Hydraulic hoses and fittings for specialist vehicles

Hydraulic hose for the construction, agricultural and mining industries have to be robust and flexible. Hydraulic fittings have to be up to the job, too, but first let’s look at hose types. Of course, there are different types of hydraulic hose, but what they all have in common is this: their pressure capacity dictates how the hose is constructed.

High-pressure hoses are used in the most demanding applications, from backhoe hydraulic systems and hydraulic trenchers to tractor hydraulic hoses and combine harvester hydraulic systems. Medium-pressure hose is also common in off-road applications, but heavy engineering often calls for high-pressure hose.

Anatomy of a hydraulic hose

All hose, whether low-, medium- or high-pressure, consists of the same parts: cover, reinforcement and tubing. The difference between high- and low-pressure hydraulic hose really comes down to the material of the reinforcement. Low-pressure hose usually has a synthetic textile braid, while medium- and high-pressure hose typically have wire braiding, though not always. Some are made of thermoplastic or even textiles.

Hose type and pressure ranges

It helps to break down low-, medium- and high-pressure hose by looking at their operating – better known as working – pressure ranges, which are measured in pounds per square inch (psi). Keep in mind that burst pressure is a different animal. It’s the point at which the hose will burst, and that figure is typically four times the psi. So if you have a hose with a 5,000 psi, its burst pressure is 20,000 psi.

Spiral hose

High- and extremely high-pressure hoses are reinforced with spiralled, high-tensile steel wire, which winds around the tube in alternating, even-numbered layers to balance pressure and containment forces. High-pressure hoses typically have what’s called a “four wire” reinforcement, while extremely high-pressure hose usually has a six-wire reinforcement. The number of layers of spiral wire actually has to do with the inner diameter (ID) of the hose. If the ID is less than 1 inches, then it will most likely have four layers.

As you might expect, braided hose, made of textiles, is more flexible than spiral hose.

Hose for hydraulic system designs

Below is a range of hydraulic hose commonly used in heavy engineering. We’re focussing on EN and SAE standards. What does SAE stand for in hydraulic fittings and hose? The Society of Automotive Engineers. U.S. based, the SAE is today known as SAE International. There are many hose standards around the world, but by far the ones most widely followed are those of the SAE. While not as common around the world as SAE hoses, EN are European standards. Standards often align with each other. For example, Deutsches Institut für Normung is the German national organization for standardization and also used in Europe. So if you’re in England and looking for a DIN or EN hose – or DIN EN, as it often appears – you’ll usually see the SAE standard code next to the European codes to let you know that it meets SAE standards:

MEDIUM-PRESSURE HYDRAULIC HOSE-R7

Applicable Standard: DIN EN 855 / SAE 100 R7

Also know that standards are voluntary only. Manufacturers apply the standards to give customers continuity and similarities.

Hydraulic hose types

The construction, agricultural and mining industries rely on these types of hoses.

High-pressure hose

Medium-pressure hose

What size hydraulic hose do I need?

To determine the hose size your system requires, see our helpful how-to guide: Hydraulic hose sizing nomograph.

What are hydraulic fittings?

These are the components that connect hoses, tubing and pipes in hydraulic designs to pumps, valves, cylinders and other areas of the system. Most hose fittings have a male and female part that form the connection. It’s the hydraulic hose fittings that hold and direct the flow of fluid, prevent leaks and maintain pressure. With different types of hose fittings, you can change the direction of the flow and the elevation of lines.

What are hydraulic crimp fittings?

Crimping is often performed to assemble hose and fittings. This is done using a crimping machine.

Manufacturers provide crimp specifications for hose, which are used to adjust the machine’s setting for crimping diameter. The fitting is lubricated, placed at the hydraulic hose end and put in the machine, which attaches the fitting to the hose.

Can I use fittings and hose from different manufacturers?

No. It might be tempting, but it carries dangerous risks, which in turn leaves you vulnerable to liability. Hydraulic connectors, hoses, crimping equipment, accessories – these are designed by the manufacturer so that they work together. Tolerances are different between manufacturers, so don’t assume these components are compatible. Using fittings from one manufacturer and hose from another can lead to bursting hoses and leaking couplings. Worse, ends can blow off, causing severe injury or even death.

Ensure fittings and hose share the same psi

If a hydraulic system has a 5,000 psi, and that includes spikes, you not only need hose rated at 5,000 psi, but your fittings should be too. The fittings are your system’s weakest link. If your fittings are rated 4,500 psi, but they’re connected to a 5,000-psi hose, then what you have is a 4,500-psi system – and potentially a dangerous situation.

Common hydraulic fittings

Typical hose connector types for specialty vehicles include hydraulic adapters and fittings:

Hydraulic quick coupling types

The construction and agricultural industries must be able to connect and detach hoses from cylinders, pumps and manifolds on a frequent basis. Quick couplings enable the user to do this with convenience and speed. No tools are needed and the couplings self-seal when released. When connected, male and female couplings form a fluid-tight seal to avoid fluid spills.

Sizing your fittings

To ensure the integrity of the pressure-holding capacity and seal reliability, you need to size your fittings and any adapters correctly. If you’re using SAE hose, use SAE fittings from the same manufacturer. You’ll find charts for all thread standards and sizes, along with a step-by-step guide on how to measure in Identifying threads and connectors.

While not specific to specialty vehicles, you can also learn more about fittings in general in Your hydraulic fitting: which should you choose and why?

Download free CADs and try before you buy

Free CADs are available for most solutions, which you can download. You can also request free samples to make sure you’ve chosen exactly what you need. If you’re not quite sure which solution will work best for your application, our experts are always happy to advise you.

Whatever your requirements, you can depend on fast despatch. Request your free samples or download free CADs now.

Questions?

Email us at sales@essentracomponents.com or speak to one of our experts for further information on the ideal solution for your application 800-847-0486.