Abstract:
A resistance device for an exercise machine which includes a flywheel which is mounted for rotation about an axis and two actuators, on opposed sides of the flywheel, which are mounted for rotation in unison about the axis and which are directly coupled to the flywheel.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This invention relates to a resistance device which is of compact construction and which can be used in a variety of applications e.g. in an energy storage mechanism, or in an exercise machine such as a treadmill, exercise cycle, elliptical-type machine, or a fly-wheel based system, and wherein, according to requirement, the exercise machine can be actuated by a user&#39;s hands and arms, or legs.  
       SUMMARY OF INVENTION  
       [0002]     The invention provides a resistance device which includes a load-resisting member which is mounted for rotation about a first axis, a drive member which is mounted for rotation about the first axis, at least a first actuator for rotating the drive member, and a drive transfer arrangement for translating rotational drive from the drive member into rotational drive of the load-resisting member, and wherein the rotational speed of the load-resisting member is greater than the rotational speed of the drive member.  
         [0003]     The first actuator may take on any suitable form but, preferably, is in the nature of a crank.  
         [0004]     Preferably the resistance device includes a second actuator and the first and second actuators are located, respectively, on opposed sides of the load-resisting member. In the case in which each actuator is a crank the cranks are preferably angularly displaced at 180° relatively to each other.  
         [0005]     The load-resisting member may be mounted on an axle and it may be freely rotatable about the axle. In other words the load-resisting member is not necessarily fixed to the axle. Each actuator may be directly fixed to the axle.  
         [0006]     The drive member may be mounted to the axle and it may be fixed to the axle.  
         [0007]     The drive transfer arrangement may be of any appropriate type and preferably includes a shaft which is parallel to the first axis, a first pulley which is driven by means of a belt, chain or similar device from the drive member and which is mounted to the shaft on a first side of the load-resisting member, the first pulley being of a smaller diameter than the diameter of the drive member, a second pulley which is positioned on a second side of the load-resisting member, remote from the first side, the second pulley being fixed to the shaft, a third pulley which is fixed to the load-resisting member and which is on the second side of the load-resisting member, the third pulley being smaller in diameter than the second pulley and being rotatable in at least a first direction about the first axis, in unison with the load-resisting member, and a belt, chain or similar device for driving the third pulley from the second pulley.  
         [0008]     The third pulley may be fixed to the load-resisting member via a one-way drive device, such as a one-way clutch or bearing so that rotational drive in a first direction is transferred from the pulley to the load-resisting member. However the action of the one-way drive device is such that drive is not transferred from the load-resisting member to the third pulley.  
         [0009]     “Pulley” is used herein in a generic sense and includes a pulley, cog, roller or similar rotational drive or driven device.  
         [0010]     The load-resisting member may of any appropriate kind and preferably is in the nature of a flywheel. The flywheel may be braked in any appropriate way to provide a yielding load-resisting force which acts against free rotation of the flywheel. In this regard use may be made of a belt or similar friction device which acts against movement of the flywheel, a magnetic brake, or any equivalent device. The invention is not limited in this regard.  
     
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0011]     The invention is further described by way of example with reference to the accompanying drawing which illustrates, in exploded form, a resistance device according to one form of the invention.  
     
    
     DESCRIPTION OF PREFERRED EMBODIMENT  
       [0012]     The accompanying drawing illustrates, in exploded form, a resistance device  10  according to the invention. Only those components which are necessary for an understanding of the working of the invention are illustrated. It is to be understood that other components such as a housing, safety guard or the like have been omitted for clarity of illustration.  
         [0013]     The device  10  includes an axle  12  which is positioned on a first axis  14 . A load-resisting device in the form of a flywheel  16  is mounted for free rotation on the axle. Thus the flywheel is not rotatable together with the axle but is rotatable about the axle.  
         [0014]     The axle  12 , on a first side  18 , has a number of flat surfaces  20 . A drive member  22 , in the nature of a ribbed pulley, is fitted over an end of the axle which protrudes on the first side and is fixed thereto so that the pulley and the axle are rotatable in unison.  
         [0015]     A cranked actuator  24  with a hole  26  which is complementary to the end of the axle with the flat surfaces  20 , is engaged with the flat surfaces in a non-releasable manner. The actuator includes a lever  28  which terminates in a handle  30  which is rotatable about a stub axle  32 .  
         [0016]     A support frame member  34  is used to support the protruding end of the axle and to shield the actuator  24  from the drive member  22 .  
         [0017]     A shaft  40 , located on a second axis  41  which is spaced from and which is parallel to the axis  14 , is mounted, at one end, to a bearing, not shown, which is engaged with the support frame member  34 . A first pulley  42  is fixed to the shaft so that it is rotatable together with the shaft. The pulley has a smaller diameter than the drive member  22 . A ribbed belt  46  which passes over a jockey wheel  48  is used for transferring rotational movement from the drive member  22  to the first pulley  42 .  
         [0018]     A second pulley  60 , which is larger in diameter than the first pulley  42 , is mounted to one end of the shaft  40  on a second side  62  of the flywheel  16 . A ribbed belt  64  is engaged with the second pulley and is used for transferring rotational movement from the second pulley to a third pulley  70  which is fixed to the flywheel. The third pulley  70  is smaller in diameter than the second pulley. The axle  12  protrudes from the flywheel and the third pulley  70 , on the second side  62 . This protruding end of the axle is similar to the protruding end on the first side of the flywheel and carries flat formations  20 A which are similar to the flat surfaces  20 . A crank actuator  80  is engageable with the flat formations  20 A.  
         [0019]     In this example the actuator  80  is offset, in an angular sense, by 180° with respect to the actuator  24 . The actuators are however linked and when one actuator is rotated in a first direction about the axis  14  the other actuator is rotated in the same direction and at the same rate.  
         [0020]     In the illustrated example the device  10  is designed to be actuated by hand. The flywheel  16  may be frictionally braked using a belt or similar device, which is engaged with a periphery of the flywheel, using techniques which are known in the art. Preferably however a magnetic brake, of a kind which is known in the art, is used for inhibiting free rotation of the flywheel, according to requirement. The magnetic brake typically includes one or more magnets  90  which are fixed to the flywheel and which are rotated, together with the flywheel, passed ferro-magnetic components in which electromagnetic fields are induced which restrain flywheel rotation. This kind of brake is readily adjustable to exert a greater or lesser braking force on the flywheel.  
         [0021]     If the axle  12  is rotated, by operating one or both of the actuators  24  and  80 , then the drive member  22  is rotated in the same direction. Rotational drive is then transferred to the shaft  40 . As the drive member  22  is larger in diameter than the first pulley the rotational speed of the first pulley is greater than the rotational speed of the member  22 . The second pulley has a larger diameter than the first pulley and thus, although it moves at the same rotational speed as the first pulley, its peripheral speed is greater. This means that the third pulley, which is of smaller diameter than the second pulley, is rotated at an increased rotational speed. The third pulley, as noted, is fixed to the flywheel and the flywheel therefore rotates at a substantially increased speed relatively to the rotational speed of the actuators  24  and  80 .  
         [0022]     The construction illustrated is of a compact nature and is highly effective in offering load-resisting movement of the flywheel when the actuators are employed.  
         [0023]     Each handle  30 , in this example, is designed to be used by hand, but, through suitable shaping, may readily act as a pedal so that the device may be hand or foot operated, according to requirement.  
         [0024]     The resistance device can be incorporated in various forms in exercise machines such as treadmills, elliptical trainers, cycles, rowing-type machines, and the like. Also, the resistance device can be used as an energy storage mechanism, with rotational energy stored primarily in the flywheel.  
         [0025]     A one-way clutch or bearing  84  can be used between the flywheel  16  and the third pulley  70  so that the rotational drive is transferred in a first direction only from the pulley to the flywheel. Rotational movement will not however be transferred from the flywheel to the pulley.