HYDRAULIC HOSE COUPLINGS
hose couplings IMPROPER
selection or improper use of hoses, tubing, fittings and assemblies can cause failures, personal injury or property damage. Understanding the hose assembly and following the installation instructions provided by manufacturers will reduce these risks. Engineers looking to specify hose couplings need to consider a few things besides correct size. Will the couplings be reused or permanent? Will they need a locking mechanism to prevent involuntary disconnection? Is one-handed operation required?
A COLLECTION OF quick connect couplings, including flat face, screwto-connect, threadless connection and pressure diagnostic quick disconnects. Image courtesy of CEJN
Couplings can be two types: permanent and field-attachable (reusable). Permanent couplings are generally more reliable, easier and quicker to attach than field-attachable couplings, which makes them widely used in industry. Crimping or swaging equipment (sometimes both) is needed to put a permanent coupling on a hose. Permanent couplings can be preassembled (one piece), with a ferrule permanently attached to the stem. Higher-pressure hoses use field-attachable couplings, as well as permanent couplings. Field-attachable couplings fit right on the hose using only a wrench and a vise. No special equipment is required. While handy, they do cost more than permanent couplings and take more time to attach. There are three common types of coupling interfaces used in hydraulics today: thread interface, mated angle and O-ring. 6 • 2016
FLUID POWER WORLD
6/17/16 4:43 PM
Fluid Power World Handbook 2016