Earth working – With drive means for tool or cleaner – Guided by walking attendant
Reexamination Certificate
2003-02-14
2004-03-23
Novosad, Christopher J. (Department: 3671)
Earth working
With drive means for tool or cleaner
Guided by walking attendant
C172S103000, C172S123000, C172S125000, C192S003510
Reexamination Certificate
active
06708774
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to cultivating machines or cultivators which, though rotations of cultivating claws provided on a cultivating shaft, not only cultivate the ground but also travel in directions instructed by a human operator; such machines are commonly called “front-tine cultivators. Such cultivators are popularly used today because of their handiness and capability of making small sharp turns. Typical example of the conventionally-known cultivators is discussed below in relation to FIG.
9
.
BACKGROUND OF THE INVENTION
FIG. 9
is a schematic view of the conventionally-known cultivator
100
, where an engine
101
capable of rotating only in one rotational direction has an output shaft
102
extending downward from the body of the engine
101
. Transmission shaft
104
is coupled via a centrifugal clutch
103
to the output shaft
102
, and a horizontal cultivating shaft
106
having a plurality of cultivating claws
107
is connected to the transmission shaft
104
via a worm gear mechanism
105
.
The transmission shaft
104
is secured at its top to a hub
109
of an outer cup
108
of the centrifugal clutch
103
by spline coupling. The worm gear mechanism
105
includes a worm (driving gear)
111
provided on the transmission shaft
104
, and a worm wheel (driven wheel)
112
provided on the cultivating shaft
106
. The centrifugal clutch
103
, transmission shaft
104
and worm gear mechanism
105
are together accommodated in a transmission casing
113
. The transmission casing
113
supports, via a first rolling bearing
114
, the outer cup hub
109
against axial displacement. Specifically, the first rolling bearing
114
has an inner race secured via a retaining ring
115
to the hub
109
against axial displacement, and an outer race secured via a retaining plate
116
and retaining screw
117
to the hub
109
against axial displacement. Further, the transmission casing
113
supports, via second and third rolling bearings
118
and
119
, the transmission shaft
104
against axial displacement. Specifically, the second and third rolling bearings
118
and
119
are held against axial displacement, by means of a retaining ring
125
and stepped portions defined between the transmission shaft
104
and the worm
111
and defined in the transmission casing
113
.
The transmission casing
113
has a first opening
121
formed at its lower end for insertion therein of the transmission shaft
104
and worm
111
, as well as a second opening
122
formed at its side end for insertion therein of the worm wheel (driven gear)
112
. After the transmission shaft
104
and worm
111
are inserted through the first opening
121
into the transmission casing
113
and fixed in place within the transmission casing
113
, the first opening
121
is closed with a first lid
123
. Similarly, after the worm wheel
112
is inserted through the second opening
122
into the transmission casing
113
and fixed in place within the transmission casing
113
, the second opening
122
is closed with a second lid
124
.
In the conventional cultivator
100
of
FIG. 9
, the cultivating shaft
106
and worm wheel
112
are each constructed to rotate only in a forward rotational direction R
10
(counterclockwise direction in the figure), so that the worm wheel
112
would produce thrust reaction force Fs acting on the transmission shaft
104
via the worm
111
in a direction toward the centrifugal clutch
103
. The thrust reaction force Fs is applied via the second rolling bearing
118
to the transmission casing
113
.
However, the conventional cultivator
100
of
FIG. 9
, which employs the retaining ring
115
, retaining plate
116
and retaining screw
117
to prevent the outer cup
24
and first rolling bearing
114
from accidentally coming off or getting disengaged from the transmission casing
113
, undesirably requires a great number of necessary component parts, lowers the manufacturing (component-part-installing) efficiency and increases the necessary number of man-hours. Particularly, where the cultivator
100
is of a small size, such inconveniences would become more notable because the component parts have to be assembled and installed in a very narrow space within the small-size transmission casing
113
.
Further, because the transmission casing
113
in the conventional cultivator
100
has the first and second openings
121
and
122
oriented in different directions, two separate lids
123
and
124
are required to close the respective openings
121
and
122
, which further increases the number of necessary component parts, lowers the manufacturing (component-part-installing) efficiency and increases the necessary number of man-hours. Moreover, in the conventional cultivator
100
, the worm
111
and worm wheel
112
are inserted into the transmission casing
113
in two different directions, which would even further lower the manufacturing (component-part-installing) efficiency. Besides, because the retaining ring
125
is employed to prevent the coming-off or disengagement, from the transmission casing
113
, of the worm
111
, the number of necessary component parts would increase even further.
SUMMARY OF THE INVENTION
In view of the foregoing prior art problems, it is an object of the present invention to provide a novel technique suitably applicable to a cultivator of a type where a main shaft portion of a transmission shaft, having a driving gear provided thereon, is connected, via a clutch, to an engine rotatable only in one rotational direction, and which, with a reduced number of component parts, allows the clutch and first bearing, supporting the clutch, to be efficiently installed in a transmission casing against accidental coming-off from the transmission casing.
It is another object of the present invention provide a novel technique suitably applicable to a cultivator of a type where a worm is operatively connected, via a main shaft portion of a transmission shaft, to an engine rotatable only in one rotational direction and the worm, worm wheel and main shaft portion are collectively accommodated in a transmission casing, and which, with a reduced number of component parts, allows the worm, worm wheel and main shaft portion to be efficiently installed in the transmission casing against accidental coming-off from the transmission casing.
In order to accomplish the above-mentioned objects, the present invention provides an improved cultivator which comprises: an engine capable of rotating only in one predetermined rotational direction; a transmission shaft having a driving gear provided thereon, the transmission shaft having a main shaft portion that is smaller in diameter than the driving gear and projecting from one end of the driving gear toward a clutch, the main shaft portion being operatively connected to the engine via the clutch; a cultivating shaft having cultivating claws and also having a driven gear provided thereon to meshingly engage with the driving gear; and a transmission casing having the driven gear, driving gear, main shaft portion of the transmission shaft and clutch collectively accommodated therein, the transmission casing having a first bearing for preventing the clutch from being displaced toward the driving gear and a second bearing for preventing the driving gear from being displaced toward the clutch. In the present invention, the main shaft portion of the transmission shaft is screw-coupled to the clutch and a direction in which the screw-coupling between the main shaft portion and the clutch is tightened corresponds to the one predetermined rotational direction of the engine.
The first bearing prevents the clutch from being displaced toward the worm while the second bearing prevents the worm from being displaced toward the clutch, and the main shaft portion is screw-coupled to the clutch. Thus, in the present invention, the clutch, main shaft portion and first and second bearings can be reliably prevented from displacement toward the driving gear and the driving gear can be prevented from displace
Kobayashi Hideaki
Miyahara Kazuyoshi
Honda Giken Kogyo Kabushiki Kaisha
Novosad Christopher J.
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