Walk-behind type work vehicle

A walk-behind type work vehicle has two running wheels on an axle, an upright power-take-off shaft for driving a selectably attachable implement, as well as an engine with an upright output shaft forwardly upwardly of the running wheels. Transmission system is adapted to transmit the power from the engine output shaft as parallelly divergingly branches off to the running wheels and to the power-take-off shaft.

BACKGROUND OF THE INVENTION 
(1) Field of the Invention 
This invention relates to a walk-behind type work vehicle provided with two 
running wheels on an axle, a power-take-off shaft for driving an implement 
or attachment for instance as a rotary mower or the like, as well as an 
engine for driving the axle and the shaft; thus of the so-called mono-axle 
two-wheel type. 
(2) Description of the Prior Art 
Transmission system adopted in the conventional work vehicles of the 
above-mentioned type is such that the engine has its output shaft 
extending in an upright posture, from which the power is transmitted via 
reduction gears to a transmission shaft extending also in an upright 
posture, which in adapted to drive the axle via a worm gear, while the 
power-take-off shaft is disposed again to extend in an upright posture and 
is adapted to be driven by the said upright transmission shaft via 
pulley-belting means. A specific example of such work vehicles is seen in 
JP-Y1 No. SHO. 49 (=1974)-44583. 
In the case that the vehicle is adapted to be equipped with such an 
attachment for instance as a rotary mower as driven by the power-take-off 
shaft, the said conventional construction results in the vehicle wherein 
the engine, the wheels and the rotary mower are disposed to span rather a 
lengthy range in the fore-and-aft direction of the vehicle, thus making it 
impossible to obtain a compact vehicle. 
Another drawback of such construction is further seen in so driving the 
rotary mower, which should preferably be operated in high rotation, via 
the upright power-take-off shaft which in turn is driven by the said 
upright transmission shaft, in view that this latter shaft is rotated 
through heavy speed reduction for the ultimate proper driving of the 
running wheels and is thus rather too slow to sufficiently drive the 
rotary mower to attain the proper cutting performance. 
SUMMARY OF THE INVENTION 
The primary object of this invention is to eliminate the said drawbacks of 
such conventional walk-behind work vehicles, thus each provided with an 
engine having an output shaft, a transmission case, an axle journaled on 
the transmission case, two running wheels mounted on the axle, and a 
power-take-off shaft; more specifically to make it possible: to provide a 
compact vehicle of such type in its overall entirety, to simplify the 
transmission system from the engine output shaft to the power-take-off 
shaft, and to drive the power-take-off shaft in relatively high rotation. 
In order to attain the said object, the improvement according to this 
invention comprises in combination that the engine is mounted on the 
transmission case at a portion thereof forwardly and upwardly of the 
running wheels, that the engine output shaft is disposed to extend in an 
upright posture, that the power-take-off shaft is disposed, for driving an 
implement or attachment, to downwardly protrude in an upright posture 
through the transmission case in a portion thereof forwardly of the 
running wheels, and that the transmission system is adapted to transmit 
the power from the engine output shaft as parallelly divergingly branches 
off to the running wheels and to the power-take-off shaft. 
It is hereby made possible to provide the implement, such for instance as a 
rotary mower or the like, as located underneath the engine and as snugly 
accommodated in a space provided forwardly in between the right and left 
running wheels, to therefore provide the vehicle compact both in the 
fore-and-aft and right-and-left directions, in its overall entirety as 
equipped with such implement. Moreover, since the engine power is 
divergingly split directly from the engine output shaft to the 
power-take-off shaft and to the axle, the power transmitted to the 
power-take-off shaft does not undergo the speed reduction for the running 
wheel driving, thus bringing forth also an advantage of easily attaining 
the proper cutting performance in the case an implement requiring high 
speed rotation, as for instance the rotary mower or the like, is actually 
attached to the power-take-off shaft. 
Detailed description to follow hereunder will make apparent still further 
objects and advantages of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Describing in detail the specific embodiment of a walk-behind type grass 
mower, thus an illustrative example of the work vehicle according to this 
invention with reference to the drawings, a transmission case (1), in 
shape generally of an inverted L as viewed in side elevation consists of a 
first case portion (1a) and a second case portion (1b), and serves as a 
supporting base for a maneuvering handle (2) disposed to bifurcatedly 
extend rearwards with respect to the vehicle travel. An engine (E) is 
mounted on a front end portion of the first case portion (1a). A pair of 
right and left running wheels (3), (3) are mounted on an axle (4) which is 
journaled on the second case portion (1b) to extend at a lower end portion 
thereof. A power-take-off shaft (5) is disposed to extend downwards 
beneath the engine (E). To the power-take-off shaft (5) there is 
operatively connected a grass-mowing cutter (6), illustrated as a rotary 
mower, with intermediary of an after-defined rotary shaft (12); and a 
transmission system is completed as is adapted to transmit the power from 
the engine (E) as branches off to the running wheels (3), (3) and to the 
power-take-off shaft (5), as described more in detail hereunder: 
Double-step gearing reduction mechanism (7) is accommodated in a hollow 
space in between the first and second case portions (1a), (1b). The engine 
(E) has an output shaft (8) which is operatively connected, via a main 
clutch (9), to the said power-take-off shaft (5) downwardly extending 
concentrically in extension to the lower end thereof. Power for driving 
the axle (4) is transmitted from the said power-take-off shaft (5) via: 
the said reduction mechanism (7); a vertical transmission shaft (7a) 
accommodated in the said second case portion (1b) to extend in parallel 
with the power-take-off shaft (5); and a bevel-gearing mechanism (11). 
The already-mentioned rotary shaft (12) carries the said cutter (6) as 
securely mounted to integrally rotate therewith, and is operatively 
connectable to the said power-take-off shaft (5), in concentrical 
extension thereto, by being screwed thereto in a direction opposite to the 
cutter rotation. A sleeve case (13) to cover the rotary shaft (12) is at 
its upper end securely bolted to an upper front end portion of the first 
case portion (1a), and a reinforcement stay (14) is provided to bridge 
over a lower portion of the sleeve case (13) and a lower portion of the 
second case portion (1b). The said cutter (6) is so disposed that its 
major portion, thus over half, on the side to the rear with respect to the 
vehicle travel is snugly accommodated in a space provided in between the 
right and left running wheels (3), (3), so that outward scattering of the 
cut grass scraps may accordingly be abated as the scattering scraps are 
hindered by the inner lateral side of the running wheels (3), (3). 
The handle (2) is connected at its lower end to a rear lower portion of the 
second case portion (1b), for free pivotal rocking about a horizontal axis 
(P), and has a portion to engage with a bracket (15), which is pivoted on 
the second case portion (1b) at a rear upper end portion thereof, more 
particularly to engage with any one of set mating engagement positioning 
means provided on the bracket for such free arbitrary selection of the 
actual egagement position, the selection thus corresponding to accordingly 
select the slant angle at which the handle (2) extends with respect to the 
case (1). 
The pair of right and left running wheels (3), (3) mentioned hereinabove 
are mounted on the axle (4) in a manner free to mount and dismount, so 
that the vehicle may as well be used for various different works other 
than grass-cutting, such for instance as cultivation work and the like, by 
mounting the respective proper implements instead of the said running 
wheels (3), (3) and, when needed, by further mounting a ground-engaging 
resistor bar (16) on the said bracket (15) as shown in phantom in FIG. 1. 
Designated in FIG. 1 at (17) is a fuel tank. 
As for the cutter (6), same is not limited or restricted to be of the 
rotary disc blade type as described hereinbefore but may as well be of the 
reciprocating clipper type, and this invention may be applied also to such 
case. 
By the way, though the single power-take-off shaft (5) in the 
above-described specific embodiment is the one serving as an input shaft 
of the transmission system, as is operatively connected to the engine 
output shaft (8) with intermediary of the main clutch (9), such is not 
necessarily the imperative requirement of this invention and some other 
construction may as well be possible, such for instance as providing 
individually separate input shaft and power-take-off shaft as operatively 
connected in straight concentrical extension with each other or as 
juxtaposed within a common plane and operatively connected with each other 
by gearing or chain means, what is essential to this invention being thus 
to provide both the engine output shaft (8) and the power-take-off shaft 
(5) in uprightly extending posture and to provide the output end of the 
power-take-off shaft (5) on the side protruding downwards.