Abstract:
A hydraulically-powered bicycle having a frame, handle bars, a front tire, and a hydraulically powered drive wheel. The drive wheel is powered by oil from a sump which is pressurized by a pair of foot-operated pumps. An accumulator selectively stores and releases energy stored in a spring under the control of a control valve. When released the stored energy provides an energy boost to the bicycle. The pumps are dual piston devices that selectively couple a second piston to a first piston. The pumps implement a power control using the dual pistons. Coupling the pistons together is performed by a linkage assembly having linkage arms and linkage pivots.

Description:
RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 62/041,308, which was filed Aug. 25, 2014, the entire disclosures of which are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to bicycles. More particularly it relates to a multiple speed bicycle having a hydraulic drive system with stored energy assist. 
     BACKGROUND OF THE INVENTION 
     Modern concerns about health and physical fitness have produced an abundance of people who almost religiously participate in a wide variety of exercise activities to stay in shape. One (1) of the most popular exercise activities is bicycling. The muscular and cardiovascular workout associated with bicycling makes it an effective means by which to stay fit as well as an ecologically friendly, low cost and fun way to get from one (1) place to another. 
     While bicycle technology has changed much over the years, one basic aspect which has remained relatively static is the chain and sprocket drive system used to transfer mechanical energy from the rider to the bicycle wheel. Such chain and sprocket drive systems are noisy, prone to failure, and potentially dangerous should an article of clothing or an extremity become caught in the chain. 
     Accordingly, there exists a need for an alternative bicycle drive system which addresses the foregoing deficiencies. Preferably such an alternative bicycle drive system would retain the health and recreational benefits of bicycling while providing a clean, quiet and safe propulsion system. 
     SUMMARY OF THE INVENTION 
     The principles of the present invention provide for a hydraulically-powered bicycle drive system which retains the health and recreational benefits of prior art bicycling while providing clean, quiet and safe propulsion. 
     In one (1) aspect the present invention takes the form of a hydraulically-powered bicycle having a frame, handle bars, a front tire, and a hydraulically-powered drive wheel. Also included are a hydraulic motor for driving the drive wheel, a hydraulic sump for retaining oil, and a hydraulic control valve having at least a first operational position, a second operational position, and a third operational position. The hydraulically-powered bicycle also includes a first hydraulic pump operated by a first pedal and which is operatively connected to the sump and to the control valve. The first hydraulic pump is for pressurizing oil received from the sump. There is also a second hydraulic pump operated by a second pedal and which is operatively connected to the sump and to the control valve. The second hydraulic pump is also for pressurizing oil received from the sump. Also included is the necessary piping for directing pressurized oil from the control valve when the control valve is in the first operational position into the hydraulic motor. 
     In practice the piping also directs oil from the hydraulic motor back into the sump. The oil directed back into the sump beneficial passes through the control valve as it flows into the sump. The control valve will usually include an internal valve spool that directs the flow of oil within the control valve. 
     Beneficially, the hydraulically-powered bicycle according also includes an accumulator for receiving and storing pressurized oil when the control valve is in the second operational position. The accumulator may be comprised of a rigid vessel having an accumulator input port and a spring-biased diaphragm which divides the accumulator into an expandable compartment and a fill space. Then, oil directed into the accumulator pushes the diaphragm against the spring which causes the expandable compartment to expand and to store energy in the compressed spring. The control valve continues to direct oil flow toward the motor when in the second operational position. Energy stored in the compressed spring is released when the control valve is moved to the third operational position. The compressed spring causes oil in the expandable compartment to pass through the control valve and toward the hydraulic motor. Energy stored in the compressed spring increases the power output of the hydraulic motor. 
     The first pump maybe a dual piston pump having a two-part housing. In that case the first pump will have a first piston and a second piston as well as the two-part housing. The first pump is beneficially configured to selectively use the second piston along with the first piston. Selective use can be performed by a lock-linkage that selectively connects the second piston to the first piston. That lock-linkage can include linkage arms interconnected at pivots. 
     In another aspect the present invention takes the form of a hydraulically-powered bicycle having a frame, handle bars, a front tire, and a hydraulically-powered drive wheel which is driven by a hydraulic motor. Also included is a hydraulic sump for retaining oil, a hydraulic control valve having at least a first operational position, a second operational position, and a third operational position. Also included is a first hydraulic pump operated by a first pedal and operatively connected to the sump and to the control valve for pressurizing oil received from the sump. The first hydraulic pump includes a first piston, a second piston, a two-part housing and a lock-linkage for selectively operatively connecting the first piston to the second piston. The hydraulically-powered bicycle also has a second hydraulic pump that is operated by a second pedal and which is operatively connected to the sump and to the control valve. The second hydraulic pump for also for pressurizing oil received from the sump. Piping directs pressurized oil from the control valve when the control valve is in the first operational position into the hydraulic motor. 
     In practice the lock-linkage includes linkage arms that are interconnected by pivots. The hydraulically-powered bicycle further includes an accumulator for receiving and storing pressurized oil. The accumulator is comprised of a rigid vessel having an accumulator input port and a spring-biased diaphragm which divides the accumulator into an expandable compartment and a fill space. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The advantages and features of the present invention will become better understood with reference to the following more detailed description and claims taken in conjunction with the accompanying drawings in which like elements are identified with like symbols and in which: 
         FIG. 1  is an elevation view of a hydraulically-powered bicycle  10  that is in accord with the preferred embodiment of the present invention; 
         FIG. 2  is a schematic of the drive of the hydraulically-powered bicycle  10  shown in  FIG. 1 ; 
         FIG. 3  is an isolated view of a first pedal  30   a  and a second pedal  30   b  used in the hydraulically powered bicycle  10  of  FIG. 1 ; 
         FIG. 4 a    is a cross-sectional view taken along section line A-A of  FIG. 1  showing an empty accumulator  170 ; 
         FIG. 4 b    is cross-sectional view of a fully charged accumulator  170 ; 
         FIG. 5 a    is cross-sectional view taken along section line B-B of  FIG. 3  showing a first pump  50   a  of the hydraulically-powered bicycle  10  expanded for an influx of oil  200  from a sump  190 ; 
         FIG. 5 b    is cross-sectional view of the first pump  50   a  while being compressed so as to force oil  200  to flow into a control valve  150 ; 
         FIG. 5 c    is cross-sectional view of the first pump  50   a  depicting a locked lock linkage  110 ; and, 
         FIG. 5 d    is a cross-sectional view of the first pump  50   a  depicting the lock linkage  110  engaged to force additional oil  200  to flow into the control valve  150 . 
     
    
    
     DESCRIPTIVE KEY 
     
         
         
           
               10  hydraulic-powered bicycle 
               22  frame 
               24  front wheel 
               26  drive wheel 
               27  handle bar 
               28  lower beam 
               30   a  first pedal 
               30   b  second pedal 
               32  pedal arm 
               34  pedal arm pivot 
               36  pump actuation link 
               38  footpad 
               40  pedal return link 
               42  pedal return pivot 
               44   a  first finger 
               44   b  second finger 
               50   a  first pump 
               50   b  second pump 
               51  housing 
               52  fixed pump segment 
               54  base 
               56  fixed wall 
               58  chamber wall 
               60  first piston chamber 
               62  first inflow check valve 
               64  first outflow check valve 
               66  second inflow check valve 
               68  second outflow check valve 
               72  first piston 
               74  first piston seal 
               78  rod 
               80  second piston chamber 
               82  second piston 
               84  second piston aperture 
               86  second piston seal 
               88  rod seal 
               90  moveable pump segment 
               92  top plate 
               94  cable aperture 
               96  moveable wall 
               98  wall seal 
               100  third chamber 
               102  void 
               110  lock linkage 
               112  end pivot 
               114  linkage arm 
               118  linkage pivot 
               122  piston pivot 
               124  slide ring 
               126  cable pivot 
               130  cable gathering system 
               132  shift cable 
               134  lock lever 
               136  lock lever pivot 
               150  control valve 
               152  valve spool 
               154   a  first operational position 
               154   b  second operational position 
               154   c  third operational position 
               156  vent 
               160  motor 
               162  motor inlet port 
               164  motor outlet port 
               170  accumulator 
               172  vessel 
               174  diaphragm 
               176  spring 
               178  compartment 
               182  space 
               184  accumulator input port 
               190  sump 
               194  piping 
               200  oil 
           
         
       
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The preferred embodiment of the present invention is depicted within  FIGS. 1-5   d . However, the invention is not limited to what is specifically illustrated and described. A person skilled in the art will appreciate that many other embodiments of the invention are possible without deviating from the basic concept of the invention. Any such work around also falls with the scope of this invention. 
     The terms “a” and “an” herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items. In addition, unless otherwise denoted all directional signals such as up, down, left, right, inside, outside are taken relative to the illustration shown in  FIG. 1 . 
     Refer now to  FIG. 1  for an elevation view of the present invention, which is a two-speed hydraulically-powered bicycle  10  having a hydraulic drive system and advanced pumps. The hydraulically-powered bicycle  10  includes a hydraulic accumulator  170  that selectively stores and releases hydraulic energy through a hydraulic drive motor  160  to provide a power assist such as when climbing a hill. The hydraulically-powered bicycle  10  uses a long molecular chain, hydrocarbon-based, non-compressible Newtonian fluid for power transmission. That fluid is referred to hereafter as oil  200  (see  FIG. 2 ). 
     Refer now to both  FIG. 1  and to  FIG. 2 , which is a hydraulic schematic of the hydraulically powered bicycle  10 . The hydraulically-powered bicycle  10  includes some of the components of a prior art bicycle, including a frame  22 , handle bars  27 , a front wheel  24  having a front tire, and a rear tire. However, the rear tire is mounted on a hydraulically powered drive wheel  26 . The prior art bicycle components are modified as necessary to incorporate the hydraulic drive system described in more detail subsequently. For example, the frame  22  has a cross-through design. 
     The hydraulically-powered bicycle  10  also includes components not found in the prior art. Those components include a first pump  50   a  that is operated by a first pedal  30   a , a second pump  50   b  that is operated by a second pedal  30   b  (see  FIGS. 2 and 3 ), a multi-positional control valve  150 , the hydraulic motor  160 , a sump  190 , and the accumulator  170 . Also included on the frame  22  are various hoses and tubes, hereinafter called piping  194 , which moves oil  200  and transfers pressure from one (1) component to another. 
     Referring now also to  FIG. 3 , the foot pedals  30   a ,  30   b  are used to compress oil  200  drawn from the sump  190  by the operations of the first pump  50   a  and second pump  50   b . The sump  190  is an oil reservoir held at or near atmospheric pressure. Oil  200  is drawn into the pumps  50   a ,  50   b  for use in propulsion as is explained in more detail subsequently and then exhausted back into the sump  190 . When the control valve  150  is in a first operational position  154   a  pumped oil  200  is directed through the motor  160 . This results in rotation of an output shaft (not shown) which drives the drive wheel  26 . 
     The preferred motor  160  is an INTERMOT IAM H Series® radial piston motor or a similar motor. Thus the motor is well known and available in the prior art. In operation when a valve spool  152  in the control valve  150  is in operational position  154   a  the motor  160  receives pressurized oil  200  in a first cylindrical cavity via a motor inlet port  162 . This causes displacement of a motor piston within the first cylindrical cavity at a rate dependent on the oil  200  flow rate. Displacement of the motor piston results in rotation of the motor shaft. When the first motor piston reaches the bottom of its stroke a valve within the motor  160  causes oil  200  to enter the next sequential cavity. Oil  200  then causes displacement of a second motor piston which in turn causes further rotation of the motor shaft. This procedure continues until the oil  200  input flow stops. Oil flow can be stopped either by the user stopping peddling or by displacement of the valve spool  152  in the control valve  150  to one of the other operational positions  154   b - 154   c.    
     When either the first motor piston or the second motor piston reaches the bottom of its stroke a valve inside the motor  160  enables oil  200  to leave the cavity it is in and to pass through a motor outlet port  164 . Expended oil  200  then passes through the control valve  150  along a path dictated by the porting of the valve spool  152  and back into the sump  190 . This continues until the motor  160  stops rotating. When the valve spool  152  is in operational position  154   a  the accumulator  170  is blocked and oil  200  cannot enter or exit the accumulator  170 . 
     In a second operational position  154   b  of the control valve  150  the valve spool  152  also directs oil  200  from the first pump  50   a  and from the second pump  50   b  into the motor  160  to cause that motor to rotate as previously described. However, the control valve  150  also directs oil  200  into the accumulator  170 . Referring now to  FIGS. 4 a  and 4 b   , the accumulator  170  is comprised of a rigid vessel  172  having an accumulator input port  184  and a spring  176  biased diaphragm  174 . The diaphragm  174  divides the accumulator  170  into a sealed, expandable compartment  178  on the input side and a fill space  182  on the other side. Oil  200  directed into the compartment  178  pushes the diaphragm  174  against the spring  176 . This causes expansion of the compartment  178 , a corresponding reduction in the volume of the fill space  182 , and energy to be stored in the compressed spring  176  (see  FIG. 4 b   ). The oil  200  continues flowing into the accumulator  170  until the oil pressure in the accumulator  170  rises to that produced at the pedals  30   a ,  30   b  plus inertial energy from the motor  160 . Motor  160  drive of the drive wheel  26  stops when the difference in oil  200  pressure across the motor  160  produces no torque. This produces regenerative braking since the drive wheel  26  is slowed by the storage of potential energy in the spring  176 . In practice a user can switch the valve spool  152  between the first operational position  154   a  and the second operational position  154   b  to partially charge the accumulator  170 . 
     The stored energy in the spring  176  can be used when additional power is needed, such as when going uphill. To use the stored energy the valve spool  152  is moved to a third operational position  154   c . In operational position  154   c  oil  200  from the first pump  50   a  and from the second pump  506  is again directed into the motor  160  via the motor inlet port  162 . This causes the motor  160  to rotate as previously described. In addition, oil flow and oil pressure from the accumulator  170  is directed into the motor  160 . Since the output speed of the motor  160  is directly proportional to the oil flow rate through the motor  160  and since the output torque is directly proportional to the pressure across the motor inlet port  162  and the motor outlet port  164 , the additional oil  200  from the accumulator  170  increases the output of the motor  160 . While not all stored energy in the accumulator  170  can be recovered since the accumulator  170  traps some of the oil  200  the stored energy that is recovered can be highly beneficial. 
     As shown in  FIG. 2  the hydraulically-powered bicycle  10  can includes a vent  156  in the valve spool  152 . The vent  156  can be used to depressurize the system. Not all hydraulically-powered bicycles  10  may include a vent  156 . Furthermore, other fluid conditioning and monitoring equipment such as, but not limited to, heat exchangers and filters may be incorporated into the hydraulically-powered bicycle  10 . 
     The valve spool  152  is moved from one (1) operational position  154   a - 154   c  to another either by using a direct mechanical linkage such as a cable or a pivoting handle or by electrical servos or solenoids. The valve spool  152  can also be equipped with a mechanical holding device such as centering springs or mechanical detents to preferentially position the valve spool  152  in any one (1) of the operational positions  154   a - 154   c  and operation of the vent  156 . 
     Refer now primarily to  FIG. 3  for an isolated view of the pedals  30   a ,  30   b  and their associated components. The pedal  30   a ,  30   b  are pivotally attached on opposite sides of the frame  22 . The pedals  30   a ,  30   b  each have pedal arms  32  that pivot on pedal arm pivots  34 . The pedals  30   a ,  30   b  also each have footpads  38  at their distal ends. The footpad  38  may be equipped with a cage-like device for encircling a user&#39;s foot to enable an upward force to be placed on the pedal arm  32 . At the lower part of the frame  22  between the down tube and the wheel frame is a lower beam  28 . The lower beam  28  has a centrally located annular pedal return pivot  42  having a pedal return link  40 . The pedal return link  40  has an arcuate first finger  44   a  projecting from a first side and a similarly shaped second finger  44   b  projecting from an opposite side. The pedal return link  40  returns a depressed pedal arm  32  to a full upright position when the other pedal arm  32  is pushed down. 
     In use, a downward force exerted by a user on the footpad  38  of the first pedal  30   a  causes the pedal arm  32  to rotate about the pedal arm pivot  34 . This results in actuation of the first pump  50   a . Simultaneously, that pedal arm  32  depresses the first finger  44   a , thereby causing the pedal return link  40  to rotate on the pedal return pivot  42 . This causes the subsequent elevation of the second finger  44   b  against the pedal arm  32  of the second pedal  30   b . This forces the pedal arm  32  to raise the second pedal  30   b . Conversely, depression of the second pedal  30   b  results in a returning the first pedal  30   a  upward. 
       FIG. 5 a    presents a cross-sectional view taken along line B-B of  FIG. 3  with the first pump  50   a  when expanded.  FIG. 5 b    presents a cross-sectional view of the first pump  50   a  of the hydraulically powered bicycle  10  when collapsed. FIG.  5   c  presents a cross-sectional view of the first pump  50   a  with a lock linkage  110  locked.  FIG. 5 d    presents a cross-sectional view of the first pump  50   a  with the lock linkage  110  engaged to force additional oil  200  into the control valve. While the specific illustrations of  FIGS. 5 a  through 5 d    concern the first pump  50   a  it should be understood that the second pump  50   b  is the same as the first pump  50   a . Consequently the following explanation of the first pump  50   a  is also applicable to the second pump  50   b.    
     As shown in  FIGS. 5 a   , the first pump  50   a  is a dual piston pump having a two-part housing  51 . The housing  51  includes a movable pump segment  90  that operates along the longitudinal axis of a fixed pump segment  52 . The fixed pump segment  52  has a planar base  54  and an encircling fixed wall  56  that are joined along their abutting edges to form an interior second piston chamber  80 . The first pump  50   a  is fixed to a lower part of the frame  22 . 
     Passing through the base  54  are hydraulic fittings that control the flow of oil  200  into and out of the pump  50   a . A first outflow check valve  64  is situated between the piping  194  that runs between the sump  190  and the second piston chamber  80 . The outflow check valve  64  blocks oil  200  from exiting the second piston chamber  80  while permitting an easy flow of oil  200  into the second piston chamber  80 . An inflow check valve  62  is inserted into the piping  194  that runs between the second piston chamber  80  and the control valve  150 . The inflow check valve  62  blocks oil  200  from entering the second piston chamber  80  while permitting an essentially free flow from the second piston chamber  80 . 
     Disposed within the second piston chamber  80  and attached to the base  54  is a centrally located chamber wall  58 . The chamber wall  58  forms the lateral boundary of a cylindrical first piston chamber  60 . Disposed within the chamber wall  58  is a second outflow check valve  68 . The outflow check valve  68  blocks oil  200  from leaving the first piston chamber  60  while enabling essentially a free flow into the first piston chamber  60 . Disposed in the base  54  is a second inflow check valve  66  that is connected to the hydraulic piping  194  that runs to the control valve  150 . The second inflow check valve  66  blocks oil  200  from entering the first piston chamber  60  while permitting an essentially free flow of oil  200  out of the first piston chamber  60 . 
     The moveable pump segment  90  has a planar top plate  92  that connects to an encircling moveable wall  96  to form an internal third chamber  100 . The moveable pump segment  90  is attached to the pedal arm  32  of a pedal  30   a  (or  30   b ) via a pump actuation link  36  (also see  FIG. 3 ). The pump actuation link  36  is designed to minimize axial misalignment between the moveable pump segment  90  and the fixed pump segment  52 . The moveable pump segment  90  fits over the fixed pump segment  52 . A wall seal  98  is disposed between the fixed wall  56  and the moveable wall  96  to provide a hydraulic seal. The wall seal  98  is preferably an annular ring constructed of polymer and is seated in an annular seat that is formed into the fixed wall  56 . 
     A cylindrical rod  78  connects the end plate  92  to a first piston  72  that moves within the first piston chamber  60 . The cylindrical rod  78  slides through a second piston aperture  84  of a second piston  82 . The housing  51 , the pistons  72 ,  82 , the second piston chamber  80 , and the rod  78  are all constructed of such material that can withstand the total forces exerted with the hydraulically powered bicycle  10 . 
     The first piston  72  maintains fluid communication with the first piston chamber  60  while the second piston  82  maintains fluid communication with the second piston chamber  80 . The first piston chamber  60  is defined by the base  54  and the interior of the chamber wall  58 . The top of the first piston chamber  60  is closed with a first piston seal  74 . Oil  200  can only be drawn into the first piston chamber  60  through a second outflow check valve  68  and can only exit through the second inflow check valve  66 . The second piston chamber  80  is defined by the first piston  72 , the second piston  82  and the walls  56 ,  96 . The second piston chamber  80  is closed by a second piston seal  86  and by a rod seal  88 . Oil  200  can only be drawn into the second piston chamber  80  through the first outflow check valve  64  and can only exit through the first inflow check valve  62 . The first piston seal  74 , the second piston seal  86 , and the rod seal  88  are all annular rings of comprised of a polymer material and are seated in respective annular grooves. The seals  74 ,  86 , and  88  restrict the by-pass of oil  200 . 
     The third chamber  100  is defined by the second piston  82  and the top plate  92 . The third chamber  100  forms a void  102  without oil  200 . Within the void  102  is a lock linkage  110  that is attached to the second piston  82  and to an interior face of the top plate  92 . The lock linkage  110  has a plurality of linkage arms  114  that are interconnected through end pivot  112 , linkage pivot  118 , and piston pivot  122 . The lock linkage  110  selectively permits displacement of the second piston  82  relative end plate  92 . Movement of the second piston  82  is enabled by freeing the linkage arms  114  to rotate about the pivots  112 ,  118 ,  122 . 
     The movements of the linkage arms  114  are controlled by a cable gathering system  130  that is operated by a lock lever  134 . Movement of the lock lever  134  is controlled by rotation about a lock lever pivot  136 . Rotation causes a shift cable  132  to be pulled through a cable aperture  94  in the top plate  92  so as to either lock or free the linkage arms  114 . When the linkage arms  114  are locked there is a rigid connection between the second piston  82  and the moveable pump segment  90  (best shown in  FIGS. 5 c  and 5 d   ). Locking the linkage arms  114  is actually performed by having the shift cable  132  routed through cable pivots  126  of a slide ring  124 . The slide ring  124  moves along the rod  78  to compensate for lateral movement of the linkage pivots  118 . Selective engagement of the lock linkage  110  by a user configures the first pump  50   a  (and the second pump  50   b ) to use the second piston  82  to pump oil  200  through the control valve  150 . 
       FIG. 5 a    shows that as the first pedal  30   a  is raised such that the moveable pump segment  90  is displaced relative to the fixed pump segment  52 . This moves the rod  78  and the first piston  72  up to expand the first piston chamber  60 . This creates a partial vacuum. The partial vacuum causes an inflow of oil  200  from the sump  190  through the piping  194 , through the first outflow check valve  64 , into the second piston chamber  80 , and then through the second outflow check valve  68  into the first piston chamber  60 . The influx of oil  200  into the first piston chamber  60  continues through the entire upward displacement of the moveable pump segment  90 . This is referred to as the first piston in-stroke. At the maximum height of the first pedal  30   a  the first piston chamber  60  is at peak oil volume. During the first piston in-stroke oil  200  from any other source is blocked from entering the first piston chamber  60  by the second inflow check valve  66 . 
     Referring now to  FIG. 5 b   , as the first pedal  30   a  is depressed the first piston  72  is forced toward the base  54  via the rod  78  and the mechanical connection of the pump actuation link  36 , thus collapsing the first piston chamber  60 . Oil  200  is then forced to flow out through the second inflow check valve  66  where it is directed by the piping  194  to the control valve  150 . Oil  200  is forced from the first piston chamber  60  during the entire down stroke of the first piston  72 . This is referred to herein as the first piston outstroke. During the first piston outstroke the oil  200  is blocked from flowing into the sump  190  by the second outflow check valve  68 . 
     Referring back to  FIG. 3 , as the first pedal  30   a  is depressed to perform a first piston outstroke the second pedal  30   b  is raised to perform a first piston in-stroke in the second pump  50   b . After completion of the first piston outstroke a user can depress the second pedal  30   b  to bring about a first piston outstroke in the second pump  50   b . Continued alternating operation of the first pedal  30   a  and the second pump  50   b  circulates oil  200  and propels the hydraulically-powered bicycle  10 . 
     Turning now to  FIG. 5 c   , which shows the lock linkage  110  locked. That is, the shift cable  132  is pulled upward to force the linkage pivots inward. Thus as the first pedal  30   a  is raised the moveable pump segment  90  is displaced relative to the fixed pump segment  52 . This moves the second piston  82  as well as the first piston  72  upward. This expands both the first piston chamber  60  and the second piston chamber  80 . Expansion of the first piston chamber  60  and second piston chamber  80  creates a partial vacuum in both areas. This creates an inflow of oil  200  from the sump  190  through the piping  194 , through the first outflow check valve  64  and into the second piston chamber  80 , and through the second outflow check valve  68  and into the first piston chamber  60 . This oil  200  influx continues during upward displacement of the moveable pump segment  90  is referred hereinafter as the pump in-stroke. At the maxim height of the first pedal  30   a  the first piston chamber  60  and the second piston chamber  80  are at their peak oil volumes. During the pump in-stroke oil  200  from any other source is blocked by the second inflow check valve  66  and by the first inflow check valve  62 . 
     Referring now to  FIG. 5 d   , which also shows the lock linkage  110  locked, as the first pedal  30   a  is depressed the first piston  72  is forced toward the base  54  via the rod  78  while the second piston  82  is forced toward the base  54  by the lock linkage  110 . This collapses both the first piston chamber  60  and the second piston chamber  80 . Oil  200  is then forced out the first inflow check valve  62  and out the second inflow check valve  66  and into the piping  194  and thus into the control valve  150 . Oil  200  continues to be forced from the piston chambers  60 ,  80  during downward displacement of the moveable pump segment  90 . This is referred as the pump outstroke. During pump outstroke oil  200  is blocked from flowing into the sump  190  by the outflow check valves  64 ,  68 . The combined flow of oil  200  from the first piston chamber  60  and from the second piston chamber  80  is greater than that possible using only the first piston chamber  60 . The increased oil  200  flow translates to an increased speed of the motor  160 . However, due to the increased area of the second piston  82  the output pressure during pump outstroke is less than that from the first piston outstroke due to spreading of applied forces over a larger area. Thus activation of the lock linkage  110  is somewhat akin to up-shifting a derailleur system in that speed is increased at the expense of increased force requirements. 
     The preferred embodiment of the present invention can be utilized by the common user in a simple and effortless manner with little or no training. The method of using the hydraulically powered bicycle  10  can be performing by acquiring a model of the hydraulically powered bicycle  10  having a desired style to suit a user; installing oil  200  into the sump  190 ; setting the cable gathering system  130  to release the lock linkage  110  so as to have the ability of moving the moveable pump segment  90  independently from the second piston  82 ; placing the valve spool  152  into the vent position  156 ; depressing the second pedal  30   b  to draw oil  200  into the first piston chamber  80 ; placing the valve spool  152  of the control valve  150  into the first operational position  154   a ; hydraulically powered bicycle  10 ; depressing the first pedal  30   a  to compress oil  200  in the first piston chamber  60 , thereby forcing that oil  200  into the motor  160  through the control valve  150  to result in a forward propulsion while simultaneously causing the second pedal  30   b  to rise and draw oil  200  into the second pump  50   b ; depressing the second pedal  30   b  to compress the oil  200  in the second pump  50   b  thereby forcing that oil into the motor  160  through the control valve  150  to additional forward propulsion while causing the first pedal  30   a  to rise and draw oil into the first pump  50   a ; and continuing alternating depressions of the first pedal  30   a  and second pedal  30   b . The user can selectively set the cable gathering system  130  to engage the lock linkage  110 , thereby increasing the flow during a pump outstroke to increase the speed of the hydraulically-powered bicycle  10 . During travel a user can change the control valve  150  to the second operational position  154   b  to enter a regenerative braking mode that charges the accumulator  170  with oil  200  for later use. With a charged accumulator  170  a user can avail themselves with of the potential energy in the accumulator  170  by moving the control valve  150  to the third operational position  154   c.    
     The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated.