Introduction
Hydraulic quick couplers are specialized devices used in hydraulic systems to quickly connect and disconnect hydraulic lines. They allow for rapid operation while ensuring secure and leak-free connections. These couplers do not require tools for connection or disconnection, significantly improving work efficiency and reducing downtime. This guide provides a comprehensive overview of the types, mechanisms, advantages, and standards associated with hydraulic quick couplers.
What Are the Common Types of Quick Couplers?
Common types of quick couplers include:
Ball-Lock Type: Enables fast connections with high reliability.
Flat-Face Type: Designed to prevent fluid leakage and contamination.
Push-Pull Type: Can be operated with one hand for ease of use.
Threaded Type: Offers the most secure connection, suitable for high-pressure and high-vibration environments.
These quick couplers are selected based on their characteristics and are widely used in pneumatic and hydraulic systems, including excavators, agricultural equipment, and spray guns.
Types of Hydraulic Quick Couplers:
Ball Fittings
Mechanism:
Ball lock quick couplings typically consist of a male and a female connector. The connection mechanism relies on the coordinated function of steel balls and a spring. Multiple steel balls are embedded around the circumference of the coupling to lock the male connector in place. The outer sleeve controls the locking ball mechanism; when the sleeve is pulled back, the steel balls can move freely. An internal check valve automatically opens or closes the passage during connection or disconnection to prevent leakage.
During connection, inserting the male connector into the female connector pushes the locking balls aside; once fully inserted, the balls snap back into place to secure the connection. To disconnect, simply pull the outer sleeve to release the locking balls, allowing the male connector to be withdrawn.
Standards:
These couplings conform to the ISO 7241 standard, which is internationally recognized to ensure interchangeability between different manufacturers. The series includes ISO 7241-1 A Series, ISO 7241-1 B Series, ISO 5675 Series, as well as common Chinese types such as the P-type, K-type, and the Non-Valve Series.
Advantages:
Quick Connection: Fast and convenient plug-and-play operation, can be done with one hand. Especially suitable for applications requiring frequent hose changes.
High Versatility: Available in various pressure ratings and sizes, covering a wide range of hydraulic applications.
Push-Pull Couplings
Mechanism:
The basic structure of push-pull couplings is similar to that of ball-lock couplings, but with the added functionality of enabling quick connect or disconnect operations via pushing or pulling. This makes them ideal for one-handed or blind operations.
The structure includes:
Locking Mechanism: Typically still uses a ball-lock design to secure the male connector.
Automatic Release Mechanism: Allows the user to connect or disconnect the coupling by simply “pushing” or “pulling” without the need to manually slide a sleeve.
Fixed Mounting Base: The female connector is usually mounted on a panel or equipment bracket, so operation does not require both hands.
To connect, the male connector is pushed into the panel-mounted female connector; a “click” sound indicates a successful lock. To disconnect, simply pull the male connector—no twisting or sleeve sliding is necessary.
Standard:
ISO 5675 is an international standard developed by the International Organization for Standardization specifically for hydraulic quick couplings used in agricultural and forestry machinery. It defines the structural dimensions, performance requirements, and interchangeability of couplings to ensure compatibility, safety, and efficiency across different equipment and brands.ISO 5675 Series is designed by Fescolo for frequent operational needs.
Advantages:
One-Handed Operation: No tools or two-handed effort required, making it ideal for frequent accessory changes or operations in hard-to-reach locations.
Stable Panel Mounting: Commonly used with brackets or panel clips, the coupling is fixed on the equipment, allowing faster and more efficient connect and disconnect actions.
Flat Face Couplings
Usage
When using the connection, clean the flat surfaces at both ends first to ensure that there is no dust or particles; Align the male connector with the female connector and insert it; Or tighten the screw sleeve to complete the connection; The valve automatically opens, establishing a fluid pathway. Release the locking mechanism at both ends to automatically close the valve core when disconnected; Pull out the male connector, and the liquid will not drip.
Mechanism: The core feature of the flat quick connector is that the connection surfaces at both ends are completely flat, and there is an automatic shut-off valve inside to ensure almost zero liquid leakage during connection and disconnection, and it is not easy to inhale air or impurities.
Standard: ISO 16028 is an internationally recognized standard, and Fescolo mainly provides the ISO 16028 Series, which is commonly used for construction machinery and suitable for harsh environments.
Threaded Couplings
How to operate
Firstly, clean the interface by using a cloth to clean the connection surfaces of the male and female connectors, ensuring that there are no impurities. secondly. Insert the male connector into the female connector, then rotate the nut to lock it until it reaches the contact stop point. At this point, the internal valve core will automatically open and hydraulic fluid can pass through. When disconnecting, first unload the system pressure, loosen the threaded ring, then pull out the male connector, and then automatically close the valve to prevent liquid leakage.
Mechanism
The structure of Threaded Couplings includes the following components: a threaded locking system, which securely locks both ends of the male joint by tightening the threaded ring to prevent detachment; Built in shut-off valve, automatically closes the valve core when the connector is disconnected to prevent oil from flowing out; When connected, the valve core opens to form a passage; Anti residual pressure, commonly used in emergency repairs and hydraulic tools; Heavy duty sealing system, high-pressure sealing ring+metal support ring, suitable for high pressure and impact loads
Advantages:
Strong resistance to high pressure: able to withstand system pressures of 30-70 MPa
Extremely strong sealing: High quality O-ring combined with metal support, with extremely low risk of leakage.
Adapt to impact and vibration loads: Thread locking will not loosen due to vibration, especially suitable for heavy engineering machinery, mining, construction equipment, etc.Selection criteria for hydraulic quick couplings.
Related factors to pay attention to when using Quick Couplers
Pressure
The maximum pressure that a joint can withstand during continuous operation is usually expressed in bar, MPa, or psi. The joint must meet or exceed the maximum working pressure of the system, and it is recommended to maintain a safety margin of 10-30%.
The following are pressure usage standards for different industries, for reference only:
Agricultural machinery generally operates at 10-25MPa and can use ISO5675 and ISO7241 A series; Industrial hydraulic systems are generally between 20-31.5MPa and can use ISO7241 B; Under high pressure conditions, threaded quick couplings are most suitable for use.
In addition, the burst pressure is the maximum pressure resistance of the joint at the limit state, usually 3-4 times the working pressure. Used to evaluate safety under extreme working conditions.
Velocity of flow
The unit is usually L/min or GPM.
The flow rate is closely related to the inner diameter of the joint, and choosing the appropriate diameter can prevent excessive pressure drop and heat generation.
Material
Steel: Steel is known for its high strength and durability, making it very suitable for withstanding large mechanical forces
Brass: Brass has excellent corrosion resistance, but its strength is not as good as steel. It is suitable for applications with corrosive liquids and relatively low pressure.
Plastic: Plastic also has a certain degree of corrosion resistance, but its heat resistance is not as good as steel and brass, often considering the combination of cost and application.
Aluminum alloy: The significant advantage is its lightweight, average pressure resistance, and can be used on mobile devices.
Temperature
The working temperature of hydraulic systems generally has a wide range, and the temperature tolerance of coupling materials and seals needs to be considered.
Chemical substances: In hydraulic systems, contact with cleaning agents, solvents, and process fluids is not uncommon. When selecting materials for hydraulic quick couplings, the chemical properties of the fluid medium need to be considered.
Corrosion: Corrosion is not a common issue, as corrosive substances can cause degradation of joint materials, leading to leakage and system failures.
Conclusion
Hydraulic quick couplings are important components of hydraulic systems, providing quick connections and disconnections for hydraulic systems in different industries. Different types of couplings enable them to adapt to different application fields with different requirements. With the introduction of this guide, you can have a clear understanding of the selection and cognition of hydraulic couplings. Fescolo hopes to help you with your selection.
