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What is in a door closer?

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What is in a door closer? Why those components are very important in a door closer? In this article, we will explain all the details and let you know the additional functions of the door closer will be need in the different application scenarios.

What is in a door closer?

A door closer is an adjustable and spring-loaded mechanical arm that closes a doorautomatically after it has been opened. Door closers are usually filled with hydraulic fluidwhich dampens the door swing and controls its operation. Installing a door closer adds aevel of control to your door's safety and security.A door closer is a mechanical device that is typically installed on doors to automatically close them after they have been opened. It helps control the speed and force at which the door closes, ensuring that it closes smoothly and securely without slamming. The exact components and design of a door closer can vary depending on the specific model and manufacturer, but here are some basic components you might find in a door closer:

Main Components

Key Features Of The Main Components


The casing or housing of the door closer contains the internal components and mechanisms. It is usually mounted on the door frame or the door itself.

Spring Mechanism

Most door closers use a spring mechanism to control the closing force. The spring is responsible for storing energy when the door is opened and releasing it gradually to control the door's closing speed.

Control Valves

Control valves regulate the flow of hydraulic fluid (or air, in pneumatic door closers) within the door closer. By adjusting these valves, you can control the speed at which the door closes and the force it exerts

Hydraulic Fluid or Pneumatic Gas

Hydraulic door closers use a hydraulic fluid to dampen the motion of the door, while pneumatic door closers use compressed air or gas for the same purpose. The fluid or gas helps control the speed of the door's movement and ensures a controlled and smooth closing action.

Piston and Cylinder

The piston and cylinder arrangement is crucial for the functioning of hydraulic door closers. As the door opens, the piston is moved within the cylinder, compressing the hydraulic fluid. When the door is released, the fluid expands, pushing the piston and assisting in closing the door.

Arm and Linkage

The arm of the door closer connects the door to the door frame or jamb. It transmits the force from the closer mechanism to the door. The linkage system includes various connecting rods and arms that ensure a controlled and even closing action.

Adjustment Screws

Door closers often come with adjustment screws that allow you to fine-tune the closing speed, closing force, and latching action of the door. These adjustments help accommodate different door sizes, weights, and environmental conditions.

Mounting Hardware

Various screws, brackets, and other mounting hardware are provided to attach the door closer to the door and door frame securely.

End-of-Travel Cushioning

Some advanced door closers have built-in mechanisms to provide cushioning at the end of the door's closing motion. This helps prevent slamming and reduces stress on the door and closer components.


Why those components are very important in a door closer?

After getting know different components of the door closer, we also need to know why we will choose such materials to manufacture door closer. Right now the below contents will explain different features of the main material such as case body, gear shaft and piston, seal, spring and bearing, and the reasons why Kaida will select those materials to produce a door closer.


Q1: Why we need to use aluminum alloy to produce the case body of door closer?

Our door closer are made of high-quality aluminum alloy ADC12 die-casting or high-hardness aluminum profile. On the special CNC technology control equipment, it relies on the imported PCD tool from Germany to use one-time clamping compound processing to ensure the roundness and roughness of thecylinder. Effectively control the center distance and verticality of the gear shaft and piston during the movement; Use Japanese infiltration process to reduce the risk of aluminum alloy die-casting leakage hydraulic oil, and ensure.

Q2: Why gear shaft and piston is important for a door closer?

The gear shaft and piston are made of high-qualitycarbon steel. After nearly 20 mechanical machiningon the precision machine tool, the heat treatment and surface treatment are carried out twice in the middle. The quality is stable and the mechanical properties are excellent. A fine grinding fit is formed between the cylinder block and the O-ring. The operation is flexible and smooth, and the seal is superior.

Q3: Why seals are important for a door closer?

The seals used in the door closer are all imported from Europe. After strict quality inspection, it can still seal normally from 60℃ to -40 ℃ ,which greatly guarantees the quality of the door closer. Some countries are very hot and some countries are very cold, without this high-quality seals, it will increase the oil leakage of the door closer.

Q4: Why springs are important for a door closer?

Made of high-quality spring steel, the optimal production process is selected, heat treated and hardened to ensure the closing force and improve the service life of the product.

Q5: Why bearings are important for a door closer?

The use of powder metallurgy oilimpregnated bearings or needle bearings greatly reduces the friction between the gear shaft and the shaft, which improves the efficiency of the door closer and makes it easier to open the door.

Q6: Why hydraulic oil is important for a door closer?

Selecting the door closer hydraulic oil for door closers from Germany's "FUCHS" company, whether it is low temperature or high temperature, it can guarantee normal operation and greatly improve the service life of the door closer.


Which accessories do you need in different installation methods?

After getting know what is in a door closer, next we will show which accessories you may need it when install a door closer in different application scenarios such as standard mount, top jamb mount and parallel mount as the picture showed below.




The body of the door closer is installed on the side of the sliding door, and the support arm is installed on the door frame. This installation method is suitable for the narrow door frame and there is not enough space to install the door closer. This installation method is also applicable when there is no obstacle in the door opening direction and the door is opened to a large enough angle, and the door closer will not hit foreign objects.



The door closer is installed on the push door side, and the support arm is installed on the door. This installation method is suitable for wide door frame, there is enough space to install the door closer. Compared with the standard installation, this installation method is suitable for obstacles such as walls in the door opening direction. Compared with the standard installation, this installation method has a higher closing force and is suitable for larger and heavier doors.



Compared with the standard mount on the pull side, the parallel mount is on the opposite side which will be mounted onto the push side, and the closer arm and parallel plate are all installed onto the frame. Viewed from the side, we will see that the arm’s position is parallel with the top of the door frame, that is why we called this method “parallel mount”. This installation method is suitable for very narrow door frames or almost no door frames. After installation in this way, it is more aesthetically pleasing because there are no protruding connecting rods and rocker arms. Compared with the standard installation, this installation method is suitable for obstacles such as walls in the door opening direction. It is very comment to use in schools and hospitals which open with high frequency due to this installation method can reduce the noise compared with the other two methods.



There are so many accessories such as hold-open link arm, buckle arm, parallel plate we will need to use it based on different installation method as we discuessed before. Here is the picture shows above that which accessories that Kaida Hardware can supply to satisfy differnt needs and wants according to different application scenarios, if you want to know more about these, please do not hesitate to contact us, or browse our website (www.justor,cn) if you like.


How to adjust the control zones in a door closer?

Our Kaida JUSTOR door closers are strictly classified according to the requirements of relevant standards. The related products have obtained the certifications required by China, the European Union and other countries or regions. Thousands of door closers have been used to serve human beings all over the world.You can select the appropriate door closer according to your door weight, door width and installation environment. The door width listed in the table is only for general installation.


When the door is opened, the door body drives the connecting rod to move, and the transmission gear is rotated to drive the rack plunger to move to the right. When the plunger moves to the right, the spring is compressed, and the hydraulic oil in the right chamber is also compressed. The one-way valve ball on the left side of the plunger is opened under the effect of oil pressure, and the hydraulic oil in the right cavity flows into the left cavity through the one-way valve. When the door opening process is completed, because the spring is compressed during the opening process, the accumulated elastic potential energy is released, and the plunger is pushed to the left, driving the transmission gear and the door closer connecting rod to rotate, and the door is closed.


In some special cases, when the door is taller or heavier, Or when the site is in a windy environment and when special installation is required, a door closer with a higher power level should be used; Based on the different application scenarios, some clients may need back-check, delayed action or adjust the speed of closing and latching those functions, so the below contents will show how to adjust those control zones based on our American standard door closer. 


Back check 

Q1: What is back-check function? What is the advantages of choosing a back-check function?

After the door is quickly opened to a certain position, a damping buffer is generated, and the damping buffer force and range can be adjusted according to the use requirements; this function is used to prevent the door or lock from colliding with the wall when the door is quickly opened forcefully, or to prevent people from colliding with the wall when opening the door quickly during emergency escape. Weightless and leaning forward to the ground. By the way, it also can reduce the impact force of the door opening (such as pushing the door or strong wind pressure), and avoid damage to the wall or door leaf as much as possible.

Q2: How to adjust the back-check function on the closer body?

As the picture showed below, Counterclockwise adjustment is to adjust a little faster, then clockwise adjustment is to slow it down. 


Closing  and Latching speed Control 

Q1: What is range between closing speed control and latching speed control?

The range of closing speed control is from 180° to 15°, and the range of latching speed control is from 15° to 0°

Q2: How to adjust the closing speed control and latching speed control on the closer body?

As the picture showed below, Speed 1 is Closing speed control, Speed 2 is Latching speed control.  Counterclockwise adjustment is to adjust a little faster, then clockwise adjustment is to slow it down. 

Delay Actions 

Q1: What is delay actions function?

Delayed action is an optional door closer control function. Delayed action control will delay the door when the door started to close, to be simple, delay actions is used to slow the door down when the door automaticly to close.

Q2: Why we need to use delay action function?

The DA function of the door closer can make the door start to close after opening for a certain period of time, and this time can be set by adjusting the regulator on the door closer. This function can prolong the opening time of the door, facilitate the passage of people with reduced mobility, and also prevent the door from being accidentally closed when people enter and exit, causing danger. At the same time, the DA function can also reduce the noise and vibration generated when the door is closed, making the door close more smoothly and prolonging the service life of the door. Therefore, the DA function of the door closer is widely used in some public places, hospitals, nursing homes, schools and other places that require frequent entry and exit, which can improve the efficiency and safety of the door.

Q3: How to adjust the delay action function on the closer body?

As the picture showed below, Counterclockwise adjustment is to adjust a little faster, then clockwise adjustment is to slow it down. 



In conclusion, door closers are indispensable devices that ensure the controlled and safe operation of doors in various environments. They contribute to security, fire safety, energy conservation, and accessibility. With different types and adjustable features available, door closers offer versatility and functionality for diverse applications. Whether it is a commercial building or a residential space, a properly installed and well-maintained door closer provides peace of mind, convenience, and efficiency to occupants and users alike. 

This is the product segmentation of our Kaida door closers, all selected the best quality spare parts production and manufacturing on the market to become the most popular products on the market and our factory's top process production of products


  • This is a regular type of product from Kaida

  • Here are the hidden door closers and products with more certificates

Look forward to working with you Thanks.

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