an anchor pad 238 that is bolted on the other side of the vehicle chassis 32 at a position substantially directly opposite the position at which anchor pad 232 is bolted to the chassis 32 actuation of hydraulic motors 220 and 222 is in unison upon such actuation the push frame 16 and thereby the variable wing plow blade 110 are tipped forwardly or backwardly about the axis of the pivot bearings 62 66 or 64 68 in the pivot mounts 58 and 60 to position the plow blade to the desired pitch angle position with the length of each of the arms 224 and 226 selected to form a parallelogram with the combined length of frames 12 14 and 16 such adjusted pitch angle of the plow blade is not changed upon variation in the height above the ground of the plow blade in general the fluid supply means the hydraulic piping or circuitry and the control panel means for selectively actuating the several hydraulic motor means form no part of the present invention and have not been illustrated in order to avoid undue complication of the drawing the invention features however the use of relief valve means in connection with the hydraulic motors 206 and 208 provided for actuating the wing blades 116 and 114 respectively for releasing pressure in the associated hydraulic motor cylinder in the event either wing blade hits an immovable object while the vehicle is in motion upon such release in pressure in the hydraulic cylinder the associated wing blade is allowed to deflect around it hinge connection to the center blade 112 thereby avoiding damage to the wing blade and also to.