Mid-mount mower having a mower unit disposed between a front wheel unit and a pair of right and left rear wheels arranged rearwardly of a vehicle body to be independently shiftable

A mid-mount mower having a front frame unit including a pair of right and left front longitudinal frames, a first cross frame interconnecting the front longitudinal frames in forward positions thereof longitudinally of the vehicle body, and a second cross frame interconnecting the front longitudinal frames in rearward positions thereof longitudinally of the vehicle body, the front frame unit supporting the front wheel unit and also supporting a lift mechanism for vertically movably suspending the mower unit; a rear frame unit including a pair of right and left rear longitudinal frames, the rear frame unit being connected to the front frame unit; and a rear wheel drive unit interconnecting the rear longitudinal frames. The second cross frame has a downwardly opening recess disposed adjacent a middle position thereof, the recess allowing entry thereto of an upwardly protruding portion of the mower unit without interference when the mower unit is raised by the lift mechanism. The second cross frame includes a first profile member (13a) having a gate-shape portion (13aa) defining a recess (28) and horizontal plate portions (13ab) connected respectively to lower ends of the gate-shape portion, and a vertical plate member (13b) connected to a rear end surface of the first profile member.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a mid-mount mower having a mower unit mounted between a front wheel unit and a pair of right and left rear wheels arranged rearwardly of a vehicle body to be independently shiftable.

2. Description of the Related Art

A riding mid-mount mower, known from Japanese Unexamined Patent Application Publication 2000-351330, includes a body frame having a pair of right and left front longitudinal frames and a pair of right and left rear longitudinal frames. The front longitudinal frames support front wheels and suspend a mower unit through links. Each rear longitudinal frame is connected to a rear wheel drive section. The right and left front longitudinal frames are connected to each other through forward and rearward cross frames. The front longitudinal frames and the rear longitudinal frames are connected through the rearward cross frame.

A riding mower keeps a mower unit in a raised position during a non-operational run. When the mower runs over a rough terrain or rides over a curb, it is desirable to raise the mower unit to a higher position to avoid contact with the ground. In this type of mower, a gear case is protrusively mounted on a deck of the mower unit to convert torque transmitted in a longitudinal direction from a PTO shaft disposed in a rear part of the vehicle body, into rotation of a vertical shaft for transmission to rotary blades arranged in the mower deck. A limit to the raising of the mower unit is determined by interference between the vehicle body and the gear case or a shaft transmission system connected to the gear case.

In a conventional riding mower, a footboard is disposed on front longitudinal frames of the vehicle body with a mower unit suspended therefrom. Where the body frame is positioned higher for elevating the limit to the raising of the mower unit, the center of gravity of the vehicle body is raised and, as a result, the vehicle body is destabilized. Conversely, where the vehicle body is positioned lower in favor of stability of the vehicle body, the height of the raised mower unit relative to the ground is also lowered. Thus the vehicle body stability and the sufficient mower unit height have been incompatible.

SUMMARY OF THE INVENTION

This invention has been made having regard to the state of the art noted above, and its object is to provide a riding mower of excellent stability and running performance, which secures a sufficient height of a mower unit relative to the ground while allowing a vehicle body to have a low center of gravity.

The above object is fulfilled, according to this invention, by a riding mower has a front frame unit for supporting a front wheel unit and a rear frame unit connected to the front frame unit. The front frame unit includes a pair of right and left front longitudinal frames, a first cross frame for interconnecting the front longitudinal frames in forward positions thereof longitudinally of the vehicle body, and a second cross frame for interconnecting said front longitudinal frames in rearward positions thereof longitudinally of the vehicle body, and the rear frame unit includes a pair of right and left rear longitudinal frames. The front frame unit is capable of carrying a lift mechanism for vertically movably suspending the mower unit. A rear wheel drive unit interconnects the rear longitudinal frames. The second cross frame has a downwardly opening recess disposed adjacent a middle position thereof, the recess allowing entry thereto of an upwardly protruding portion of the mower unit without interference when the mower unit is raised by the lift mechanism.

With the above construction, when the mower unit is raised, the upwardly protruding portion (e.g. a gear case protrusively mounted on the upper face of a mower deck, and a shaft transmission system connected thereto) enters from below the recess formed adjacent a middle position in the right and left direction of the second cross frame. That is, even where the vehicle body is positioned low, the upwardly protruding portion of the mower unit may enter the recess of the second cross frame, and the mower unit may be raised high. The riding mower according to this invention is capable of raising the mower unit sufficiently high relative to the ground while keeping low the center of gravity of the vehicle body.

In this invention, in order to make the second cross frame strong enough in spite of the recess formed thereon, the second cross frame includes a first profile member having a gate-shape portion defining a recess and horizontal plate portions connected respectively to lower ends of the gate-shape portion, and a vertical plate member connected to a rear end surface of the first profile member. Further, the horizontal plate portions are arranged to receive rear ends of a footboard sheet member disposed as sunken between the right and left front longitudinal frames, and the vertical plate member having an upper end thereof supporting a pivotal axis of a driver's seat.

In order to provide the second cross frame with a substantially box shape section, the second cross frame, in a preferred embodiment of the second cross frame, includes a first profile member having a gate-shape portion defining a recess and horizontal plate portions connected respectively to lower ends of the gate-shape portion, a tilted vertical plate member connected to a rear end surface of the first profile member, a rear wall member connected to a rear end of the tilted vertical plate member to define therewith an internal space extending transversely of the vehicle body, and side plates for covering the internal space from lateral directions.

Other features and advantages of this invention will be apparent from the following description of the embodiment to be taken with reference to the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1shows a side view andFIG. 2shows a plan view of a riding mid-mount mower according to the invention. In this lawn mower, a vehicle body for riding1has a pair of right and left front wheels2and rear wheels3, and a mower unit4vertically movably suspended between the front and rear wheels. An engine5is mounted at a rearmost part of the vehicle body1, and a driver's seat6is placed on a longitudinally middle part of the vehicle body. The pair of right and left front wheels2are in the form of freely rotatable caster-type wheels, and the pair of right and left rear wheels3are drive wheels independently and steplessly changeable in speed and switchable between forward drive and backward drive. By driving both rear wheels3at the same speed forward or backward, the vehicle may be controlled to run straight forward or backward, and by driving the right and left rear wheels3at different speeds, the vehicle may be controlled to turn in any direction.

As shown inFIGS. 3 and 4, a body frame assembly7of the vehicle body1consists of a front frame unit7A supporting the front wheels2and suspending the mower unit4through front and rear links8and9, and a rear frame unit7B having a rear wheel drive section10connected thereto. The front frame unit7A includes a pair of right and left front longitudinal frames11composed of channels opposed to each other with a wide spacing therebetween, a first cross frame12composed of a channel interconnecting front ends of the right and left front longitudinal frames11, and a second cross frame13interconnecting rear ends of the right and left front longitudinal frames11. The rear frame unit7B includes a pair of right and left rear longitudinal frames14composed of flat plates arranged with a smaller spacing therebetween than that of the front frame unit7A and connected to the second cross frame13. The rear wheel drive section10is connected to rear ends of the longitudinal frames14. The engine5, which is an air-cooled gasoline engine, is mounted, with an output axis thereof extending in the longitudinal direction, on an engine-mounting frame15extending rearward from the rear wheel drive section10.

As shown in detail inFIG. 5, the second cross frame13is a welded metal plate structure protruding above the front longitudinal frames11, including a first profile member13ahaving a gate-shape portion13aadefining a recess28and horizontal plate portions13abconnected to lower ends of the gate shape-portion, a tilted vertical plate member13bconnected to a rear end face of the first profile member13a, a rear wall member13econnected to the rear end of the tilted plate member13bto create therewith an internal space extending transversely of the vehicle body, and side plates13dfor covering the internal space from lateral directions. An upper part of a transversely middle portion of the tilted plate member13bforming the second cross frame13is connected to a stay19through an arch-shaped reinforcing plate83.

As shown inFIGS. 6 through 8, the tilted plate member13bforming the second cross frame13has fulcrum metal fittings16disposed on front parts thereof for supporting the driver's seat6to be pivotable about an axis “a”. The driver's seat6is placed above the rear frame unit7B so that the front end thereof reaches above the second cross frame13.

A support shaft17extending transversely through the internal space of and supported by the second cross frame13is connected to upper ends of the rear links9for suspending the mower unit4. A single-acting hydraulic cylinder20is mounted between a drive arm18fixed to the support shaft17and the stay19interconnecting the right and left rear longitudinal frames14. When the hydraulic cylinder20is extended by pressure oil supplied thereto, the rear links9are swung upward to raise the mower unit4, and when the hydraulic cylinder20is contracted by the pressure oil drained therefrom, the mower unit4descends by gravity. A restraining arm21extending from the drive arm18limits the descent of the mower unit4by abutting on a stopper22having stepped contacts formed by a spiral. The stopper22may be turned by a knob23to change a contact position stepwise to receive the restraining arm21, thus adjusting the height of the suspended mower unit4relative to the ground, i.e., the cutting height.

The mower unit4is constructed so that three blades (not shown) driven to rotate about vertical axes are transversely arranged in a deck25, and grass clippings are discharged through the right end of the deck25. A gear case26is centrally disposed on the upper face of the deck25, and changes torque inputted from rearward into rotation about a vertical axis for transmission to each blade through a drive belt27.

As shown inFIGS. 7 and 8, when the mower unit4is raised, the gear case26and/or a universal joint47may enter the downwardly opened recess28defined by the gate-shape portion13aapositioned in a transversely middle region of the first profile member13aforming the second cross frame13. In this way, the mower unit4may be raised to a large extent to secure a good height over the ground.

A footboard30made of metal plate is fitted to the front frame unit7A of the body frame assembly7in a position under the driver's feet. A pair of rear wheel fenders31are disposed, respectively, at the right and left sides of the driver's seat6. An engine hood32is provided behind the driver's seat6. Further, as shown inFIGS. 9 and 10, the footboard30mounted to cover the front frame unit7A is pressed to a shape having a sunken portion between the right and left front longitudinal frames11, and thus the footboard level is low enough to allow the driver to be seated a well-balanced condition with a low center of gravity. Rear end portions of the footboard30are mounted on and connected to the horizontal plate portions13abof the first profile member13aforming the second cross frame13. The middle part at the rear end of the footboard30is bulged along the shape of the gate-shape portion13aaof the first profile member13ato fittingly cover the gate-shape portion13aa.

As shown inFIGS. 11 through 13, the rear wheel drive section10includes a central transmission case41for receiving output from the engine5, a pair of hydrostatic stepless transmissions (HST)42attached to right and left sides of the central transmission case41, and a pair of right and left reduction cases43supporting the axles of rear wheels3. Engine power inputted to the central transmission case41through its rearward part is divided and transmitted to right and left variable displacement pumps42P of stepless transmissions42. Outputs in varied speeds from motors42M of the stepless transmissions42are decelerated through the reduction cases43and transmitted to the axles of the rear wheels3. A PTO shaft45projects forward from the front face of the central transmission case41, to be operatively connected to a rearwardly projecting input shaft46of the gear case26through a pair of universal joints47and a transmission shaft48.

The hydrostatic stepless transmissions42employed herein are the well-known axial plunger type, with the swash plate angle of each pump42P variable to vary the volume and direction of oil delivery, whereby the motor42may be driven forward and backward in steplessly variable speed. Swash plate angle control shafts, not shown in the drawings, are operatively connected to shift levers50arranged at opposite sides of the driver's seat6to be rockable backward and forward. The shift levers50held in neutral position place the stepless transmissions42in neutral stop position. When the shift levers50are rocked forward from the neutral position, the stepless transmissions42are shifted to forward drive speed positions. When the shift levers50are rocked rearward from the neutral position, the stepless transmissions42are shifted to backward drive speed positions. In front of the central transmission case41, an oil filter51is disposed on an oil supply line for supplying pressure oil to a charging circuit of hydrostatic stepless transmissions42. By rocking the driver's seat6forward to open the upper part of the rear wheel drive section10, the oil filter51is fully exposed in a position between the pair of right and left rear longitudinal frames14, and may easily be mounted and dismounted with hands reaching from above.

The right and left reduction cases43are provided, respectively, with multiple disk brakes53acting on motor shafts52. Control shafts53aof the brakes53are operatively connected through rods55to a brake pedal54disposed around a middle forward part of the footboard. The brake pedal54, when depressed, actuates the right and left brakes53at the same time. Further, a brake lock pedal56for parking is disposed laterally of the brake pedal54to hold the brake pedal54in a depressed position.

Port blocks57, having the hydraulic circuits of the hydrostatic stepless transmissions42inside, are formed of high strength castings that also serve as covers for reduction cases43. To the outward side of each port block57, the rear end of the rear longitudinal frame14forming the rear frame unit7B of the body frame assembly7is connected. To the inward side of each port block57, the front end of the engine-mounting frame15is connected.

As shown inFIG. 14, a gate-shaped safety frame61, foldable backward about an axis “b” in the vertically middle portion thereof, is erected behind the driver's seat6. The safety frame61has right and left proximal pole ends61asupported by proximal supports62disposed on the rear outward surfaces of right and left rear longitudinal frames14of the body frame assembly7. Each proximal support62, as shown inFIGS. 15 and 16, includes a square boss member63rigidly welded to the outward surface of the rear longitudinal frame14, and a bottom plate member64serving as a reinforcing plate rigidly welded to the outward surface of the rear longitudinal frame14. A stay73interconnects the right and left square boss members63of the proximal supports62at rear surfaces thereof. With each proximal pole end61ain the form of a square pipe is inserted from above into the proximal support62and received by the bottom plate member64, bolts65inserted from behind through the proximal support62and the proximal pole end61aare screwed into nuts66fixed to the front surface of the proximal support62, whereby the bolt heads push the proximal pole end61aforward and press it against the forward inner face of the proximal support62. Thus the safety frame61is firmly fixed in its upstanding position. In this case, the bolts65may be handled with facility with a large space secured behind the safety frame61.

A reinforcing member67is welded, with its plate surfaces oriented horizontally, to the outer surface of each rear longitudinal frame14in order to increase the strength of the frame14. Further, front and rear ends of this reinforcing member67are welded to the rear surface of the second cross frame13of the front frame unit7A and to the bottom plate member64of the proximal support62. The reinforcing members67provided in this way strengthen the stepped connections between the two different width frames, i.e. the wide-width front frame unit7A and the small-width rear frame unit7B, and also strengthen the proximal supports62for supporting the upstanding safety frame61.