N 150 X 120 X 19.8 G18

 

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G18 U-Cup

G18 (Use With Double Acting Piston Assemblies)

Automatic U-ring sets G18 are designed for use on double-acting piston assemblies for medium to heavy load conditions. The set comprises a proofed fabric U-ring and a hard fabric female adapter. Axial support of the U-ring is provided by the integrally molded tongue, making a separate male adapter unnecessary, and together with a hard fabric female ring, allowing a shallower installation depth.

The hard fabric female adapter prevents extrusion of the seal through the clearance gap, created by the expansion of the cylinder under pressure. The soft elastic U-ring portion of the set remains therefore undamaged. Under higher pressures the hard fabric female adapter will expand and provides additional sealing.

The arrangement of the U-ring sets either side of the piston ensures adequate wiping effect. The guide bushing which separates the seals is therefore protected from any foreign matter which may enter the cylinder, but at the same time receives sufficient lubrication. The adjacent metal parts viz, guide bush and cylinder bore are consequently not worn and will operate over a long period.

Pistons are normally designed with short guide bushings, but in those cases where a longer bushing is desirable, spiral grooves must be provided on the o/d surface of the bushing to prevent any possibility of a pressure trap particularly under high speed conditions. The integral U-ring and male tongue adapter prevents any turning of the seal under pressure in the event of a pressure trap between the seals. The elastic nature of the U-ring lip constrains the pressure and maintains an oil film, allowing the pressure to dissipate quickly. This is in contrast to normal U-rings which tend to turn in the housing.

Operating Conditions:

Maximum Speed: 0.5 m/s

Temperature: -30°C to 120°C (-22°F to 248°F)

Maximum Pressure: 400 bar

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