desired force versus displacement characteristics of the solenoid valve in a fashion familiar to those skilled in the art therefore the depth of insertion of collar 17 into cylindrical portion 18 is determined by the desired performance characteristics of the particular application pole piece 31 generally closes the respective end of the solenoid as embodied in the plugging function of the collar 17 and screw 19 where the additional feature of spring bias force adjustability is not desired cylindrical portion 18 may be eliminated and the pole piece 31 formed without the central aperture therethrough the axial end of armature 41 closest to pole piece 31 is slidably disposed through non magnetic bearing 61 preferably non magnetic stainless steel is used for bearing 61 since such material provides thermal expansion characteristics similar to those of the ferromagnetic material of cylindrical portion 37 of pole piece 31 and has cycle wear qualities providing long life bearing 61 is fixably coupled to cylindrical portion 37 of pole piece 31 by press fitting a cylindrical extension thereof to the inner surface of the cylindrical portion 37 of pole piece 31 critical to high frequency pwm operation the actual bearing surface that is to say the inner surface of bearing 61 has a substantially smooth surface finish a surface.