Metal Bellows Expansion Joints are primarily used in automotive applications where there is a need to keep air moving while maintaining structural integrity. Metal Bellows Expansion Joints technology was developed in the 1930's and has been around ever since.
In addition to its use in automobiles, Metal Bellows Expansion Joints have been used in many other industries including construction, chemical processing, marine transportation, power generation, steel making, mining, etc.
There are several different types of Metal Bellows Expansion Joints depending on the application. One example would be the type used in automobile engines. There are two common configurations, straight and corrugated. Straight bellows are simple, low-cost, and only slightly affect engine efficiency. Corrugated bellows are more durable, cost less, and provide better performance than straight bellows.
Corrugated bellows are manufactured from high-strength stainless steel or aluminum, then coated with Teflon® to resist abrasion and corrosion. Corrugation provides greater durability and flexibility, as well as improved noise reduction. All bellows expand and contract along their length, but they tend to work best when they are either fully expanded or contracted. Once the bellows is installed, it should never be compressed down. If there is any pressure placed on the bellows, it may cause damage and could eventually lead to failure of the system.
The bellows is designed to allow movement between components while keeping them securely attached at the same time. In order for the bellows to move, it requires some sort of mechanism to open and close. These mechanisms can be manual or automatic. Manual mechanisms are generally operated using cables, rods, or levers. Automatic mechanisms are driven by motorized systems, hydraulics, or pneumatics.
Motorized mechanisms are becoming increasingly popular due to their reliability and ease of operation. Motorized systems can make adjustments based on temperature changes and/or load conditions. Pneumatic systems consist of a small pneumatic cylinder that is connected to a valve assembly. When the valve opens, air flows into the cylinder, causing the bellows to expand and then close the valve once it returns to its original size. Hydraulic systems operate similarly; however, instead of using air, water is pumped into the cylinders. A piston is then moved inside the cylinder, expanding or contracting the bellows accordingly.
Since Metal Bellows Expansion Joints are often installed under vehicle hoods and near critical engine components, the bellows need to be protected from debris, road salt, moisture, and other contaminants. To prevent these things from injuring the bellows, manufacturers offer protective covers or gaskets to protect the bellows. In addition, the bellows may require some sealing material to help maintain proper airflow.
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