referring to the drawings in detail , reference character 10 generally indicates an exercise machine having a frame apparatus 12 which generally comprises a platform portion 14 and an elongated upright portion 16 . an exercise bar is pivotally attached to the upper end of the frame by way of a horizontally extending fulcrum or pivot pin 20 . one end of the elongated exercise bar 18 extends over the platform portion 14 of the frame and is equipped with suitable operator interface or actuator devices such as a pair of spaced shoulder pads 22 and a plurality of handle members of pairs of hand gripping rods 24 and 26 . the platform portion 14 of the frame member is provided with a platform plate 28 for supporting the operator of the machine and is rigidly attached to the upright frame members 16 by a plurality of horizontal bars 30 and angle support members 32 which are structurally functional to provide rigidity of the entire frame 12 . the upper end of the upright frame member 16 is provided with a cavity 34 which serves as a hydraulic reservoir having a fluid fill port and associated cap 36 . the lower end of the cavity 34 is also provided with a port 38 for a purpose that will be hereinafter set forth . the upright frame member 16 is further provided with a mounting block 40 which supports the exercise bar 18 by means of the pivot pin 20 . the upright frame member 16 also comprises a second outwardly extending block member 42 having at least one upwardly extending mounting ear 44 . the exercise device further comprises an elongated hydraulic cylinder 46 having a piston 48 reciprocally disposed inside the cylinder to separate the cylinder into an upper chamber 50 and a lower chamber 52 . an elongated piston rod 54 is attached to the upper surface of the piston 48 and extends through a port 56 in the upper end of the cylinder , the outer end of the piston rod 54 being pivotally attached to the exercise bar 18 by a horizontal pivot pin 58 . the lower end of the cylinder 46 is attached to the mounting ears 44 of the frame block 42 by means of a horizontally disposed pivot pin 60 . the pivotal mounting of the upper end of the piston rod 54 is spaced from the fulcrum pin 20 of the elongated exercise rod such that said fulcrum 20 is between the pivot pin 58 and the operator interface equipment consisting of the pads 22 and the handle members 24 and 26 . it is noted at this point that the fulcrum pin 20 , the pivot pin 58 and the pivot pin 60 are all parallel such that the movement of the elongated exercise arm 18 is within a vertical plane perpendicular to said pivot pins . further , the distance between the fulcrum point 20 and the operator interface portion of the exercise bar is of considerable length whereby movement of the operator interface over relatively short distances will be in a substantially vertical direction . the lower end of the hydraulic cylinder 46 is provided with a fluid port 62 which is connected by suitable hydraulic lines 64 and 66 to the fluid port 38 of the cavity or reservoir 34 in the frame member 16 . interposed between the lines 64 and 66 is a valve assembly 68 . the valve assembly 68 has a first passageway 70 connecting the lines 64 and 66 , said passageway 70 having an adjustable restriction orifice passageway 72 with an exterior adjustment knob 74 for effectively changing the size of the orifice passageway 72 . the valve 68 has a second parallel passageway 76 , said passageway having a check valve 78 installed therein whereby fluid may freely flow through the passageway 76 and check valve 78 when flowing from the reservoir 34 into the fluid chamber 52 of the hydraulic cylinder 46 . the check valve 78 will prevent fluid flowing from the hydraulic cylinder 46 toward the reservoir through the passageway 76 thereby requiring any fluid passage in that direction to be through the restriction orifice 72 . also attached to the valve assembly 68 is a pressure gauge 80 having a sensor member 82 which is in communication with the hydraulic line 64 . stated another way , the sensor 82 , since it is in communication with line 64 thereby senses pressure between the restriction orifice 72 and the hydraulic cylinder chamber 52 . it is noted at this point that the piston 48 provides a fluid seal between the hydraulic chambers 50 and 52 . however , the chamber 50 is vented to atmosphere by a suitable vent 82 or simply by tolerances between the opening 56 and the piston rod 54 . the pressure gauge 80 is provided with an arcuate calibration dial 84 which is calibrated in pounds or other units of force and relates the actual amount of force applied at the operator interface of the exercise bar 18 to the fluid back pressure provided between the hydraulic piston 48 and the restriction orifice 72 . in the case of the squat - jump type exercise hereinbefore described , the user places his shoulders against the operator interface pads 22 , grips the handles 24 or 26 and pulls that end of the exercise bar 18 down to the squat position . he then can quickly try to straighten his legs which results in a resistance force due to back pressure of the hydraulic fluid passing through the orifice 72 . the machine will allow the user to straighten to the full upright position against said force and then he may rapidly return to the squat position since fluid flow in the opposite direction encounters substantially no resistance through the check valve 78 . this allows the operator to perform the repetitions of the squat jump exercise in rapid succession . further , if greater resistance is desired , the restriction orifice may be adjusted to provide such greater resistance . the more rapidly the user attempts to operate the machine the more force he encounters due to the nature of the fluid flow through the orifice . hence , the machine may be used by many different athletes in a group , one after another , without any substantial adjustment to the machine and without the dangers accompanied by weight lifting due to the dropping of weights , changing of weights and possible muscle strain encountered by positioning the weights for the particular exercise . whereas the present invention has been described with particular relation to the drawings attached hereto , it is pointed out that other and further modifications apart from those shown or suggested herein may be made within the spirit and scope of the invention .
an exercise machine utilizing a pivotal bar wherein resistance to applied force in one direction is provided by the passing of hydraulic fluid through an adjustable orifice and including a fluid bypass around said orifice to eliminate resistance to the force applied in the opposite direction .