JPH068153Y2 - Forklift mast device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of use) The present invention relates to a mast device for a forklift truck, and more particularly to an improvement of a free lift type mast device.

(Prior Art) FIGS. 6 and 7 show a conventional free-lift type mast device. As shown in the figure, lift cylinders 4 are arranged behind the pair of left and right masts, and the upper ends of the piston rods 5 of the lift cylinders 4 are connected to the chain beam 6.
Are connected to each other by. A lift chain 9 is mounted on each of the left and right chain wheels 8 supported by the chain beam 6, and one end of the lift chain 9 is connected to the lift cylinder 4 or the outer mast 2.
The other end is connected to the lift bracket 10. Therefore, the chain beam 6 can be moved up and down through a bush 11 to a guide rod 12 vertically provided on the lower surface of the upper tie beam 3a of the inner mast 3, which allows the lift bracket 10 (specifically, the lift bracket 10 A free lift amount L determined by the length of the guide rod 12 is given to the attached attachment, for example, a fork.

(Problems to be Solved by the Invention) In the free lift type mast device as described above, the upper tie beam 3a for connecting the upper end portions of the rear surfaces of the left and right inner masts 3 to each other is welded to the inner mast 3 to form the upper tie beam 3a.
However, since the required free lift amount L is formed between the lower surface of the upper tie beam 3a and the bush 11, the thickness of the upper tie beam 3a cannot be freely increased. However, this is disadvantageous in that the welding margin of the upper tie beam 3a is limited and the welding strength is sufficiently increased.

Further, in the free lift type mast device, there is a small gap in the front-rear direction between the chain beam 6 and the upper tie beam 3a, and therefore there is a risk of pinching a finger. Such a problem of fingers being caught is not a problem that occurs during normal cargo handling work. For example, in the case where a worker rides on an attachment mounted on the lift bracket 10 to raise and lower the mast, it is a special work form. This is something that can happen, and is a matter that occurs in the free lift section in a situation where the worker is gripping the connecting portion of the upper tie beam 3a with the inner mast 3, but in any case, such a finger pinching problem. The reason is that the vicinity of the fixed portion of the upper tie beam 3a with respect to the mast and the vicinity of the fixed portion of the chain beam 6 with respect to the piston rod 5 face each other with an unfavorable gap in the front-rear direction. Therefore, it is possible to take a large gap to eliminate the trapping of fingers, but such a countermeasure is not effective because it results in a longer vehicle length.

In view of the above problems, it is an object of the present invention to provide a mast device for a forklift truck that is capable of strengthening the fixing of the upper tie beam to the inner mast and solving the problem of finger pinching in the free lift section. .

(Means for Solving the Problems) In order to solve the above problems, the present invention is directed to a beam for mutually connecting the piston rods of the left and right lift cylinders arranged at the rear of the left and right masts, and the upper end portions of the left and right inner masts. In a mast device having an upper tie beam connecting rear surfaces to each other and having a free lift amount between the upper tie beam and the beam, a longitudinal reinforcing plate is welded to the upper rear surface of the inner mast, and the reinforcing plate is also welded. The lower end surface of the upper tie beam is welded to the upper end surface of the upper tie beam, and a reinforcing plate having a total length corresponding to the free lift amount set between the beam and the upper tie beam and flush with the rear end surface of the upper tie beam. Is set to.

(Operation) The reinforcing plate in the mast device configured as described above makes it possible to increase the welding allowance of the upper tie beam, and in addition to supporting the upper tie beam from below, also relates to the free lift section. The distance between the front and back of the beam is reduced as much as possible to effectively prevent the fingers from being caught.

(Embodiment) An embodiment of the present invention will be specifically described below with reference to the drawings. As shown in the figure, lift cylinders 4 are provided behind the pair of left and right masts 1, respectively. The left and right lift cylinders 4 are specifically erected on the lower cross beam 2a of the outer mast 2 and the piston rods 5 thereof are provided.
Have their upper ends connected to each other by a chain beam 6. Chain wheels 8 are attached to the left and right lower surfaces of the chain beam 6 via wheel brackets 7, respectively. One end of a lift chain 9 mounted on the chain wheels 8 is connected to the lift cylinder 4, and the other end is connected to the inner mast 2. It is connected to a lift bracket 10 that moves up and down along the line.

The left and right wheel brackets 7 are respectively formed with bushes 11 having an up-down direction as an axial direction. The bushes 11 are positioned in front of the front end surface of the chain beam 6, and the upper tie beam 3a of the inner mast 3 is positioned. It is slidably fitted to a guide rod 12 vertically provided on the lower surface. Thus, upper tie beam 3
Free lift L between the lower surface of a and the upper surface of the bush 11
Is set. A predetermined interval is set in the front-rear direction between the upper tie beam 3a and the chain beam 6, so that the bush 11 moves up in the free lift section and comes into contact with the lower surface of the upper tie beam 3a as shown in FIG. The chain beam 6 is located right behind the upper tie beam 3a and overlaps in the front-back direction. Reference numeral 13 is a fork attached to the lift bracket 10.

In the free lift type mast device configured as described above, the reinforcing plate 14 is attached to the upper rear surface of the inner mast 3. The reinforcing plate 14 has a vertical length corresponding to the free lift amount L, is fixed to the inner mast 3 by welding, and the end portion of the upper tie beam 3a is placed on the upper end surface thereof. It is fixed by welding. That is, the end portions of the upper tie beam 3a are welded to the upper surface of the reinforcing plate 14 and the rear surface of the inner mast 3, respectively, whereby the coupling strength of the upper tie beam 3a is achieved. Further, the rear end face of the reinforcing plate 14 and the rear end face of the upper tie beam 3a are set to be flush with each other, and the thickness of the reinforcing plate 14 is set so that the front end face of the chain beam 6, particularly the front end near the joint with the piston rod 5. The gap with the surface is set to be as narrow as possible (for example, 5 mm or less).

Therefore, when the lift cylinder 4 is lifted, the chain beam 6 moves up along the guide rod 12 via the bush 11, so that the lift bracket 10 moves up via the lift chain 9 with the mast height kept constant. It After the bush 11 contacts the lower surface of the upper tie beam 3a, the inner mast 3 is pushed up together with the upper tie beam 3a. Then, in an exceptional form in which a worker rides on the fork 13 or the load, which is an attachment attached to the lift bracket 10, to perform work, specifically on the rear surface of the inner mast 3, specifically, the reinforcing plate 14 or the upper tie beam. When the operator grips the rear surface of the connecting portion of 3a and moves up, the reinforcing plate 14 exists in the free lift section in which the bush 11 moves up along the guide rod 12, and the reinforcing plate 14 and the chain beam 6 are connected to each other. Since the front and rear clearances are small, it is possible to prevent a finger from being caught in the clearance.

In addition, in this embodiment, when the reinforcing plate 14 is installed, as shown in FIG. 1, a case is shown in which a part of the reinforcing plate 14 is mounted so as to project inward from the inner end surface of the inner mast 3. As shown in FIG. 5, when the inner mast 3 is mounted so as not to be protruded from the inner end surface, it is effective in securing a front view from the driver's seat.

(Effects of the Invention) As described in detail above, according to the present invention, by installing a reinforcing plate on the rear upper end of the inner mast, the welding allowance of the upper tie beam with respect to the inner mast is substantially expanded to increase its bonding strength. Since the reinforcing plate has a vertical length corresponding to the range in which the chain beam rises as the free lift section, the reinforcing plate can prevent finger trapping accidents that may occur in the free lift section. .

[Brief description of drawings]

1 to 4 show an embodiment of the present invention, and FIG. 1 is a front view of a free-lift type mast device viewed from the driver's side, and FIG.
The figure is also a side view, FIG. 3 is a plan view, FIG. 4 is a perspective view, FIG. 5 is a front view showing a modification of installation of a reinforcing plate, and FIG. 6 is a conventional view seen from the driver's side. FIG. 7 is a front view showing the free-lift type mast device, and FIG. 7 is a plan view of the same. 1 ... Mast, 3 ... Inner mast 3a ... Upper tie beam, 4 ... Lift cylinder 6 ... Chain beam, 8 ... Chain wheel 9 ... Lift chain, 11 ... Bushing 12 ... Guide rod, 14 ... Reinforcement plate

Claims (1)

[Scope of utility model registration request] 1. A beam for mutually connecting piston rods of left and right lift cylinders respectively arranged at the rear of the left and right masts, and an upper tie beam for mutually connecting upper end rear surfaces of the left and right inner masts, A mast device having a free lift amount between the upper tie beam and the beam, wherein a vertically long reinforcing plate is welded to an upper portion of a rear surface of the inner mast, and a lower end surface of the upper tie beam is welded to an upper end surface of the reinforcing plate. A mast device for a forklift truck, wherein the reinforcing plate has a total length corresponding to the free lift amount set between the beam and the upper tie beam and is flush with the rear end surface of the upper tie beam.