Copyright Goodheart-Willcox Co., Inc. 194 Fluid Power These fi ttings are used on off-the-shelf hose assem- blies. If proper equipment is available, an end user may apply these connections in the fi eld. Reusable hose-end fi ttings allow more fl exibility in servicing hose assemblies. This is possible because these fi ttings can be attached to the hose using basic hand tools. They can also be removed from a conduc- tor assembly that has failed and reused with a length of new hose. Reusable hose ends are generally clas- sifi ed as either screw-together or clamp types. See Figure 8-24. The screw-together, reusable hose-end fi tting con- sists of two parts. The fi rst part is an outer shell fi tted with internal threads that allow it to be threaded over the outer diameter of the hose. One end of this outer shell contains a smaller threaded opening through which a nipple is turned into the inner tube of the hose. This forces the hose to slightly expand, producing a leakproof seal between the hose and the fi tting. The end of the insert opposite of the nipple contains the connection to be used for attaching the hose to system components. Clamp type, reusable hose-end fi ttings typically consist of three parts. One part is an insert that is forced into the inner tube of the hose. This insert is con- structed with a nipple on one end to aid in insertion. The other end of the insert contains the connections needed for attachment to system components. Two or four bolts are used to tighten two clamp pieces around the hose. This clamping action forces the hose onto the insert and produces a positive seal. Hose Flexible hose is attached to a hose-end fi tting that includes an attachment mechanism designed to con- nect to other hydraulic lines, control valves, actuators, or other system components. This attachment mecha- nism or fi tting may use pipe threads, 37° or 45° fl are, fl ange, or other confi guration. In some cases, the hose- end fi tting is directly connected to system components. However, in most situations, an adapter fi tting is used between the hose-end fi tting and the component. Hose-end fi ttings are available in permanently attached or reusable styles. A permanently attached unit consists of a nipple and socket on one end of the connector body and a threaded or other style of connection on the opposite end. The hose is forced over the nipple, fi lling the space between the nipple and socket. The metal of the socket is then swaged or crimped. This locks the connector over the hose and forms a permanent connection. See Figure 8-23. Solid Male Female Nut Thread OD Thread ID 24° Tubing Compression sleeve Gates Corporation Figure 8-21. A number of different fittings depend on compression between the fitting and the tubing for a seal. Goodheart-Willcox Publisher Figure 8-22. Split-flange fittings that have been brazed or hard soldered to the tubing may be used to attach tubing to hydraulic components. A B Gates Corporation Figure 8-23. Permanently attached hose-end fittings are crimped or swaged onto the hose and cannot be removed. A—External view showing compression of the fitting socket. B—Cutaway showing hose materials held by the fitting nipple and compressed socket.