What is a UNF thread?
The UNF (Unified National Fine) thread is a standard American fine-pitch thread, part of the Unified Thread Standard (UTS) system, used mainly in North America and countries that have adopted imperial standards. It is characterized by an increased number of threads per inch (TPI – Threads Per Inch), which makes the thread more precise and ensures better tightness compared to the standard UNC (Unified National Coarse) thread, which has a larger pitch.
Straight AA UNF (JIC) fittings, double female swivel UNF hydraulic fittings
Straight AA UNF fittings (also known as AA JIC female adapters / UNF double-female connectors) are standardized power hydraulic fasteners designed for secure, leak-free connection of flexible hoses and components equipped with JIC male external threads. The AA type design is characterized by the presence of swivel nuts with internal threads on both sides (side A and side A), allowing for trouble-free installation in the line of hoses without the need to rotate them or dismantle adjacent installation elements. The fittings use the American fine-pitch inch UNF/UN thread with a 74° sealing cone (37° seat angle according to SAE J514 / ISO 8434-2). Made of free-cutting steel with a galvanic zinc coating, straight AA UNF fittings provide 100% mechanical tightness through metal-to-metal contact and high resistance to working pressures reaching up to 400 bar in agricultural, construction, forestry machines, and industrial equipment of American and European manufacture.
Application and technical characteristics of straight AA UNF (JIC) fittings
Double-female straight AA UNF fittings are indispensable during service work, modernization, and connecting two sections of pressure hoses terminated with rigid plugs or JIC (AGJ) male threads. The use of swivel nuts eliminates torsional stress in flexible hydraulic hoses.
- Double female (AA) design: A swivel nut with an internal UNF thread on both sides of the fitting allows for quick connection of two male JIC ends.
- American UNF / JIC thread standard: Support for popular fine-pitch sizes (e.g., 7/16"-20, 9/16"-18, 3/4"-16, 7/8"-14, 1.1/16"-12, 1.5/16"-12 UNF).
- 74° cone seal (JIC 37°): Mechanical fitting of metal-to-metal contact surfaces eliminates the need for Teflon tapes, adhesives, or rubber washers.
- High pressure and mechanical resistance: The massive steel body withstands working pressures up to 215–400 bar (depending on thread size) and impulse spikes.
- Corrosion protection: The electro-galvanized surface with white passivation protects the element against moisture, harsh weather conditions, and mineral oils.
Why choose straight AA UNF fittings at the HYDRON store?
Straight AA UNF fittings offered by the HYDRON brand are manufactured maintaining strict dimensional tolerance regimes in accordance with SAE J514 and ISO 8434-2 standards. Precisely cut threads and perfectly ground internal cones prevent micro-leaks of hydraulic oil and eliminate the risk of thread seizure during tightening. They serve for efficient adaptation of attachments in machines of brands such as John Deere, Caterpillar, Case, Bobcat, Komatsu, or New Holland. For complete construction and service of a pressure system, we encourage you to select other components from our offer, such as flexible hydraulic hoses, matching steel hose fittings, self-sealing test points and reliable hydraulic quick couplings.
Technical specification
Frequently Asked Questions (FAQ)
What are the characteristics of a straight AA type UNF fitting?
An AA type UNF fitting has swivel nuts with internal fine-pitch inch UNF (JIC) threads on both sides. It is used to directly connect two elements or hoses terminated with JIC male external threads.
What is the difference between a 74° and a 37° cone angle in JIC fittings?
It is exactly the same connection. The 74° designation refers to the full apex angle of the cone, while 37° means the inclination angle of a single sealing seat wall relative to the fitting axis.
Does a JIC UNF cone connection require the use of sealants on the thread?
No. Sealing in JIC fittings occurs automatically on the contact surface of the metal-to-metal cones under the influence of tightening the nut. The use of Teflon tapes or adhesives is unnecessary and may prevent proper compression of the cone.
In what machines are fittings with UNF / JIC threads used?
JIC/UNF fittings are commonly used in agricultural, construction, and forestry machines of American brands and in newer global equipment (John Deere, Case, Caterpillar, Bobcat, Volvo, JCB).
