Exercise rowing machine

An exercise rowing machine uses a flywheel as a resistance member and has cam sector arms which are pivoted to rotate with the machine's oars. A bicycle-type chain is pulled to drive a sprocket drive on the flywheel when the oars are stroked. The arcuate shape of the cam sector arms provides a constant resistance force to the stroke of the oars over the oar sweep. The position of the foot stretcher plate is adjustable. A shroud for the flywheel has an adjustable throttle or shutter to control air flow and thus adjust the amount of resistance.

BACKGROUND OF THE INVENTION 
This invention pertains to exercise apparatus, and more particularly to 
exercise rowing or sculling machines The invention is more specifically 
directed to a rowing or sculling machine which simulates the sweeping, 
rowing motion characteristic of a rowing or sculling shell, and which 
imparts a resistance to the pull of the oars similar to that of an actual 
rowing or sculling shell. 
Typical rowing machines have employed friction brakes or hydraulic 
resistance devices to simulate the drag resistance met by the oars in 
water. In these machines, the friction or hydraulic resistance devices are 
incorporated as part of an oar lock and form the pivot for the simulated 
oars. Typical rowing machines are illustrated in U.S. Pat. Nos. 3,528,653 
and 1,111,269. These rowing machines provided, at best, a crude sensation 
of rowing, and it was difficult or impossible to set the resistance 
accurately. The amount of resistance in these machines can change over 
time, as the device ages. Because it is not possible to control the 
resistance to the sweep of the oars, and thus cannot program exercise 
stress for the individual, these rowing machines do not permit optimum use 
in an exercise training program. 
A different approach to a stationary rowing machine was taken in U.S. Pat. 
No. 4,396,188. With that rowing machine, a flywheel with air vanes 
translates air movement resistance into resistance to a rowing stroke-like 
motion. The machine of U.S. Pat. No. 4,396,188 operates by a chain which 
is pulled to rotate the flywheel. The subject rower sits on a sliding seat 
and "rows" by pulling on a handle connected to one end of the chain. A 
one-way clutch allows the chain to be spring-returned without interfering 
with the flywheel rotation. 
While the above device provides accurate and repeatable resistance, it is 
not possible to use a true sweeping motion, so the sensation is not truly 
that of rowing or sculling. Moreover, because the hands are kept together 
on the handle, and are not spread at the beginning and end of each stroke, 
this machine does not exercise all of the muscle groups that are used in 
rowing, particularly those of the chest and shoulders. 
OBJECTS AND SUMMARY OF THE INVENTION 
It is an object of this invention to provide a rowing or sculling exercise 
machine that surpasses the devices of the prior art in the simulation of 
rowing or sculling action, and which avoids the drawbacks of the art. 
It is a more particular object of this invention to provide a rowing or 
sculling exercise machine that has a realistic sweeping rowing motion, and 
that provides an even, consistent resistance to the pull of the oars 
throughout their sweep. 
According to an aspect of this invention, a rowing or sculling exercise 
machine as provided for a human subject to be seated thereon to simulate 
rowing or sculling motion. The machine imparts a resistance to the rowing 
motion similar to the resistance of a boat being rowed or sculled on 
water. The rowing machine of this invention has a generally horizontal 
frame, a seat, a track on which the seat slides permitting longitudinal 
motion of the seat relative to the frame, a foot rest plate or foot 
stretcher for positioning the subject's feet, and an oar or preferably a 
pair of oars having respective oar locks mounted laterally of the frame, 
with the oars being pivotal relative to the associated oar locks to 
simulate the rowing or sculling motion. Sector arms, or similar cam 
members, are mounted to rotate with the oars about respective pivot 
points, and define an arcuate cam surface. A flywheel is journaled on the 
frame and includes air vanes or equivalent means for imparting a 
resistance to its rotation. A drive chain assembly has a drive chain and a 
drive sprocket mounted on the flywheel to rotate the same in one 
direction. A non-stretching cable is affixed to the cam means cam members 
to ride over their arcuate surfaces, and is also connected to pull the 
drive chain. An elastic cord or equivalent resilient return member is 
connected to the drive chain to return the chain and the cable when the 
oars are rotated reversely. The oars, the cam members, the cable, the 
chain, the flywheel, and the return means are arranged so that the human 
subject pulling on the oars meets a generally even resistance transmitted 
to the oars from the flywheel, and this even resistance exists throughout 
the oar stroke. In the preferred embodiment, the flywheel is mounted 
horizontally beneath the frame, and rearwardly of the subject seated on 
the machine. Also in the embodiment described herein, the oar locks are 
arranged to permit rotation of the oars about their own axis at the ends 
of the oar strokes, to simulate feathering of the oars. Preferably, the 
cam arrangements are such that their arcuate surfaces are at an equal 
radius from the pivot points substantially over their operative lengths, 
so that the resistance to the pull of the oar is substantially constant 
over the sweep of the oar's stroke. 
The above and many other objects, features, and advantages of this 
invention will be more fully understood from the ensuing detailed 
description of a preferred embodiment, which should be considered in 
connection with the accompanying drawing.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
With reference to the drawing figures, a rowing or sculling machine 10 is 
illustrated as an example embodying the principles of this invention, and 
has a generally horizontal frame 12 formed of a longitudinal bar 14 and a 
cross bar 16 extending transversely thereto. The vertical support leg 18 
is affixed to the aft end of the longitudinal bar 14, and has a transverse 
foot 20 for resting on the floor. Another support leg 22 is affixed to the 
bar 14 toward the fore end thereof, and has a tee foot 24 in contact with 
the floor. A seat 26 has rollers 27 which track on rails 28, the latter 
being attached on supports 30 to the fore portion of the longitudinal 
frame bar 14. A foot stretcher or foot rest plate 32 is adjustably mounted 
on the bar 14 by means of an adjustable mount 34, which permits the foot 
position of a human subject S seated on the set 26 to be adjusted 
according to the subject's individual physique. 
A pair of oars 36 are provided, here, having round cross-sectional shafts 
and with handles 38 at their free ends Oarlock assemblies 40 are provided 
at the ends of the crossbar 16, for mounting the oars 36. Each oarlock 
assembly 40 has a vertical sleeve 42 affixed to the end of the crossbar 
16, and a post 44 within the sleeve 42 and rotatable therewith. A square 
tube retaining frame 46 affixed to the top of the post 44 retains the 
shaft of the oar 36, the outboard end of frame 46 has a slot 50 which 
relieves protuberance 52 on the end of the oar 36, the latter traveling 
upwards and downwards over the length of the slot 50. A spring 54 attached 
to the protuberance 52 serves as a counterpoise for the oar 36 and is 
connected to the protuberance 52 and to a lower end of the sleeve 42. 
Extending beneath the frame 12 from the lower end of the post 44 is a 
sector arm 56, here, configured of a constant radius design. The sector 
arms 56 each have a radial bar 58 that is affixed at one end to rotate 
with the post 44, the bar 58 bearing a cam member 60, the latter having a 
grooved circumferential cam surface 62. In this embodiment, the cam 
members 60 are circularly curved, and the surface 62 is the arc of a 
circle. However, in alternative embodiments, other curved surfaces could 
be employed for the surface 62, depending on the desired resistance 
characteristic for the oars 36. 
A cord 64 or equivalent flexible member of a non-stretching material is 
affixed to each of the cam members 60 and travels over the cam surface 62 
thereof. The cord 64 extends over a pulley 66 disposed on the support leg 
18, and then forward to a guide pulley 68 beneath the longitudinal bar 14, 
then aft again to another pulley 66 disposed also at the support leg 18, 
and from there to the other cam member 60. A bicycle-type drive chain 70 
has one end connected to the guide pulley 68, and serves to drive a 
horizontal flywheel 72 disposed between the tee foot 24 and the fore end 
of the longitudinal bar 14. The flywheel 72 has a vertical axle 74 which 
is attached to a pair of mounts 76 disposed respectively on the bar 14 and 
the foot 24, and has a sprocket 78 on which the chain 70 rides. A 
plurality of air vanes 80 are disposed about the flywheel 70 and are 
preferably arranged to pull air from above and discharge beneath. The 
chain 70 continues over an idler sprocket 82 and then to an anchorage 84 
at the fore portion of the bar 14. A shock cord or bungie cord 86, or 
other resilient similar member is connected at one end to the idler 
sprocket 82 and provides a return force onto the chain 70. In this 
embodiment, the cord 86 extends beneath the bar 14 and then out and across 
underneath the cross bar 16, over several guide rollers (not shown). Also 
provided are a chain guard 88 at the fore portion of the frame 12 over the 
chain 70, and a flywheel cage or guard 90 around the flywheel 72. This 
guard 90 shown only symbolically here, can be arranged as an air guide to 
deflect air from the vanes 80 in a downwards direction. As shown in FIG. 
5, an adjustable throttle or shutter opening 92 on top of guard 90 
effectively throttles intake air to alter resistance, thereby changing 
resistance on the oars 36. 
The shroud or guard 90 has a circumferential member 94 directing the air 
axially downward, and protecting persons in the vicinity from 
inadvertently coming into contact with the moving flywheel. The shutter or 
throttle 92 consists of a group of radial fixed plates 96 and movable 
plates 98, the latter being movable to define the opening size. Of course 
many other shutter or throttle mechanisms could be employed to control air 
flow. A control (not shown) permits a rower to adjust the throttle 
opening. 
As shown in FIG. 6, the aerobic effect, i.e. the amount of effort involved 
in rowing, depends both on the rowing speed and on the degree of opening 
of the shutter on throttle 92. This is because the effort is related to 
the air flow speed, and the air flow varies both with the rowing speed 
(i.e., flywheel speed) and the degree of opening, as indicated in the 
chart of FIG. 7. 
The human subject S is seated on the seat 26, in a fashion as he would be 
seated in a scull, rowing shell, or boat, that is, facing aft with his or 
her feet on the foot stretcher 32 and with his or her hands on the oar 
handles 38. By pulling on the oars 38, the post 44 and cams 60 of the 
sector arms 56 are rotated, and this pulls the cord 64, which in turn 
pulls the chain 70 and rotates the flywheel 72. The vanes 80 provide a 
fairly constant resistance for any given flywheel speed, and provide more 
resistance for higher speeds. The rowing machine assembly as illustrated 
simulates true rowing motion, including a reaching motion on the return of 
the oars. This stretches the muscles of the shoulder and chest, while the 
sweeping draw or pull of the oars 36 strengthens the muscles of the 
shoulders and the back. 
An alternative version machine 10 can be provided for sweep rowing, i.e., 
with just the right oar 36 or just the left oar 36 gripping the handle 38 
with both hands. The subject S should row for a time on each side so as to 
exercise evenly. 
The oars 36 can be rotated 90 degrees at the ends of the arc of the stroke 
to simulate feathering of the oars. Still further, the movable foot 
stretcher 32 adjusts for rowers or subjects of different height who might 
be using the machine 10, and allows the foot position to be selected 
relative to the oar pivot points defined by the lock assemblies 40. 
Not shown are a sensor for sensing the rotational speed of the flywheel 72 
and the number of rotations (equivalent to the distance rowed or sculled). 
These data together can be fed to an ergometer recorder (also not shown 
here) to measure the amount of exercise stress to the human subject S. 
The principles of this invention could also be employed to a tandem 
(two-position) rowing machine, to a machine with a friction-type flywheel 
rather than a vane-type flywheel, or to a machine which uses a belt or 
cord, rather than a chain, to drive the flywheel. 
Another important improvement of the exercise machine 10 of this invention 
is its horizontal disposition of the flywheel 72 behind the subject S and 
within the protective shroud 90. This arrangement is significantly more 
safe to other persons in the exercise area, as well as to the subject S, 
than previous flywheel-type rowing devices. 
An alternative air shutter arrangement is shown in FIG. 8. There, a shroud 
190 has a circumferential member 194 that continues as upper surface 195 
over the flywheel (concealed in this view) up to a rectangular, screened 
air inlet 198, and downwards to a cage 197 or the like, which extends 
about another two inches beneath the shroud to protect the users fingers 
and toes from the spinning flywheel and the other moving parts. A sliding 
air inlet control plate 196 is moved fore-and-aft beneath the seat rails 
128 to adjust the opening size of the air inlet 198 and thus control the 
amount of resistance. The frame 112 and the rear support leg 122 are 
included in this view to show the orientation of the shroud 190. The flow 
of air as indicated by the arrows is vertically downward into the inlet 
198 and out beneath the flywheel. Additional screened openings can be 
placed on the upper surface 195 of the shroud 190. 
While a particular embodiment has been described herein above, this 
embodiment was given by way of example, and not for purposes of 
limitation, and it should be apparent to those skilled in the art that 
many modifications and variations thereof are possible without departure 
from the scope and spirit of this invention, as defined in the appended 
claims.