BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an exercise device which is adapted to facilitate the performance of three distinctly different types of bodily exertion. In particular, the present apparatus is readily adapted to serve as a device which simulates the climbing of stairs, cross country skiing motions, or walking. 
     2. Description of Related Technology 
     Numerous devices have been developed to permit exercise that simulates vigorous body movement which would normally cause the person exercising to move over the surface of the ground a considerable distance, but which instead permit this activity to occur while the person exercising remains on a stationary platform. The obvious advantages are that the exercise may be performed in a small space, indoors, and without a large specially prepared surface. The disadvantage of such devices is that they have typically either simulated a natural activity, such as walking, fairly poorly, or while simulating a particular exercise fairly well, have been limited to that single type of exercise activity. Therefore, a person who would wish to participate in a wide variety of activities on a stationary platform would have to purchase a variety of discrete, dedicated exercise platforms. 
     Examples of such stationary exercise platforms include that disclosed in U.S. Pat. No. 1,909,190, issued to Sachs, which is an inclined platform utilizing reciprocating foot platforms, interconnected by a cable, such that a walking motion may be simulated. 
     U.S. Pat. No. 2,052,102, issued to Morgan, discloses a &#34;walking in place&#34; device, in which two foot pads, residing side by side, are interconnected to a coil spring arrangement such that the foot pad is constrained to move vertically. The coil spring provides greater resistance as the foot pad moves towards a lower horizontal plane. 
     U.S. Pat. No. 2,892,455, issued to Hutton, discloses a power driven walking trainer which causes pivoted foot pedals to move automatically, the person&#39;s feet being affixed to the moving pedals so as to force the person&#39;s body to simulate a walking motion. A similar device is disclosed in U.S. Pat. No. 3,316,898, issued to Brown, wherein a motor drives two pivoted foot pedals. The Brown device is intended for a person in a somewhat healthier condition than the Hutton device, insofar as the Brown device does not include any means for supporting the patient&#39;s body and requires that the patient maintain their own balance and posture during exercise. 
     U.S. Pat. No. 3,501,142, issued to Johansson, discloses a bicycle type exercise device including a flywheel which is brought into frictional engagement with a belt, thereby permitting the resistance to movement to be varied, and permitting simulation of bicycling along an incline. 
     U.S. Pat. No. 3,746,355, issued to Fichter et al., discloses a starting block and rail assembly which may be used for supporting a foot, ostensibly as a starting block for use during track events. 
     U.S. Pat. No. 3,833,216, issued to Philbin, discloses a bicycle exercise device having a manually operated lever to vary the resistance encountered by the cycler. A retainer device is included so that the resistance setting, once chosen, is maintained within predetermined limits. 
     U.S. Pat. No. 3,970,302, issued to McFee, discloses a stair climbing device with diagonally sliding carriages having pneumatic or hydraulic cylinders to provide resistance to a pair of reciprocating foot rests. In an alternate embodiment, a pair of pivoting levers are used as the foot supports. 
     U.S. Pat. No. 4,047,715, issued to Gjessing, discloses a rowing device incorporating a one-way clutch apparatus such that a flywheel may rotate in only one direction. 
     U.S. Pat. No. 4,188,030, issued to Hooper, discloses a bicycle device including reciprocating hand levers which move automatically in response to the cycling motion caused by operation of the cycle foot pedals. 
     U.S. Pat. No. 4,496,147, issued to Decloux et al., discloses a stair climbing device having hydraulically phased steps operating along an inclined track. The Decloux et al. device may be collapsed to form a relatively compact structure, thereby simplifying storage problems in a household environment. 
     U.S. Pat. No. 4,537,396, issued to Hooper, discloses a device which permits the simulation of a swimming motion with the arms, and in an alternate embodiment a rowing activity or a pedaling activity. 
     U.S. Pat. No. 4,555,108, issued to Monteiro, discloses a stair stepping device having a disk with eight projections, each projection serving as a stair. Rotation of the disk is retarded somewhat by a hydraulic resistance mechanism, thereby permitting the user to rotate the disk at the same rate at which the projections, or stairs, are climbed. 
     U.S. Pat. No. 4,643,418, issued to Bart, discloses an exercise treadmill containing electric motors which allow the entire treadmill frame to be inclined during use. 
     U.S. Pat. No. 4,659,077, issued to Stropkay, discloses an exercise device which simulates a cross country skiing exercise. 
     U.S. Pat. No. 4,679,786, issued to Rogers, discloses a combination exercise device which simulates bicycling, rowing, as well as a skiing motion 
     U.S. Pat. No. 4,681,316, issued to Decloux, discloses a stair climbing device having interconnected hydraulic systems and a diagonally mounted track. 
     U.S. Pat. No. 4,685,666, issued to Decloux, discloses a trackless climbing simulation device in which a pair of steps are connected to cylinder rods, thereby simulating a stair climbing motion. 
     U.S. Pat. No. 4,685,669, issued to Decloux, discloses a stair climbing device including a hydraulic fluid system for altering the stair climber&#39;s center of gravity during the descent phase of the step. 
     U.S. Pat. No. 4,708,128, issued to Ancillotti, discloses a stationary bicycle in which the position of the pedals may be altered so as to aid in the treatment of various knee injuries. 
     U.S. Pat. No. 4,708,338, issued to Potts, discloses a stair climbing device using pivoting lever members. 
     U.S. Pat. No. 4,709,918, issued to Grinblat, discloses an exercise device which can simulate cross country skiing, rowing, and a variety of pulling exercises designed to stimulate the arms and torso. 
     U.S. Pat. No. 4,712,791, issued to Edwards, discloses an exercise machine designed to simulate a jogging motion, with the added feature of being able to incline the exerciser rearwardly while jogging. 
     U.S. Pat. No. 4,720,093, issued to Delmar, discloses a stair climbing device designed to be used in the weightless environment of space. 
     U.S. Pat. No. 4,726,581, issued to Chang, discloses a stair climbing device which simulates stair climbing with a system of revolving steps connected to an endless belt or chain. 
     U.S. Pat. No. 4,786,050, issued to Geschwender, discloses a device having a pair of pivoted foot pedals simulating a climbing motion which are interconnected to a pair of hand cranks, thereby simulating a skiing motion 
     U.S. Pat. No. 4,798,379, issued to Jenkins, discloses an exercise machine in which the user sits while manipulating pivoting lever members for both the arms and the legs. 
     U.S. Pat. No. 4,842,268, issued to Jenkins, discloses a second embodiment of a stair climbing device with pivoting lever members for the arms and legs. The device is used while the exerciser is in a sitting position 
     U.S Pat. No. 4,946,162, issued to Lubie, discloses a portable exercise device which simulates a pedaling motion. The device is designed to be used while a person is sitting in a chair. 
     U.S. Pat. No. 4,960,276, issued to Feuer et al., discloses a cross country ski simulation device including a series of parallel tracks for engagement by foot grips and hand levers. 
     U.S. Pat. No. 3,511,500, issued to Dunn, discloses a constant resistance exercise device in which the user &#34;teeter-totters&#34; on foot pads while holding an anchored handle in each hand. 
     U.S. Pat. No. 4,618,139, issued to Haaheim, discloses an exercise machine in which the user&#39;s feet slide back and forth on wheeled trucks while the arms push and pull pivoting lever members. 
     U.S. Pat. No. 4,838,543, issued to Armstrong et al., discloses a low impact exercise device which simulates stair climbing by means of pivoting lever members. 
     U.S. Pat. No. 3,747,924, issued to Champoux, discloses an oscillating pedal exercise device in which the user balances on pivoting lever members. 
     U.S. Pat. No. 4,563,001, issued to Terauds, discloses a portable exercise device which simulates stair climbing as well as arm exercises utilizing pivoting lever members. 
     U.S. Pat. No. 3,759,511, issued to Zinkin et al., discloses an adjustable friction type exercising device which simulates a running motion with pivoting lever members and supports for the chest and hands. 
     U.S. Pat. No. 4,600,187, issued to Schenker, discloses a stair climbing device with pivoting lever members. 
     U.S. Pat. No. 4,830,362, issued to Bull, discloses a stair climbing and arm exercise device utilizing pivoting lever members. 
     U.S. Pat. No. 4,477,072, issued to Decloux, discloses a bimodal exercise device which simulates both &#34;sitting down&#34; and &#34;standing up&#34; bicycle pedaling motions. 
     U.S. Pat. No. 4,519,603, issued to Decloux, discloses an exercise device which simulates a &#34;tanding up&#34; pedaling motion. 
     U.S. Pat. No. 4,934,690, issued to Bull, discloses a stair climbing and arm exercising device utilizing pivoting lever members. 
     As the aforementioned devices demonstrate, a need exists for a single integrated device which permits the simulation of stair climbing, cross country skiing and running and walking type exercise motions. 
     SUMMARY OF THE INVENTION 
     The present invention provides an apparatus of the type on which a person exercises. The present apparatus is a combined ski machine, stair stepper and treadmill. In the ski machine configuration, two foot locks or skates are individually slidable along generally horizontal bases or skate rails. An arm exerciser, which includes a central upright member, a chest pad and a pivoting arm exerciser tube that carries a cord and drum assembly is secured to a pedestal anchored at one end of the skate rails. When the device is used as a stair stepper, the skate rails are removed from the device. 
     The treadmill is attached to an endless loop or conveyor that passes around front and rear rollers supported at each end of the skate rail assemblies. The front roller axle also supports a flywheel mechanism which is at the base of the pedestal assembly. In the preferred embodiments, the stair stepper pedals are attached to either hydraulic or pneumatic cylinders which simulate a stair climbing motion. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of an apparatus constructed in accordance with the principles of the present invention; 
     FIG. 2 is a front elevation of the apparatus depicted in FIG. 1; 
     FIG. 3 is a perspective view of the apparatus of FIG. 1 with the addition of skate or foot pads used in a cross country skiing exercise; 
     FIG. 4 is a rear elevation of the apparatus of FIG. 3; 
     FIG. 5 is a top plan view of the apparatus depicted in FIG. 4; 
     FIG. 6 is a perspective view showing the underside of the skate or foot pad depicted in FIG. 5; 
     FIG. 7 is a perspective view showing the skate or foot pads of FIG. 6 mounted on the apparatus of FIG. 5; 
     FIG. 8 is a perspective view of a portion of the base of the apparatus depicted in FIG. 5 showing details of the securing arrangement for the foot pads of FIG. 7; 
     FIG. 9 is a perspective view of the apparatus of FIG. 1 showing the stair stepping levers extended for use in a stair stepping exercise; 
     FIG. 10 is a perspective view showing the stair stepping mechanism of one embodiment of the apparatus depicted in FIG. 9; 
     FIG. 11 is a perspective view showing details of a second embodiment of a mechanism used in the device of FIG. 9; 
     FIG. 12 is an enlarged left-side view of the rotational resistance means comprising a part of the apparatus depicted in FIG. 11; 
     FIG. 13 is a perspective view of a portion of the rotational resistance means depicted in FIG. 12 as mounted on the apparatus depicted in FIG. 9; 
     FIG. 14 is an exploded perspective view of the rotational resistance means depicted in FIG. 13. 
     FIG. 15 is an enlarged front view of a cone member comprising a part of the rotational resistance means shown in FIG. 12; 
     FIG. 16 is a perspective view showing details of the mounting arrangement of the cone clutch depicted in FIG. 15; and 
     FIG. 17 is a side elevation of the apparatus depicted in FIG. 1, with a portion broken away to reveal details of the flywheel mechanism. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, an exercise device built in accordance with the principles of the present invention is shown generally at 1. The device includes a substantially planar base portion 2 which is supported at a rearward end by pads 3 and 4, while the forward end is supported at a somewhat greater height by base supports 5 and 6. The result is that base portion 2 is inclined from a horizontal plane at a fixed angle within the range of 0° to 50°. 
     Base 2 is formed by side rails 7 and 8, which define an area between them occupied by tread 9. Tread 9 is formed as a continuous loop of a resilient material spanning substantially the entire width between rails 7 and 8, and is supported at the rear by spool 10 and is supported at its forward end by another spool or roller mechanism (not shown). Thus, a person standing on treadmill 9 may engage in a walking or running motion while the upper surface of treadmill 9 translates in a rearward direction, the person exercising thereby remaining in a substantially stationary position above base or deck 2. 
     In order to aid in the support and balance of the person exercising, a chest or stomach support 11 is provided. Support 11 is pivotably attached to pedestal 12 which is supported at the forward end of base 2. 
     Stomach support 11 pivots about hub 13 and may be stopped at a series of angular orientations controlled by the position of stops 14, 15, 16, 17, etc. At an opposite end of stomach support 11 are affixed hand holds 18, 19, 20 and 21, as well as padded support 22. A person using the apparatus 1 may either grasp any of the handles 18-21 and/or rest a portion of their torso against padded support 22 while walking or running on treadmill 9. 
     Resistance of the treadmill may be conveniently controlled by the user by manipulating knob 23, while the rate of exercise or other parameters may be conveniently displayed on indicators 24 and 25 mounted at the top of pedestal 12. Referring to FIG. 17, the flywheel 118 is seen to be interconnected to front axle 119 upon which treadmill 9 is suspended. Tension adjustment knob 23 is connected by bowden cable 120 to a tension adjustment lever 121. By extending the length of cable 121, the friction producing strap 122 is tightened around flywheel 118, thereby increasing the resistance perceived by a user of the treadmill. 
     Additionally, a person utilizing the treadmill 9 may also exercise the arms by manipulating cables 26 and 27 which may be grasped by handholds (not shown) when the cables are extended from drum 28. The resistance to movement of the cables 26 and 27 may be controlled by a person adjusting knob 29 which is mounted on drum 28. 
     Drum 28 is supported on pivoting arm 30, which pivots at its base 31. When use of the cables 27 and 26 is not desired, the entire drum/arm assembly 28/30 may be pivoted and stored within recess 32 which is formed within the front surface 33 of pedestal 12. 
     Referring now to FIGS. 3-8, a second configuration of the apparatus 1 is described. In the cross country skiing configuration, right foot pad 34 and left foot pad 35 are placed on treadmill 9. Footpad 34 includes a relatively resilient, high coefficient of friction foot engaging surface 36 and toe restraint 37 mounted at the forward portion of substantially planar surface 38. Footpad 34 is advanced along rollers which include one-way clutch mechanisms. 
     Affixed to the left side 39 of foot pad 34 is a rail engaging member 40. 
     As seen in FIG. 6, left foot pad 35 is formed in a substantially identical manner to right foot pad 34, except that rail engaging member 41 is affixed to the right side 42 of foot hold 35. 
     Toe restraint 43 is secured to planar member 44 by means of bolts 45, 46, 47 and 48. 
     At the forward end of foot pad 35 is affixed a spool or roller 49 incorporating a one-way clutch mechanism which is rotatably affixed to side walls 42 and 50 by axle 51. Similarly, a rear spool or roller 52 having a one-way clutch incorporated therein is affixed to the rear portion of foot pad 35 by means of axle 53. 
     As can be seen in FIGS. 6 and 8, the rail gripping member 41 is formed so as to have a T-shaped channel 54 and a substantially planar &#34;T&#34; flange 55. The flange 55 fits within groove 56 which is formed adjacent to side rail 7 of base member 2. A similar groove 57 is formed within left rail 8 and grasps rail engaging member 40 of left foot pad 34. 
     In operation, a person wishing to do a cross country ski exercise places their feet in foot pads 34 and 35 and slides their feet along tread 9, thereby simulating a skiing motion. As mentioned earlier, the footpads 34, 35 slide on rollers incorporating one-way clutch mechanisms such that rearward movement of either footpad disengages the clutch, thereby preventing rotation of the rollers. Thus, the rollers grip belt 9, causing belt 9 to move rearwardly. On the forward stroke, the rollers are free to turn, thereby rolling over the surface of belt 9. 
     As in the walking or running configuration, the user may grasp handles 18, 19, 20 or 21, or may rest a portion of their torso against pad 22 and grasp cables 27 and 28 in order to provide exercise for the arms. 
     Referring to FIGS. 9-11, a third configuration of the apparatus 1 is described. This third configuration simulates a stair climbing or stair stepping exercise In the stair climbing configuration, foot pads 34 and 35 have been removed from tread 9, although they may be slid to the rearward portion of tread 9, adjacent to spindle 10, if desired. 
     Right stair step 58 and left stair step 59 are shown after they have been pivoted downwardly from their storage position within pedestal 12. The relative positions of steps 58 and 59 are dictated by their interconnection to each other by means of strap 60, which passes over pulley 61. When fully depressed, one of the steps may come into contact with tread 9, and a small bumper 62, 63 is placed beneath each step surface to prevent marring tread 9. 
     In the first embodiment of the stair stepper mechanism 64, the steps 65 and 66 are affixed to a pair of tubular support members 67 and 68, respectively. The steps 65 and 66 are constrained to move within parallel planes due to the fact that each has an end 69 and 70 pivotably attached to a single axle 71. The axle is secured in place by slanted bracing members 72 and 73, which have base ends 74 and 75 secured to rail 76. 
     Rail 76 may be stabilized in a variety of ways, but in one embodiment the first end 77 is secured to orthogonal rail 78 while second end 79 is secured to orthogonal rail 80. A cross member 81 passes between rail 78 and 80 to provide additional stability. 
     Attached to the ends 82, 83 of the orthogonal members 78 and 80, and opposite rail 76, are vertical supports 84 and 85, which join at horizontal cross member 86. 
     The upper ends 87 and 88 of sloping support members 72 and 73 are affixed to horizontal cross member 86, thereby providing a secure framework for stair stepping subassembly 64. 
     In order to provide the appropriate resistance to simulate a stair stepping exercise, the stair step supports 67 and 68 are constrained in their movement by hydraulic or pneumatic cylinders 89 and 90. The lower end 91 of cylinder 90 is clamped or otherwise affixed along support 68 in a region relatively nearer to end 70, such that cylinder 90 assumes a substantially vertical orientation. The upper end 92 of cylinder 90 is attached to axle 93 which passes through sloping support members 72 and 73 and is attached at opposite ends to the upper end 94 of cylinder 89. The lower end 95 of cylinder 89 is attached near pivoting end 69 of the support rod 67, and also assumes a near vertical orientation. The upper ends 90 and 92 of the cylinders 89 and 90 are free to pivot about axle 93, with one cylinder being extended while the other cylinder is compressed during the reciprocating stair stepping motion. The strap 60 is clamped to supports 67 and 68 at a point relatively near the foot steps 66 and 65. 
     Referring to FIG. 11, a second embodiment 96 of the apparatus 1 may be seen. The brace assembly is somewhat modified such that a relatively smaller rail 97 is rigidly affixed between orthogonal members 78 and 80. A single sloping brace 98 passes between rail 97 and cross bar 99, cross bar 99 being supported between vertical members 84 and 85. 
     Extending upwardly from cross member 81 are vertical members 100 and 101 which support horizontal axle supports 102 and 103 respectively. The horizontal supports 102 and 103 have a first end 105 affixed to vertical members 100 and 101, respectively, while second ends 106 and 107 are rigidly affixed to a lower end of vertical supports 85, 84 respectively. 
     Rotatably secured between horizontal supports 102 and 103 is an axle 108, to which are rigidly secured steps or pedals 58 and 59. Axle 108 is supported near its mid-region 110 by cone resistance brace 111, which has an opposite end secured to sloping support member 98. 
     Affixed to either side of clutch support 111 are conical resistance mechanisms 112 and 113, the operation of which will now be described. 
     Referring to FIGS. 12, 14 and 15, in a preferred embodiment the conical resistance mechanism 112 includes a fixed friction member 114 secured relative to the axle 108 by means of clutch support member 111, which is rigidly secured to sloping support member 98. The fixed friction member 114 has a conical internal surface 115 that is coated with a plastic known in the art as &#34;ultra-high molecular weight polyethylene.&#34; The conical internal surface 115 faces rearward from the support bracket 111 and is designed to mate with a forwardly facing conical external surface 116 on a coaxially aligned rotatable friction member 117. The conical external surface 116 is coated with rubber, such that rotation of the rotatable friction member 117 relative to the fixed friction member 114 is resisted by a frictional force between the rubber coated conical external surface 116 and the plastic coated surface 115. 
     A shaft member 108 is coaxially aligned relative to the fixed friction member 114 and the rotatable friction member 117 and passes through centrally located openings therein. The shaft member 108 has a first end that is rigidly secured to the support bracket 111 and an opposite, second end that passes through second clutch 113. A large metal washer (not shown) is rigidly secured to the second clutch 113, and a large nylon washer (not shown) is positioned between the large metal washer and the tube member 108. That portion of the shaft member 108 which passes through the rotatable friction member 117 is substantially smooth about its circumference. 
     In the embodiment shown in FIG. 15, upon rotation of the shaft member 108 in a first shaft direction S1, the rotatable friction member 117 rotates in conjunction with the shaft member 108 and relative to the fixed friction member 114, thereby providing some degree of resistance to rotational movement. 
     Upon rotation of the shaft member 108 in a second shaft direction S2, opposite the first shaft direction S1, the shaft member 108 again rotates in conjunction with the rotatable friction member 117, and relative to the fixed friction member 114, again providing some degree of resistance to rotational movement. 
     By providing resistance to both downward and upward motion, a reciprocating stair stepping motion is provided. As can be seen by reference to FIG. 11, the downward motion of step 59 causes belt 60 to raise step 58, while the lowering of step 58 will necessarily cause belt 60 to raise step 59. 
     When use of the stair stepping exercise is not desired, each step may be individually folded upwardly into the pedestal 12. At that time, the device may be used either as a treadmill, or, by placing the foot pads 34 and 35 within rails 56 and 57, a cross country skiing exercise may be simulated. Arm 30 may be raised or lowered during any of the three exercises. 
     Other embodiments of the invention will be obvious to those skilled in the art. Thus, the change of shape of either the treadmill, pedestal, foot pads, or the tubular arm 30 are changes of form, not substance, and do not affect the basic function of the single device which can assist in the performance of three materially different exercises. Such changes are within the scope of the claims which follow.
An exercise device (1) capable of performing three discrete exercise activities, and including a treadmill (9) suitable for simulating a running or walking exercise, and further including a pair of slidable foot restraints (34, 35) mounted within rails (56, 57) adjacent to the treadmill (9) in order to simulate a cross country skiing exercise. A pair of reciprocating, pivotable foot paddles (58, 59) are cooperatively attached in a first embodiment to pneumatic cylinders (89, 90), while in a second embodiment are cooperatively attached to conical resistance mechanisms (112, 113) so as to simulate a stair climbing activity. A pivotable torso support (11) is provided to assist the balance of a person performing any of the three exercise activities.