referring now to fig1 there is shown a towed implement 10 and a towing vehicle 12 . the implement 10 is configured as a mowing implement , but may , however , be a ground breaking implement , a harvesting implement , a plant processing implement , or any other towed implement . the implement 10 includes a frame 14 and wheels 16 that support it on the ground and carry a front attached crop mowing and windrowing arrangement 18 . a bearing 20 is provided at a center location between opposite ends of the frame 14 and couples a rear end of a draft tongue 22 for swinging transversely thereabout , the forward end of the draft tongue 22 being coupled over a bearing 24 and draft coupler 26 to a draft hitch arrangement 28 of the towing vehicle 12 . the relative position of the draft tongue 22 to the frame 14 is controlled by an extensible and retractable hydraulic actuator 30 , whose actuation is performed by a control arrangement 32 , shown in fig2 . the control arrangement 32 includes a fluid reservoir 34 , a pump 36 , a pressure relief valve 38 , a direction control valve 40 , an interrupter valve 54 , an actuating device 42 , a switching device 44 and a deactivating element 46 . the control arrangement 32 is located partially on the implement 10 and partially on the towing vehicle 12 , where the deactivating element 46 leads to the towing vehicle in the vicinity of the operator . the hydraulic actuator 30 is configured as a double - acting hydraulic cylinder and includes a piston rod 48 and a cylinder housing 50 in which the piston rod 48 with its piston , not described in any further detail , is guided in a straight - line motion . the reservoir 34 is filled with hydraulic fluid that can be drawn by the pupmp 36 over a line , not described in any further detail . the pump 36 is configured for an open system and conducts pressurized hydraulic fluid through the relief valve 38 to the direction control valve 40 . a configuration as a closed system would require a few changes but could also be employed . the relief valve 38 operates to return pressurized fluid to the reservoir 34 , when the system pressure exceeds a certain threshold , for example , if the valve 40 is open and the actuator 30 has reached one or the other of its end positions . the direction control valve 40 is configured as a four - way , three - position valve , that is here shown as controlled manually , but may be controlled electrically or hydraulically . in a retracting position “ a ”, pressurized fluid is conducted by the pump 36 to the piston rod end of the cylinder housing 50 , and from the head end of the cylinder housing 50 into the reservoir 34 . in a neutral position “ b ”, a flow of pressurized fluid is prevented in every direction and the pressurized fluid conducted by the pump 36 is returned to the reservoir 34 . in an extension position “ c ”, pressurized fluid is conducted from the pump 36 to the head end of the cylinder housing 50 and out of the piston rod end of the cylinder housing 50 into the reservoir 34 . obviously other embodiments of the valve 40 are possible , for example , even valves separated from each other , whose operation attains the same results as the valve 40 . the interrupter valve 54 is configured as a two - way , two - position valve and can be brought into a switch position “ d ” with a pressurized fluid opening 70 and a switch position “ e ” with a check valve 72 . a spring 52 is provided on the interrupter valve 54 that always forces the interrupter valve 54 into its position “ d ” with free pressurized fluid flow . the actuating device 42 is configured as a lever which can also be configured differently with other embodiments , for example , with cams , tilting arms or the like . the actuating device 42 is located in the path of movement of the switching device 44 and can be repositioned by this during the repositioning of the piston rod 48 . when the actuating device 42 is grasped by the switching device 44 , the interrupter valve 54 moves out of its position “ d ” into its position “ e ” and interrupts the pressurized fluid flow out of the hydraulic actuator 30 . the deactivating element 46 is formed in this embodiment by a tension device 56 configured as a rope that acts upon the actuating device 42 . when the deactivating element 46 is actuated , the actuating device 42 moves out of the path of movement of switching device 44 , which has the result that the interrupter valve 54 remains in its position “ d ” until a repositioning by the spring 52 occurs , and the piston rod 48 can be fully extended . the tensioning device 56 extends from an operator &# 39 ; s cab of the towing vehicle 12 to the actuating device 42 . however , a lever could be provided to which the tensioning device 56 is attached and the tensioning device 56 could also be configured as a push - pull cable control . the arrow shown in the actuating device 42 represents its repositioning capability and should not be confused with an actual embodiment . referring now to fig3 - 5 , there is shown the details of the hydraulic actuator 30 and part of the control arrangement 32 including the interrupter valve 54 , the actuating device 42 , the switching device 44 and the deactivating element 46 . the interrupter valve 54 is mounted on the cylinder housing 50 , in particular , between its ends at a location that corresponds to the transition region from the range of operating positions to the transport position . the actuating device 42 is configured as a lever pivoted from the interrupter valve 54 with a contact arm 60 and an actuating arm 62 . the switching device 44 is configured as an elongate rail having a first end fastened to the free end of the piston rod 48 and which extends in parallel , radially spaced relationship to the cylinder housing 50 , and is guided on the cylinder housing 50 by means of a screw 64 received in a slot 66 extending lengthwise in the rail . provided on the end of switching device 44 that is remote from the piston rod 48 is a stop or abutment 68 in the form of a plate that can be brought into alignment with the contact arm 60 of the actuating device 42 . in the retracted condition of the hydraulic actuator 30 , the switching device 44 extends generally over the entire length of the cylinder housing 50 . the deactivating element 46 , configured as a simple , flexible tensioning element 56 , is connected to the actuating arm 62 . if tension is applied to the element 56 , then the actuating device 42 pivots into its position shown in fig5 in which it cannot be contacted by the stop or abutment 68 . when the direction control valve 40 is in its position “ a ”, the piston rod 48 is retracted , as is shown in fig3 . the hydraulic actuator 30 remains in this position as long as the valve 40 is in its position “ a ” or “ b ”. in order to extend the hydraulic actuator 30 , the valve 40 is brought into its position “ c ”. if the deactivating element 42 is not actuated , the switching device 44 , in particular , its stop 68 comes into contact with the contact arm 60 due to the extending movement of the piston rod 48 after a certain path has been covered , and moves the arm 60 so as to reposition the interrupter valve 54 into its position “ e ”, in which the flow of pressurized fluid is interrupted . this position marks the one end of the operating region , as indicated in fig1 . if the hydraulic actuator 30 is to be fully extended , the deactivating element 42 is actuated by a pull on the tension element 56 , which acts to pull on the actuating arm 62 , before the contact arm 60 comes into contact with the stop 68 so that the contact arm 60 is no longer loaded by the stop 68 and the interrupter valve 54 is no longer brought into its position “ e ” preventing the return of fluid from the rod end of the actuator 30 . the interrupter valve 54 remains in its position “ d ”, the valve 40 in its position “ c ” and so the piston rod 48 of the hydraulic actuator 30 is extended until it is fully extended whereupon pressure builds and opens the relief valve 38 . other solutions are also conceivable with which the interrupter valve 54 can be brought into its position “ d ” even during the contact of the arm 60 on the stop 68 , and the actuator 30 then extends further . while in this embodiment , the interrupter valve 54 or the actuating device 42 are provided at the cylinder housing 50 and the switching device 44 is provided at the piston rod 48 , this obviously can also be reversed . furthermore , the actuating device 42 could be provided at the frame 14 or the like ; it is essential that the actuating device 42 can be brought into connection with the adjustment path of the hydraulic actuator 30 . furthermore , the actuating device could be configured in such a way that it can be loaded in one direction , that is when the piston rod 48 is retracted , but by reason of a free - wheeling arrangement or the like it cannot bring about a switching movement . it will be appreciated that the invention can be easily retrofit to existing machines since it merely requires that the switching device 44 and interrupter valve 54 with the actuating device 42 be mounted on the cylinder of the hydraulic actuator normally provided for swinging the implement draft tongue . further , it will be appreciated that the interrupter valve 54 could be controlled electrically through the use of a solenoid selectively energized by completing an electrical circuit , for example , through the use switches , light barriers , reed switches or the like that are actuated when the circuit is on and the hydraulic actuator 30 reaches a pre - selected state of extension . the deactivating element can also be controlled remotely without wiring if desired . having described the preferred embodiment , it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims .
an implement draft tongue is moved through a range of working positions to a transport position extending transverse to the working direction of the implement by an extensible and retractable hydraulic actuator . a control for the hydraulic cylinder includes an interrupter valve that is actuated , in response to a preselected extension of the hydraulic cylinder so as to prevent the cylinder from extending beyond a position for moving the draft tongue to one extreme of its operating range , when an actuating device for the interrupt valve is enabled . when the actuating device for the interrupt valve is disabled , the hydraulic actuator may be extended fully to place the draft tongue in its transport position .