JPH0370448B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a cutter drive device for a mower.

<Prior art> In a mid-mount type mower, a mounting shaft is rotatably provided on the mower deck via a bearing case, a cutter is fixed to the lower end of this mounting shaft with bolts, etc., and this is attached to a gear on the upper end of the mounting shaft. Usually, the rotation is driven via a mechanism or a belt transmission mechanism.

<Problems to be Solved by the Invention> That is, conventionally, no means has been taken to actively absorb impact loads in the cutter drive system. Therefore, when the cutter comes into contact with a stone, tree stump, etc. during operation, a large impact load is applied, causing damage to the cutter. In addition, since the drive system must be able to withstand this impact load, it must be stronger than necessary, which not only increases the size of the mechanism but also requires additional costs. It was hot.

<Means for Solving the Problems> The present invention is intended to solve these conventional problems, and as a specific means for that purpose, it includes a drive shaft, a mounting shaft equipped with a cutter on the lower end side, and a mounting shaft provided with a cutter on the lower end side. are provided vertically corresponding to each other so as to be rotatable on the same axis in the vertical direction, and between this drive shaft and the mounting shaft,
A coil spring for power transmission is interposed so as to expand when an impact load of a predetermined value or more is applied, and a cylindrical portion for restricting the expansion of the coil spring is provided on one side of the drive shaft and the mounting shaft.

<Function> When driving the cutter, power is transmitted from the drive shaft to the mounting shaft via the coil spring to rotate the mounting shaft. When the cutter comes into contact with a stone, etc.
An impact load acts on the coil spring in the direction of expansion, and the coil spring expands to cushion and absorb the impact. On the other hand, when the coil spring expands, it comes into contact with the cylindrical portion and its expansion is restricted.

<Example> Hereinafter, the present invention will be described in detail with reference to the illustrated example. In FIG. 2, 1 is a tractor, 2 is a front wheel,
3 is the rear wheel. Reference numeral 4 denotes a mid-mounted mower that is attached to the lower abdomen of the tractor 1 so as to be able to rise and fall freely, and includes a mower deck 5 and cutters 6 and 7 at the center and on both left and right sides disposed below the mower deck.
Gauge wheels 8 and 9 are provided before and after the mower deck 5.

The drive system for driving the central cutter 6 is constructed as shown in FIG. That is, in FIG. 1, 10 is a bearing case, which is attached to the mower deck 5, and the bearing 1 is attached to this bearing case 10.
1 and 12 and oil seals 13 and 14, a cylindrical portion 16 of the mounting shaft 15 is rotatably supported around an axis in the vertical direction. A blade-shaped cutter 6 and a bowl-shaped protective cover 17 are attached to the lower end of the mounting shaft 15.
are fastened and fixed with bolts 18. As shown in FIG. 3, the protective cover 17 includes a recess 21 in the center of the bottom 19 that is recessed upward so that the head 20 of the bolt 18 is accommodated and does not protrude downward, and a peripheral wall portion with a notch 22. It has 23.
The peripheral wall portion 23 is rotatably fitted onto the lower end side of the bearing case 10 with a space therebetween. Further, there are two notches 22 corresponding to the radial direction, and the cutter 6 is passed through these. 24 is a drive shaft, which is connected to the gear case 2 through bearings 25 and 26 so that it is coaxial with the mounting shaft 15 and corresponds to the upper and lower phases.
7 and is rotatably supported. gear case 2
7 is mounted on the mower deck 5, and an input shaft 28, bevel gears 29, 30, etc. are assembled to this gear case 27, and the tractor 1 is mounted on the mower deck 5.
It is configured to accept power from the PTO shaft. A boss body 31 is spline-fitted to the lower end of the drive shaft 24 and attached by a roll pin, and this boss body 31 is provided with a pulley 32 for transmitting power to another cutter 7.
The boss body 31 is fitted inside the upper end of the cylindrical portion 16 with a gap in between. 33 is a coil spring for power transmission, which connects the boss body 31 of the drive shaft 24 and the mounting shaft 1.
It is interposed between 5 and 5. As shown in FIG. 4, the mounting shaft 15 has a spiral receiving surface 34 with which the lower end surface of the coil spring 33 contacts in the entire circumferential direction, and an engagement surface with which the end surface of the lower end wire of the coil spring 33 abuts and engages. It includes a surface 35 and a protrusion 36 that fits and positions the lower end of the coil spring 33. Boss body 31
A receiving surface 34 of the mounting shaft 15 and an engaging surface 3 are provided on the lower end side of the
A receiving surface 37 and an engaging surface 38 corresponding to 5 are formed, and these receive and engage the upper end side of the coil spring 33. Note that the radial end surfaces of the coil springs 33 are in surface contact with the engaging surfaces 35 and 38. The upper end of the coil spring 33 is connected to the drive shaft 24
It is fitted externally to the lower end of the . The coil spring 33 is configured to expand when an impact load of a predetermined value or more is applied, and there is a gap inside the cylindrical portion 16 for limiting expansion.
It is fitted with the

The drive system of the cutter 7 is constructed as shown in FIG. That is, 39 is a bearing case, and a drive shaft 44 is rotatably supported by this through bearings 40, 41 and oil seals 42, 43. The drive shaft 44 has a downward cylindrical portion 45, and the cylindrical portion 4
A mounting shaft 47 is fitted into the lower end side of 5 with a bush 46 interposed therebetween. The cutter 7 and the protective cover 48 are fixed to the mounting shaft 47 with bolts 49, and the protective cover 48 has a bottom portion 50, a recessed portion 51, a peripheral wall portion 52, a cutout portion 53, etc. as described above. A receiving surface 5 is provided on the opposing surface between the drive shaft 44 and the mounting shaft 47.
4, 55 and engaging surfaces 56, 57 are formed, and a coil spring 58 is interposed between both shafts 44, 47 via these. A pulley 59 is attached to the upper end of the drive shaft 44, and this pulley 59 is interlocked and connected to the pulley 32 via a belt 60. The mounting shaft 47 has a shaft portion 61 for holding the center of the coil spring 58 and a small diameter threaded portion 62. The threaded portion 62 is inserted through the drive shaft 44, and a nut 63 is screwed onto the upper end thereof. Therefore, the mounting shaft 4
7 is free to rotate only relative to the drive shaft 44 when an impact load is applied. Note that 64 and 65 are friction materials.

In the above configuration, when mowing a lawn or the like, the mower 4 moves while following the undulations of the ground with the gauge wheels 8 and 9 in contact with the ground. Of course, at this time, each cutter 6, 7 is kept in a rotationally driven state. That is, when the power from the PTO shaft of the tractor 1 is transmitted to the input shaft 28, the bevel gear 29,
30, the drive shaft 24 rotates, and the mounting shaft 15 rotates via the boss body 31 and the coil spring 33, so that the central cutter 6 attached to the mounting shaft 15 rotates. On the other hand, pulley 32,
The left and right drive shafts 4 pass through the belt 60 and pulley 59.
Power is transmitted to the drive shaft 44, and the left and right cutters 7 are rotated by the power of the drive shaft 44 via the coil spring 58 and the mounting shaft 47.

When the cutters 6 and 7 are mowing the lawn, etc., a load is applied to the coil springs 33 and 58 in the direction of expansion, but since this load is small, the coil springs 33 and 58 are in the illustrated state or in this state. It maintains a state close to . For example, cutter 6
When the drive shaft 24 attempts to rotate, the mounting shaft 15 temporarily becomes unable to rotate when it comes into contact with a stone, etc., and an impact load acts on the coil spring 33, causing it to expand and cause the coil spring 33 to expand. It cushions and absorbs the impact of the above-mentioned strong impact loads. In this case, the drive shaft 24 and the mounting shaft 15 are connected to the coil spring 33.
By expanding, the coil spring 33 rotates relatively to about 270 degrees, and when the coil spring 33 rotates up to that point, the coil spring 33 comes into close contact with the inner circumference of the cylindrical portion 16 due to the expansion and is regulated. Power will be transmitted through the Therefore, the coil spring 16
Abnormal loads can be reduced.

During reaping work, the bottom part 1 of the protective cover 17, 48
9, 50 do not touch the ground, but in locally raised areas, the bottoms 19, 50 of the protective covers 17, 48 touch the ground, so the cutters 6, 7 do not touch the ground.
It is possible to prevent or reduce earth removal on uneven ground.
In addition, the protective covers 17 and 48 have recessed portions 21 and 51.
Since the heads of the bolts 18 and 49 are inserted therein, wear and tear on the heads can be prevented, and the bolts 18 and 49 can be easily rotated when removing the cutters 6 and 7. Further, the oil seals 14 and 43 at the lower ends of the bearing cases 10 and 39 can be protected by the protective covers 17 and 48, thereby suppressing damage caused by intrusion of grass clippings and the like. That is, the protective covers 17, 48
has surrounding wall portions 23, 52, and the surrounding wall portions 23, 5
2 is fitted onto the outer periphery of the lower end portions of the bearing cases 10, 39 with a slight gap between them, thereby preventing grass etc. from entering the oil seals 14, 43 side.

Further, in place of the cutout portion 22, an insertion hole slightly larger than the thickness of the cutter 6 may be provided in the peripheral wall portion 23 of the protective cover 17. Furthermore, cutter 6,
The shape of 7 may be other than a blade shape.

<Effects of the Invention> According to the present invention, power is transmitted from the drive shaft to the mounting shaft via the coil spring, and when an impact load of a predetermined value or more is applied, the coil spring expands to absorb the relaxation. As a result, breakage of the cutter can be prevented and excess strength of the drive system can be suppressed. Furthermore, since the cylindrical portion is provided to limit expansion of the coil spring, damage to the coil spring can be prevented.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a cross-sectional view of the main parts, FIG. 2 is a schematic plan view, FIG. 3 is a perspective view of a protective cover, FIG. 4 is a perspective view of a mounting shaft, and FIG. The figure is a sectional view of the main part. 5...Moadetsuki, 6,7...Katsuta, 1
0,39...Bearing case, 15,47...Mounting shaft, 16,45...Cylinder part, 17,48...Protective cover, 18,49...Bolt, 19,50...Bottom, 21,51... ... Recessed portion, 23, 52 ... Peripheral wall portion, 24, 44 ... Drive shaft, 33, 58 ... Coil spring.

Claims (1)

[Claims] 1. A drive shaft and a mounting shaft equipped with a cutter on the lower end side are provided vertically corresponding to each other so as to be rotatable on the same axis in the vertical direction, and between the drive shaft and the mounting shaft,
A coil spring for power transmission is interposed so as to expand when an impact load of a predetermined value or more is applied, and a cylindrical portion is provided on one side of the drive shaft and the mounting shaft to limit expansion of the coil spring. mower cutter drive device.