JP2000095160A - Tension device for crawler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tension device for crawler that applies sufficient tension to the crawler by preventing looseness of the rod for smooth movement. SOLUTION: A cylinder unit 29 is provided that urges the idler 9 in the direction opposite to the driving wheel so as to give tension to the crawler disposed between the driving wheel and the idler. The cylinder unit 29 includes a cylinder 38, and a piston rod 42 internally slidably fitted thereto. By press- inserting pressure medium into the cylinder 38, the piston rod 42 is formed on a straight outer peripheral surface with no stepped portion in the range being internally fitted to the cylinder 38 in the tension device of a crawler structured to urge the idler by the piston rod 42.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crawler tension device used in a turning machine such as a backhoe.

[0002]

2. Description of the Related Art In a turning work machine such as a backhoe,
A crawler traveling device having a crawler that is an endless track belt rotatable left and right is employed. In general, the crawler traveling device includes a crawler tension.
Is provided for adjusting the tension to an appropriate value.

[0003] As such a crawler tensioning device, for example, one disclosed in Japanese Patent Application Laid-Open No. Hei 8-239068 is known. This conventional one, in order to give tension to the crawler hung between the drive wheel and the idler,
A cylinder device that urges the idler to the side opposite to the drive wheel is provided, the cylinder device has a cylinder and a piston rod slidably fitted in the cylinder,
By pressing a pressurized medium into the cylinder, the idler is urged by the piston rod.

[0004]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. 8-239 is disclosed.
In the related art described in Japanese Patent No. 068, the rod inserted into the cylinder is formed into a piston portion having an outer diameter substantially equal to the inner diameter of the cylinder and a stepped rod smaller in diameter than the piston portion. And the stopper part was formed in the opening end part of the cylinder so that the said piston rod might not come out.

[0005] Therefore, since the thickness of the piston portion is short, the range in which the rod is supported on the inner surface of the cylinder is reduced, and the rod rattles in the cylinder, causing a kinking phenomenon.
There is a possibility that smooth movement may be impeded, and a problem that sufficient tension may not be applied may occur. SUMMARY OF THE INVENTION It is an object of the present invention to provide a crawler tension device capable of preventing a rattling of a rod, enabling smooth movement, and applying sufficient tension.

[0006]

In order to achieve the above object,
The present invention has taken the following technical measures. That is, the present invention is provided with a cylinder device for urging the idler to the side opposite to the drive wheel in order to apply tension to the crawler looped between the drive wheel and the idler, and the cylinder device includes a cylinder and A piston rod slidably fitted in the cylinder, and a crawler tensioner configured to force the idler by the piston rod by press-fitting a pressurized medium into the cylinder. In the device, the piston rod is a crawler tension device formed on a straight outer peripheral surface without a step in a range where the piston rod is fitted inside the cylinder.

By adopting such a configuration, the contact length between the piston rod and the cylinder becomes longer, and the movement of the piston rod becomes smoother. The crawler is formed by connecting a chain, and if the minimum fitting allowance between the piston rod and the cylinder is set to the length of 1 to 1/2 link of the chain, the rod is prevented from falling out and falling.

That is, in order to apply tension to the crawler wound around the drive wheel and the idler, a cylinder device for biasing the idler to the side opposite to the drive wheel is provided, and the cylinder device comprises a cylinder, A crawler tensioner having a piston rod slidably fitted in the cylinder, and configured to urge the idler with the cylinder rod by pressing a pressurized medium into the cylinder. In the above, the piston rod is formed on a straight outer peripheral surface without a step in a range in which the piston rod is internally fitted to the cylinder, and a fitting margin between the cylinder and the piston rod is such that the piston rod is moved from the standard position of the idler to a maximum. The length is such that it will not fall out of the cylinder when pushed out to the adjustment range.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 4 shows a small turning backhoe 1 exemplifying a turning work machine adopting the present invention, and this backhoe 1 is mainly composed of a traveling device 2, a revolving unit 3 and an excavating device 4.

Hereinafter, the running direction of the backhoe 1 (the left-right direction in FIG. 7) is referred to as the front-rear direction, and the lateral direction orthogonal to the front-rear direction (the direction passing through the plane of FIG. 7) is referred to as the left-right direction.
As shown in FIG. 4, the traveling device 2 includes a pair of left and right crawler traveling bodies 6 around which rubber or iron crawlers 5 are wound, and the traveling apparatus 6 is driven by a traveling motor M. The device is employed.

That is, the traveling device 2 comprises a track frame in which a pair of left and right side frames 7 are connected to each other by a central bearing frame, a driving wheel 8 provided at the rear end of each side frame 7, An idler (idle wheel) 9 provided at the front end of the frame 7, a small wheel 10 provided at a lower portion of each side frame 7, the crawler 5 wound around a range from the drive wheel 8 to the idler 9,
It has.

A dozer 1 is provided in front of the traveling device 2.
The crawler traveling body 6 of the traveling device 2 is provided with a crawler tension device 27 described later. The revolving unit 3 includes a revolving frame 13 rotatably supported around a vertical revolving axis by a bearing body 12 provided on an upper part of a bearing frame of the traveling device 2, and various devices mounted on the revolving frame 13. Bonnet 1 covering
4 and a cabin 17 that covers a seat 15 provided on the hood 14 and a control section 16 in front of the seat 15.

The revolving frame 13 is provided with an outer periphery of a base plate having mounting brackets for various driving devices on its upper surface.
The rear portion of the revolving frame 13 is constituted by a counterweight 18 which is fixed to the base plate and balances the weight of the revolving frame 13 with the excavator 4 at the front of the revolving frame 13. I have. The turning frame 13 is turned around a turning axis X by a turning motor (not shown) fixed to the base plate.

The backhoe 1 shown in FIG. 4 is of a so-called small backward turning type, and is formed in an arc shape so that the rear side surface of the revolving unit 3 does not protrude from the vehicle width of the traveling device 2. That is, when the revolving unit 3 turns, the turning trajectory drawn by the rear surface of the revolving unit 3 falls within the left and right widths of the left and right crawler traveling units 5. A pair of upper and lower support members 19 that support the excavator 4 project from the front end of the turning frame 13. A swing bracket 20 is pivotally attached to the support member 19 via a support shaft so as to be swingable right and left around the vertical axis.
It is swung by a swing cylinder (not shown) provided inside the.

The excavator 4 includes a boom 21 whose base is pivotally attached to a swing bracket 20 so as to be swingable about the left and right axes.
And an arm 22 pivotally attached to the distal end side of the boom 21 so as to be swingable around the left and right axes, and a bucket 23 attached to the distal end side of the arm 22 so as to be free to squeeze and dump. The boom 21 is swung by a boom cylinder 24 provided between the swing bracket 20 and the middle part of the boom 21, and the arm 22 is provided with an arm cylinder 25 provided between the middle part of the boom 21 and the base of the arm 22. The bucket 23 is swung and dumped by the bucket cylinder 26 provided between the base of the arm 22 and the mounting link of the bucket 23.

As shown in FIGS. 1 to 3, each of the left and right crawler traveling bodies 6 is provided with a tension device 27. The tension device 27 supports the idler 9 rotatably, and A yoke 28 is inserted into the front end so as to be movable back and forth, a cylinder device 29 housed in the side frame 7 such that the front end abuts the yoke 28, and a cylinder device 29 abuts on the rear end of the cylinder device 29. And a support plate 30 fixed in the side frame 7 to back up the data.

A partition 31 is provided on the side frame 7, and a yoke 28 is slidably provided in the partition 31 in the front-rear direction. The idler 9 is rotatably supported on the yoke 28. The yoke 9 is urged forward by the cylinder device 29 to apply tension to the crawler 5. In this embodiment, the left and right crawlers 5 are constituted by iron crawlers to which a chain 32 is connected.

The cylinder device 29 has a grease injection rod 33 inserted in the support plate 30 so as to be slidable in the front-rear direction. The grease injection rod 33 has a grease hole passing through the center thereof in the front-rear direction. A grease nipple 35 is attached to the rear end. A screw portion 36 is formed on the rear outer peripheral surface of the grease injection rod 33, and a nut 37 is screwed into the screw portion 36. By rotating the nut 37, the grease injection rod 33 is rotated.
Are movable back and forth with respect to the support plate 30.

The tip of the grease injection rod 33 is formed in a large diameter portion, and a cylinder 38 is fitted on the large diameter portion so as to be movable in the front-rear direction. A flange 39 is provided at the front end of the cylinder 38 so as to project radially outward.
The spring washer 40 is engaged with 9. And cylinder 3
A compression spring 41 is fitted over the outer peripheral portion of the spring 8, and the front end of the spring 41 contacts the spring washer 40, and the rear end thereof contacts the support plate 30.

From the front end opening of the cylinder 38, a piston rod 42 having a straight outer diameter (not having a step) is slidably inserted in the front-rear direction. The distal end surface of the rod 42 is in contact with the yoke 28. Then, by injecting grease as a pressure medium from the grease nipple 35, the grease is pressed into the cylinder 38 through the grease hole 34 of the grease injection rod 33, and presses the piston rod 42 forward, and the yoke By urging the crawler 5 forward, the idler 9 is biased forward to apply tension to the crawler 5.

At this time, since the piston rod 42 is formed in a rod shape having a straight outer diameter, the contact area with the cylinder 36 and the length thereof become longer, and the piston rod 42 rattles or bends. You won't get twisted. When the crawler 5 is extended and the tension force is reduced, grease is injected from the grease nipple 35 and the piston rod 42 is moved forward to apply tension to the crawler 5. This tension adjustment is performed by the chain 32
About one pitch. If the chain 32 is further extended, one link of the chain 32 is removed and adjustment is performed. That is, the travel distance of the idler 9 by the cylinder device 29 is about one pitch of the chain 32. Therefore, it is sufficient to provide a fitting allowance for the piston rod 42 so that the piston rod 42 does not drop from the cylinder 38 when the piston rod 42 is moved by the maximum amount. That is, the fitting allowance between the cylinder 36 and the piston rod 42 is set so that the piston rod 42 does not fall from the cylinder 36 when the piston rod 42 is pushed out from the standard position of the idler 9 to the maximum adjustment range. Specifically, the minimum value of the fitting margin is preferably 1 to 1/2 pitch of the chain 32.

The portion of the grease injection rod 33 projecting rearward from the support plate is covered with a bellows-type dustproof cover 43 so that mud and the like do not adhere to the screw portion 36. When adjusting the nut 37, the cover 43 is detachable. Note that the present invention is not limited to the above-described embodiment.
In the present embodiment, the case where the present invention is applied to the backhoe 1 with a small backward turning is exemplified. However, the present invention is applicable to a larger standard type backhoe and the same when the excavator 4 is moved up.
Can be adopted also in a super-small backhoe that does not protrude from the revolving locus of the revolving superstructure 3. Further, the pressurizing medium is not limited to grease.

[0023]

According to the present invention, the rattling of the piston rod is prevented, the rod can be moved smoothly, and a sufficient tension can be applied.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a cylinder device.

FIG. 2 is an overall side view of the tension device.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a left side view showing the entire structure of the small turning backhoe.

[Explanation of symbols]

 5 Crawler running body 8 Drive wheel 9 Idler 29 Cylinder device 38 Cylinder 42 Piston rod

Claims (3)

[Claims] 1. A cylinder device for biasing an idler to a side opposite to a drive wheel is provided to apply tension to a crawler wound around the drive wheel and an idler, the cylinder device comprising: a cylinder; A crawler tensioner having a piston rod slidably fitted in the cylinder and configured to press the pressurized medium into the cylinder to urge the idler with the piston rod. The tension device for a crawler according to claim 1, wherein the piston rod is formed on a straight outer peripheral surface without a step in a range in which the piston rod is fitted inside the cylinder. 2. The chain according to claim 1, wherein the crawler is configured to connect a chain, and a minimum fitting allowance between the piston rod and the cylinder is set to a length of 1１〜 link of the chain.
A crawler tension device as described. 3. A cylinder device for urging the idler to a side opposite to the drive wheel is provided to apply tension to a crawler wound around the drive wheel and the idler, the cylinder device comprising: a cylinder; A crawler tensioner having a piston rod slidably fitted in the cylinder, and configured to urge the idler with the cylinder rod by pressing a pressurized medium into the cylinder. In the above, the piston rod is formed on a straight outer peripheral surface without a step in a range in which the piston rod is internally fitted to the cylinder, and a fitting margin between the cylinder and the piston rod is such that the piston rod is moved from the standard position of the idler to the maximum. A crawler tensioning device characterized in that the length is such that it does not fall off the cylinder when pushed out to the adjustment range.