JP2531321B2 - Forklift mast device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mast device for a forklift, and more specifically, a liner is interposed on a sliding surface between an outer mast or a middle mast and an inner mast which is vertically movable with respect to the mast. Related to the mast device of the structure.

[0002]

2. Description of the Related Art FIGS. 4 and 5 schematically show a conventional standard specification semi-free lift structure mast device. As shown, an inner mast 2 is attached to the pair of left and right outer masts 1 so as to be vertically movable via lift rollers 3, 4, 5. A pair of left and right lift cylinders 6 are erected on the back side of the mast, and piston rods 7 of both lift cylinders 6 are connected to each other by a connecting plate 8. On the lower surface of the upper tie beam 9 of the inner mast 2, two left and right guide rods 10 vertically penetrating the connecting plate 8 are vertically provided, and the upper tie beam 9 and the connecting plate are connected at the descending end of the mast. A clearance S corresponding to the free lift amount is set between the clearance S and That is, until the connecting plate 8 comes into contact with the upper tie beam 9 by the extension operation of the lift cylinder 6 to start the lifting of the inner mast 2, only the lift bracket is lifted via a lift chain (not shown). It has a lift structure.

In a normal mast device, the forward tilting load (moment in the direction of arrow F in the figure) acting on the inner mast 2 is lifted by the lift roller 4 attached to the lower end of the inner mast 2 and the upper end of the outer mast 1. The load is supported by the lift roller 3 attached to the rear portion of the inner mast 2 and the load in the backward tilt direction (moment in the direction of the arrow R in the figure) is applied to the lift roller 5 on the lower side of the inner mast 2 and the liner 11 attached to the upper end of the outer mast 1. Is supported by. The liner 11 is attached to the front upper end of the rear flange 1a of the outer mast 1,
The inner mast 2 slides on the rear surface of the rear flange 2a.

[0004]

By the way, in the mast device having the semi-free lift structure, when the lift cylinder 6 is lowered in the most elevated state of the mast, the lift cylinder 6 is lowered within the range of the free lift amount. Even if the inner mast does not fall, a so-called "hanging phenomenon" may occur. This "hanging phenomenon" is generally considered to be caused by the rear surface of the rear flange 2a of the inner mast 2, which is a sliding surface for the liner 11, hooking on the liner 11, and therefore the conventional liner 11 is used. By applying grease to the inner mast 2, the slidability of the inner mast 2 with respect to the sliding surface is improved to avoid the "hanging phenomenon". However, if grease is simply applied to the liner 11, the grease will run out immediately after repeated use. Therefore, the frequency of grease replenishment is high. If the grease is not replenished frequently, the "hanging phenomenon" will reoccur. There is a problem of doing.

Therefore, in view of the above problems, the present invention is capable of maintaining good slidability of the liner interposed between the masts for a long period of time, and by extension is effective in preventing the "hanging phenomenon" of the inner mast. Providing a mast device is a technical problem to be solved.

In order to solve the above problems, the present invention is configured as follows. That is, a forklift in which a liner for receiving a longitudinal load or a lateral load acting on the inner mast is provided on a sliding surface between the outer mast or the middle mast and an inner mast that is vertically movable with respect to the mast. The mast device is characterized in that the mast is provided with a grease groove extending continuously over substantially the entire length on the sliding surface with the liner.

[0007]

In the mast device of the present invention configured as described above, the grease applied to the sliding surface of the mast can be stored in the grease groove, so that the liner can be sufficiently replenished with grease for a long period of time. As a result, it becomes possible to secure good slidability. Further, the grease groove is formed at the same time when the mast is manufactured because the mast is generally manufactured by drawing.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. First, the embodiment shown in FIGS. 1 and 2 will be described. This embodiment is applied to a mast device having a semi-free lift structure, and since the structure for raising and lowering the mast device is the same as that of the conventional mast device shown in FIGS. 4 and 5, the same reference numerals are used. And omit the explanation,
The structure of the sliding surface of the outer mast 1 and the inner mast 2 which is the main part of the invention will be described in detail.

As shown in FIG. 2, the outer mast 1 is formed to have a U-shaped cross section, and the inner mast 2 is formed to have a U-shaped cross section. The inner mast 2 has a rear surface of the rear flange 2a on the rear side of the outer mast 2. Rear flange 1
It is arranged so as to face the front surface of a. The liner 1 is provided on the upper end of the front surface of the rear flange 1a of the outer mast 1.
1 is attached, and the rear surface of the rear flange 2a of the inner mast 2 which is a sliding surface with the liner 11 is provided with one to three grease grooves 12 (in the figure, the case of one) is formed. Further, in this embodiment, the grease groove 1
The reference numeral 2 is formed in a semi-circular shape in cross section, and continuously extends over the entire length of the sliding surface in the sliding direction as shown in FIG.

This embodiment is constructed as described above, and therefore the inner mast 2 which is the sliding surface of the liner 11 is formed.
Since the grease applied to the rear surface of the rear flange 2a of the above can be sufficiently stored in the grease groove 12, the liner 11 is replenished with grease when the inner mast 2 is moved up and down, and the good slidability is maintained for a long period of time. Will be secured. This relieves the frequent grease replenishment work that has been conventionally required, and can prevent the “hanging phenomenon” of the inner mast 2 that occurs in the mast device having the semi-free lift structure. Further, since the mast is generally manufactured by drawing, the grease groove 12 can be formed at the same time when the inner mast is manufactured. Therefore, the grease groove 12 can be easily manufactured as compared with a case where a grease reservoir is provided on the liner 11 side. Therefore, the processing cost can be reduced.

Next, another embodiment of the present invention shown in FIG. 3 will be described. In this embodiment, the inner mast 2 is formed to have a U-shaped cross section, and the outer mast 1 having a U-shaped cross section is used.
FIG. 3 shows an example of application to a mast device of a type in which the mast is housed inside and guided by a liner for vertical movement of the inner mast. In FIG. 3, the upper part of the mast is shown in a plane on the left side and the lower part of the mast is shown in a cross section on the right side. ing. In the mast device of the above type, as shown in the drawing, the front-rear direction load is received by the upper and lower front and rear liners 13 and 14 interposed between the flanges 1a and 2a of both masts 1 and 2, and the lateral load is applied to both sides. It is received by the upper and lower side liners 15 and 16 interposed between the webs 1b and 2b of the masts 1 and 2.

As shown on the left side, however, the upper front and rear liners 13 and the side liner 15 are
Since it is attached to the upper part of the outer mast 1, the front and rear flanges 2 of the inner mast 2 which are sliding surfaces for these
A grease groove 17 is formed in each of a and the web 2b. On the other hand, as shown on the right side, the lower front and rear liners 14 and the side liners 15 are attached to the lower part of the inner mast 2, so that the front and rear flanges 1a and the web 1b of the outer mast 1 which are sliding surfaces for them are respectively attached. Each grease groove 18 is formed. This makes it possible to increase the amount of grease held on the mast sliding surface for each of the liners 13 to 16 as in the case of the above-described embodiment.

In this embodiment, the inner mast 2 is described as a two-stage mast which is vertically moved along the outer mast 1. However, in the case of a three-stage mast, a middle mast is used instead of the outer mast 1. That is the subject.

[0014]

As described in detail above, according to the present invention,
By providing the grease groove on the mast side, which is the sliding surface with the liner, the amount of grease retained on the sliding surface is greatly increased, and good slidability of the inner mast is maintained for a long period of time. Therefore, it is possible to be freed from the frequent grease refilling work that has been conventionally required, and eventually to prevent the "hanging phenomenon" of the inner mast. Also,
According to the present invention, since the grease groove can be formed at the same time when the mast is manufactured, a special manufacturing process for forming the grease groove is unnecessary, and the manufacturing is easy and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a side sectional view of a mast device according to an embodiment of the present invention.

FIG. 2 is a plan view showing one side of the mast device.

FIG. 3 is a half sectional plan view showing a mast device according to another embodiment of the present invention.

FIG. 4 is a rear view showing a conventional mast device having a semi-free lift structure.

FIG. 5 is a side sectional view of the same.

[Explanation of symbols]

1 ... Outer mast 2 ... Inner mast 11 ... Liner 12 ... Grease groove 13-16 ... Liner 17, 18 ... Grease groove

Claims (1)

(57) [Claims] 1. A liner for receiving a longitudinal load or a lateral load acting on the inner mast is provided on a sliding surface of an outer mast or a middle mast and an inner mast that is vertically movable with respect to the mast. Mast device for a forklift, wherein the mast is provided with a grease groove extending continuously over substantially the entire length on a sliding surface with the liner.