Patent Abstract:
A hydraulic system that allows pressurized fluid to be stolen from a master or lift cylinder and directed to a single acting cylinder to perform a function. The system utilizes a spring in the single acting cylinder to force the fluid to retract through the same single line that powered the single acting cylinder. The fluid is then routed to the unloaded side of the master cylinder. This system provides many cost efficiencies and may be utilized by work vehicles to perform secondary functions such as attaching and removing an implement and locking and unlocking a loader.

Full Description:
FIELD OF THE INVENTION 
   The present invention relates generally to hydraulic cylinders, and more specifically to an apparatus for integration with a tractor, skid steer, or vehicle wherein pressurized fluid is taken from a master cylinder to activate a small single acting cylinder for the performance of a secondary function. 
   BACKGROUND OF THE INVENTION 
   Work vehicles such as tractors, skid steers, four wheelers and bulldozers are often equipped with many types of attachments. Loaders are often attached to the front of such equipment with arms and hydraulic controls that allow the loader to be raised and lowered, and also rolled forward and backward. Many different implements can be attached to the front of these work vehicles allowing the operator to accomplish various tasks via a single work vehicle. 
   Conventional front-end loaders have a pair of lifting arms or boom assemblies that have rearward ends that pivotally attach to a tractor, and forward ends that pivotally attach to an implement. A coupler is often used to connect various implements to the lifting arms. This allows the owner of a work vehicle to change the implement attached to the work vehicle in order to address the needs of a particular job. Exemplary implements found on conventional front-end loaders include buckets, clam shells, plows, fork lifts, bale spears, etc. 
   Generally the arms of the loader and the attached implement are controlled by a hydraulic system. Hydraulic cylinders are provided for operating front-end loaders and their attached implements. Hydraulic lines can be found extending along the exterior (or routed along the interior) of the front-end loaders for powering the hydraulic cylinders. In addition, when attaching front-end loaders to a tractor, it is often necessary to separately and manually connect the hydraulic lines on the front-end loader to the hydraulic lines on the tractor. 
   The current hydraulic systems used to attach the various implements to loaders suffer from a number of drawbacks. Typically, a third function hydraulic or electric valve is required to power hydraulic couplers. Additionally, multiple hydraulic lines, components and couplings are required to perform additional functions, thereby increasing costs. Furthermore, these additional hydraulic lines must be coupled each time a loader is attached to the work vehicle. 
   A drawback of hydraulic systems that use diverter valves is that only a single function may be completed at a time. An improved system that allows multiple cylinders to be used and activated simultaneously is needed. 
   Yet another drawback of the current hydraulic systems is that the vehicle must be powered on so that the pump can provide pressurized fluid to perform a secondary function. It is desirable to be able to perform a secondary function without necessarily turning the vehicle on and going to the pump. 
   A primary object of the present invention is to overcome one or more of the disadvantages of the prior art hydraulic systems for work vehicles. The present invention allows secondary functions or operations to be completed while the primary use of the loader is uninterrupted. This provides the benefit of a more responsive system, since there is no time lapse while one system is waiting on the other. 
   Another feature of the present invention is that it provides economic savings by reducing the number of hydraulic lines, components and couplings required. The present invention also eliminates the need for a third function hydraulic or electric valve. 
   Yet another feature of the present invention is that it does not require an additional set of two hydraulic lines to be coupled each time a quick-mount loader is attached. Furthermore, this results in a more cost efficient system because additional lines back to the pump are no longer required. 
   An additional feature of the present invention is that the single acting cylinder can be activated without going to the pump or turning the tractor on, as long as the loader is off the ground or the lift cylinder is under pressure. Here the power comes from the weight of the loader and the things attached to it. 
   SUMMARY OF THE INVENTION 
   The preferred embodiment of the present invention provides an improved hydraulic cylinder system that utilizes a master cylinder under pressure to power a single acting cylinder to perform a function. Fluid is taken from the master cylinder by a single acting cylinder so that both cylinders can perform tasks simultaneously. Once the secondary function is complete and the single acting cylinder is no longer receiving pressurized fluid, the single acting cylinder is forced to retract causing the fluid to flow back through the hydraulic conduit and into the backside of the master cylinder. 
   The second preferred embodiment of the present invention provides an improved hydraulic cylinder system that utilizes a master or lift cylinder under pressure to power a single acting cylinder to perform a function. Fluid is taken from the master cylinder and directed to a single acting cylinder. Once the secondary function is complete and the single acting cylinder is no longer receiving pressurized fluid, a spring causes the single acting cylinder to retract forcing the fluid to flow back through the hydraulic conduit and into the backside of the master cylinder. 
   In the third preferred embodiment, the present invention is modified for use on a tractor, skid steer or vehicle. For example, the single acting cylinder steals pressurized fluid from a lift cylinder to perform a secondary function such as connecting or disconnecting an implement to a front-end loader, or locking or unlocking a frond-end loader to the vehicle. 
   A fourth preferred embodiment incorporates a switching block and solenoid valve wherein the switching block and the solenoid valve direct a portion of the pressurized fluid away from the lift cylinder to power the single acting cylinder. 
   A fifth preferred embodiment incorporates a check valve. The check valve is connected to the lift cylinder. The check valve only allows fluid to flow into the non-pressurized side of the lift cylinder. Further, the check valve only allows the fluid to return to the lift cylinder when that cylinder side is not pressurized, sometimes causing the oil to remain inside the single acting cylinder. 
   A sixth preferred embodiment modifies the current system so that when the lift cylinder is under pressure, the single acting cylinder will work without going to the pump or turning on the tractor. 
   The preferred embodiments offer cost efficiencies, less and smaller hydraulic lines and additional functionality in a hydraulic system. This and other advantages will become apparent as this specification is read in conjunction with the accompanying drawings and appended claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side view of the improved hydraulic system displaying a lift cylinder connected to the switching block. 
       FIG. 2  is a perspective view showing the switching block connected to a coupler at the distal end of the lifting arms of a tractor. 
       FIG. 3  is a view of a coupler, including the single acting cylinder. 
       FIG. 4  is a view of a single acting cylinder. 
       FIG. 5  is a view of the dashboard of a tractor with a switch to activate the solenoid of the switching block. 
   

   DETAILED DESCRIPTION 
   The present invention may be used with any vehicle having at least one master, lift or implement cylinder and at least one, small single acting cylinder. Although the preferred embodiment of the present invention is intended and adapted for use with a tractor or skid steer, those of skill in the art will recognize that the present invention is equally adaptable for use with other utility vehicles and for use in other applications using multiple cylinders to perform multiple functions. However, for descriptive purposes, the present invention will be described for use on a tractor or skid steer. 
     FIG. 1  shows the conduits of the present hydraulic system connecting the lift cylinder  10  to the switching block  5 . The major components shown in  FIG. 1  include a lift cylinder  10 , a switching block  5 , a solenoid  3 , a lifting arm  15 , an electrical line  2 , hydraulic conduits  1  and  4  connecting to a single acting cylinder  21  (shown in  FIG. 4 ), conduits  8  and  9  connecting to a hydraulic pump (not shown) and conduits  6  and  7  connecting the switching block  5  and the lift cylinder  10 . 
     FIG. 2  shows the hydraulic system of the present invention connected to moveable lifting arms  15  of a tractor. The major components shown in  FIG. 2  include the hydraulic conduits  1 ,  4 ,  6  and  7 , coupler  12  and peg  13 . 
     FIG. 3  shows a view of coupler  12  with the single acting hydraulic cylinder  21 . The major components of  FIG. 3  include hydraulic conduit  4 , tube  20  and the single acting cylinder  21 . 
     FIG. 4  shows a single acting cylinder  21 . The major components of  FIG. 4  include a port  31 , a piston  33 , a piston rod  35 , a stationary block  34 , a spring  32 , a bar  37 , an air-port  38 , an air space  39  and a peg  13 . 
     FIG. 5  shows a perspective view of the dashboard of a tractor, including switch  36 . 
   As shown in  FIG. 1 , hydraulic conduit  6  connects the lift cylinder  10  to the switching block  5 . It should be understood that the name “lift cylinder” is used because of the placement of the cylinder on the loader assembly and its function to raise and lower the loader assembly. However, the lift cylinder  10  can be used for different applications. The name “lift cylinder” is used as a matter of convenience and does not limit how the cylinder is used. It should also be understood that the lift cylinder  10  may be referred to as a “master cylinder” because it describes the cylinder that is providing the pressurized fluid to the single acting cylinder  21 . 
   It should be understood that the name “single acting cylinder” is used because the pressurized fluid is provided to one side of the cylinder. Typically when the fluid pressure is cut-off, the single acting cylinder will hold its normal position. The cylinder can be returned to the retracted position by an opposing force, such as a spring or an external load. 
   Hydraulic conduit  9  carries pressurized fluid to the lift cylinder  10 . Line  2  is an electrical line, which connects the solenoid  3  to the dashboard of the tractor. A switch  36  ( FIG. 5 ) on the dashboard allows the solenoid  3  to be activated from the seat of the tractor. When the solenoid  3  is activated, the switching block  5  allows the conduit  6  to steal pressurized fluid from the lift cylinder  10 . The switching block  5  directs pressurized fluid through the conduits  1  and  4  to their respective single acting cylinders  21  located at the end of each lifting arm  15  of the tractor. Since the single acting cylinder  21  is relatively small compared to the lift cylinder  10 , both the lift cylinder  10  and the single acting cylinder  21  can operate at the same time. The minor volume of fluid stolen from the lift cylinder  10  has no adverse effects on the operation of the lift cylinder. 
   When the single acting cylinder  21  is no longer receiving pressurized fluid, a spring  32  forces the single acting cylinder  21  to re-track, reversing the flow of the once pressurized fluid. The fluid re-tracks back through the same hydraulic conduits  1  and/or  4  to the switching block  5 , where the fluid is routed through the conduit  7  to check valve  11 . At check valve  11  the fluid is only allowed to flow into (and not out of) the backside of the non-pressurized side of the lift cylinder  10 . Finally, conduit  8  returns oil to the reservoir and pump (not shown). 
     FIG. 2  shows the hydraulic system connected to the moveable lifting arms  15  of a tractor. Conduit  1  crosses the front of the tractor to the corresponding lifting arm on the other side (not shown). Conduit  4  connects to and provides pressurized fluid to the single acting cylinder  21  (see  FIG. 4 ) located inside the coupler  12 . Peg  13  allows the coupler  12  to connect to an implement (not shown). 
     FIG. 3  shows a coupler  12  with the single acting hydraulic cylinder  21 . The single acting cylinder  21  receives pressurized oil through conduit  4 . Tube  20  conceals the conduit  4  as it connects to the single acting hydraulic cylinder  21 . 
     FIG. 4  shows the single acting cylinder  21  wherein pressurized fluid is received via conduit  1  or  4  (not shown) through port  31 . The pressurized fluid causes the piston  33  to move into the air space  39 . The piston  33  is connected to the piston rod  35 , which is connected to a bar  37  which extends through the stationary block  34 , and connects to peg  13 . As the piston  33  receives pressurized fluid, the piston  33  extends, forcing the air in the air space  39  through a hole (not shown) through the center of the piston rod  35  where it escapes through the air-port  38 . The movement of piston  33  forces the peg  13  to retract (although those with skill in the art will recognize that the orientation of the cylinder  21  and the arrangement of the spring  32  can be modified so that the peg  13  extends). When the pressurized fluid is cut off, the spring  32  expands from stationary block  34 , forcing the piston  33  to retract and moving the corresponding peg  13  back to its original position. The ability to extend and retract the peg  13  of the coupler  12  allows the coupler  12  to attach and detach various implements (not shown) to the lifting arms  15  of the tractor. 
     FIG. 5  shows a perspective view of the dashboard of a tractor. Switch  36  allows the switching block  5  to be operated from the seat of the tractor. Once the switch  36  is activated, the single acting cylinder  21  will cause the peg  13  to retract. Once the switch  36  is no longer activated the spring  32  causes the peg  13  to return to its original position. This arrangement provides an added safety feature as the peg  13  will only remain retracted so long as the switch  36  is activated. Therefore, any accidental loss of hydraulic pressure will not cause an implement to detach. 
   The switch  36  also allows the operator to perform various functions, such as connecting and disconnecting implements to the lifting arms of the tractor without leaving the seat. The switch and hydraulic system of the present invention can also be used to lock and unlock a quick mount loader to and from the tractor. 
   Other alterations, variations, and combinations are possible that fall within the scope of the present invention. Although the preferred embodiment of the present invention has been described, those skilled in the art will recognize other modifications that can be made that would nonetheless fall within the scope of the present invention. Therefore, the present invention should not be limited to the apparatus and method described. Instead, the scope of the present invention should be consistent with the invention claimed below.

Technology Classification (CPC): 5