Hydraulic parts, such as hoses, tubes, pipes, pumps, valves, and cylinders all need to be connected with a configuration of hydraulic hose fittings. Fittings must have the correct shape, materials, threading, and sealing options to keep the hydraulic system running efficiently and without any major safety issues.
The following will focus on two different types of hydraulic fittings; permanent crimp fittings and field attachable hose ends.
Permanent Crimp Fittings
These are fittings that are attached permanently to the hose by a crimping machine. There are two types of these fittings:
- Single component
- Two-component
The single-component is where the ferrule and the stem are attached. The ferrule is the outside shell that fits over the hose end. The stem is the part that is inserted into the hose. A two-component fitting has a stem that is separate from the ferrule.
There are two types of ferrules:
- Skive ferrules
- Non-skive ferrules
Skiving is a process that shaves or removes part of the hydraulic hose cover, the inner tube, or both before attaching hose fittings. Non-skive hoses and fittings are designed so that the hose and the fittings are ready to be assembled without having to apply the skiving process first. Because of advanced hose technology and additional costs in time that skiving requires, skiving has become obsolete.
However, there is probably hydraulic equipment around that may still use skive hoses and ferrules. Skive ferrules have rounded serrations or teeth. Non-skive serrations are very sharp to bite through the hose cover as they are crimped.
If using a single-component fitting, gently tap the stem into the inner tube of the hose. If using a two-component fitting, place the separate ferrule on top of the outer hose cover then gently tap in the stem. Consult the crimp specifications to select the appropriate die and settings for the crimping machine. Place the hose assembly between the appropriate die and the machine will do the rest.
Field Attachable Hose Ends
These types of fittings can be installed using a vise and two crescent wrenches. These fittings come in many forms:
- Skive
- No-skive
- Lock-on
- 100R5 (C5) DOT approved
Lock-on or push-lock hose fittings are used for low-pressure hydraulic systems, such as shop air and general industrial purposes. These fittings do not have serrations or teeth which would secure the fitting to the hose. Instead, they have a specialized set of barbs which, when inserted into the hose, the internal liner material conforms under the pressure of the braid and the outer skin of the hose. Attempting to pull the fitting from the hose makes for a tighter grip around the barbs.
Assembly of these types of field attachable fittings can be quite daunting, especially if the hose is cold, or it is a small diameter hose. In addition, if the fitting is impossible to insert after the first two barbs are already in, this will require the hose to be cut and the installation to start over.
The advantages of field attachable hose ends are:
- No special equipment required
- Reduced downtime
- A faster repair option than permanent crimp fittings
- Reusable, which reduces long-run costs
The disadvantages of these fittings are:
- Difficult to assemble, especially the lock-on fittings
- The cost per unit is more than the permanent crimp fittings
Changing out your field attachable fittings is something that can be done in the field, but keep in mind they must be the correct ones for the hose. To ensure the safety and efficiency of your hydraulic system, contact us at Custom Hose for any questions regarding your field attachable fittings or to help with permanent crimp fittings for your hydraulic hoses.