Exercise machine

An exercise machine for simulating the stroke of a canoe paddle is disclosed. A tube is pivotably mounted on the longitudinal axis of a frame. A paddle-like shaft is pivotally connected to a frictional resistance element sidably mounted on the tube. The frictional resistance element provides greater resistance to movement in one directional sense than to movement in the other directional sense to that the stroke and return stroke of a canoe paddle can be simulated. The frictional resistance element is formed of an outer member having a conical inner surface and an inner member having a conical outer surface, the inner member being fabricated into two halves on either side of a longitudinal plane. The tube passes through a longitudinal bore of the inner member, the bore being lined with frictional material. Forces acting to move the frictional resistance element in a first direction cause the outer member to compress the halves of the inner member as a function of the cone angle. The compression of the halves of the inner member increases the frictional force between the tube and the inner member, thus resisting further movement. The compression is eliminated for movements in the opposite directional sense.

BACKGROUND OF THE INVENTION 
1. Field of the Invention: 
The present invention relates to an improved exercise machine having 
components with increased resistance to movement depending upon the 
direction of movement. More particularly, the present invention relates to 
a device for simulating the paddling of a canoe and for determining the 
quantity and quality of work performed during an exercise session. Such an 
exercise device can be part of an overall program of physical conditioning 
in which strength and stamina may be measured over time or in comparison 
to other individuals. 
2. Description of the Prior Art: 
Exercise machines have been known in the prior art. These devices provide 
resistance to movement and increased the strength and stamina of the user. 
Rowing or paddling a canoe is an excellent form of exercise for 
strengthening the upper body, particularly the arms, improving 
cardio-vascular functions and for training for competitive events. 
However, it is not always convenient for an individual to paddle a canoe 
or to row a boat and thus attempts have been made to design an exercise 
machine which will simulate the paddling of a canoe or the rowing of a 
boat. The paddling of the canoe and the rowing of the boat have the common 
feature that the resistance to movement varies depending upon the 
direction of movement. That is, in such rowing or paddling, resistance is 
great during the paddle stroke but is minimal during the return stroke. 
Thus, exercise machines which simulate the paddling or rowing motions must 
provide such differential resistance. 
For example, U.S. Pat. No. 228,277 to Saunders discloses an exercising 
machine that simulates the rowing of a boat. This patent provides a 
differential resistance by use of an air pump. The air pump has a working 
stroke that requires effort and a return stroke that is practically free 
of effort. However, such an air pump is costly and easily broken and is 
considered to be unsatisfactory. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an exercise machine 
which offers differential resistance to motion depending upon the 
direction of movement. 
It is another object of the present invention to provide an exercise 
machine which simulates the paddling of a canoe. 
It is another object of the present invention to provide an exercise 
machine which provides data for permitting a user to analyze the work 
performed during an exercise session. 
It is a final object of the present invention to provide an exercise 
machine which converts physical exercise into heat and measures the 
produced heat so that the quantity and quality of work performed can be 
analyzed. 
The present invention achieves the above objects in a structure which 
includes a support frame upon which the user can sit during an exercising 
session. A pair of support arms are pivoted to either end of the frame 
along the longitudinal axis of the frame. The other ends of the support 
arms carry an elongated tube so that the tube can rotate to either the 
left or right side of the frame by pivoting about the longitudinal axis 
thereof. A frictional resistance element of the machine is slidably 
mounted on the tube and is constructed so that it provides a low 
resistance to movement in one directional sense along the tube but a much 
higher resistance to movement in the opposite directional sense. A 
paddle-like shaft is pivotally fixed to the frictional resistance element. 
Thus, a user sitting upon the frame can simulate the stroking of a canoe 
paddle by grasping the paddle-like shaft and applying the forces to the 
frictional resistance element through the shaft, thereby reciprocating the 
frictional resistance element along the tube. Several strokes of the 
paddle-like device can be performed on, for example, the left side of the 
user, after which time the tube and frictional resistance element are 
pivoted to the right side of the user for further strokes, thus simulating 
the motions when paddling the canoe. 
The frictional resistance element consists of a truncated conical inner 
member housed within a coaxial outer member. The inner member is 
bifurcated on either side of a plane extending along the axis of the inner 
member so as to form two inner member halves. The inner member includes a 
longitudinal bore within which the tube is positioned. The longitudinal 
bore of the inner member is lined with frictional material, such as wool 
pads, so that the bifurcated halves of the inner member can slide along 
the length of the tube with frictional contact provided by the frictional 
material. 
The outer member is hollow. It has a conical inner surface whose slope is 
identical to that of the outer surface of the inner member so that the 
outer member can snugly fit around the inner member with surface contact 
along the entire length. An axial force on the outer member in the 
direction of the base thereof will thus tend to move both the outer and 
the inner members in that direction. However, due to the conical slope of 
the inner surface of the outer member and the outer surface of the inner 
member, a portion of the axial force will be converted into a radial 
component compressing the bifurcated halves of the inner member, the 
magnitude of this radial component being a function of the cone angles. 
Thus, if a user "strokes" with the paddle, e.g. moves the paddle toward 
himself in the direction of the base of the cones, the bifurcated halves 
of the inner member will compress against the tube, increasing the 
frictional force between the frictional material and the tube so that the 
resistance to motion will be increased. 
Upon a "return stroke", i.e. the movement of the paddle forward away from 
the user and in the direction of the apex of the cones, the outer member 
will tend to move away from the inner member so that the compressive 
component upon the halves of the inner member will be eliminated. 
Accordingly, the frictional resistance between the frictional material and 
the tube will dramatically decrease and there will be a noticeably lower 
resistance to movement of the frictional resistance element during the 
return stroke. 
The return stroke also has the effect of causing the inner and outer 
members to tend to separate in the axial direction. Thus, the present 
invention provides means for maintaining the inner member housed within 
the outer member. This is provided by a half-washer fixed to the apex and 
of one of the inner member halves and extending radially outward so that 
it can engage the apex end of the outer member. Movement of the outer 
member in the direction of the apex of the cones during a return stroke 
will therefore cause the apex end of the outer member to engage the 
half-washer and thus carry one of the halves of the inner member in the 
same direction. A washer fixed to the other end of the inner member half 
engages the base end of the other inner member half and moves this other 
half in the apex direction as well. 
Accordingly, exercise with the machine of the present invention consists of 
sitting upon the frame seat with the support arms extending to either the 
left or the right side, performing several strokes and return strokes and 
switching the support arms to the opposite side at regular intervals, thus 
simulating the paddling of the canoe. During the stroking of the paddle, 
physical work is performed by movement of the frictional resistance 
element in opposition to the frictional force between the frictional 
resistance element and the tube. This movement in opposition to frictional 
resistance converts the energy of the user into heat which raises the 
temperature of the tube. The tube is formed of a material having good heat 
transfer properties and the temperature of the tube will thus rise in a 
fairly uniform manner. According to the present invention, a temperature 
sensor, such as a thermistor, is positioned within the tube for measuring 
the temperature of the tube. The thermistor is electrically connected to a 
digital thermometer mounted on the frame and having a readout visible to 
the user. The user can measure the maximum temperatures which the tube 
reaches during exercise, thus giving an indication of the strength of the 
strokes. The user can also plot the temperature over time, and the rate of 
decline of temperature over time, thus determining his stamina. Plots of 
temperature over time can be compared during the extent of the exercise 
program or amongst different individuals, for making comparisons. A strip 
chart recorder or microprocessor could be employed to plot the time versus 
temperature during an exercise session.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The present invention will now be described with reference to the 
accompanying drawings in which like reference numerals will identify the 
same or similar parts throughout the various views. 
As best seen in FIG. 1, the exercise machine of the present invention is 
mounted upon a frame 2 which is preferably constructed of lightweight 
steel or aluminum tubing having a circular or rectangular cross-section. 
The main frame member 4 extends from the front to the back of the machine 
along the longitudinal axis 6. The main frame member 4 is supported by a 
pair of legs 8 and leg bases 10 mounted to the main frame adjacent either 
end thereof. The frame members can be secured to one another by any 
desired method, such as by welding or bolting. 
A seat post 12 is mounted to the top of the main frame member near the rear 
end (right end in FIG. 1) thereof. A seat 14 is mounted on the seat post. 
The seating position can be fixed as is shown in FIG. 1, but could also be 
adjustable in height or along the length of the main frame member. 
At either end of the main frame member is mounted a support brace 16 which 
extends transverse to the longitudinal axis 6 of the main frame member. 
Support rods 20 are rotatably held by each of the support braces for 
rotation about axis 6. The support rods 20 may be rotatably secured to the 
support braces by bolt 18, or by any other desired means. Stops such as 
plate extensions 22 are secured to the underside of the ends of each 
support brace 16. These stops limit the angle rotation of the support rods 
to 180 degrees. Thus, the support rods can pivot from the positions shown 
in FIG. 1 wherein they extend horizontally to the left of a user sitting 
in the seat 14 and facing the front of the exercise machine, to a position 
in which they extend horizontally to the right of the user. Accordingly, 
paddling can be simulated on either the right or left side of the user by 
pivoting the supports rods 20 about the axis 6. 
Secured to the distal ends of each of the support rods, and extending 
therebetween, is a thin-walled rigid structural tube 24 formed of a 
material having good heat transfer characteristics, such as steel or 
aluminum. The frictional resistance element, identified generally as 26, 
is slidably mounted upon the tube 24 for sliding movement along the axis 
28 of the tube 24. A paddle-like shaft 30 having a handle 32 is pivotally 
mounted to a lug 34 extending from the frictional resistance element. The 
shaft 30 is rotatably mounted on the lug 34 about an axis transverse to 
the axis 28 of the tube, by means of a screw 36 passing through a hole 38 
of the lug. 
The frictional resistance element is best seen in FIGS. 2 through 4. It 
consists of an outer member 40 to which the lug 34 is fixed and an inner 
member coaxially housed within the outer member. As best seen in FIG. 3a 
and 3b, the inner member is bifurcated on either side of a plane extending 
longitudinally of the axis of the inner member, thus forming a first inner 
member half 42 and an identical second inner member half 44. 
As best seen in FIGS. 2 and 4, the outer member 40 is in the form of a 
hollow truncated cone having a base end 46 and an apex end 47. Although in 
the preferred embodiment both the inner and outer surfaces of the outer 
member are conical with the same slope .theta., only the inner surface 
need be conical; the outer surface of the outer member could be 
cylindrical or of some other form. 
The halves 42 and 44 of the inner member are normally positioned within the 
outer member 40 with the planar faces 46 and 48 facing one another, and 
the planer faces 50 and 52 facing one another so that the inner member 
halves together form a truncated conical outer surface within the interior 
of the outer member. The conical slope .theta. of the outer member inner 
surface and the inner member outer surface are identical so that the inner 
member can seat itself with surface contact within the outer member, as 
best seen in FIG. 4. When so seated, the halves 42 and 44 remain separated 
by a gap 54. 
The inner member halves 42 and 44 each define the halves 56 and 58 of a 
cylindrical bore extending through the entire length of the inner member 
coaxial with the longitudinal axis thereof. The surfaces of the bore 
halves 56 and 58 are lined with a wool pads 60 and 62, such as frictional 
material affixed to the walls of the bore with glue. 
The inner member halves are mounted on the tube 24, as shown in FIG. 4 so 
that the tube 24 fits within the longitudinal bore and in contact with the 
frictional material 60 and 62. The inner member halves 42 and 44, together 
forming an inner conical member, remain separated by the gap 54 which is 
maintained by the contact of the frictional material with the tube 24. 
The inner and outer members 40, 42 and 44 are preferably formed of 
polyurethane elastomers but could instead be formed of any hard 
engineering thermoplastics. As best seen in FIG. 4, the end of the rod 30 
is bifurcated into two arms, only one of which 60 is shown, which fit on 
either side of the lug 34 adjacent to the hole 38 for passage of the screw 
36 so that the shaft 30 is pivotably fixed to the lug 34. 
The frictional resistance element is positioned upon the tube 24 with the 
base end 46 facing towards the back (to the right in FIG. 1) of the frame. 
A force acting in the direction 62 (FIG. 4), such as might be imparted by 
a stroking movement applied to shaft 30, will tend to cause the outer 
member 40 to move in the direction 62. This movement of the outer member 
40 transmits a force having radial and axial components to the inner 
member, the proportions of the radial and axial components being a 
function of the angle .theta.. Thus, the movement of the outer member 40 
in the direction 62 tends to radially compress the halves 42 and 44, 
particularly at the frictional material 60 and 62, due to the radial 
component of the force transmitted from the outer member 40. The increased 
compressive forces between the frictional material 60 and 62 and the 
surface of the tube 24 increases the frictional resistance of the 
frictional resistance element 26 to movement along the tube. As the gap 54 
decreases, the inner member axially moves slightly with respect to the 
outer member 40 and fits more snugly within the outer member so that the 
radial pressure on the inner member is maintained. Thus, movement of the 
frictional resistance member in the direction 62 will be opposed by a 
strong frictional resistance force resulting from the frictional material 
compressed against the tube 24. 
The magnitude of the resultant resistance force to movement in the 
direction 62 is a function of the coefficient of friction between the tube 
24 and the frictional material, as well as the angle .theta.. In 
particular, if the angle .theta. is greater than the angle of the 
coefficient of friction, it will be impossible to move the frictional 
resistance element in the direction 62. The angle .theta. should therefore 
be selected so as to provide the desired degree of resistance to movement. 
It has been found that an angle of 14 degrees provides good resistance 
when using a steel tube 24 with wool friction pads. 
As discussed above, movement of the frictional resistance element in the 
direction 62 increases the frictional force between the frictional 
material and the tube 24. Thus, moving the shaft 30 in the direction 62 
simulates the stroke of a canoe paddle against the resistance of water. 
The return stroke of the paddle is simulated by moving the paddle in the 
direction 64 (to the left in FIG. 1) and must offer reduced resistance 
since a canoe paddle is normally out of the water during the return 
stroke. Referring to FIG. 4, a force in the direction 64 imparted on the 
outer member 40 by the shaft 30 causes the inner conical surface of the 
outer member to separate from the conical halves of the inner member, thus 
eliminating the increased radial compressive forces between the tube 24 
and the frictional material 60 and 62. Therefore, resistance to the 
movement of the frictional resisting element 26 is greatly reduced in the 
direction 64, effectively simulating the return stroke of a canoe paddle. 
However, movement of the outer member 40 in the direction 64 also tends to 
axially separate the inner and outer members and thus some means is 
necessary for maintaining the inner member housed within the outer member 
40 as the outer member moves in the direction 64. According to the present 
invention, a half-washer 66 is fixed, as by screws, to the apex end of one 
of the inner member halves 42. The half-washer 66 extends radially outward 
from the outer surface of the inner member half 42 so that when the outer 
member 40 moves in the direction 64 by a distance 68, the apex end 47 of 
the outer member will make contact with the washer 66 and carry the inner 
member half 42 in the direction 64. The distance 68 is selected such that 
the resulting relative axial movement between the outer member and the 
inner member permits the inner member halves 42 and 44 to radially 
separate sufficiently for the resistance to movement in the direction 64 
to be practically eliminated. A washer 70 fixed to the base end of the 
inner member half 42 makes contact with the base end of the inner member 
half 44 and moves the inner member half 44 in the direction 64 together 
with the inner member half 42. 
The frictional opposition of the movement of the frictional resistance 
element in the direction 62 produces heat which raises the temperature of 
the tube 24, the produced heat being proportional to the work performed by 
the user. Because the tube 24 is formed of steel or aluminum, which have 
good heat transfer properties, the temperature of the thermistor 72, which 
is located within the tube 24 preferably at a point near the front end of 
the tube is raised. The increased temperature sensed by the thermistor 72 
is registered by the digital thermometer 74 to which the thermistor is 
electrically connected. Thus, by noting the temperature of the tube 24, 
one can assess the power being generated by a user. The stamina of the 
user can be charted by noting the rate of decline of the temperature over 
time. Time versus temperature graphs of the user may be plotted, either 
manually or with the aid of a strip chart or microprocessor for comparing 
the performance of a user over time or for comparing the performances of 
several users. 
Obviously, numerous modifications and variations of the present invention 
are possible in light of the above teachings. It is therefore to be 
understood that within the scope of the appended claims, the invention may 
be practiced otherwise than as specifically described herein.