 in	1.875 in	0.3125 in
U31-1.25-37B Polyurethane U-Seal	0.3125 in	1.25 in	1.875 in	0.375 in
U31-1.37-37B Polyurethane U-Seal	0.3125 in	1.375 in	2 in	0.375 in
U31-1.37-SQB Polyurethane U-Seal	0.3125 in	1.375 in	2 in	0.3125 in
U31-1.50 Polyurethane U-Seal	0.3125 in	1.5 in	2.125 in	0.3125 in
U31-1.75-37B Polyurethane U-Seal	0.3125 in	1.75 in	2.375 in	0.375 in
U31-1.87 Polyurethane U-Seal	0.3125 in	1.875 in	2.5 in	0.3125 in
U31-2.00 Polyurethane U-Seal	0.3125 in	2 in	2.625 in	0.3125 in
U31-2.00-50B Polyurethane U-Seal	0.3125 in	2 in	2.625 in	0.5 in
U31-2.25-50B Polyurethane U-Seal	0.3125 in	2.25 in	2.875 in	0.5 in
U31-2.37 Polyurethane U-Seal	0.3125 in	2.375 in	3 in	0.3125 in
U31-2.50 Polyurethane U-Seal	0.3125 in	2.5 in	3.125 in	0.3125 in
U31-2.50-50B Polyurethane U-Seal	0.3125 in	2.5 in	3.125 in	0.5 in
U31-2.75 Polyurethane U-Seal	0.3125 in	2.75 in	3.375 in	0.3125 in
U31-2.75-50B Polyurethane U-Seal	0.3125 in	2.75 in	3.375 in	0.5 in
U31-2.87 Polyurethane U-Seal	0.3125 in	2.875 in	3.5 in	0.3125 in
U31-3.00-50B Polyurethane U-Seal	0.3125 in	3 in	3.625 in	0.5 in
U31-3.37-50B Polyurethane U-Seal	0.3125 in	3.375 in	4 in	0.5 in
U31-4.00 Polyurethane U-Seal	0.3125 in	4 in	4.625 in	0.3125 in
U31-4.00-56B Polyurethane U-Seal	0.3125 in	4 in	4.625 in	0.5625 in
U31-4.37 Polyurethane U-Seal	0.3125 in	4.375 in	5 in	0.3125 in
U31-4.50 Polyurethane U-Seal	0.3125 in	4.5 in	5.125 in	0.3125 in
U37-1.25 Polyurethane U-Seal	0.375 in	1.25 in	2 in	0.375 in
U37-1.75 Polyurethane U-Seal	0.375 in	1.75 in	2.5 in	0.375 in
U37-2.50-50B Polyurethane U-Seal	0.375 in	2.5 in	3.25 in	0.5 in
U37-2.75 Polyurethane U-Seal	0.375 in	2.75 in	3.5 in	0.375 in
U37-3.25-50B Polyurethane U-Seal	0.375 in	3.25 in	4 in	0.5 in
U37-3.50 Polyurethane U-Seal	0.375 in	3.5 in	4.25 in	0.375 in
U37-3.75-50D Polyurethane U-Seal	0.375 in	3.75 in	4.5 in	0.5 in
U37-4.00-62B Polyurethane U-Seal	0.375 in	4 in	4.75 in	0.625 in
U37-4.25-50D Polyurethane U-Seal	0.375 in	4.25 in	5 in	0.5 in
U37-4.25-62B Polyurethane U-Seal	0.375 in	4.25 in	5 in	0.625 in
U37-4.25-SQB Polyurethane U-Seal	0.375 in	4.25 in	5 in	0.375 in
U37-4.50-62B Polyurethane U-Seal	0.375 in	4.5 in	5.25 in	0.625 in
U37-5.00-62B Polyurethane U-Seal	0.375 in	5 in	5.75 in	0.625 in
U37-5.25 Polyurethane U-Seal	0.375 in	5.25 in	6 in	0.375 in
U37-5.25-50D Polyurethane U-Seal	0.375 in	5.25 in	6 in	0.5 in
U37-6.25-50D Polyurethane U-Seal	0.375 in	6.25 in	7 in	0.5 in
U50-2.00-SQB Polyurethane U-Seal	0.5 in	2 in	3 in	0.5 in
U50-2.50 Polyurethane U-Seal	0.5 in	2.5 in	3.5 in	0.5 in

Product Questions & Answers (2)

Question by: Duane H on Oct 22, 2025, 11:08 AM

What kinda pressure can this handle before it gives out?

Answer by: Customer Support on Oct 24, 2025, 6:50 AM

This U-seal is rated to handle pressures up to 6,000 PSI, so it should hold up in demanding hydraulic applications.

Question by: Daryl P on Jan 12, 2026, 11:12 AM

Got a 4-inch bore cylinder that needs a new piston seal, will this one fit right, and what's the cross section on it?

Answer by: Customer Support on Jan 14, 2026, 6:56 AM

For a standard 4-inch bore hydraulic cylinder, the dimensions here line up well. The OD is 4.00 inches, ID is 3.25 inches, and the cross section runs 0.375 inches. The height comes in at 0.50 inches, which puts it in the deep-type profile category since the height is greater than the cross section. As long as your groove is cut to accept those dimensions, it should drop right in as a piston seal.