of the vehicle 10 in order for the support frame 20 to be lowered and raised in accordance with the principles of the present invention the support frame 20 comprises a rear portion 74 and a front portion 76 pivotally mounted thereto as it will be best understood below with reference to fig1 a to 10c the front portion 76 can pivot upwardly with respect to the rear portion 74 in order to provide greater ground clearance when the plow 26 is not in use in the present embodiment the rear portion 74 and the front portion 76 are pivotally connected by a pair of hinges 78 and 80 which define a substantially horizontal rotation axis 79 see fig3 in other embodiments the rear portion 74 and the front portion 76 could be pivotally connected by only one hinge or by more than two hinges referring now to fig7 to 9 from an operative position of the front portion 76 see fig7 the hinges 78 and 80 are configured to allow only upward pivotal movements of the front portion 76 with respect to the rear portion 74 i e to an inoperative position see fig8 in that sense the rotation axis 79 of the hinges 78 and 80 is located in the upper portion of the hinges 78 and 80 see fig7 and 8 the hinge 78 comprises complementary hinge members 82.