JPH11343631A - Parallel link device for wheel loader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dispense with the replacement of a link device by adding a bracket to a Z-bar link device, and connecting a cylinder thereto. SOLUTION: The posture of a bucket is changed when a lift cylinder 6 is operated for lift up. The pivotal position of a tilt cylinder to a front frame is situated in O' under the pivotal point P of a boom. Accordingly, a reverse parallel link of P-O'-A-C-P is formed in the rear of the boom, and a reverse parallel link of C-B-E-D-C is formed in the front of the boom. These links cancel the mutual operations to realize the same operation as a parallel link mechanism. It is necessary to hold the stroke of the tilt cylinder constant during operation. Thus, preparation of two kinds of link devices as in the past is dispensed with, and a user only replaces an attachment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a link device for supporting a work attachment such as a loading bucket or a fork in a wheel loader.

[0002]

2. Description of the Related Art A conventional link device attached to a wheel loader employs a Z-bar link mechanism shown in FIG. 2 when loading earth and sand into a dump or the like.
A link device using the parallel link mechanism shown in 3 was required.

[0003]

SUMMARY OF THE INVENTION The present invention relates to a conventional wheel loader equipped with a Z-bar link, in which the pivot point on the bottom side of the tilt cylinder on the front frame is moved below the pivot point of the boom. 2 parallel links
Provided is a link device which enables operation by a conventional parallel link mechanism by forming a step or double structure, and which does not require replacement of the link device simply by separately providing a tilt cylinder bottom side pivoted portion. Things.

[0004]

According to the present invention, there is provided a link device comprising a boom with a lift cylinder, the tip of which is connected to a boom mounting pin on the back of a work attachment; a bell crank pivotally mounted on an intermediate upper portion of the boom; The lower end of the bell crank is pivotally connected to an operation pin located above the boom mounting pin via a connecting link, and the upper end is connected to a rod of a tilt cylinder, and the bottom of the tilt cylinder is below the fixed pivot of the boom. The lift cylinder is operated in a state where the tilt cylinder stroke is fixed, and the lift cylinder is operated.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 1 denotes a wheel loader,
Reference numeral 2 denotes a front frame, reference numeral 3 denotes left and right brackets, and reference numeral 4 denotes a tilt cylinder mounting bracket which is fixed in front of the middle. 5 is a boom with P as the axis, 5a is the front, 5b
Is the back. 6 is a lift cylinder, and Q and R are pivots. 7 is a tilt cylinder, O and A are connection pins. 8 is a bell crank, 8a is an upper part, 8b is a lower part. Reference numeral 9 denotes a support member for connecting the booms, and a bracket 10 is fixed in the middle. The bracket 10 supports the pivot C of the bell crank 8. Reference numeral 11 denotes a bucket as a tip attachment, which is provided with a mounting pin D and an operation pin E (not shown) on the back surface, the boom tip is pivotally attached to the mounting pin D, and the operation pin E is connected to the bell crank via a connecting link 12. Are connected to each other at the lower end B thereof. In the state shown in the figure, the positional relationship between P and O 2 is located on the front and back in a substantially horizontal plane. The operation of the above device and the attitude of the bucket are as shown in FIG. 2, and when the lift cylinder 6 is lifted up, the attitude of the bucket also changes. When loading earth and sand into a dump truck or the like, there is an advantage that the loading operation is facilitated by the combined operation with the tilt cylinder 7, but it is unsuitable when loading and unloading wood or the like while keeping a horizontal level like a forklift. In this case, the parallel link device shown in FIG. 3 is employed. Since the parallel link device and its characteristics are well known, only the corresponding reference numerals are described and the detailed description of the mechanism is omitted. Figure
4 is a diagram showing the link mechanism of the present invention, in which the pivot position O of the tilt cylinder with respect to the front frame in FIG. 1 is located below the pivot point P of the boom. This creates an anti-parallel link of PO'-A-C-P-P at the back of the boom and a C-B-E-D-C-C at the front of the boom.
Are formed. These operations cancel each other's operations, and the same operation as the parallel link mechanism of FIG. 3 is realized. During the above operation, the stroke of the tilt cylinder 7a needs to be kept constant.

[0006] An example of an actual device provided with the link mechanism of the present invention is shown in FIG.
5, as shown in FIG. 6, a support frame 15 with a second bracket 14 having an L-shaped cross section is separately provided, and the center of the shaft hole of the second bracket 14 is
It is detachably fixed on the front frame 2 so that O 'is located vertically below the center axis P of the base of the boom 5. No. 2
Since the distance between A and O 'of the tilt cylinder 7a is larger than the distance between A and O of the tilt cylinder 7 of the Z-bar link, a longer cylinder is pivotally connected. The distance between PO and O 'is usually about 30 cm. In this device, if a fork is attached to the work attachment, wood or other long objects can be loaded or unloaded while maintaining the horizontal position. In order to return the present apparatus to the Z-bar link apparatus, it is only necessary to remove the cylinder 7a and the support frame 15, replace the support plate with the bracket 4 (not shown), and pivotally connect the cylinder 7.

[0007]

As described above, according to the link device of the present invention, the operation of the parallel link device can be realized only by connecting the cylinder by adding the bracket 14 to the conventional Z-bar link device. There is no need to prepare a link device, and the user can respond only by replacing the attachment.

[Brief description of the drawings]

FIG. 1 is a perspective view of a Z-bar link device in a wheel loader.

FIG. 2 is a diagram showing a relationship between a Z-bar link mechanism and a bucket.

FIG. 3 is a diagram showing a relationship between a parallel link mechanism and a bucket.

FIG. 4 is a diagram showing a relationship between the link mechanism of the present invention and a bucket.

FIG. 5 is a main part plan view showing the embodiment of the present invention.

FIG. 6 is a vertical sectional side view of the same as above.

[Explanation of symbols]

 1 Wheel loader 2 Front frame 3 Boom bracket 4 Tilt cylinder bracket 5 Boom 6 Lift cylinder 7,7a Tilt cylinder 8 Bell crank 10 Bracket 11 Bucket 12 Joint link 14 Second bracket 15 Support frame

Claims (1)

[Claims] 1. A boom with a lift cylinder, the tip of which is connected to a boom mounting pin on the back of a work attachment; The tilt pin is fixed to the tilt cylinder stroke by pivotally attached to the operation pin on the back of the attachment and connected at the upper end to the rod of the tilt cylinder, and the bottom of the tilt cylinder is pivotally attached below the fixed pivot of the boom. A link device for maintaining a bucket in parallel, wherein the lift cylinder is operated in a state.