568-129 BUNA 70 SQUARE CUT RINGS

The SH70129 is an AS568-129 black Buna-N (Nitrile) 70 Shore A Square-Cut Ring built to an inside diameter of 1.549 in (39.34 mm), a cross section of 0.103 in (2.62 mm), and an outside diameter of 1.755 in (44.58 mm). This square-cut ring resists the spiral failure that affects round rings on long reciprocating strokes.

As a material, Buna-N (Nitrile) is widely chosen for reliable performance in both static and dynamic service, low compression set under sustained load. It resists water, petroleum-based oils, and propane and butane. Continuous operating temperature is published at -40°F (-40°C) to 250°F (121.1°C). It is not the right choice where strong acids or ozone and direct sunlight are present. The profile itself contributes a rectangular section that will not roll in the groove and a flat contact band that spreads sealing load across a wider area. Note that a square section is less suited to high-speed rotary service, where the larger contact area raises friction and heat.

Maintenance and OEM teams specify it across fluid power, agricultural equipment, and automotive.

This item is sold individually under part number SH70129. Unit weight is approximately 0.6746 g and nominal inside diameter is listed as 1 9/16 inch. Application requirements vary, so validate compatibility with your process conditions prior to installation. Not finding the exact configuration you need? APG cross-references from prints, samples and competitor part numbers.