Extension springs - Almech

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    Extension springs

    Extension springs alongside compression springs are the most widely used type of springs. Extension springs can be characterized as springs, that during operation are only stretched. Their second unique feature is that they are the only kind of spring possessing a so-called preload, which can be defined as the force accumulated in the spring and which must be applied to stretch the spring from its resting state L0. In this type of spring all coils are active, also at the ends of each spring there is a hook that allow the spring to be mounted.

    There are several basic types of hooks used for extension springs: A - the german hook, B - english hook, C - extended hook, D – swivel hook, as well as custom hooks shaped specifically in order to be incorporated into the assembly in which they are to be used.

    A – German hook
    B – English hook
    C – catch hook
    D – custom
    shaped hook

    Hooks in extension springs can be placed in the following positions:

    • 1) - central (along the axis of the spring),
    • 2) - sideways (adjacent to the cylindrical surface of the spring) or
    • 3) – outward (facing outwards from the spring).

    1 – central position
    2 – side position
    3 – external position

    Extension springs have a very wide range of application such as in; sofa beds, toys, automotive, garage doors and many others. For their production we use patented galvanized wire, copper covered, coated in zinc and aluminium alloys or without a coat, and also stainless. ALMECH spring manufacturer offers extension springs made of high carbon spring wire with anti-corrosive coating or without the coating, and also stainless steel wires. The wire diameter of the tension springs we produce ranges from ø 0,10 mm to ø 7,00 mm. On customer’s request, we may provide an examination certificate geometrical and physical parameters for each batch of springs produced.