relief valve export back pressure: back pressure, opening and closing characteristics, and general export back pressure should not exceed 0.1Mpa. High can be a relief valve back to the oil alone, can reduce the back pressure, but also improve stability.

 the main valve fluid dynamic effects: the main valve fluid power, opening and closing characteristics, in order to reduce the flow force of the main valve can be taken appropriate to increase the diameter of the main valve to change the direction of access to the oil.

 needle valve fluid dynamic effects: not very obvious. The cone valve cone angle