Abstract:
A cycle (or an adaptation for a cycle) comprises a primary crank arranged for rotation about a first axis, a secondary crank, and connection means for selective connection of the secondary crank to the primary crank at a selected one of a plurality of positions on both the primary crank and the secondary crank. A pedal is mounted on the secondary crank, and selectively operable means is provided for either permitting or preventing rotation of the secondary crank relative to the primary crank, in dependence of the nature of the disabilities or injuries of the user of the cycle.

Description:
FIELD OF THE INVENTION 
     This invention relates to exercise and rehabilitation equipment and has for its object the provision of improved equipment which enables people with lower limb disabilities to use cycling as a form of exercise or rehabilitation. 
     In U.S. Pat. No. 4,915,374 there is described an exercise cycle which includes a frame, a shaft rotatably mounted on the frame, a primary crank at each end of the shaft and a secondary crank pivotally connected to each primary crank. A pedal is pivotally connected to a selected location along each secondary crank. 
     The exercise cycle described in said US specification can accommodate limited ranges of movement of both legs but it is a specific object of the present invention to provide a cycle (or an adaptation for a cycle) which provides for a wider range of adjustability than the exercise cycle described in U.S. Pat. No. 4,915,374. 
     SUMMARY OF THE INVENTION 
     According to the present invention there is provided a cycle (or an adaptation for a cycle) comprising a primary crank arranged for rotation about a first axis, a secondary crank, connection means for selective connection of the secondary crank to the primary crank at a selected one of a plurality of positions on both the primary crank and the secondary crank, a pedal mounted on the secondary crank, and selectively operable means for either permitting or preventing rotation of the secondary crank relative to the primary crank. 
     Other features of the invention are defined in the subsidiary claims presented herewith. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a first primary crank, 
     FIG. 2 shows a second primary crank, 
     FIG. 3 shows the method of attachment of either of the primary cranks to an axle, 
     FIG. 4 shows a secondary crank assembly, 
     FIG. 5 is a side view of a bicycle adaptation, 
     FIG. 6 is a front view of the adaptation shown in FIG. 5, 
     FIG. 7 is an exploded view of a further device which has been designed to enable people with lower limb disabilities or injuries to use cycling as a form of exercise or rehabilitation, 
     FIG. 8 is a side view of the secondary crank of the device shown in FIG. 7, and 
     FIG. 9 is a diagrammatic side view of an exercise cycle incorporating the features of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1 to  6  show an assembly designed to fit cycles, cycle ergometers and exercise bikes. The system provides for incremental adjustment and opposing orientation of two cycle cranks in a fixed or swinging mode, allowing for varying degrees of strength, movement or flex in an affected limb, exercising actively or dynamically, and isolating the effect of the non-affected limb. 
     FIG. 1 shows a first primary replacement crank  10  for a cycle ergometer. The crank  10  is in the form of a circular plate formed with three radially extending series of equally spaced fixing holes  11 ,  12  and  13 . In operation, the primary crank  10  is intended to rotate in the direction indicated by the arrow  14 . Crank  10  is also formed with two mounting holes  15  equally spaced from the centre of the circular plate forming the crank  10 . 
     FIG. 2 shows a second primary replacement crank  16  which is in the form of an elongated plate  17  at one end of which there is a circular portion  18 . The elongated plate  17  is formed with an axially extending row of equally spaced fixing holes  19  arranged at the same spacing as the fixing holes  11 ,  12  and  13 . The circular portion  18  is formed with a pair of arcuate slots  20  which are spaced from the centre of the circular portion by a distance equal to the spacing of the mounting holes  15  from the centre of the circular plate forming the crank  10 . 
     FIG. 3 shows one end of an axle  21  as commonly used on a bicycle or on a cycle ergometer. A mounting plate  22  is attached to the axle  21  by means of a bolt  23 . Either primary crank  10 ,  16  can then be attached to the mounting plate  22  by means of bolts  24  which pass through either the mounting holes  15  of crank  10  or the arcuate slots  20  of crank  16 . 
     A second crank mechanism will be mounted on the other end of the axle  21  for engagement by the other foot of the user. In particular, the system herein described can be repeated on the other end of the axle  21 . 
     FIGS. 5 and 6 show a bicycle or exercise bicycle adaptation in which a primary crank  25  is attached to the outside of a commonly used bicycle crank  26 . An adaptor plate  27  replaces the existing centre bolt of the bicycle and a stud  28  replaces the existing cycle pedal. The primary crank  25  is attached to the bicycle crank  26  and to the adaptor plate  27  by means of bolts  29  and  30  which pass through holes  31  and  32  in the primary crank  25 . A row of equally spaced fixing holes  33  is formed in the primary crank  25 . 
     The bicycle crank  26  will be arranged for rotation about the axis of an axle (not shown) at the other end of which there will be either a conventional pedal and crank drive system or a primary/secondary crank assembly in accordance with the present invention, depending on the requirements and disabilities of the user. 
     A secondary crank assembly  34  is shown in FIG.  4  and comprises a crank arm  35 , a crank arm housing  36  formed with recesses  37 , a pair of locking clips  38  and  39 , and a journal  40 . The crank arm  35  is located in the housing  36  by means of a T-slot arrangement (not shown). 
     Three different modes of operation of the apparatus can be obtained by use of the components and assemblies shown in FIGS. 1 to  6 . These modes of operation are as follows:a) 
     a)the swinging mode, 
     b) the fixed mode, and 
     c) the advance mode. 
     In the swinging mode, the secondary crank assembly  34  is attached to one of the primary cranks  10 ,  16 ,  25  via fixing holes  11  (FIG.  1 ), fixing holes  19  (FIG. 2) or fixing holes  33  (FIG.  6 ). Locking clips  38  and  39  are depressed so as to locate in recesses  37  and to fix the crank arm housing  36  to the journal  40 . This allows the secondary crank assembly  34  to be fixed by either a clockwise or an anti-clockwise rotation into fixing holes  11  (FIG.  1 ), fixing holes  19  (FIG. 2) or fixing holes  33  (FIG.  6 ). 
     Locking clips  38  and  39  are then pulled out to their furthest extent to allow adjustment of the crank arm  35  in the direction of the arrow  41  in FIG.  4 . Notches  42  are provided along both sides of the crank arm  35  and are at equal spacings at a pitch which is the same as the pitch of the fixing holes  11  (FIG.  1 ), fixing holes  19  (FIG. 2) and fixing holes  33  (FIG.  6 ). Once the crank arm  35  has been fixed at the desired length, locking clips  38  and  39  are depressed so as to locate in the notches  42 . 
     In the swinging mode, the crank arm housing  36  rotates freely about journal  40 . A pedal  42  at the lower end of the crank arm  35  follows a circular path which has its centre at the centre line of the journal  36 . The swinging mode allows full extension of a limb while producing incremented anomalies of flexion. 
     In a first fixed mode, the secondary crank assembly is attached to a primary crank  10 ,  16  or  25  as described above and a fixed setting pin (not shown) is passed through a hole  44  and inserted in an appropriate fixing hole  11  (FIG. 1) or  19  (FIG. 2) or  33  (FIG. 6) along the same row of holes as that to which the secondary crank assembly  34  is attached. 
     In a second fixed mode, the secondary crank assembly  34  is attached to a primary crank  10 ,  16  or  25  as described above and locking clip  38  is replaced by an indexable plunger pin (not shown). When depressed, the plunger pin engages with a selected one of a series of holes  45  in primary crank  10 , or holes  46  in primary crank  16  or holes  47  in primary crank  25 . 
     With the equipment in either the first fixed mode or the second fixed mode, the pedal  43  follows a circular path having a fixed radius about the axis of axle  21 . This allows for anomalies of fixed flexion deformity of a limb to a range of flexion. 
     The advance mode provides passive or dynamic exercise using the primary crank  10 . The secondary crank assembly  34  is attached to the primary crank  10  as described above, except that the secondary crank assembly  34  is attached to a selected one of the fixing holes  12  and  13  (instead of to the fixing holes  11 ) in an advanced position. This provides passive movement on the side advanced and dynamic movement of the opposite side, in varying degrees, in either a fixed or swinging mode. In the fixed mode, the longitudinal axis of the secondary crank assembly  34  extends parallel to the row of holes  11  in the primary crank  10  whereas, in the advance mode, the longitudinal axis of the secondary crank assembly  34  extends at an inclination to the row of holes  11 . 
     The primary crank  16  shown in FIG. 2 includes a series of fixing holes  19  to which, as described above, the secondary crank assembly  34  can be attached in an advance crank position. Bolts  47  engaged in arcuate slots  20  can be released to allow the primary crank  16  to be advanced in the direction of the arrows  48 . A series of locations (not shown) are provided in the bottoms of the counter-bored slots  20  to give a positive location. Once the desired advance position has been reached, the bolts are re-tightened. This arrangement provides passive movement on the side which has been advanced and dynamic movement on the opposite side in varying degrees in a fixed or swinging mode. 
     Turning next to FIGS. 7 and 8, these show a design which provides for anomalies in lower limb joint motion or muscle strength in a unilateral or bilateral mode. 
     The device shown in FIGS. 7 and 8 includes a primary crank  50 , which may be the crank arm of a bicycle or exercise bike, and a secondary crank  51 . The primary crank  50  is mounted on the bicycle or exercise bike and has a fixed axis of rotation  58 . The secondary crank  51  is connected to the primary crank by means of a linked shaft  52  and housing  53 . The shaft  52  and housing  53  are arranged to rotate independently of each other, except when an Allen key is inserted through a hexagonal hole  54  extending along the axis of the shaft  52  and tightened. The assembly comprising the linked shaft  52  and housing  53  is fixed into primary crank  50  using a threaded fixing such that the assembly  52 ,  53  is movable relative to the primary crank  50  in the direction of its longitudinal axis  55 . Secondary crank arm  51  is then attached in a similar manner, i.e. using a threaded fixing such that the secondary crank arm  51  is movable relative to the assembly  52 ,  53  in the direction of the longitudinal axis  56 . 
     The pedal  60  is mounted on the secondary crank  51  at a fixed point along the longitudinal axis of the secondary crank  51  whereas the connection of the secondary crank  51  to the primary crank  50 , i.e. the axis of the hexagonal hole  54 , is at a position which is adjustable along the axes of both cranks  50  and  51 , thereby providing a large range of adjustment possibilities and ensuring that the physiotherapist or sports therapist can set the equipment depending on the requirements of the user. As an alternative to having a threaded fixing to provide for movement of the assembly  52 ,  53  in the direction of the longitudinal axis of the second crank  51 , the secondary crank  51  may be provided with a row of spaced holes, in any one of which the assembly  52 ,  53  can be inserted. 
     In operation, with the linked shaft  52  and housing  53  free to rotate independently of each other, the primary crank  50  will rotate about its axis of rotation  58  in the direction of the arrow  59  in FIG.  8  and the secondary crank  51  will pivot relative to the primary crank  50  such that a pedal  60  mounted at the lower end of the secondary crank will follow a circular path with the longitudinal axis  56  of the secondary crank  51  remaining vertical. 
     When the shaft  52  and housing  53  are fixed against movement relative to one another, the primary crank  50  and the secondary crank  51  will rotate together about the axis  58  and the pedal  60  will travel along a circular path whose radius can be varied as required by adjusting the position of the shaft and housing  52 ,  53  relative to the primary crank  50  in the direction of the arrow  55 , and/or by adjusting the position of the shaft and housing  52 ,  53  relative to the secondary crank  51  in the direction of the arrow  56 . The secondary crank  51  can be fixed against movement relative to the primary crank  50  either with the longitudinal axes of the two cranks  50  and  51  parallel to one another or at an acute angle to one another. 
     The primary crank  50  and the secondary crank  51  will normally form part of a cycle or exercise cycle which includes a second assembly  50 ,  51  arranged for rotation about the axis  58 . The assembly shown in FIGS. 7 and 8 and the second assembly  50 ,  51  will be adjustable individually so that, when a user is carrying out an exercise or rehabilitation program, the settings of each assembly, in the swinging, fixed or advance mode, will be adjusted by the physiotherapist or sports therapist depending on the requirements of the user. 
     Turning next to FIG. 9, this shows rehabilitation equipment in the form of an exercise cycle for use under the supervision of a physiotherapist or sports therapist. The equipment comprises a stand  70  including ground-engaging feet  71  and  72 , an upright member  73  provided with hand-grips  74 , an adjustable stem  75  on which a seat  76  is mounted, a pair of primary cranks  77  arranged for rotation about a common horizontal axis and a pair of secondary cranks  78 , one mounted on each primary crank  77 . The two primary cranks  77  are connected to an axle (not shown) in a manner similar to that shown in FIG. 3 and a pedal  79  is mounted on the secondary crank  78 . 
     Each primary crank  77  may correspond to that shown in FIG. 1, i.e. it will have three radial rows of fixing holes, corresponding to the rows of holes  11 ,  12  and  13 . Each secondary crank  78  may correspond to that shown in FIG. 4 or that shown in FIG. 8, i.e. it will either be arranged for connection to the primary crank  77  at a plurality of positions spaced axially of the secondary crank  78 , or the point of connection of the secondary crank  78  to the primary crank  77  will be movable axially of the secondary crank. 
     The primary/secondary crank assemblies  77 ,  78  will be independently adjustable and capable of being set in their swinging, fixed and advance modes as described above. 
     As shown in FIG. 9, the pedal  79  is contained within the circumference of the primary crank  77  and the range of relative positions into which the primary crank  77  and the secondary crank  78  can be set will be such that this relationship will be maintained, i.e. the pedal will not project beyond the perimeter of the primary crank  77 . No additional ground clearance is accordingly required as compared to a conventional exercise bike. This is in contrast with the arrangement shown in U.S. Pat. No. 4,915,374, which is in the form of a recumbent exercise cycle to provide the required ground clearance. 
     The apparatus of the present invention thus enable a very wide range of exercises to be provided, tailored to the needs of the user, either in the form of an adaptation for an existing cycle or exercise cycle or in the form of a purpose-built item of equipment.