Hydraulic hose assembly

The hydraulic hose assembly consists of three parts:

Hydraulic hose: composed of an inner rubber layer, a reinforcement layer, and an outer rubber layer, responsible for flexibly accommodating and transporting fluids.

Joint: usually made of metal (such as carbon steel, stainless steel), installed at both ends of the hose, used to connect the hose with other components in the hydraulic system (such as oil cylinders, pumps, valve blocks).

Buckling sleeve: used to firmly fix the joint on the rubber hose for a long time.

These three parts are combined together through a focused crimping process to form an inseparable whole, which constitutes the 'assembly'.

Core structure and working principle

The hydraulic hose itself is a multi-layer composite structure designed to withstand high pressure, pulses, and harsh environments:

Inner rubber layer: It comes into direct contact with hydraulic oil and is usually made of synthetic rubber (such as NBR nitrile rubber) that is oil resistant and corrosion-resistant (based on actual reports). Require smoothness to reduce pressure loss and friction.

Enhancement layer: It is the "skeleton" of the rubber hose, which bears all the working pressure. It is usually woven or wound from multiple layers of high-strength steel wires (also known as low-pressure pipes made of textiles). The more layers, the higher the pressure it can withstand.

Weaving: Good flexibility and excellent anti twisting performance.

Entanglement: High pressure bearing capacity, long pulse life, but relatively large bending radius.

Outer adhesive layer: protects the reinforcement layer from external environmental damage, such as wear, impact, weather (ozone, ultraviolet), oil pollution, and chemicals. Usually made of wear-resistant (based on actual reports) and weather resistant rubber (such as CR chloroprene rubber).

Working principle: When high-pressure fluid flows inside the pipe, the inner adhesive layer confirms the seal, the reinforcement layer provides strength to resist expansion and bursting, and the outer adhesive layer provides external protection. The assembly is connected to the system through threads (such as metric, imperial, NPT, etc.) or flanges of joints to achieve excellent fluid transmission.

Main technical parameters and selection guide

Choosing the appropriate hydraulic hose assembly is crucial, as it directly affects the safety and lifespan of the system. When selecting, the following core parameters need to be considered:

Work pressure: The high pressure that occurs during normal system operation. It is necessary to choose a rubber hose with a rated working pressure greater than or equal to the system's maximum pressure. There is usually an Enron coefficient (such as 4:1), which means that the burst pressure is four times the rated working pressure.

Inner diameter: The inner diameter of the hose determines the flow rate and velocity. A too small inner diameter can lead to high flow velocity, resulting in pressure drop and overheating; Excessive inner diameter can increase costs and unnecessary weight. The appropriate diameter needs to be calculated based on the system flow.

Temperature range: including fluid temperature and ambient temperature. Both the inner and outer rubber layers of the hose have their applicable temperature range, and exceeding this range can cause the rubber to harden, soften, or fail.

Fluid compatibility: Confirm that the hydraulic oil (or other medium) is compatible with the inner rubber layer material of the hose. Incompatibility can cause the inner adhesive layer to expand, soften, or decompose, contaminating the system.

Bending radius: Rubber hoses should be used above a small bending radius, otherwise it will seriously damage the reinforcement layer and shorten the service life. The length of the assembly should be protected from excessive bending or stretching within its range of motion.

Type of connector: Select the connector form and thread standard that matches the system port. Common types include:

Long term connection type: such as compression type (commonly used), reusable type (less commonly used).

Detachable type: such as flange type, Quick Release Couplings.

Thread standards: Metric thread, UN/UNF thread, NPT/NPTF thread, BSPP/BSPT thread, etc., can be mixed according to the contract.

Application environment: Consider whether there is external wear, impact, extreme weather, chemical contact, or flammable and explosive environments, which determine the requirements for the material of the external adhesive layer and whether protective sleeves (such as spring sleeves, nylon sleeves) need to be installed.

Common word-of-mouth standards

In order to confirm quality and interchangeability, hydraulic hose assemblies follow a series of reputation standards, commonly including:

SAE: Society of Automotive Engineers standards (such as SAE 100R series, SAE 100R1AT, R2AT, R12, R13, etc.), which are widely recognized by the public.

ISO: Word of mouth standardization organization standards (such as ISO 18752, ISO 3862).

DIN: German Industrial Standard (such as DIN 20023).

GB/T: Chinese National Standard.

Identification: Qualified hose assemblies usually have long-term identification, including manufacturer, standard (such as SAE 100R2AT), inner diameter, rated pressure, production date (week/year), and other information, for easy traceability and identification.

Installation, use and maintenance precautions

Do not twist: During installation, the hose must not be twisted, otherwise it will greatly reduce its lifespan. You can check the marking line on the hose to confirm that it is not in a spiral shape.

Maintain slack: The installation length should be slightly longer than the actual measured distance, leaving a slack margin to absorb length changes caused by pressure fluctuations and equipment vibrations.

Avoid sharp bends: The bending radius should not be less than the specified small bending radius, and bending near the root of the joint should be avoided.

Prevent friction: Ensure that the rubber hose does not come into contact with any sharp edges or high-temperature surfaces, and use pipe clamps and protective sleeves as needed.

Regular inspection: Daily inspection is the key to preventing malfunctions. The inspection includes:

External adhesive layer: whether there are cracks, bulges, hardening, softening, wear or oil leakage.

Joint: Check for rust, leakage, or looseness.

Overall: Is there any abnormal twisting or stretching.

Timely replacement: Once any signs of damage are found, the machine should be stopped immediately for replacement. Do not take risks on high-voltage systems.