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Jack Bolt Function and Specification

Jack bolts are hydraulically tightened long studs that come equipped with a built-in hydraulic connection, keeping the upper main bearing controls intact. Moreover, they do not pass through the main bearing housing, but do hold their application by applying external hydraulic tension. These fastening components find use in technical applications, electronic connectors, and more.

Depending on the country of origin and their product specifications, jack bolt fasteners are subjected to rigorous standards. For example, one such set of standards include DIN standards which are the result of work completed by the German Institute for Standardization. They provide companies with a basis for quality, safety, and minimum functionality expectations.

Next, ASTM standards are another type which consist of procedures and standards that are approved by the American Society for Testing and Materials. They improve product quality, enhance health and safety, and ensure the reliability of products. Lastly, British Standards (BS) are the last type which are set in place by the BSI Group which is a part of the royal charter belonging to the UK.

Beyond needing to meet certain standards, jack bolts must be designed with clear specifications. As such, a majority of jack bolts run from 3mm to 200mm in length, and the tolerances are typically within +/-0.01mm to +/-0.05mm. It is important to note that jack bolts can be selected based on bolt diameter, width across flats, width across corners, and head height for further optimization. 

Materials also vary greatly, offering different resistances, protection, and load capabilities. For instance, nickel alloy eye bolts offer higher toughness, increased corrosion and oxidation resistance, and improved strength at higher and lower temperatures. Stainless steel eye bolts, on the other hand, offer impact resistance and strength, fire and heat resistance, and extended service lives. Other common materials include copper base alloys, aluminum alloys, and nonmetallic materials.

Jack bolts provide several advantages, the biggest being their working principle. To begin, jack bolts are positioned on top of the upper detent, unlike their conventional counterparts which are usually mounted on the side of the detent as they are passed through the hole provided on the housing for the stud. This configuration allows the tie rod to be placed closer to the crankshaft centerline, reducing the bending stresses on the cross girder of an engine.

One must keep in mind that jack bolts are not ever-lasting components and must be regularly checked to ensure their optimal functionality. Making sure that your jack bolt has been properly fitted onto the assembly at hand is critical. Clearances between the jack bolt and surface it is intended to penetrate or adhere to can be detrimental to the entire assembly.

If you find yourself in need of jack bolts, U bolts, fasteners, bearings, or other related components, look no further than NSN Gamut. NSN Gamut is a leading online distributor of aviation components, NSN parts, semiconductor supplies, electrical connectors, and more. With over 2 billion ready-to-purchase items on our digital database, you are bound to find what you need with ease. Peruse our ever-expanding listings at your leisure and fill out an RFQ form when you find an item that sparks your interest. With the information you provide us, we can craft a customized solution that meets your requirements quickly and easily. More than that, our inventory is subjected to a series of quality assurance measures, tests, verifications, and assessments. With this in mind, we operate with  AS9120B, ISO 9001:2015, and FAA AC 00-56B accreditation, allowing us to guarantee our items’ authenticity. Kickoff the procurement process with a competitive quote and see how NSN Gamut can serve as your strategic sourcing partner!


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