Patent Publication Number: US-6711984-B2

Title: Bi-fluid actuator

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This Application claims the benefit of U.S. Provisional Application Serial No. 60/289,774 filed on May 9, 2001. 
    
    
     TECHNICAL FIELD 
     The present invention relates to apparatus for accurate movement and positioning of a load, and in particular relates to a bi-fluid actuator for usage in accurately moving and positioning a load appropriately for use in automated movement, assembly manufacturing, related robotics tasks, and other industries requiring precise motion control. 
     BACKGROUND OF THE INVENTION 
     Actuators are well known in automated assembly and related tasks that utilize pneumatic, mechanical or hydraulic positioning systems. For example, it is well known to utilize an actuator to move a load carriage in repetitive movements in assembly-line manufacturing. Typical actuators include rod actuators, wherein a piston within a hollow container variably moves a rod extending out of the container back and forth between desired positions, and a load or load carriage is secured to the rod. A rodless actuator includes a sliding piston within a hollow elongate container such as a cylinder, wherein the piston is secured mechanically or magnetically to a load carriage secured to a rail or support adjacent to the hollow object so that movement of the piston moves the load carriage. 
     Such actuators are often powered by hydraulic fluid utilizing a controller that pumps the fluid to a chamber on a first or an opposed second side of the piston, and that also permits movement of the hydraulic fluid out of the chamber into which the piston is to be moved. Such controllers also serve to detect the position of the piston, and stop movement when the piston and linked load carriage have achieved a desired position. Hydraulic actuators provide for precision of a rate of movement and positioning of the load, however they also have substantial drawbacks associated with a necessity of pumping a hydraulic fluid that is typically freeze and boiling resistant and hence is also often a hazardous waste, along with problems of the substantial cost, complexity and service requirements of pressurized hydraulic cylinders, seals, accumulators, by-pass valves, connecting lines to and from controllers, etc. Some actuators are electro-mechanically powered with electric motors, servo motors, threaded shafts, ball screws, toothed belts, etc. They also involve substantial cost in manufacture, substantial difficulties in accurate, rapid positioning of loads, and quite significant care and service requirements. 
     It is also known to power existing actuators with pneumatic, or compressible fluids such as air in order to minimize cost and the difficulties associated with hydraulic and electro-mechanical actuators. However, pneumatic actuators have substantial difficulties associated with characteristics of compressible fluids and chambers having variable dimensions, etc. For example, as a chamber on one side of a piston receives compressed air to move the piston away from that chamber, the piston resists movement due to stiction, wherein seals between the piston and an interior wall of the container housing the piston, such as a cylinder, tend to adhere to the cylinder wall as a function of a pressure of the incoming pressure of the compressed air. When the stiction resistance is finally overcome, the piston commences to move and it acquires an inertia of the load that tends to sustain movement of the piston at a lower force then that required to commence movement of the piston. As the piston moves within the cylinder, the dimensions of the chamber of the piston receiving the compressed air changes, so that a constant feed of the compressed air will not exert a constant force upon the piston, and compensation in the rate of delivery of the compressed air must be made if precision is required in a rate of movement of any load secured to the piston, or to a rod, or to a load carriage secured to the piston. A constant rate of movement of the piston will also be effected by variations in dynamic forces acting upon the load, such as mechanical linkages, etc., that will cause the load to change its resistance, thereby interrupting a constant rate of motion of the piston. When it is desired to stop the moving piston at a precise location, it is necessary to take into consideration a limited braking capacity of the compressible fluid within a chamber of the cylinder into which the piston is moving as the compressible fluid is compressed by the force of the moving piston. Because of the limited braking capacity of the compressible fluid, precise motion control is unobtainable under normal conditions. 
     Many efforts have been undertaken to provide pneumatic actuators that provide for a relatively constant rate of motion of a load carriage and that can accurately and rapidly position a load in a repetitive fashion between varying positions. One exemplary pneumatic linear actuator is sold under the trademark “PRECISIONAIRE” by the TOL-O-MATIC, Inc. company of Hamel, Minn., U.S.A. The “PRECISSIONAIRE” actuator utilizes an elongate, hollow container housing a piston linked to a load carriage, wherein the piston is also secured to a toothed belt that forms an endless loop extending between pulleys at opposed ends of the hollow container or cylinder. A complex proportional magnetic particle brake is secured to one pulley along with a rotary encoder that is in communication with a controller which cooperate to control a rate of motion of the load carriage by braking, and to control accurate positioning by the rotary encoder and controller. While such hybrid mechanical and pneumatic actuators offer some of the convenience of compressed air pneumatic actuators, they are nonetheless expensive to manufacture and service, and are essentially limited to linear actuators. In many situations, their accuracy for position location is not satisfactory for sensitive applications. 
     Accordingly, there is a need for an inexpensive actuator that provides the efficiency and low cost of pneumatic actuators with the precision of rates of motion and positioning provided by hydraulic actuators or servo motors for all applications from robotics to precision assembly. 
     SUMMARY OF THE INVENTION 
     The invention is a bi-fluid actuator for precise bi-directional movement and positioning of a mechanical object. The bi-fluid actuator includes a pneumatic fluid container containing a compressible, pneumatic fluid; a hydraulic fluid container containing a non-compressible, hydraulic fluid; a first mechanical object positioned between a first chamber and an opposed second chamber of the pneumatic fluid container so that the first mechanical object may be impacted and moved by the pneumatic fluid; a second mechanical object linked to the first mechanical object and positioned so that the second mechanical object may be impacted and positioned by the hydraulic fluid; a pneumatic fluid controller that selectively directs pressurized pneumatic fluid into either the first or opposed second chamber of the pneumatic fluid container; and a hydraulic fluid controller that selectively permits passage of the hydraulic fluid between the first and opposed second chambers of the hydraulic container, so that the pneumatic fluid controller selectively powers the first and linked second mechanical objects to move in either a first or opposed second direction, and the hydraulic fluid controller selectively permits movement and controls a rate of movement and position of the second and linked first mechanical object in the first or opposed second direction by selectively permitting, controlling a rate of, and then terminating passage of the hydraulic fluid between the opposed first and second chambers of the hydraulic fluid container. In essence, the hydraulic controller and hydraulic container form a closed loop hydraulic circuit that provides for flow control and accurate positioning while the pneumatic fluid powers movement of the first and second linked mechanical objects. 
     In an exemplary dual rod embodiment of the bi-fluid actuator, the pneumatic and hydraulic fluid containers are adjacent hollow, elongate containers, the first and second mechanical objects are pistons with rods within the hollow, elongate containers that are connected by way of the rods extending out of the containers to contact and move a load carriage typically utilized to precisely move an apparatus in automated assembly or manufacturing. By powering movement of the load carriage with a compressible or compressed, pneumatic fluid such as air, and controlling movement rate and positioning of the carriage with a non-compressible, fluid such as standard hydraulic fluid, precision of movement and positioning may be achieved by simply controlling passage of the non-compressible, hydraulic fluid at very modest pressure loads. The hydraulic fluid is selectively directed by the hydraulic fluid controller to flow through the controller between the first and second chambers of the hydraulic fluid container. 
     For example, if it is desired to move the load carriage away from the first chamber of the hydraulic fluid container, the chamber of the pneumatic fluid container aligned with the first chamber of the hydraulic fluid container receives compressed fluid from the pneumatic fluid controller. The hydraulic fluid controller then permits movement of the non-compressible, hydraulic fluid to pass from the second chamber into the first chamber of the hydraulic fluid container and the pneumatic fluid will then power movement of the linked first and second mechanical objects and load carriage away from the chamber having the compressed fluid, away from the first chamber of the hydraulic fluid container until a desired position of the load carriage is obtained. At that point the hydraulic fluid controller then terminates passage of the hydraulic fluid into the first chamber, thereby terminating further movement of the linked first and second mechanical objects and load carriage. 
     The bi-fluid actuator therefore provides for an elegant, low-powered, clean solution to precise movement of automated mechanical objects. Because the hydraulic fluid may control positioning at low pressure loads in a closed system, traditionally expensive and complicated sealing, feeding, and pressurizing of known hydraulic systems in automated actuators may be avoided. Because freely available, compressible, air fluid is utilized only for powering movement of the first mechanical object, and hence the load carriage, the known difficulties of accurate positioning of traditional pneumatic actuators is avoided. Accurate movement rates and positioning is achieved by movement of the second mechanical object by the hydraulic fluid through a cooperative integration of the hydraulic fluid controller with the pneumatic fluid controller. Additionally, because the powering source is readily available air, substantial power is available for moving high mass loads upon the load carriage without known cost and environmental risk factors associated with complex, highly pressurized hydraulic actuators. 
     Accordingly, it is a general object of the present invention to provide a bi-fluid actuator that overcomes deficiencies of prior actuators in accurate movement of a load. 
     It is a more specific object to provide a bi-fluid actuator that provides for precision of a rate of motion and of positioning of a load without pumping a non-compressible, hydraulic fluid. 
     It is yet another object to provide a bi-fluid actuator that may be utilized as a linear, or rotary actuator. 
     It is a further object to provide a bi-fluid actuator that may be produced utilizing either metal or plastic components. 
     It is still another object to provide a bi-fluid actuator that may be utilized as either a rodless actuator, or as a moving rod actuator. 
     These and other objects and advantages of this invention will become more readily apparent when the following description is read in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic view of a bi-fluid actuator constructed in accordance with the present invention as a dual rod embodiment of the bi-fluid actuator. 
     FIG. 2 is a partial fragmentary, perspective of a single rod embodiment of the bi-fluid actuator. 
     FIG. 2A is a first partial view of the FIG. 2 single rod embodiment of the bi-fluid actuator. 
     FIG. 2B is a second partial view of the FIG. 2 single rod embodiment of the bi-fluid actuator. 
     FIG. 3 is a partial fragmentary, perspective view of a rodless piston embodiment of the bi-fluid actuator. 
     FIG. 4 is a schematic view of a rodless valved piston embodiment of the bi-fluid actuator. 
     FIG. 4A is an enlarged, partial view of the FIG. 4 rodless valved piston embodiment of the bi-fluid actuator. 
     FIG. 4B is an exploded view of a second mechanical object of the FIG. 4 rodless valved piston embodiment of the bi-fluid actuator. 
     FIG. 5 is an exploded, perspective view of a rotary embodiment of the bi-fluid actuator. 
     FIG. 6 is an exploded, perspective view of a rotary vane embodiment of the bi-fluid actuator. 
     FIG. 7 is a fragmentary, perspective view of a mechanically valved embodiment of the bi-fluid actuator. 
     FIG. 7A is a blow-up of a segment of FIG. 7 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In FIG. 1, a dual rod embodiment of the bi-fluid actuator is shown, and generally designated by the reference numeral  10 . The dual rod embodiment  10  includes a hollow, elongate pneumatic fluid container  12  and an adjacent hollow, elongate hydraulic fluid container  14 . A first mechanical object  16  is in the form of a first piston within the pneumatic fluid container  12 , and a second mechanical object  18  is in the form of a second piston within the hollow hydraulic fluid container  14 . A first rod  20  is connected to the first mechanical object  16 , and a second rod  22  is connected to and passes through the second mechanical object  18 . The two rods  20 ,  22  are secured to a load or load carriage  24  typically utilized to precisely move an apparatus in automated assembly or manufacturing. The load carriage  24  may have a plurality of wheels  25 A,  25 B or other known structures to facilitate back and forth motion. A hydraulic fluid controller  26 , such as a proportional hydraulic flow control valve, is secured in fluid communication through a hydraulic lines  27 A,  27 B with a first hydraulic fluid chamber  28  and a second hydraulic fluid chamber  30  defined on opposed sides of the second piston  18  so that the hydraulic fluid controller  26  controls flow of a non-compressible fluid, such as hydraulic fluid, between the first and second hydraulic fluid chambers  28 ,  30  to thereby control movement of the second mechanical object or piston  18  and second rod  22 . 
     A pneumatic fluid controller  32 , such as a four-way pneumatic valve, is secured in fluid communication through pneumatic lines  33 A,  33 B between a first pneumatic fluid chamber  34  and a second pneumatic fluid chamber  36  defined on opposed sides of the first mechanical object or piston  16  so that the pneumatic fluid controller  32  may permit pressurized, compressed or compressible fluid into either the first or second pneumatic fluid chambers  34 ,  36 , to power the first piston  16 , first rod  20  and load carriage  24  secured thereto to move in a direction either toward or away from the pneumatic and hydraulic containers  12 ,  14 . 
     By powering movement of the load carriage  24  with a compressible, pneumatic fluid such as air, and controlling movement rate and positioning of the carriage with a non-compressible fluid such as standard hydraulic fluid, precision of movement and positioning of the load carriage  24  may be achieved by simply controlling passage of the non-compressible, hydraulic fluid with the hydraulic fluid controller  26 . The hydraulic fluid is selectively directed by the hydraulic fluid controller  26  to flow through the controller  26  between the first and second chambers  28 ,  30  of the hydraulic fluid container  14 . 
     A positioning controller  38  may be secured to detect the position of the load carriage  24  between movement range limits  39 A,  39 B of the load carriage. The positioning controller may detect the position of the load carriage either optically, mechanically, electrically, or through any known positioning detection technology, and to communicate detected positioning information through a first position information transfer mechanism  41 A to the hydraulic fluid controller  26 , and through a second position information transfer mechanism  41 B to the pneumatic fluid controller  32 . The three controllers  38 ,  26 ,  32  may therefore function cooperatively to position the load carriage  24  in desired positions at selected times, and to move the load carriage  24  between selected positions within the movement range limits  39 A,  39 B at desired rates of travel. The positioning controller  38  may be any known controller capable of implementing a positioning program including detecting positions, communicating detected positions to pneumatic and/or hydraulic controllers or control valves so that the control valves may open or close in response to the communications from the positioning controller, as is well known in the art of automated actuators. The first and second position information transfer mechanisms  41 A,  41 B may be standard electric lines, or may be wireless transmission apparatus known in the art. The positioning controller  38  may include, or be in electrical communication with, an overall controller means for receiving information from and transmitting information to the pneumatic and/or the hydraulic controllers  26 ,  32  through the first and second position information transfer mechanisms  41 A,  41 B so that the positioning controller  38  may change, for example, to a program of detection and/or implementation of differing desired positions and/or rates of travel of the load carriage  24 . The positioning controller  38  may include, for example, computers utilized for controlling positions and rates of travel of moving objects; proximity switches; linear encoders; programmable logic controllers; etc. In certain embodiments, the positioning controller  38  may communicate with only the hydraulic fluid controller  26  or only the pneumatic fluid controller  32 . An exemplary positioning controller utilized in actuator technology that could be utilized with the various embodiments of the bi-fluid actuator disclosed herein is manufactured by the GALIL Motion Control Company, of Mountain View, Calif., U.S.A., and is available under the model number “DMC1415 CONTROLLER”. 
     It is stressed that the phrase “pneumatic fluid controller” is meant to include the capacity of selectively compressing and/or directing flow of a compressed or compressible, pneumatic fluid, such as air, and may also include an ordinary air compressor as is often included in association with regular and proportional valve controllers known in the art. For purposes herein, the word “selectively” as in “a pneumatic controller” or “hydraulic controller” that “selectively directs”, or “selectively permits”, is meant to indicate that the controller may be controlled to stop flow; permit flow at any of varying rates of flow; or pump flow of a fluid passing through the controller. It is also to be understood that for purposes herein, the term “chamber” as used to describe voids defined on opposed sides of mechanical objects such as the above-described first and second pistons  16 ,  18 , is meant to describe chambers or voids of varying dimensions and volumes as the mechanical objects move, and is not to be construed as voids of limited or specific dimensions or volumes. 
     The following embodiments of the bi-fluid actuator also include a pneumatic fluid controller, a hydraulic fluid controller, and may also include a positioning controller appropriate for a particular task of the described embodiments of the bi-fluid actuators. The pneumatic, hydraulic and positioning controllers described below also operate in essentially the same manner as described above or as known in the art, unless otherwise indicated, and therefore the operation of those components in the following embodiments will not be repeatedly described. 
     In FIG. 2, a single rod embodiment of the bi-fluid actuator  40  is shown, wherein a pneumatic fluid container  42  surrounds as a sleeve a coaxial hydraulic fluid container  44 . A first mechanical object  46  is in the form of an “0”, or doughnut-shaped piston that surrounds or partially surrounds the hydraulic fluid container  44 , and a second mechanical object  48  is in the form of a piston within the hydraulic fluid container  44  that is mechanically linked to the first mechanical object  46  through a solid shaft  49  that is secured to and end cap  51 , which in turn is mechanically secured to a hollow rod  50 . The hollow rod  50  is secured to the first mechanical object  46  and passes out of the pneumatic fluid container  42  to be secured to and move a load carriage (not shown in FIG. 2) secured to the hollow rod  50  by way of a threaded portion of the end cap  51 , or other securing apparatus. 
     The first mechanical object  46  is secured between a first pneumatic fluid chamber  52  and a second pneumatic fluid chamber  54  of the pneumatic fluid container  42 . The second mechanical object  48  is secured between a first hydraulic fluid chamber  56  and a second hydraulic fluid chamber  58  of a hydraulic fluid container  44 , which includes the hollow rod  50 . A hydraulic fluid reservoir tube  59  lies adjacent and parallel to the hydraulic fluid container  44 , and in fluid communication with the first hydraulic chamber  56  of the hydraulic container  44 . The first mechanical object  46  may also surround the hydraulic reservoir tube  59 . Hydraulic fluid passes from the second hydraulic fluid chamber  58  through a hydraulic controller  62  into the hydraulic fluid reservoir tube  59  and then through a hydraulic fluid reservoir opening  57  defined within a hydraulic end cap  68  secured to the hydraulic fluid container  44 , and then into the first hydraulic chamber  56  to define a closed hydraulic loop. As the second mechanical object  48  moves along the hydraulic fluid container  44  away from the second hydraulic fluid chamber  58 , (from right to left as viewed in FIG.  2 ), hydraulic fluid moves from the first hydraulic fluid chamber  56  through the fluid reservoir opening  57  into the hydraulic fluid reservoir tube  59 , and through a header  65  that seals both the second pneumatic chamber  54  and the second hydraulic chamber  58 . The hydraulic fluid reservoir tube  59  is a fluid extension of the first hydraulic chamber  56 . 
     A pneumatic fluid controller  60  is secured in fluid communication between the first and second pneumatic chambers  52 ,  54  by way of standard pneumatic lines  61 A,  61 B, so that the pneumatic controller  60  may selectively direct and/or compress pneumatic fluid into either the first or second pneumatic fluid chambers  52 ,  54  of the pneumatic fluid container  42 . A hydraulic fluid controller  62  is secured in fluid communication between the first and second hydraulic fluid chambers  56 ,  58  by way of standard hydraulic lines  63 A,  63 B. Hydraulic line  63 A is in fluid communication between the hydraulic fluid controller  62  and the first hydraulic fluid chamber  56  through the hydraulic reservoir tube  59 , and hydraulic line  63 B is in fluid communication between the hydraulic fluid controller  62  and the second hydraulic fluid chamber  58 . Both hydraulic lines  63 A,  63 B pass through the header  65  secured in a first end seal  71  of the pneumatic fluid container  42  that directs the hydraulic fluid into the hydraulic fluid reservoir tube  59  or the second hydraulic fluid chamber  58 . 
     In FIG. 2A, a stationary hydraulic circuit  43  is shown and includes the hydraulic container  44 , which is secured to the header  65  on one end, and an opposed end of the hydraulic container  44  is secured to a hydraulic end cap  68  so that the hydraulic container  44  is mechanically supporting the hydraulic end cap  68 . The hydraulic fluid reservoir tube  59  is attached to the header  65  on one end and an opposed end of the hydraulic fluid reservoir tube  59  is attached to the hydraulic end cap  68  so that the hydraulic fluid reservoir tube  59  also mechanically supports the hydraulic end cap  68 . The hydraulic fluid reservoir tube  59  is in fluid communication with the hydraulic fluid reservoir opening  57  defined within the end cap  68 , and the opening  57  allows fluid to flow through the hydraulic fluid reservoir tube  59  and into or out of the first hydraulic fluid container  56 . The header  65 , the hydraulic chamber  44 , the hydraulic fluid reservoir tube  59 , the hydraulic fluid reservoir opening  57 , and the hydraulic end cap  68  do not move relative to each other. 
     A moving hydro-pneumatic circuit  45  is shown in FIG. 2B, and comprises the second mechanical object  48  which is secured to the inner solid shaft  49 , that is secured to the threaded adapter  51 , which in turn is secured to the hollow rod  50 . The hollow rod  50  is secured to the first mechanical object  46 . The entire assembly of the second mechanical object  48 , the inner solid shaft  49 , the threaded adapter  51 , the hollow rod  50 , and the first mechanical object  46  all move as one circuit  45  within the compressible or pneumatic fluid container  42 . 
     As shown in FIG. 2, the first mechanical object  46 , upon being impacted by air or another compressible fluid, moves the hollow rod  50  so that the threaded adapter of the end cap  51  moves closer or further away from a second end seal  69 , similar to typical air cylinders on the market. The air or other compressible fluid enters through lines  61 A or  61 B and creates motive force against the first mechanical object  46  to extend or retract the hollow shaft  50 . The first and second hydraulic chambers  56  and  58  are defined within the hydraulic container  44 , which includes the hollow rod  50 , as the moving hydro-pneumatic circuit  45  is integrated with stationary hydraulic circuit  43 , as shown in FIG.  2 . The first hydraulic chamber  56  acts as an accumulator to accept hydraulic fluid from the hydraulic fluid reservoir opening  57  or to force hydraulic fluid back out the hydraulic fluid reservoir opening  57 . The hydraulic fluid reservoir opening  57 , allows hydraulic fluid to flow between the hydraulic fluid reservoir tube  59  and the first hydraulic chamber  56 . The hydraulic fluid reservoir tube  59 , allows hydraulic fluid to flow through line  63 A into the hydraulic fluid controller  62 , and then into the second hydraulic chamber  58  as the hydraulic fluid is moved in one direction or another by movement of the second mechanical object  48  which is powered by movement of the first mechanical object  46 . The closed loop hydraulic circuit consisting of the moving hydro-pneumatic circuit  45  and the stationary hydraulic circuit  43  can be used to control the rate of movement and/or starting and stopping of the hollow rod  50 . Due to the sealed environment inside the system it is necessary to include a relief opening  53  for air to escape from the hollow rod  50 . 
     A positioning controller  64  may be secured to detect a position of any load carriage or apparatus (not shown) secured to the rod  50  moved by the linked first and second mechanical objects  46 ,  48  between range limits  66 A,  66 B. The positioning controller  64  may communicate detected positioning information through a first information transfer mechanism  67 A to the pneumatic fluid controller  60 , and through a second information transfer mechanism  67 B to the hydraulic controller  62 . The three controllers  60 ,  62 , and  64  may be integrated, such as through computerized overall controller means known in the art for positioning the hollow rod  50  in desired positions at desired times, and to be moved at desired rates of speed. 
     In FIG. 3, a rodless piston embodiment of the bi-fluid actuator  66  is shown, wherein a pneumatic fluid container  73  is in the shape of a sleeve, or partial sleeve defining an “O” or “C” shaped void, and a hydraulic fluid container  70  is a hollow, elongate container positioned within and coaxial with the pneumatic fluid container  73 . A first mechanical object  72  is an “O” or “C” shaped piston magnetically (as shown in FIG. 3) or mechanically linked to a second mechanical object  74  which is in the shape of a rodless or flat piston. The first mechanical object  72  is dimensioned to fit within the pneumatic fluid container  73  while making a sliding air seal within the container  73 . The first mechanical object  72  may also be dimensioned to surround, or partially surround the hydraulic fluid container  70 , and is also mechanically or magnetically (as shown in FIG. 3) linked to a load carriage  76  supported on a track  78  adjacent to the pneumatic fluid container  73  and extending between a first end seal  77  and a second end seal  79  of the pneumatic fluid container  73 . The first mechanical object  72  is secured between a first pneumatic fluid chamber  80  and a second pneumatic fluid chamber  82 . The second mechanical object  74  is secured between a first hydraulic fluid chamber  84  and a second hydraulic fluid chamber  86 . 
     A pneumatic fluid controller  88  is secured in fluid communication through pneumatic lines  87 A,  87 B between the first and second pneumatic fluid chambers  80 ,  82 . A hydraulic fluid controller  90  is secured in fluid communication through hydraulic line  91 A,  91 B between the first and second hydraulic fluid chambers  84 ,  86 . As described above with reference to FIG. 2, The pneumatic controller  88  may direct compressed pneumatic fluid through pneumatic line  87 A into the first pneumatic fluid chamber  80 , and permits pneumatic fluid to move out of the second pneumatic fluid chamber  82  through pneumatic line  87 B to be released to the atmosphere. The hydraulic controller  90  may then permit passage of hydraulic fluid from the second hydraulic fluid chamber  86 , through hydraulic line  91 B, through the hydraulic fluid controller  90 , through hydraulic fluid line  91 A, and into the first hydraulic fluid chamber  84  in order to permit movement toward the second end seal  79  of the second mechanical object  74 , linked first mechanical object  72 , and the load carriage  76  that is also linked to the first mechanical object  72 . 
     A positioning controller  92  may be secured or arranged properly in order to detect a position of the load carriage  76  or other apparatus secured to the linked first and second mechanical objects  72 ,  74  between movement range limits  89 A,  89 B. The positioning controller  92  may communicate detected positioning information through a first information transfer mechanism  93 A to the pneumatic fluid controller  88 , and through a second information transfer mechanism  93 B to the hydraulic controller  90 . The positioning, pneumatic and hydraulic controllers  92 ,  88 ,  90  would work generally as described above to control position and rate of travel of the load carriage  76 . The positioning controller may include, be integrated with, or be in communication with an overall controller means for communicating detected and desired positioning commands to the hydraulic and pneumatic controllers  88 ,  90 , as described above for all embodiments of the bi-fluid actuator. 
     In FIG. 4, a rodless valved piston embodiment of the bi-fluid actuator  94  is shown, wherein a pneumatic fluid container  96  is in the shape of a sleeve, or partial sleeve, defining an “O” of “C” shaped void, and a hydraulic fluid container  98  is a hollow elongate container positioned within and coaxial with the pneumatic fluid container  96 . A first mechanical object  100  is in the shape of a “O” or “C” shaped piston magnetically (as shown in FIG. 4) or mechanically linked to a second mechanical object  102  which is in the shape of a rodless piston. The first mechanical object  100  is mechanically or magnetically linked (as shown in FIG. 4) to a load carriage  104  supported on a track  106  adjacent to or defined in the pneumatic fluid container  96 . The track  106  extends between a first header  105  and a second header  107  of the pneumatic fluid container  96 . The first mechanical object  100  is secured between a first pneumatic fluid chamber  108  and a second pneumatic fluid chamber  110 . The second mechanical object  102  is secured between a first hydraulic fluid chamber  112  and a second hydraulic fluid chamber  114 . 
     A pneumatic fluid controller  116  is secured in fluid communication through pneumatic lines  117 A,  117 B between the first pneumatic fluid chamber  108  through a first header  119  in the first header  105 , and through a second header  121  in the second header  107 . A hydraulic fluid controller  118  is secured in fluid communication between the first and second hydraulic fluid chambers  112 ,  114 . A positioning controller  120  is secured to detect a position of the load carriage  104  or other apparatus secured to the linked first and second mechanical objects  100 ,  102  between movement range limits  115 A,  115 B. The positioning controller  120  may communicate detected positioning information through an information transfer mechanism  123  to the pneumatic fluid controller  116 . The positioning controller  120  may be integrated with or be in communication with an overall controller means. A plurality of seals  111 , such as standard “O-ring” seals, are secured between the first and second mechanical objects  100 ,  102  and the pneumatic and hydraulic fluid containers  96 ,  98 , in a standard manner well known in the art to provide fluid seals while permitting sliding motion. 
     As shown in FIG. 4, in the rodless valved piston embodiment of the bi-fluid actuator  94 , the hydraulic fluid controller  118  is in the form of a two-way, spring pre-set valve  118  secured within the second mechanical object  102 , so that a specific valve-override pressure load of the pneumatic fluid directed by the pneumatic fluid controller  116  to either the first or second pneumatic fluid chambers  108 ,  110  will direct an adequate force through the linked first and second mechanical objects  100 ,  102  to override a pre-set pressure of the valve  118  to thereby open it to movement of the non-compressible, hydraulic fluid through the valve  118 . That permits movement of the second mechanical object  102 , linked first mechanical object  100  and load carriage  104  away from the pneumatic fluid chamber having the specific valve-override pressure load, or the powered chamber. The positioning controller  120  and the pneumatic fluid controller  116  then cooperate to decrease the compressed fluid load to the powered chamber whenever the positioning controller detects the load carriage at a desired location so that the hydraulic fluid controller or two-way, spring pre-set valve  118  closes to terminate movement of the hydraulic fluid through the valve  118 , and thereby terminate movement of the second mechanical object  102 , first mechanical object and linked load carriage  104 . 
     As best seen in FIGS. 4A and 4B, the two-way, spring pre-set valve  118  includes an outer sleeve  250  that houses a by-pass barrel  252 . The by-pass barrel  252  defines at least one or a plurality of first hydraulic chamber fluid by-pass grooves  254 A,  254 B that are in fluid communications with a corresponding plurality of first hydraulic fluid chamber ports  256 A,  256 B (shown best in FIG.  4 A). The by-pass barrel also defines at least one or a plurality of second hydraulic fluid chamber by-pass grooves  258 A,  258 B, that are in fluid communication with a corresponding plurality of second hydraulic fluid chamber by-pass ports  260 A,  260 B. The by-pass barrel  252  also defines a by-pass throughbore  131  having a spring wall  262  (shown only in FIGS. 4 and 4A) that may be integral with the by-pass barrel  252 , or secured within the barrel  252 , between the first hydraulic chamber by-pass ports  256 A,  256 B and the second hydraulic chamber by-pass ports  258 A,  258 B. 
     A first coiled spring  264  is secured within the by-pass throughbore  131  against a side of the spring wall  262  nearest to the first hydraulic chamber  112 , and a second coiled spring  266  is secured within the by-pass throughbore  131  against a side of the spring wall  262  nearest the second hydraulic fluid chamber  114 . A first moving seal  268  is secured to the first coiled spring  264 , and a second moving seal  270  is secured to the second coil spring  266 . A first seal lock  272  is secured within the by-pass throughbore  131  adjacent to the first moving seal  268  when the first coiled spring  264  is extended so that the when the first coiled spring  264  is compressed, a void is defined between the first seal lock  272  and the first moving seal  268 . The first seal lock  272  defines a first by-pass passage  274 . A second seal lock  276  is secured within the by-pass throughbore  131  adjacent to the second moving seal  270  when the second coiled spring  266  is extended so that the when the second coiled spring  266  is compressed, a void is defined between the second seal lock  276  and the second moving seal  270 . The second seal lock defines a second by-passage  278 . 
     The diameters of the first and second moving seals  268 ,  270  are cooperatively dimensioned to be larger than corresponding diameters of the first and second by-pass passages  274 ,  278  so that whenever the first or second coiled springs  264 ,  266  force the first or second moving seals  268 ,  270  into contact with adjacent first or second seal locks  272 ,  276 , the moving seals  268 ,  270  completely block the first or second by-pass passage  274 ,  278  thereby restricting movement of the hydraulic fluid through the blocked first or second by-pass passage  274 ,  278 . Such blocking may be facilitated by having chamfered ends of the first and second moving seals  268 ,  270 , or by other known sealing means known in the art, such as compressible “O-ring” seals (not shown), etc. Shortest diameters of the first and second moving seals  268 ,  270  are also cooperatively dimensioned to be less than diameters of the by-pass throughbore  131 , so that whenever the first or second moving seal  268 ,  270  are displaced out of contact with the first or second seal lock  272 ,  276 , hydraulic fluid may flow around the first or second moving seal  268 ,  270 , and then into either the plurality of first or second hydraulic fluid chamber by-pass ports  256 A,  256 B,  260 A,  260 B and their corresponding plurality of first or second hydraulic fluid chamber grooves  254 A,  254 B,  258 A,  258 B. 
     In use of the two-way, spring pre-set valve  118 , the first and second coil springs  264 ,  266  are selected to have a specific compressive force or valve-override pressure load that must be achieved to compress the springs  264 ,  266 . If it is desired to move the load carriage in a specific direction to a specific location, such in the direction of the arrow  133  in FIG. 4, the pneumatic controller, which may be an overall controller means as described above, or may be a pneumatic proportional valve integrated with a four-way solenoid valve, directs an adequate air pressure into the second pneumatic chamber  110  to overcome the valve-override pressure load of the first coil spring  264 . The first coil spring  264  and first moving seal  268  then move out of contact with the first seal lock  272  (as shown best in FIG. 4A) so that hydraulic fluid may move from the first hydraulic fluid chamber  1112  through the by-pass throughbore  131  into the second hydraulic fluid chamber  114 , thereby permitting motion of the second mechanical object  102 , the first mechanical object  100  and load carriage. 
     Whenever it is desired to stop movement of the load carriage, such as when the positioning controller  120  detects the load carriage at a desired location, then the pneumatic controller  120  or any other known controller means directs the pneumatic controller to decrease the pressure of the compressible fluid within the second pneumatic chamber  110  to below the specific valve-override pressure load of the first coil spring  264 . The spring  264  then moves the first moving seal  268  back into contact with the first seal lock  272  so that the hydraulic fluid can no longer move through the by-pass throughbore, or actually, so that the second mechanical object  102  can no longer move through the hydraulic fluid within the hydraulic container  98 , thereby terminating movement of the second mechanical object  102 . 
     The two-way, spring pre-set valve  118  may be in the above-described form, or may be any two-way, spring pre-set valve means for permitting and terminating two-way flow of a non-compressible fluid through the valve in response to pressure changes acting upon the valve that are known in the art. Additionally, the two-way, spring pre-set valve  118  may be situated in fluid communication with the second mechanical object  102  through standard hydraulic lines, but external to the pneumatic and hydraulic containers  96 ,  98 . 
     The pneumatic controller  116  must include a proportional pressure valve (not shown) in fluid communication with a four-way solenoid valve (not shown), that is in fluid communication with the pneumatic lines  117 A,  117 B. The positioning controller  120  would be in communication with the proportional pressure valve and/or the four-way solenoid valve. The pneumatic controller may also include an air pressure monitoring device (not shown) that is constantly sending pressure readings within the powered pneumatic chamber (such as the second pneumatic chamber  110  in the above example of operation) to the pneumatic controller, or an overall controller integrated with or in communication with the pneumatic controller  116 . Additionally, the pneumatic controller may include a precision regulator known in the art that is able to change precise pressure levels very quickly for enhanced efficiency of operation of the rodless valved piston embodiment  94  of the bi-fluid actuator. 
     In FIG. 5, a rotary embodiment of the bi-fluid actuator  122  is shown, wherein a pneumatic fluid container  124  is in the form of a first deformable tube, and a hydraulic fluid container  126  is in the form of a second deformable tube secured adjacent to the first deformable tube  124  in parallel circular alignment. Such “deformable tubes” are commonly referred to in the art as “peristaltic tubes”. Both the first and second deformable tubes  124 ,  126  are secured within a cylindrical housing  128 . A first mechanical object  130  is in the form of a first pinch roller that pinches or deforms the pneumatic fluid container  124  against the housing  128 , and a second mechanical object  132  is in the form of a second pinch roller that is secured to the first pinch roller  130 , and that pinches or deforms the hydraulic fluid container  126  against the housing  128 . 
     The first and second mechanical objects  130 ,  132  or pinch rollers  130 ,  132  are secured to an armature  134  that is dimensioned to rotate about a center of a circle defined by the first and second deformable tubes  124 ,  126  and housing  128 . The armature  134  may be secured to a keyed shaft  153  which is secured to a rotatable bearing  157  to which a load carriage (not shown) or other mechanical structure that is to be rotated between specific positions at specific rates of travel may be secured. Housing cap  135  may be secured to the cylindrical housing  128 . The first pinch roller or first mechanical object  130  deforms the pneumatic fluid container  124  to define a first pneumatic fluid chamber  136  and a second pneumatic fluid chamber  138  on an opposed side of the first pinch roller  130 . The second pinch roller or second mechanical object  132  deforms the hydraulic fluid container  126  to define a first hydraulic fluid chamber  140  and a second hydraulic fluid chamber  142  on opposed sides of the second pinch roller  132 . 
     A pneumatic fluid controller  144  is secured in fluid communication between the first and second pneumatic fluid chambers  136 ,  138  by way of pneumatic lines  137 A,  137 B that are secured to a junction header  139  that defines separate pneumatic passages to which the first and second pneumatic chambers  136 ,  138  are secured in fluid communication. A hydraulic fluid controller  146  is secured in fluid communication by way of hydraulic lines  141 A,  141 B between the controller  146  and the junction header  139  that also defines separate hydraulic passages secured in fluid communication with the first and second hydraulic fluid chambers  140 ,  142 . 
     A positioning controller  148  may be secured or arranged properly in order to detect a rotational position of the bearing  157  or load carriage secured thereto between movement range limits  149 A,  149 B. The positioning controller  148  may communicate detected positioning information through a first information transfer mechanism  151 A to the pneumatic fluid controller  144 , and through a second information transfer mechanism  151 B to the hydraulic controller  146 . The positioning, pneumatic and hydraulic controllers  148 ,  144 ,  146  would work generally as described above to control position and rate of travel of the bearing  157 . In the rotary embodiment of the bi-fluid actuator  122 , the keyed axle shaft  153  would be dimensioned to mate with a keyed axle throughbore  155  defined within the armature  134  to be secured to the bearing  157  to rotationally secure the armature  134  to the bearing  157 . 
     The action of the second mechanical object or second pinch roller  132  being impacted and moved by movement of the hydraulic fluid between the first and second hydraulic chambers  140 ,  142  is similar in structure to known peristaltic pumps well known in the art of pumping fluids through deformable tubes where it is important that the fluid remain untouched by mechanical objects such as pump impellers, as is common in human intravenous pumps, etc. However in the present rotary embodiment of the bi-fluid actuator  122 , instead of moving the hydraulic fluid, the second mechanical object or second pinch roller  132  is being powered by the force of the compressed pneumatic fluid upon the linked first mechanical object or first pinch roller  130 , and a rate of movement, direction of movement, and positioning of the linked first and second mechanical objects is being controlled by movement of the hydraulic fluid between the first and second hydraulic fluid chambers  136 ,  138 , as controlled by the hydraulic fluid controller  146 . 
     In FIG. 6, a rotary vane embodiment of the bi-fluid actuator  150  is shown, wherein a pneumatic fluid container  152  is in the form of a half-cylinder, and a hydraulic fluid container  154  is in the form of an opposed half cylinder defined within a common cylindrical housing  156 . A non-rotating containment wall  158  is secured between and defines non-circular walls of the pneumatic and hydraulic fluid containers  152 ,  154 . A first mechanical object  160  is in the form of a first half vane that bi-sects the pneumatic fluid container  152 , and a second mechanical object  162  is in the form of a second half vane that bi-sects the hydraulic fluid container  154 , wherein the first and second half vanes or first and second mechanical objects  160 ,  162  are linked to each other and to an armature  164  at the center of a circle defined by the housing  156  so that movement of the first half vane  160  moves both the second half vane  162  and armature  164 . The first half vane or first mechanical object  160  defines a first pneumatic fluid chamber  166  and a second pneumatic fluid chamber  168  on opposed sides of the first half vane  160 . The second half vane or second mechanical object  162  defines a first hydraulic fluid chamber  170  and a second hydraulic fluid chamber  172  on opposed sides of the second half vane  162 . 
     A header cap  165  is dimensioned to be secured in a non-rotational manner to the cylindrical housing  156  and to make a fluid seal of the pneumatic and hydraulic containers  152 ,  154  with the header cap  165 . The header cap  165  also includes an armature sleeve  167  dimensioned to permit the central armature  164  to pass through the sleeve  167  while restricting passage of fluid through the sleeve  167  so that a load carriage (not shown) may be secured to the central armature extending beyond the header cap  165  to permit limited rotational movement of the load carriage. The header cap  165  also includes a first hydraulic fluid fitting  169  and a second hydraulic fluid fitting  171  that each define separate hydraulic fluid passages. The first hydraulic fitting  169  is secured on or defined in the header plate  165  so that hydraulic fluid passing through it will be directed into or out of the first hydraulic fluid chamber  170 , and the second hydraulic fluid fitting  171  is secured to or defined in the plate  165  so that hydraulic fluid passing through the fitting  171  will pass into or out of the second hydraulic fluid chamber  172 . 
     Similarly, the header plate  165  also includes a first pneumatic fluid fitting  173  and a second pneumatic fluid fitting  175 , both of which fittings  173 ,  175  define separate pneumatic passages. The first pneumatic fitting  173  is defined in the header plate  165  so that pneumatic fluid passing through it will be directed into or out of the first pneumatic fluid chamber  166 , and the second pneumatic fluid fitting  175  is defined in the plate  165  so that pneumatic fluid passing through the fitting  175  will pass into or out of the second pneumatic fluid chamber  168 . 
     A pneumatic fluid controller  174  is secured in fluid communication between the first and second pneumatic fluid chambers  166 ,  168 , by way of standard pneumatic lines  177 A,  177 B secured between the controller  174  and the first and second pneumatic fittings  173 ,  175  of the header plate  165 . A hydraulic fluid controller  176  is secured in fluid communication between the first and second hydraulic fluid chambers  170 ,  172  by way of standard hydraulic lines  179 A,  179 B secured between the controller  176  and the first and second hydraulic fittings  169 ,  171  of the header plate  165 . A positioning controller  178  may be secured or arranged properly in order to detect a rotational position of the bearing central armature  164  or any load carriage (not shown) secured to the armature  164  between movement range limits  181 A,  181 B. The positioning controller  178  may communicate detected positioning information through a first information transfer mechanism  183 A to the pneumatic fluid controller  174 , and through a second information transfer mechanism  183 B to the hydraulic controller  176 . The positioning, pneumatic and hydraulic controllers  178 ,  174 ,  176  would work generally as described above to control position and rate of travel of the central armature  164  or any load carriage (not shown) secured thereto. 
     The rotary vane embodiment of the bi-fluid actuator  150  would be especially appropriate for rotational movement of objects having desired ranges of motion that are restricted to less than one hundred and eighty degrees, and wherein a desired rate of rotational motion may be significantly greater than an efficient rate of rotational motion for a load carriage rotated by the rotary embodiment of the bi-fluid actuator  122  described above and illustrated in FIG.  5 . 
     In FIG. 7, a mechanically valved embodiment of the bi-fluid actuator  180  is shown, wherein a pneumatic fluid container  182  is in the form of an elongate, hollow container. A first mechanical object is in the form of a piston  184  including a secured hollow rod  186 , wherein the rod passes out of the pneumatic fluid container  182  to be secured by a threaded rod adaptor  185  to a load carriage (not shown). A hydraulic fluid container  188  is in the form of a void defined within the hollow rod  186  of the first mechanical object or piston  184 . The piston  184  or the first mechanical object defines a first pneumatic fluid chamber  190  and a second pneumatic fluid chamber  192  on opposed sides of the piston  184 . A T-piston  191  including a seal  195  is secured adjacent to the first mechanical object or piston  194  and between the first and second pneumatic chambers  190 ,  192 . 
     A mechanical valve hydraulic fluid controller  194  includes a second mechanical object or rotational port valve assembly  196  secured within the hydraulic fluid container  188 . The rotational port valve  196  includes a rotational port plate  213  that is secured to a valve stem  198  that is coaxial with the hollow rod  186  secured to the first mechanical object  184 , and that is secured to a mechanical valve trigger  200  positioned outside of the pneumatic fluid container  182  adjacent to a first end seal  187  of the pneumatic fluid container  182 . A second end seal  189  is secured to an opposed end of the pneumatic fluid container  182 , and the rod  186  passes through the second end seal  189 . 
     The valve stem  198  is supported within a stem sleeve  211  that surrounds the valve stem  198 , and the valve stem  198  and stem sleeve  211  terminate with the rotational port valve assembly  196 . As best seen in the blow-up insert of the rotational port valve assembly  196  in FIG. 7A, the valve stem  198  includes a rotational valve port plate  213  that defines one or more rotational hydraulic fluid ports  214 A,  214 B,  214 C and  214 D. The rotational valve port plate  213  is dimensioned to fit snugly within the hydraulic fluid container  188  so that hydraulic fluid may only pass through the rotational hydraulic fluid ports  214 A,  214 B,  214 C and  214 D of the rotational valve port plate  213  and not otherwise around the plate  213 . The stem sleeve  211  includes a stationary port plate  216  that defines one or more stationary hydraulic fluid ports  218 A,  218 B,  218 C,  218 D. The stationary valve port plate  216  is dimensioned to fit snugly within the hydraulic fluid container  188  so that hydraulic fluid may only pass through the hydraulic fluid ports  218 A,  218 B,  218 C,  218 D of the stationary port plate  216  and not otherwise around the plate  216 . The rotational port plate  213  is secured adjacent to the stationary port plate  216  so that no fluid can flow through the plates  213 ,  216  unless the rotational hydraulic fluid ports  214 A,  214 B,  214 C,  214 D are aligned with the stationary hydraulic fluid ports  218 A,  218 B,  218 C,  218 D. The rotational port plate  213  is secured closely to the stationary port plate  216  by a raised boss  219  on the valve stem  198  adjacent to the first end seal  187 , so that the valve stem  198  may still be rotated to rotate the rotational port plate  213  while maintaining a seal between the rotational port plate  213  and stationary plate  216 . 
     By rotating the valve trigger  200  that is secured to the valve stem  198  within the fixed position stem sleeve  211 , the valve stem  198  is rotated so that the rotational valve port plate  213  and its rotational hydraulic fluid ports  214 A,  214 B,  214 C,  214 D may be rotated to overlie one of the stationary hydraulic fluid ports  218 A,  218 B,  218 C,  218 D of the stationary plate  216 , thereby permitting or terminating movement of the hydraulic fluid through the plates  213 ,  216  as the entire hydraulic fluid chamber  188  moves along with the first mechanical object  184  and adjacent T-piston  191  that includes the hydraulic fluid chamber  188 . Rotating the valve  200  trigger so that the rotational hydraulic fluid ports  214 A,  214 B,  214 C of the rotational valve port plate  213  are not overlying the stationary hydraulic fluid ports  218 A,  218 B,  218 C,  218 D of the stationary valve port plate  216  immediately stops movement of the hydraulic fluid chamber  188 , and hollow rod  186  secured to the first mechanical object  184  or piston, adjacent to the T-piston  191 , as well as any load carriage or load (not shown) secured to the adaptor  185  of the rod. 
     A first hydraulic fluid chamber  202  and a second hydraulic fluid chamber  204  are defined within the hydraulic fluid container  188  on opposed sides of the rotational valve port plate  213  and stationary valve port plate  216  of the rotational port valve or second mechanical object  196 . 
     A pneumatic fluid controller  206  is secured in fluid communication by standard pneumatic lines  201 A,  201 B between the first and second pneumatic fluid chambers  190 ,  192 . Pneumatic line  201 A is secured between the pneumatic fluid controller  206  and a first port  203  defined in the pneumatic fluid container  182  adjacent the first pneumatic chamber  190  and the first end seal  187 . Pneumatic line  201 B is secured between the pneumatic fluid controller  206  and a second port  205  defined in the pneumatic fluid container  182  adjacent the second pneumatic fluid chamber  192  and the second end seal  189 , as shown in FIG. 7. A positioning controller  208  may be secured or arranged properly in order to detect a position of the rod  186  of any load carriage (not shown) secured to the rod adaptor  185  between movement range limits  207 A,  207 B. The positioning controller  208  may communicate detected positioning information through a first information transfer mechanism  209 A to the pneumatic fluid controller  206 , and through a second information transfer mechanism  209 B to the mechanical valve trigger  200 . 
     The mechanical valve trigger  200  may be manually actuated by an operator (not shown) to move open or close the rotational port valve assembly  196 , to permit movement of the hollow rod  186 , and to control a rate of movement of the hollow rod  186 . The manual operation may be based upon sensed information from the positioning controller  208 , or in the event the positioning controller  208  is not being used, the operator may simply utilize the valve trigger  200  based upon visual observation or other information gathered directly by the operator. Alternatively, the valve trigger  200  may be electro-mechanically operated by apparatus known in the art in response to positioning and program information received from the positioning controller  208 . The positioning controller  208 , pneumatic controller  206  and an electro-mechanically operated trigger valve  200  would work generally as described above to control position and rate of travel of the hollow rod  186  or any load carriage (not shown) secured to the rod adaptor  185 . 
     In operation of the mechanically valved bi-fluid actuator  180 , rotation of the valve trigger  200  of the mechanical valve hydraulic fluid controller  194  permits movement of hydraulic fluid between the first and second hydraulic fluid chambers  202 ,  204 . Therefore, whenever the first or second pneumatic fluid chambers  190 ,  192  of the pneumatic fluid container  182  contain a compressed fluid and the valve trigger  200  is rotated, the movement of the non-compressible, hydraulic fluid between the first and second hydraulic fluid containers  202 ,  204  will permit movement of the piston  184  or first mechanical object, adjacent T-piston  191 , and the hollow rod  186  until the valve trigger  200  is rotated to stop movement of the hydraulic fluid between the first and second hydraulic fluid chambers  202 ,  204 . The mechanical valve trigger  200  may be any known trigger means for operating a valve including manual, mechanical, electro-mechanical, pneumatic, apparatus, etc. Additionally, in the illustrated embodiment, the mechanical valve trigger  220  is placed outside of the pneumatic fluid container  182 . However, the trigger  220  may be integrated within the container  182  for electro-mechanical actuation, etc. 
     It is noted that a pneumatic void  220  is defined between the piston  184  or first mechanical object and the T-piston  191 . The action of the T-piston  191  and pneumatic void  220  aid in compensating for volume changes that occur as the hydraulic fluid flows from the second non-compressible or hydraulic fluid chamber  202  into the first hydraulic fluid chamber  204  as the hollow rod  186  moves away from the first end seal  187 . The void  220  within the piston  184  is dimensioned to allow movement of the T-piston along the hollow rod  186  in order to compensate for a volume change of the second hydraulic fluid chamber  204  occupied by the stem sleeve  211  and valve stem  198  of the mechanical valve hydraulic fluid controller  194 . Because the second hydraulic chamber  204  within the hollow rod  186  includes the stem sleeve  211 , the volume change within the second hydraulic chamber  204  will be different than a volume change within the first hydraulic fluid chamber  202  hollow rod  186  which does not include the stem sleeve  211 . As the hydraulic fluid moves into the first hydraulic chamber  202  from the second hydraulic chamber  204 , the T-piston  191  is drawn into a compensating throughbore  221  defined within the first mechanical object or piston  184 . As the T-piston  191  fills the compensating throughbore  221 , the pneumatic void  220  and the second hydraulic fluid chamber  204  decrease in volume. The T-piston  191  may be replaced by its stem portion as a sliding seal within the compensating throughbore  221  in alternative embodiments. 
     The T-piston  191  or sliding seal is secured with respect to the first mechanical object or piston  184  by a partial vacuum generated by movement of the hydraulic fluid and the seal  195  between the T-piston and the compensating throughbore  221  of the piston  184 . The partial vacuum will cause the T-piston  191  to move closer to the piston  184  and into the compensating throughbore  221  or further away from the piston  184 , thus causing the pneumatic void  220  to increase or decrease in volume. To prevent any excess build up of air in the pneumatic void  220 , a reed valve  193  is secured within the piston  184  in fluid communication between the pneumatic void  220  and the second pneumatic chamber  192  to permit any air build up between the piston  184  and the T-piston  191  to be released from the pneumatic void  220  into the second pneumatic fluid chamber  192 . 
     Extended movement of the hollow rod  186  so that the rod adaptor  185  is at its farthest extension away from the second end seal  189  will create a need for more non-compressible fluid in the first hydraulic fluid chamber  202  and less non-compressible fluid in the second hydraulic fluid chamber  204 . Because of the vacuum formed by the seal  195  within the compensating throughbore  121  of the piston  184 , the T-piston will be drawn into the compensating throughbore  121 , thereby decreasing the volume of the pneumatic void  220 . As the rod adaptor  185  is moved back toward the second end  189 , the volume of non-compressible fluid occupying the first hydraulic fluid chamber  202  will move into the second hydraulic fluid chamber  204 . Because the second hydraulic fluid chamber  204  includes the stem sleeve  211 , a compensating volume expansion of that chamber  204  will be required, which is provided for by movement of the T-piston out of the compensating throughbore  121  within the first mechanical object or piston  184 . Movement of the T-piston  191  out of and away from the piston  184  increases the volume of the pneumatic void  220 , and air is admitted into the pneumatic void  220  through the reed valve  193 . Change in the volume of the pneumatic void  220  will not effect the accuracy, movement rate or positioning of the adaptor  185  as the mechanically valved embodiment  180  of the bi-fluid actuator is being utilized. 
     It can be seen that the above described dual rod embodiment of FIG. 1, single rod embodiment of FIG. 2, rodless piston embodiment of FIG. 3, rodless valved piston embodiment of FIG. 4, rotary embodiment of FIG. 5, rotary vane embodiment of FIG. 6, and the mechanically valved embodiment of FIG. 7 all show bi-fluid actuators that rely upon a common principle of using a pneumatic, compressible fluid to power movement of a mechanical object or load carriage while simultaneously integrating within the same apparatus use of a non-compressible, hydraulic fluid to precisely control that pneumatically powered movement of the mechanical object. Because the hydraulic fluid is used primarily to control position and rate of movement of the mechanical object rather than powering such movement, the hydraulic fluid does not have to be pumped or controlled with large compressors and high pressure hoses, etc. Additionally, because the primary force is supplied by a compressed pneumatic fluid, such as freely available air, the bi-fluid actuator does not present cost, service and hazardous materials risks of known hydraulic and electronic actuators. 
     While the bi-fluid actuator has been disclosed with respect to the above described and illustrated embodiments, it is to be understood that the invention is not to be limited to those described and illustrated embodiments. For example, it is within the scope of the invention that the pneumatic, hydraulic and positioning controllers of any particular embodiment may themselves be controlled by or be integrated with a computerized overall controller means known in the art. Also, the single rod embodiment of FIG. 2, the rodless piston embodiment of FIG. 3, and the rodless, valved piston embodiment of FIG. 4, are all described above as having pneumatic fluid containers that surround, or partially surround their respective hydraulic fluid containers. However, it is within the scope of the present invention that those embodiments may simply have pneumatic fluid containers that are coaxial with hydraulic fluid containers, so that the pneumatic fluid containers are at least partially surrounded by respective hydraulic fluid containers. Moreover, specific components of the described embodiments of FIGS. 1-7 may be utilized with other described embodiments. For example, the two-way, spring pre-set valve hydraulic fluid controller  118  of the FIG. 4 rodless valved piston, may be utilized as the hydraulic fluid controller of the other embodiments. A two-way, spring pre-set valve means may be secured in fluid communication with the second mechanical objects that are secured between the first and second hydraulic fluid chambers of the FIGS. 1-7 embodiments. Alternatively, a two-way spring pre-set valve means may actually be secured within the second mechanical objects of the embodiments shown in FIGS. 1-3,  6 , and  7 , as with the FIG. 4 rodless valved piston embodiment. 
     Additionally, the phrases “pneumatic fluid” and “hydraulic fluid” are not to be limited to simply “air” and known hydraulic fluids, such as hydrocarbon based oils. Rather, the phrase “pneumatic fluid” is meant to include any compressible fluid, and the phrase “hydraulic fluid” is meant to include any non-compressible fluid, including, for example, water, known antifreeze solutions, etc. Further, while the above description characterizes the “pneumatic fluid controller” as directing pressurized or compressed pneumatic fluid into either first or second pneumatic chambers to power movement of the first mechanical object between the chambers, it is to be understood that the phrase “pneumatic fluid controller that selectively directs the pneumatic fluid” may also include application of a partial vacuum to either pneumatic chambers to thereby generate a pressure differential to power the first mechanical object, such as in circumstances of moving small mass loads. Accordingly, reference should be made primarily to the attached claims rather than to the foregoing description to determine the scope of the invention.