LEVER 0801873 - Caterpillar

A. NPTF Seal
1. There are several basic fitting seals used for fluids today. The first is the metal-to-metal thread seal (NPTF) used on pipe threads. When the male pipe thread is screwed into the female socket, the seal takes place on the thread itself.2. The NPTF is a special pipe thread designed for hydraulic and fuel applications and should not be confused with NPT which is used for low pressure systems.
NPTFB. SAE Flare
1. A second is the flare type seal to a cone seal used on SAE threads*. The SAE uses a 37° flared cone seat for hydraulic applications and a 45° flared cone seat for non-hydraulic applications.
SAE FLARE - PTT*The JIC standard has been supplanted by the SAE 37° flare.C. SAE O-Ring Boss
1. A third type of seal uses a straight thread with a chamfer around the opening of the threaded port. An o-ring, which is attached to the hose fitting, seals against the chamfer upon connection.
SAE "O" RING BOSSD. SAE Split Flange
1. The SAE split flange fitting uses a forth type of seal. This fitting consists of a flanged head which has an o-ring groove and is held onto the port opening by two split flanges which are fastened on with four bolts. Thus it is named SAE-4-Bolt Split Flange.
SAE SPLIT FLANGEE. SAE Inverted Flare
1. Another type of fitting seal is the SAE inverted flare which is an inversion of the standard SAE flare type. The tube nut on this type has male threads rather than female threads. The inverted flare is used for power steering and hydraulic brake applications.F. Ors Connection
1. The ORS connection has an o-ring groove machined into its flat male face. This flat face and o-ring mate with the connection's other close tolerance machined face to form a virtually leak-free seal.2. Compression of the o-ring is accomplished by torquing the captive female nut.3. Assembly is complete when the female face is bottomed against the male, creating a metal back-up to the elastomeric seal.