Tension springs, suitable for concave and convex temperature, erosion-resistant and other task conditions, the material is mainly including stainless steel spring wire, carbon steel wire, oil quenched and tempered alloy spring wire, concave and convex temperature alloy spring wire. Tension spring characteristics: tension spring is to accept the axial tension of the coil spring, the hook way there are side hooks tension spring, long hooks tension spring, British hooks tension spring, German hooks tension spring, semi-circular hooks tension spring, duckbill hooks tension spring and so on, "hook" is used to ensure that the tension of the tension spring origin, commonly made of spring steel with a round cross-section material, in the case of not accepting the load. Tension spring between the coil and the coil are generally and tight no gap, the application of stretch after the rebound force (tension) task, used to control the activity of the machine, storage energy, measuring the magnitude of the force, etc., most of the extension springs in the inevitable level of tension, even in the absence of any load conditions. This initial tension determines the level of tightness of the extension spring wrap without any load. The use of extension springs: Tension springs are commonly used in medical respiratory equipment, activity control, medical mobile equipment, handcrafts, home care equipment, vibration damping, pump springs, mechanical and electronic protective hardware, fluid control valves, mechanical aerospace components, actuators, switchgear machinery, instrumentation. Its materials include stainless steel, piano steel, high carbon steel, phosphor bronze, oil tempered alloy spring steel, and so on.