Helical Tension spring

                     helican tension spring         

There are round hook orostays loop hook and d hook size by doing long in from coil senter. Being close coil springs this spring can be take more strength. And this spring might be avelible in the type of  

close coil and oppen coile  

The spring top end size will be changed  through senter section less and more if you do press or pulled   the coil top end.  And this springsdoes use for exmple     

 Hose pipe Or Petrol pipe  Clip

Bicycle Used for spring