For beginners
Hydraulic hose basics
Five short lessons that explain what a hydraulic hose is, how it is sized and named, and how to read one. Written for people new to hose work.
A hydraulic hose carries oil under pressure between parts of a machine that move relative to each other. It looks simple, but four things define every hose: how it is built, its bore, its type and its pressure rating. All four are printed on the hose itself.
Work through the five lessons in order if you are new. Each one takes a few minutes and ends with the questions people most often ask.
The five lessons
- 1ConstructionHow a hydraulic hose is builtEvery hydraulic hose has three parts: an inner tube that holds the oil, reinforcement that holds the pressure, and a cover that protects both.
- 2SizesHydraulic hose sizes explainedA hydraulic hose is sized by its inside diameter. The same size can be written in inches, as a dash number, or as a metric DN.
- 3TypesHydraulic hose types and standardsHose type codes such as 2SN, 4SP or R13 name a construction and a pressure class defined by a standard. A dozen codes cover almost every hose on a machine.
- 4PressureHydraulic hose pressure ratings explainedA hose has three pressures: the working pressure you design to, the proof pressure it is tested at, and the burst pressure it must survive once.
- 5LaylineHow to read a hydraulic hose laylineThe line of text printed along a hose tells you its maker, type, size, working pressure and date of manufacture. It is the first thing to read on any hose.
Hose types at a glance
| Type | Reinforcement | Pressure class | Typical use |
|---|---|---|---|
| SAE 100R1 / EN 853 1SN | One wire braid | Medium | Return lines, pilot lines, low-pressure circuits |
| SAE 100R2 / EN 853 2SN | Two wire braids | High | The general-purpose pressure hose on most machines |
| SAE 100R16 / R17, EN 857 1SC / 2SC | One or two wire braids, compact | High | Tight routing; smaller outside diameter and bend radius |
| EN 856 4SP | Four wire spirals | Very high | Pressure lines in sizes up to about 1 in |
| EN 856 4SH | Four wire spirals, heavy | Very high | Large-bore high-pressure lines, 3/4 in and above |
| SAE 100R12 | Four wire spirals | Very high | High-impulse lines on mobile equipment |
| SAE 100R13 | Four or six wire spirals | 350 bar (5,000 psi) in all sizes | Main pump and travel lines on large excavators |
| SAE 100R15 | Four or six wire spirals | 420 bar (6,000 psi) in all sizes | Highest-pressure circuits and hydrostatic drives |
| SAE 100R3 / R6, EN 854 | Textile braid | Low | Low-pressure return, drain and lubrication lines |
| SAE 100R4 | Textile with a wire helix | Suction | Pump suction lines; the helix stops the hose collapsing |
| SAE 100R7 / R8, EN 855 | Synthetic fibre, thermoplastic tube | Medium to high | Forklifts, aerial platforms, non-conductive lines |
Frequently asked questions
What do I need to know to identify a hydraulic hose?
Four things: the inside diameter, the hose type (such as 2SN or 4SP), the working pressure and the length. The first three are printed on the layline. Then identify the fitting on each end.
What is the most common hydraulic hose?
Two-wire braided hose, SAE 100R2 or EN 853 2SN, is the general-purpose pressure hose on most mobile equipment. Large high-pressure lines use four-spiral hose.
How long does a hydraulic hose last?
It depends on pressure cycles, temperature, flexing, abrasion and routing rather than age alone. Inspect hoses regularly and replace any with cover damage exposing wire, leaks at the fittings, blisters, kinks or hard, cracked rubber.