shaft rotation

I have to rotate a shaft of the machine, but when I’m doing this, the shaft rotates from 0 ° to 90 °, then jumps to 85 and goes to 90, and so on.
this is my java script:

var target: Transform;

function Update ()

{

rotacion=(hz_var*0.5);

if(hz_var!=0)
target.localEulerAngles += Vector3(rotacion,0,0);

}

//hz_var is velocity of rotation and I tried with (Eulerangles.x)

Why not use target.Rotate(Vector3.left, rotacion);

You can adjust the axis you’re rotating on, but the idea remains the same.