KR20120069816A - Forklift having load impact preventing function - Google Patents

Abstract

PURPOSE: A forklift having a load impact preventing function is provided to vary acceleration of a working machine to an optimal state using results comparing allowable acceleration for preventing impact of load and acceleration of a current working machine. CONSTITUTION: A forklift having a load impact preventing function comprises a working machine weight memory(121), a load weight measuring sensor(112), an allowable force memory for each load(122), and a control unit(120). The working machine weight memory stores weight(m_1) of a working machine driven by an actuator. The load weight measuring sensor measures weight(m_2) of load placed on the working machine. The allowable force memory for each load stores allowable value of variation(ΔF/Δt) of force applied to the load per unit hour. The control unit calculates total weight(m = m_1 + m_2) adding up the weight of the working machine moved by the actuator and the load. The control unit calculates allowable acceleration variation(Δa/Δt) per unit hour using the allowable value(ΔF/Δt) of the variable force per unit hour. The control unit restricts rapid driving of the actuator according to calculated allowable acceleration variation per unit hour.

Description

Forklift with load impact prevention function

The present invention relates to a forklift for transporting and loading various loads such as cargo, and more particularly, the impact applied to the load due to the change of state of the work machine in the process of lifting or lowering the load on the work machine is allowed for each type of load. By automatic control not to exceed the limit, the operator's sense of work is eliminated, and the impact on the load does not exceed the proper value, preventing damage or falling of the load and damaging or falling the load. The present invention relates to a forklift having a load shock prevention function capable of preventing secondary damage.

In general, forklifts are used to lift and unload heavy loads or to transport them to a desired position.

This forklift has a vehicle body 1 supported by a front drive wheel 3 and a rear steering wheel (not shown) as shown in FIG. 1, and a mast assembly 5 is installed in front of the vehicle body 1.

The mast assembly 5 constituting the working machines 5 and 7 includes an outer mast 5a and an inner mast 5b installed to overlap the inner side of the outer mast 5a. 5b), a carriage 7 having a fork in front is assembled to be movable up and down.

At this time, the inner mast 5b is lifted up and down by the lift cylinder 8 installed in the mast assembly 5 to raise and lower the carriage 7 connected thereto, and the entire mast assembly 5 is tilt cylinder 9. Is inclined forward or backward (tilt drive).

Therefore, the forklift should have a hydraulic system for operating the lift cylinder 8 and the tilt cylinder 9 as described above. The hydraulic system is, for example, an operation panel 10 and a controller 11 as shown in FIG. ) And the electromagnetic hydraulic valve 12.

Therefore, when a work machine control panel input signal is input through the control panel 10, the controller 11 outputs a current control signal, and the electromagnetic hydraulic valve 12 adjusts the opening degree according to the current control signal and the lift cylinder 8. The speeds of the working machines 5 and 7 are adjusted by adjusting the flow rate of the pressurized oil supplied to the tilt cylinder 9.

On the other hand, in the hydraulic control as described above, when the operator makes a sudden operation, a sudden change occurs at the rising edge or the falling edge of the current control signal, and correspondingly, when the work machine 5 or 7 is also rapidly displaced, the load Since a large shock is applied to the following (hereinafter referred to as 'load'), the controller 11 basically ramps the current control signal.

Currently used as such ramping is fixed as shown in (a) of FIG. 3, adjustable as shown in (b) of FIG. 3, and independent as shown in (c) of FIG. The fixed type has a negative relationship between the ramping time and the falling time of the input signal, but it is always fixed. The adjustable type has multiple ramping values. Are controlled independently of each other.

However, the conventional ramping as described above is always adjusted in a straight line with a constant slope regardless of the type of load loaded on the work machine 5 and 7 during the rise and fall time, so that the current state of the work machine 5 and 7 is never changed. Since the electromagnetic hydraulic valve 12 is adjusted in a state in which only a sudden change in the current control signal is slightly relaxed without being reflected, there is a problem that an excessive shock is still applied to the loads placed on the work machines 5 and 7.

That is, as shown in FIG. 4 showing the time (t)-speed (v), time (t)-acceleration (a), and time (t)-force (F) graphs, the working machines 5 and 7 are operated once. If stop-acceleration, acceleration-constant, constant speed-deceleration, and deceleration-stop are made sequentially during ascending or descending, a total of four discontinuous movements are made to the loaded work tool (5, 7), and excessive shock is applied to the load. There was a problem of being applied several times, even when the work machines 5 and 7 were driven inclined forward or backward by the tilt cylinder 9.

Therefore, in the related art, the operator observes the work machines 5 and 7 and has to operate the work machines 5 and 7 very carefully, and the shock applied to the load exceeds the proper value in the case of over-operation or misoperation. There is a problem that the damage or fall of the load occurs, and furthermore, there is a problem that the secondary damage that damage can be propagated to the worker, people around or the surrounding environment may occur according to the load damage or fall accident.

The present invention has been proposed to solve the problems described above, so that the impact applied to the load due to the change in the state of the working machine in the process of lifting or lowering the load on the work machine does not exceed the allowable limit for each type of load. By controlling, the operator's sense of discomfort can be eliminated, and the impact on the load does not exceed the proper value, preventing damage or drop of the load, and secondary damage caused by damage or fall of the load. To provide a forklift with a load impact protection function that can prevent the.

To this end, the forklift having a load impact protection function according to the present invention includes: a work machine weight memory in which a weight m ₁ of a work machine driven by an actuator is stored; A load weight measuring sensor measuring a weight (m ₂ ) of the load placed on the work machine; A load-specific allowable force memory for storing a tolerance of the change in force (ΔF / Δt) applied to the load per unit time; And an allowable unit using the total weight (m = m ₁ + m ₂ ) obtained by adding up the weights of the work machine and the load moved by the actuator, and the allowable change in force per unit time (ΔF / Δt) allowed for the load. And a control unit for calculating an acceleration change Δa / Δt per hour and limiting the rapid driving of the actuator according to the calculated allowable acceleration per unit time change.

In this case, the control unit includes an acceleration / deceleration pattern generator for generating the acceleration / deceleration pattern signal for controlling the actuator by calculating the acceleration change per unit time, and the acceleration / deceleration pattern signal is preferably a ramping signal. .

In addition, an acceleration measuring sensor for measuring an acceleration vector of the work machine and a difference between the acceleration vector of the work machine and the acceleration / deceleration pattern signal are compared to control the acceleration vector of the work machine to follow the acceleration / deceleration pattern. It is preferable to further include a follower.

In addition, the allowable force memory for each load is stored in the allowable value of the change in force per unit time for each load type, the driver's seat is preferably provided with a load type selection lever for selecting any one of the load type. .

In addition, the limit of the acceleration change per unit time of the work machine is preferably applied during the lifting or lowering of the work machine, or when the front inclined operation or the rear inclined operation of the work machine.

According to the forklift having a load impact protection function according to the present invention as described above, the impact applied to the load due to the change in the state of the work machine in the process of lifting or lowering the load on the work machine does not exceed the allowable limit for each type of load Is controlled automatically.

Therefore, it eliminates the inconvenience that the worker works depending on the senses, prevents the damage or fall of the load by preventing the impact on the load from exceeding the appropriate value, and the secondary damage caused by the damage or the fall of the load. To prevent it.

1 is a partial front view showing a general forklift.
Figure 2 is a block diagram showing a hydraulic control system of the forklift according to the prior art.
3 is a view showing a ramping method according to the prior art.
Figure 4 is a view showing a time zone speed / acceleration / force graph according to the prior art.
Figure 5 is a block diagram showing a forklift having a load impact protection function according to the present invention.
6 is a view showing a load type selection lever of a forklift having a load impact prevention function according to the present invention.
7 is a diagram illustrating a ramping method of a forklift having a load impact protection function according to the present invention.
8 is a schematic operation flowchart of a forklift having a load impact prevention function according to the present invention.
9 is a detailed operation flowchart of the forklift having a load impact prevention function according to the present invention.

Hereinafter, with reference to the accompanying drawings will be described in detail forklift having a load impact protection function according to a preferred embodiment of the present invention.

However, hereinafter, the working machine is lifted up and down in the vertical direction by the lift cylinder 8 as an example, but the present invention is not limited thereto, and the work machine is moved forward or backward by the tilt cylinder 9 even if not otherwise described. It will be apparent to those skilled in the art that the same or similar method is applicable even when driving backwards.

That is, while the work force is applied to the load in a direction perpendicular to the ground while the work device is moving up and down, the force is applied to the load in a direction horizontal to the ground when the work machine is driven inclined forward or backward. It is substantially the same except that the present invention can be applied even when the work machine is driven obliquely forward or backward by the tilt cylinder 9.

In addition, the "working machine" of the forklift to be described below refers to a carriage 7 having a fork in the front portion, an inner mast 5b for raising and lowering the carriage 7 and an outer side of the inner mast 5b. It includes all of the outer mast (5a) is installed to guide the lifting and lowering of the inner mast (5b), it means to directly carry out operations such as lifting or lowering the load.

In addition, hereinafter, a hydraulic cylinder such as a lift cylinder 8 and a tilt cylinder 9, etc. will be described as an example of an actuator for operating a work machine, but the present invention is not limited thereto, and the power source of the actuator is also an internal combustion engine. It will be apparent that a variety of electric motors and the like can be used.

First, as shown in FIG. 5, the forklift 100 having a load impact protection function according to the present invention has an impact applied to various cargoes (hereinafter referred to as 'load') due to a change in the state of the work machine. The input unit 110 provides various variables used for automatic control not to exceed the allowable limit for each type of load, and the work machine so that the force applied to the load is less than the allowable value using various variables provided through the input unit 110. A control unit 120 for controlling the acceleration of the control unit 120 and an output unit 130 for outputting a current control signal for controlling the opening degree of the electromagnetic hydraulic valve (see 12 of FIG. 2) under the control of the control unit 120.

In addition, the input unit 110 includes an acceleration measuring sensor 111, a load weight measuring sensor 112, and a load type selection lever 113 as a lower configuration thereof, and the controller 120 includes a work machine weight memory 121. And an allowable force memory 122 for each load, an acceleration / deceleration pattern generator 123, a follower 124, and a central processing unit (CPU) 125, and an output unit 130. Includes a current control signal generator 131.

Here, the acceleration measuring sensor 111 measures the current acceleration of the work machine in operation, and a carriage (see 7 in FIG. 1) directly related to the movement of the work machine, or an inner mast (in FIG. 1) to which the carriage 7 is connected. 5b) or a lift cylinder (see 8 in FIG. 1) to actually measure the acceleration of the work machine. Of course, it can also be installed in the outer mast (see 5a of FIG. 1) indirectly measured.

An acceleration sensor, a position sensor, and a speed sensor may be used as the acceleration measurement sensor 111. When the acceleration sensor is used, the acceleration of the work machine is detected (checked), and when the other position sensor or the speed sensor is used, It is provided by calculating the acceleration from the velocity (eg F = ma = 1/2 * mv ² = 1/2 * mgh).

Therefore, as described below, the acceleration of the current working machine is compared with the allowable acceleration to prevent the impact of the load from the input of the acceleration measuring sensor 111, and the acceleration of the working machine is changed to an optimal state by using the result. To be possible.

The load weighing sensor 112 measures the weight of the load placed on the work machine. The load weighing sensor 112 is installed on a fork provided in front of the carriage 7 to measure the weight of the load placed on the fork. Can be measured directly.

However, in this case, since the load weighing sensor 112 may be damaged by the load, it is installed at the connection portion of the carriage 7 and the inner mast 5b so that the load weight sensor 112 may be damaged from the manufacturer at the total weight of the carriage 7 and the load. It is also possible to measure variously by comparing the case where there is no load with the case where there is a load, for example, by subtracting and calculating the weight of the carriage 7 that is provided and already known.

The load type selection lever 113 is installed at the driver's seat to allow the operator to select the type of load. In the present invention, the allowable force applied to the load is classified according to the type of load through a test (or prediction). Since the acceleration of the work machine must be controlled to apply a force less than that, the load type selection lever 113 enables the operator to select the type of load.

For example, in FIG. 6, it is possible to select one of OFF, Level 1, Level 2, Level 3 and Level 4 via the load type selection lever 113. OFF does not use the acceleration limit function of the work machine according to the present invention. Level 1 is selected to be easy to break, such as glass or high art, and requires the most careful work so that the impact on the load is minimized. Level 2 to level 4 sequentially relaxes the above limitations. Make it possible.

Of course, if the weight is heavy, the level 1 to level 4 is set in the order of frequent dropping accidents when the sudden acceleration changes, or the level 1 to level 4 is set in the order to be particularly careful because of the spillover effects such as substances harmful to the human body, It is obvious that the level can be freely classified into more than four levels.

Next, the work machine weight memory 121 of the control panel stores the weight of the work machine driven by the lift cylinder 8, which is an actuator, the weight of the work machine is usually provided by the forklift manufacturer, so that the weight of the work machine It is used as a known constant value.

However, in the case where the working machine is raised or lowered, the 'worker weight' means only being driven by the lift cylinder 8, and in this case, the weight of the carriage 7 having the fork and the inner mast 5b is added up. Only the value corresponds to the weight of the working machine, and the outer mast 5a will be excluded because it only serves to guide the rise or fall of the inner mast 5b in a fixed state.

On the other hand, the 'worker weight' in the operation in which the work machine is inclined forward or backward means to be operated by the tilt cylinder 9, so that the carriage 7 and the inner mast 5b as well as the outer mast 5a ) Will also be included. This is because the carriage 7, the inner mast 5b and the outer mast 5a move integrally at the time of tilting the work machine.

Therefore, the 'worker weight' in the present invention refers to specific configurations operated by a specific actuator for a specific operation, and is not limited to the configurations of the above-mentioned names, and the force is applied by the corresponding actuator during a specific operation. It should be noted that it is defined as meaning the weight of all the parts received.

The load allowable force memory 122 stores the allowable value of the force change ΔF / Δt applied to the load per unit time, and various allowable values selected through the load type selection lever 113 described above are stored.

For example, 2N tolerances are stored for loads of level 1, 4N for level 2, 6N for level 3, and 8N for level 4, and these force limits are directly applied to each load type. Save the test by doing it, or save it through heuristics or predictions.

Is the deceleration pattern generator 123 is a weight of the work machine stored in the work machine weight memory 121, the weight of the load placed on the work machine and measured by the load weight measuring sensor 112, and the allowable force memory 122 for each load Using the allowable change of force per unit time of the load stored in) to create a pattern to limit the acceleration and deceleration of the work machine.

That is, the total weight (m = m ₁ + m ₂ ) of the sum of the weight of the work machine moved by the actuator (m ₁ ) and the weight of the load (m ₂ ), and the allowable change of force per unit time allowed for the load ( [Delta] F / [Delta] t) generates an allowable change in acceleration per unit time ([Delta] a / [Delta] t) pattern of the work machine as shown in Equation 1 below.

Equation 1 ΔF = m * Δa = ΔF / Δt = m * (Δa / Δt) = Δa / Δt = ΔF / (m * Δt)

(Where F is the force on the load, a is the acceleration of the working machine, m is the weight of the working machine and the load, t is time)

Accordingly, the present invention calculates the acceleration of the working machine (Δa / Δt <ΔF / (m * Δt)) so as not to exceed the change in force per unit time allowed for the load, and this is the electrohydraulic valve of the lift cylinder 8 12) is used as the limit value of the current pattern (acceleration / deceleration pattern) to control. Therefore, even when the worker controls the work machine rapidly, the actual work machine acceleration is automatically limited so that an impact exceeding the limit is not applied to the load.

In particular, the present invention, as shown in the lower part of Figure 7, as a pattern during the rise time and fall time of the ramping signal, using a pattern that is limited so that impacts exceeding the limit as described above is not applied to the load Thus, it is possible to significantly reduce the impact on the load compared to the acceleration pattern before improvement shown at the top of FIG. 7.

The tracking unit 124 compares the difference between the acceleration vector (ie, acceleration or deceleration) of the work machine provided by the acceleration measurement sensor 111 and the acceleration / deceleration pattern signal provided by the acceleration / deceleration pattern generator 123. Then, the following control is performed so that the measured acceleration vector of the work machine follows the ideal acceleration / deceleration pattern.

For example, if the measured acceleration of the work machine is smaller than the size of the acceleration pattern, the acceleration increase rate is increased to have a pattern similar to that of the acceleration pattern, so that the impact is not applied to the load while the acceleration is increased. If the acceleration pattern is larger than the magnitude of the acceleration pattern, the acceleration increase rate is lowered to have a pattern similar to the acceleration pattern, so that an impact beyond the allowable value is not applied to the load.

On the other hand, the output unit 130, which has not been described above, includes a current control signal generator 131, and the current control signal generator 131 may be provided with an electromagnetic hydraulic valve according to an operation command of the controller 120. A current control signal for controlling the opening degree of 12) is outputted. Therefore, the acceleration of the work machine is controlled by adjusting the speed of the pressure oil supplied to the lift cylinder 8 which is the actuator.

In addition, the central processing unit 125 processes the overall process of the control unit 120 as described above.

Hereinafter, the operation procedure of the forklift having a load shock prevention function according to the present invention having the above configuration will be described.

However, the work machine of the forklift, which will be described below, accelerates the work machine while pushing the operation panel (see 10 in FIG. 2) provided in the driver's seat to one side, and the work machine decelerates and stops when the hand is released after a certain time, and the operating panel 10 While pushing to the other side will be described as an example that the working machine is lowered and accelerated, and if the user releases the hand after a certain time, the working machine is decelerated and stopped.

First, referring to Figure 8 showing a schematic operation sequence of the forklift having a load impact protection function according to the present invention, whether the operator has input of the operating panel 10 for operating the work machine during operation using the forklift The determination is made (S110).

The input of the control panel 10 may be either an up or down operation, and the four steps of stop-acceleration, acceleration-equivalent speed, constant speed-deceleration, and deceleration-stop are the same whether rising or falling. Take as an example.

As a result of the determination, if there is no input of the operation panel 10, the controller continuously monitors whether there is an input of the operation panel 10, and if there is an input of the operation panel 10, the load weight and the load type are determined to generate an acceleration / deceleration pattern (S120).

When the deceleration pattern is generated, the opening ratio of the solenoid hydraulic valve 12 is adjusted in a general manner to drive the lift cylinder 8 and the inner mast 5b, thereby raising the load placed on the fork of the carriage 7. Let's start. At the initial rise, however, the acceleration change of the work machine should be as small as possible to avoid excessive impact on the load.

When the load starts to rise, the controller 10 continuously determines whether there is an input of the operation panel 10 (S130), and if there is an input of the operation panel 10, then the opening pattern of the electromagnetic hydraulic valve 12 is adjusted by following the acceleration pattern to adjust the inner pressure. The mast 5b is driven (S140), so that the load placed on the fork of the carriage 7 is raised, so that the load is not subjected to an impact beyond the allowable value.

On the other hand, if there is no input to the operation panel 10, by controlling the inner mast 5b following the deceleration pattern (S150), the load is stopped so as not to be subjected to an impact exceeding the allowable value and the operation is finished.

That is, as described above, when there is an input of the operation panel 10 continuously, the operation panel 10 is continuously pushed in the direction in which the work machine rises, and when there is no input of the operation panel 10, the operator moves the control panel 10. Since you are trying to stop the machine by releasing your hand, stop it without impacting the load.

Next, referring to Figure 9 showing a detailed operation of the forklift having a load shock protection function according to the present invention, whether the operator has an input of the operating panel 10 for operating the work machine during operation using the forklift Determine (S110).

As a result of the determination, if there is no input of the operation panel 10, the controller continuously monitors whether there is an input of the operation panel 10, and if there is an input of the operation panel 10, the load weight and the load type are determined to generate an acceleration / deceleration pattern (S120).

When the deceleration pattern is generated, the driving current as the current control signal is output to the electromagnetic hydraulic valve 12 (S121). The initial drive current is not following the deceleration pattern generated as described above, but is the initial drive current in the conventional and general manner.

However, during the initial rise, it is preferable that the acceleration change of the work machine is as small as possible so that an excessive shock is not applied to the load. However, if necessary, the acceleration and deceleration pattern may be followed from the beginning as described below.

When the initial driving current is supplied and the mast starts to rise (S122), it is continuously determined whether there is an input of the operation panel 10 (S130), and if there is an input of the operation panel 10, the inner mast 5b is continuously raised. It is determined that the operation panel 10 is operated, and the acceleration pattern following mast control step (see S140 of FIG. 8) is performed.

For the acceleration pattern following mast control, first read the value of the acceleration measurement sensor 111, and then calculate or confirm the current acceleration (in the case of the position sensor or the speed sensor) or confirm (in the case of the acceleration sensor) (S141, S142), and then accelerate the acceleration pattern. The value is compared with the current acceleration to determine whether they are different from each other (S143).

As a result of the determination, when the acceleration pattern value and the measured current acceleration are the same, the output is continuously performed at the current increase rate (S144). If the acceleration pattern value and the measured current acceleration are different, the acceleration pattern value is greater than the current acceleration. It is determined whether it is large (S145).

As a result of the determination, if the acceleration pattern value is greater than the current acceleration, the output current is increased larger than the current current control signal rising ratio for controlling the inner mast 5b (S145a) to follow the acceleration pattern value, and the acceleration pattern value is greater than the current acceleration. If it is small (S146), the output pattern following the acceleration pattern value is completed by outputting (S146a) smaller than the current current control signal rising rate to complete the acceleration pattern following.

On the other hand, as described above, as a result of determining whether or not the operation panel 10 is input (S130), if there is no input of the operation panel 10, the operator releases the hand from the operation panel 10 to terminate the rise of the inner mast 5b, that is, the work machine. I judge it.

Then, after reading the value of the acceleration measurement sensor 111, the current deceleration is calculated or checked to determine whether the current deceleration is '0' (ie, stop) (S151, S152, and S153).

As a result of the determination, when the current deceleration is not '0', the deceleration pattern value and the current deceleration are compared to determine whether they are different from each other (S154). If the deceleration pattern value and the measured current deceleration are different from each other, it is determined whether the deceleration pattern value is greater than the current deceleration rate (S156).

As a result of the determination, if the deceleration pattern value is greater than the current deceleration rate, the output current (S156a) is larger than the current current control signal falling rate for controlling the inner mast 5b to follow the deceleration pattern value, and the deceleration pattern value is the present deceleration rate. If smaller (S157), the output pattern S157a is smaller than the current current control signal falling rate to follow the acceleration pattern value, thereby completing the deceleration pattern following.

Then, when it is determined that the current deceleration is '0' while repeating the above process (S153), the control of the forklift for the load shock prevention function is terminated.

In the above, the specific Example of this invention was described above. It is to be understood, however, that the scope and spirit of the present invention is not limited to these specific embodiments, and that various modifications and changes may be made without departing from the spirit of the present invention. If you have, you will understand.

Therefore, it should be understood that the above-described embodiments are provided so that those skilled in the art can fully understand the scope of the present invention. Therefore, it should be understood that the embodiments are to be considered in all respects as illustrative and not restrictive, The invention is only defined by the scope of the claims.

110: input unit 111: acceleration measurement sensor
112: load weight measuring sensor 113: load type selection lever
120: control unit 121: work machine weight memory
122: allowable force memory for each load 123: acceleration / deceleration pattern generator
124: follower 125: central processing unit
130: output unit 131: current control signal generator

Claims (5)

A work machine weight memory 121 in which a weight m ₁ of a work machine driven by an actuator is stored;
A load weight measuring sensor 112 for measuring a weight m ₂ of the load placed on the work machine;
A load-specific allowable force memory 122 for storing an allowable value of a change in force (ΔF / Δt) applied to the load per unit time; And
Per unit time allowable by using the total weight (m = m ₁ + m ₂ ), which is the sum of the weights of the work machine and the load moved by the actuator, and the allowable change in force per unit time (ΔF / Δt) allowed for the load A forklift having a load shock prevention function, comprising: a control unit (120) for calculating an acceleration change (Δa / Δt) and for limiting the rapid driving of the actuator according to the calculated allowable acceleration change per unit time. . The method of claim 1,
The control unit 120 includes an acceleration / deceleration pattern generator 123 for calculating the acceleration / deceleration pattern signal for controlling the actuator by calculating the acceleration change per unit time, and the acceleration / deceleration pattern signal is ramped. A forklift having a load impact prevention function, characterized in that the signal. The method of claim 2,
Acceleration measurement sensor 111 for measuring the acceleration vector of the work machine and comparing the difference between the acceleration vector and the acceleration and deceleration pattern signal of the working machine, to control the acceleration vector of the working machine to follow the acceleration and deceleration pattern A forklift having a load shock prevention function, further comprising a follower (124). The method of claim 1,
The allowable force memory for each load 122 stores the allowable change of force per unit time for each load type, and a load type selector 113 for selecting one of the load types is installed in the driver's seat. A forklift with load impact protection, characterized in that there is. The method according to any one of claims 1 to 4,
Restriction of the acceleration change per unit time of the work machine is applied to the lifting or lowering of the work machine, or forklift with a load impact protection, characterized in that applied to the front inclined operation or the rear inclined operation of the work machine.

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