COMMISSIONER'S DECISION
Obviousness: Hydrostatic Drive For Tractor Vehicle
Hydrostatic transmissions were used in crawler type vehicles where the
motion is primarily forward and reverse. The advantages of using it in a
four wheel skid steer vehicle were not that apparent. Final Action-Reversed.
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This decision deals with a request for a review by the Commissioner of
Patents of the Examiner's Final Actions dated May 13, 1977 on application
224,388 (Class 180-3) and Feb. 2, 1977 on application 224,390 (Class 180-3)
The applications were filed on April 11, 1975, in the name of Clark
Equipment Company, and are entitled "Tractor Vehicle With Hydrostatic
Drive Means". The Patent Appeal Board conducted a Hearing on September 27,
1979, at which Mr. D.McKenzie, Mr. J. Bauer, the inventor, and Mr. E. Ruf,
the applicant's United States attorney, were present.
These applications are divisionals of application 126,196 which issued
to patent number 979,371, dated Dec. 9, 1975. There were also two other
divisional applications filed, namely 224,387 and 224,389, which have
issued as patent numbers 985,179 and 985,641, respectively.
The applications before us relate to a compact four-wheel tractor-type front-
end leader having pairs of driven wheels on opposite sides of the vehicle.
a hydrostatic transmission arrangement drives the wheels on one side of the
vehicle independently of the other side, and Figure 1 of the application
indicates what is involved.
(See formula 1)
In the Final Actions, the examiner rejected the claims as containing no
patentable subject matter in view of the following patents:
Canadian 747,216 Nov. 29,1966 Melroe et al
U.S. 2,941,609 June 21,1960 Bowers et al
U.S. 3,024,858 Mar. 13,1962 Davis et al
U.S. 3,161,245 Dec. 15,1964 Thoma
U.S. 3,416,623 Dec. 17,1968 Boone
The Melroe patent, which is owned by the applicant, is the vehicle used in
these applications except that the transmission is a clutch-driven V-belt
arrangement.
.
Thoma and Bowers each use a hydrostatic transmission for a track type vehicle.
Boone shows a hydrostatic transmission for an aircraft towing vehicle. Adams
wheeled vehicle drive has a sprocket and chain arrangement in combination
with the V-belt drive.
In the Final Action of application 224,388, the examiner stated (in part):
"The primary reference is the Melroe patent which shows a
self propelled four wheel drive vehicle having independently
driven wheels on opposite sides of the vehicle, the space
transversely between the pairs of wheels being greater than
the space longitudinally between each wheel, and a pair of
compartments containing oil reservoirs.
The Bowers, Davis, Thomsa and Boone patents each show inde-
pendent hydrostatic drive on opposite sides of a vehicle.
That such a well known hydrostatic drive could be used in a
vehicle such as applicant's or the Melroe patent vehicle
would be obvious. Merely because it has not been used in any
one particular vehicle does not make such use invention. When
there is an advance in the art, such as a new type of trans-
mission, it is not patentable subject matter to merely use
such transmission in different types of vehicles.
With respect to the sprocket and chain arrangement, this is
shown in the Adams patent, and can be used with any type of
transmission. The use of this particular arrangement is merely
a matter of choice. The use of a chain tightener is also well
known.
With respect to applicant's arguments that there is a synergistic
effect produced in the present vehicle, the examiner cannot agree.
The increased maneuverability when cornering the vehicle is the
result of a known characteristic of hydrostatic transmissions, i.e.
the ratio of speeds at which the wheels on opposite sides of the
vehicle turn being infinitely variable. The balance of power
in which the power not required by the inside drive is transferred
to the outside drive is also a characteristic of the hydrostatic
transmission whether used with a tracked vehicle or a wheeled
vehicle. The even application of power is also a result of the
infinitely variable speeds, which, as stated above, is a known
characteristic of the hydrostatic transmission."
In response to the Final Action, the applicant stated (in part):
"The issue is very simple. Claims 1 and 2 recite a novel
combination of a four wheeled skid steered front end loader type
vehicle with independent variable hydrostatic drives on each
side. While "hydrostatic" does have other meanings, it is used
extensively in this industry (and in this application) to refer
to this independent infinitely variable type of drive. The
Examiner has rejected the recited combination as being obvious
from a combination of the applicant's Canadian Parent 747,216
to Melroe et al, which shows a four wheeled vehicle with
clutched drives, Canadian Patent 755,913 to Adams, Jr., which
shows a sprocket and chain arrangement, and the other four
United States references which show track type (or two wheeled)
vehicles with independent hydrostatic drives.
The applicant is a leader in this industry and has a very
complete knowledge of these types of vehicles. In fact, an
affidavit by the inventor, Mr. J. Bauer, is attached, setting
forth some of the advantages of the applicant's "BOBCAT"
Loader over the prior art and the considerable commercial
success thereof. While skid steered front end loader type
vehicles have been in use for quite a number of years,
they have experienced a widespread and dramatic increase in
popularity since the applicant introduced this combination.
This is because the combination has produced an unexpected
synergistic improvement in performance. Although it was
previously known to use independent hydrostatic drives on
larger crawler type vehicles, these were not commercially
successful because of operational difficulties, particularly
the considerable degree of skill required to operate them
and also their loss of power.
It will be apparent that it is desirable that relatively
small vehicles of this type be able to operate quickly and
often in confined areas. Therefore, it is important that
the vehicle operate smoothly and continuously, much as a
conventionally steered vehicle, and this has been impossible
with prior art skid steered vehicles. Furthermore, it is
important that a person be able to quickly learn how to
operate the vehicle. The ratio of the speeds at which the
wheels on opposite sides of the vehicle turn is infinitely
variable, thereby enabling the vehicle to be turned through
a smooth radius at any speed which provides this dramatically
increased manoeuverability. In the previous clutched vehicles
this was a difficult "stepped" motion achieved by braking.
In crawler type vehicles improved turning is accomplished
by the special relationship of the track width to the width
of the machine and other design factors. If the track
design violates the design formula for steerability, the
machine may be turned only with great difficulty and in the
extreme may simply be propelled backward or forward. This
problem becomes even more acute in four wheel drive vehicles
because the load is distributed at four different points, two
on either side of the vehicle, and the steering forces must
be applied to the ground at these points.
The consideration before the Board is whether or not the applicant has made
a patentable advance in the art.
We have considered with care the able and interesting arguments presented at
the Hearing by Mr. McKenzie, Mr. Bauer and Mr. Ruf.
It is the examiner's position that it is obvious to replace the V-belt clutch
driven transmission of Melroe with the hydrostatic transmission. He has
cited several references to show that the hydrostatic transmission is well
known.
On the other hand, the applicant argues that combining the hydrostatic
transmission with the Melroe vehicle provides an "unexpected synergistic
improvement in performance". Mr, Bauer outlined the importance of this
type of vehicle being able to operate in confined areas with precise motion
control.While the clutch driven V-belt drive of Melroe was successful,
the addition of the hydrostatic transmission has improved its performance
considerably.
One of the problems of the clutch-driven V-belt transmission is that of
operator fatigue caused by the manual effort required to operate the
steering levers. These levers require a force of 60 to 80 pounds, which
would overstrain an operator after a few hours of work. Another shortcoming
of the transmission used in Melroe was that life expectancy was short as
the clutch expectancy is 300 hours operation, and the V-belt drive is
approximately 1000 hours. A further drawback of the V-belt transmission
was the fact that the largest available type could only transmit 30
horsepower, which was not enough for the expected 100 horsepower units
that the company wanted to produce.
Mr. Bauer concerned the combination of the hydrostatic transmission with
the Melroe vehicle in 1966, but there were no commercial hydrostatic
transmissions available for their requirement in the price range that
their company allotted for this component of the vehicle. At that time,
hydrostatic transmissions were used in crawler tractors, as evidenced in
the cited art, as well as a very expensive type used by the aerospace
industry which used it to generate electricity at constant speed from a
variable source. At this point in time, there were also several other
manufacturers producing this type of vehicle with the clutch - V-belt
transmission.
After obtaining agreement from a manufacturer to produce a hydrostatic
transmission suitable for their type of vehicle, the applicant found it
provided numerous advantages over the Melroe transmissions. One of the
inherit features of the hydrostatic transmission is that it has a life
expectancy of 250,000 hours compared to the 1000 hours belt fife of the
prior art. Also the control levers require very little effort to
manoeuver the vehicle, so there is no problem with operator fatigue.
It was found that when a comparison of identical vehicles of this type
was made, the vehicle equipped with the hydrostatic unit could do 2 to 4
times the work of one equipped with the clutch and V-belt drive arrangement.
Further, the "stepped" type of steering action was eliminated with the
hydrostatic transmission, which reduces the wear and tear on the vehicle,
with the resultant increase in life expectancy.
We believe that since this is a relatively small vehicle, its ability to
operate quickly and often in confined areas is definitely improved with
the use of the hydrostatic transmission. Granted this type of transmission
was used in crawler type tractors, but their motion is primarily straight
line movement in forward or reverse, and the advantages of using this
transmission in four wheel drive skid steer vehicle of Melroe would not
be that apparent.
Another factor that has been argued is commercial success. According to
Mr. Bauer, in 1966, prior to the use of hydrostatic transmissions, the
company sales were 7 million dollars, and the estimated industry world-
wide sales were 15 million. Currently, all companies now are using the
hydrostatic transmission. The sales for the Clark company are expected to
be $80 million, and the industry estimate is in the order of $200 to
$250 million. The nature of the invention is not one where the consumer
is susceptible to advertising pressures to obtain sales, and we have come
to the conclusion that the major reason for the commercial success is
the hydrostatic transmission.
In retrospect it may well seem that it would be obvious to place the known
hydrostatic transmissions in small wheeled vehicles, and we can understand
how the examiner came to that conclusion. However the submissions made at
the Hearing, subsequent to the examiner's Final Action, have convinced us
otherwise. Where the hydrostatic transmission was used previously in tracked
vehicles, it created problems by virtue of the forces placed upon the tracks
in turning, which frequently forced the tracks off their support. The width
of the vehicle compared to its length is basic to the success of the in-
vention. Our thinking has also been influenced by the numerous advantages possessed
by the machine claimed, and its quick commercial success once it was put
on the market.
In view of the evidence before us, we therefore conclude that there is
"ingenuity in the invention".
There was some objection raised by the applicant about the requirements for
divisional filings under Canadian practice. We have reviewed the three
patents already issued to the applicant, and find that each is directed to a
separate invention, and therefore the requirement for division was proper.
We do find however that the two applications before us are directed basically to the
combination of the hydrostatic transmission with the Melroe vehicle. It
would appear that there is only one invention involved in these applications,
and a claim complying with Rule 60 would be sufficient to meet the statutory
requirements to permit both to be combined in one application.
In summary, we are satisfied that the applicant has made a patentable advance
in the art and we recommend that the Final Action refusing the claims be
withdrawn.
G. A. Asher S.D. Kot
Chairman Member
Patent Appeal Board Patent Appeal Board
I have reviewed the prosecution of this application and agree with the
recommendation of the Patent Appeal Board. Accordingly, I withdraw the
Final Action and return the application to the examiner for resumption
of prosecution.
J.H.A. Gariepy Agent for Applicant
Commissioner of Patents
George H. Riches & Assocts.
67 Yonge St.
Toronto, Ont.
Dated at Hull, Quebec
this 1st. day of December, 1978