JP7643155B2 - Loading truck crane - Google Patents

Description

The present invention relates to a loaded truck crane. More specifically, it relates to a loaded truck crane in which the rating of the crane device is determined by the swing position of the boom. In this specification, unless otherwise specified, the descriptions of front, rear, left, right, and front, rear, and left, and right refer to the user of the loaded truck crane when the user is seated in the driver's cab of the vehicle body.

A loaded truck crane is a vehicle that has a crane device mounted on a truck with a loading platform. The crane device is mounted between the driver's cab and the loading platform. The crane device is operated by drawing power from a driving motor. When using a loaded truck crane, the boom of the crane device is rotated around the base of the crane device, the boom is raised and lowered, and the hook is raised and lowered with a winch. Cargo is hoisted and transported by this action.

In loaded truck cranes, an outrigger device is provided on the vehicle body to ensure stability of the vehicle body during crane operation. In most cases, when performing crane operation, the user of the loaded truck crane extends the outriggers that make up the outrigger device from the vehicle body and performs the operation while in a grounded state.

The rated load of a loaded truck crane is calculated from the capacity when there is no load on the platform and at the least stable turning position in the side area (unloaded stability performance) and the capacity determined from the strength of the crane's structure (crane strength performance). The graph in Figure 3 of Patent Document 1 is an example of a rated load calculated in this way, and Patent Document 1 discloses a configuration in which an alarm is issued or operation is stopped depending on the ratio of the lifting load to this rated load. In the front area of the loaded truck crane described in Patent Document 1, the rated load is set to 25% of the rated load of the crane device, taking into account the structure.

The reason why the rated load in the front area is set to 25% of the rated load of the crane equipment as mentioned above is because, due to the structure of a loaded truck crane, the loading platform is installed at the rear of the crane equipment, but the above rated load is based on the assumption that no load is placed on this platform.

In response to this, Patent Document 2 discloses a loaded truck crane equipped with rear outrigger devices, in which the function of restricting the operation of the crane device is activated using the ground reaction force signal of the rear jack. This is based on the idea that when there is a load on the bed, the load is behind the front outrigger devices, so the stability of the loaded truck crane is increased and restrictions in the front area should be relaxed to approach the crane strength performance.

Japanese Patent Application Publication No. 9-86873 JP 2019-156579 A

However, the rated load in the graph of Fig. 3 of Patent Document 1 is calculated in advance taking into account the capacity at the swing position with the worst stability in the side area, so there is a very large margin on the safety side. Furthermore, in the front area of the loaded truck crane, the rated load is set to 25% of the rated load of the crane device in consideration of the structure. This causes a problem that the rated load of the loaded truck crane is excessively limited especially in the front area.

In addition, Patent Document 2 uses the ground reaction force signal of the rear jack of the rear outrigger device, but this configuration can only be adopted in models that use rear outrigger devices, and there is a problem in that it is less versatile.

In view of the above circumstances, the present invention aims to provide a loaded truck crane that maximizes the capacity of the crane device while ensuring work safety without excessively restricting the work capacity in the forward area, and that employs a highly versatile configuration that can be used with various types of loaded truck cranes.

The loaded truck crane of the first invention is a loaded truck crane equipped with a bed and a crane apparatus, and further equipped with a tilt angle detector that measures the tilt angle of the body of the loaded truck crane, a control device that receives a tilt signal from the tilt angle detector, and an alarm connected to the control device, wherein when a boom that constitutes the crane apparatus is positioned in a forward area, the control device performs at least either a function of regulating the operation of the crane apparatus or a function of activating the alarm based on the tilt signal.
The loading truck crane of a second invention is the same as the first invention, characterized in that the tilt angle detector is provided on the crane device.
The loading truck crane of a third invention is the same as that of the first invention, characterized in that the tilt angle detector is provided inside a housing of the control device.
The loaded truck crane of the fourth invention is characterized in that, in any of the first to third inventions, the control device calculates from the tilt signal the reaction force applied to the rear wheels of the loaded truck crane when the boom of the crane equipment of the loaded truck crane is located in a forward area, and when the reaction force becomes equal to or less than a predetermined value, activates at least either a function of regulating the operation of the crane equipment or a function of activating the alarm.
The loaded truck crane of the fifth invention is characterized in that, in the fourth invention, the control device calculates the reaction force as F1 + k × L × sin((θ3 - θ2) - θ1)) (F1: reaction force of the rear wheels in an working state with the crane equipment in the stored position, k: spring constant of the chassis of the rear wheels, L: distance in a plan view between the front-to-rear center of the outrigger equipment provided on the loaded truck crane and the front-to-rear center of the rear wheels, θ1: tilt angle in an working state with the crane equipment in the stored position, θ2: tilt angle when the loaded truck crane is in a drivable state, θ3: tilt angle in an working state in the front area).

According to the first aspect of the present invention, when the boom of the crane is located in the forward area, the control device operates a function to restrict the operation of the crane in response to the tilt signal from the tilt angle detector, thereby preventing excessive limitations on the work capacity in the forward area. This makes it possible to maximize the capacity of the crane while ensuring the safety of the work. In addition, since the tilt angle detector is used, the mechanism of the loaded truck crane is not limited to cases where it has a rear jack, etc.
According to the second invention, since the inclination angle detector is provided on the crane apparatus, there is no need to install the inclination angle detector on the general-purpose truck side, and the number of assembly steps at the final assembly manufacturer of the loaded truck crane can be reduced.
According to the third invention, since the inclination angle detector is provided inside the housing of the control device, the housing of the control device has high environmental resistance, such as being waterproof, so there is no need to increase the environmental resistance of the inclination angle detector alone, thereby reducing costs.
According to the fourth invention, the reaction force of the rear wheels when the boom of the crane apparatus is located in the forward area is calculated from the tilt signal, so that the value of the reaction force applied to the rear wheels can be obtained with high accuracy.
According to the fifth aspect of the present invention, the reaction force is calculated using a predetermined formula, so that the value of the reaction force applied to the rear wheels can be obtained with greater accuracy.

FIG. 2 is a control circuit diagram of the loading truck crane according to the first embodiment of the present invention. FIG. 2 is a side view of the loading truck crane of FIG. 1. FIG. 2 is a hydraulic circuit diagram of the loading truck crane of FIG. 1. FIG. 2 is an explanatory diagram of a working area of the loading truck crane of FIG. 1. 2 is an explanatory diagram of a method for controlling the loaded truck crane of Fig. 1. (A) is an explanatory diagram from the side of the working state of the crane device 21 in the stored position, (B) is an explanatory diagram from the side of the loaded truck crane in the travellable state, and (C) is an explanatory diagram from the side of the working state in the front area. FIG. 2 is an operation flow diagram of the loading truck crane of FIG. 1 .

Next, an embodiment of the present invention will be described with reference to the drawings. However, the embodiment shown below is an example of a loaded truck crane to embody the technical concept of the present invention, and the present invention does not limit the loaded truck crane to the one described below. Note that the size or positional relationship of the components shown in each drawing may be exaggerated for clarity of explanation.

First Embodiment
(Loading truck crane 10)
Fig. 2 shows a side view of the loaded truck crane 10 according to the first embodiment of the present invention. As shown in Fig. 2, the loaded truck crane 10 has a crane device 21 mounted on a vehicle frame 29 between a driver's cab 27 and a loading platform 28 of a general-purpose truck 20. The general-purpose truck 20 has front wheels 22 symmetrically provided on the left and right. Furthermore, the general-purpose truck 20 has rear wheels 23 symmetrically provided on the left and right. The "vehicle body" of the loaded truck crane 10 refers to the general-purpose truck 20.

As shown in FIG. 2, the crane device 21 comprises a base 30 fixed on the vehicle frame 29, a post 31 rotatably mounted on the base 30, a boom 32 mounted on the upper end of the post 31 so as to be able to be raised and lowered, and an outrigger device 33 mounted on the base 30 and extending outward to the left and right from the base 30. In other words, the outrigger device 33 is located between the cab 27 and the loading platform 28 when viewed from the side. Hydraulic jacks 38 are provided on the left and right ends of the outrigger device 33 (see FIG. 4).

A winch is built into the post 31. A wire rope is led from this winch to the tip of the boom 32 and passed through a pulley at the tip of the boom 32 to a hook 34, which is then hung from the tip of the boom 32.

The crane device 21 is hydraulically driven by a hydraulic circuit 40. A group of levers 35 for operating this hydraulic circuit 40 is provided on both the left and right sides of the base 30. In addition, a control device 12 that electrically controls the hydraulic circuit 40 and controls the work vehicle is provided on the base 30.

(Hydraulic circuit 40)
Fig. 3 shows a hydraulic circuit diagram of the loaded truck crane 10 according to this embodiment. As shown in Fig. 3, the hydraulic circuit 40 of the crane device 21 mainly includes a hydraulic valve unit 41, a hydraulic pump 43 that supplies hydraulic oil in a tank 42 to the hydraulic valve unit 41, a main oil passage 44 that connects the hydraulic pump 43 and the hydraulic valve unit 41, a return oil passage 45 that connects the hydraulic valve unit 41 and the tank 42, a plurality of crane device actuators 46 for performing the raising and lowering operation of the crane device 21, the extension and contraction operation of the boom 32, the rotation operation of the boom 32, the lifting and lowering operation of the winch, and two jacks 38. The crane device actuators 46 and the jacks 38 are connected to the hydraulic valve unit 41.

The hydraulic pump 43 is connected to the engine 36 of the general-purpose truck 20 via a PTO (power take-off) device and is driven by the engine 36.

The hydraulic valve unit 41 is provided with a boom extension/retraction control valve 47a, a winch control valve 47b, a boom hoist control valve 47c, a boom rotation control valve 47d, a right jack control valve 48a, and a left jack control valve 48b. The boom extension/retraction control valve 47a is connected to the boom extension/retraction actuator 46a, the winch control valve 47b is connected to the winch hydraulic motor 46b, the boom hoist control valve 47c is connected to the boom hoist actuator 46c, and the boom rotation control valve 47d is connected to the boom rotation actuator 46d. The right jack control valve 48a is connected to the right jack 38a located on the right side, and the left jack control valve 48b is connected to the left jack 38b located on the left side.

Each of these switching control valves is equipped with a lever, and by manually operating the lever, the direction and flow rate of the hydraulic oil supplied from the hydraulic pump 43 can be switched. The levers attached to the control valves are provided on both the left and right sides of the base 30 as a lever group 35 (see Figure 2).

The control device 12 is also connected to the ECU (engine control unit) of the engine 36 and is configured to control at least the rotation speed of the engine 36. By controlling the rotation speed of the engine 36, the control device 12 can control the rotation speed of the hydraulic pump 43 and adjust the discharge volume of the hydraulic pump 43.

(Control circuit)
1 shows a control circuit diagram of a loaded truck crane 10 according to this embodiment. The input side of the control device 12 is electrically connected to a tilt angle detector 13, a boom length detector 15, a boom slewing angle detector 16, a boom hoisting angle detector 17, and a hoisting support force detector 18. The output side of the control device 12 is electrically connected to an alarm 14, a boom extension/retraction control valve 47a, a winch control valve 47b, a boom hoisting control valve 47c, a boom slewing control valve 47d, a right jack control valve 48a, and a left jack control valve 48b.

The inclination angle detector 13 is a one-axis or two-axis inclination sensor for detecting the inclination angle of the loaded truck crane 10. In this embodiment, the inclination angle detector 13 is fixed to the base 30 of the crane device 21. The inclination angle detector 13 may be a mechanical one using an air bubble or a pendulum, or may be a potentiometer or a magnet. As the inclination angle detector 13, it is preferable to use an inclination sensor (ACS) using MEMS technology or an inclination sensor (AGS) using the inclination of an electrolyte, in particular, so that digital processing is easy. When a one-axis inclination angle detector is used as the inclination angle detector 13, it is oriented to measure the inclination angle in the longitudinal direction of the vehicle. When a two-axis inclination angle detector is used as the inclination angle detector 13, only one is required, and it is oriented to measure the inclination angle in the longitudinal direction of the vehicle and the lateral direction of the vehicle.

The inclination angle detector 13 is preferably fixed to the base 30 of the crane device 21, but may also be fixed to another part. For example, the inclination angle detector 13 may be fixed inside the housing of the control device 12 or to the vehicle frame 29.

By providing the inclination angle detector 13 on the crane device 21, there is no need to install the inclination angle detector 13 on the general-purpose truck 20 side, and this reduces the number of assembly steps at the final assembly manufacturer of the loaded truck crane 10.

In addition, if the inclination angle detector 13 is provided inside the housing of the control device 12, the housing of the control device 12 has high environmental resistance, such as being waterproof, so there is no need to increase the environmental resistance of the inclination angle detector 13 alone, thereby reducing costs.

The boom length detector 15 is for detecting the length of the boom 32, and is, for example, a cord payout length detector. The cord payout length detector detects the payout length of the measuring cord by detecting the amount of rotational displacement of the cord winder.

The boom rotation angle detector 16 is used to detect the rotation angle of the boom 32, and is located at the base side of the post 31. For example, the boom rotation angle detector 16 is a potentiometer. A rotary encoder may be used instead of this potentiometer.

The boom hoisting angle detector 17 is used to detect the hoisting angle of the boom 32, and is located at the base side of the boom 32. For example, the boom hoisting angle detector 17 is a potentiometer. A rotary encoder may be used instead of this potentiometer.

The alarm 14 is for notifying the user of the loaded truck crane 10 of a predetermined condition, such as when the lifting load exceeds the rated load. In this embodiment, the alarm 14 is provided on the crane device 21.

The boom hoisting support force detector 18 is provided to detect the load suspended from the hook 34. In this embodiment, the boom hoisting support force detector 18 is a differential pressure gauge provided on a boom hoisting cylinder. The differential pressure detected by the boom hoisting support force detector 18 is output to the control device 12.

(Work area)
Fig. 4 is an explanatory diagram of the working area of the loaded truck crane 10 according to this embodiment. Fig. 4 shows a plan view of the loaded truck crane 10. In this embodiment, the loaded truck crane 10 is provided with an outrigger device 33 near the crane device 21, i.e., between the driver's cab 27 and the loading platform 28. The user of the loaded truck crane 10 lifts and lowers a load with the outrigger device 33 fully extended outward.

Structurally, the loaded truck crane 10 can safely load and unload different weights of cargo depending on the angle in the horizontal plane of the boom 32 that constitutes the crane device 21, i.e., the rotation angle. Generally, the rated load of the loaded truck crane 10 is set for each of the three areas: the rear area, the side area, and the front area. The rear area is the area (the side with the smaller angle formed by the two lines) between the center of rotation of the boom 32 in a plan view and the left-right center of each of the two rear wheels 23 on the left and right (hereinafter sometimes referred to as the "right rear wheel center CR" and the "left rear wheel center CL").

The lateral region is the region between the line segment connecting the center of rotation of the boom 32 to the center of the right rear wheel CR and the line segment connecting the center of rotation of the boom 32 to the right jack 38a (the side where the angle formed by the two lines is smaller), or the region between the line segment connecting the center of rotation of the boom 32 to the center of the left rear wheel CL and the line segment connecting the center of rotation of the boom 32 to the left jack 38b (the side where the angle formed by the two lines is smaller).

The forward region is the region between the line segment connecting the center of rotation of the boom 32 to the right jack 38a and the line segment connecting the center of rotation of the boom 32 to the left jack 38b (the side with the smaller angle formed by the two line segments). Note that in this embodiment, the three regions are defined as above, but the definitions of these regions may differ depending on the configuration of the loaded truck crane 10. In addition, the boundaries of each region are determined by the signal from the boom rotation angle detector 16, so they may strictly differ from the positions defined above.

(Control method when using the tilt angle detector 13)
Fig. 5 shows an explanatory diagram for explaining an example of a control method when the tilt angle detector 13 is used. Fig. 5 (A) to (C) are views of the loaded truck crane 10 as seen from the side, Fig. 5 (A) is an explanatory diagram showing a state in which the loaded truck crane 10 has stopped traveling, the outrigger devices 33 have been extended in the left and right directions, and the boom 32 of the crane device 21 has been positioned at a storage position in the rear area (an explanatory diagram of a working state in the storage position of the crane device 21), Fig. 5 (B) is an explanatory diagram showing a state in which the loaded truck crane 10 has stored the outrigger devices 33 and is ready to travel (an explanatory diagram of a state in which the loaded truck crane 10 is ready to travel), and Fig. 5 (C) is an explanatory diagram showing a state in which the loaded truck crane 10 has stopped traveling, the outrigger devices 33 have been extended in the left and right outward directions, and the boom of the crane device 21 is positioned at a front area (an explanatory diagram of a working state in the front area).

In the loaded truck crane 10, a tilt angle detector 13 is used to register several parameters in advance in the control device 12 in order to regulate the operation of the crane device 21 in the forward area. The registered parameters include the distance L in a plan view between the front-to-rear center of the outrigger device 33 and the center of the rear wheels 23, and the spring constant k of the chassis used in the rear wheels 23. The distance L and the spring constant k can be registered in advance depending on the vehicle type of the general-purpose truck 20.

Next, the rear wheel reaction force F1 and the first tilt angle θ1 in the state shown in FIG. 5(A) are registered. The detected values of these parameters are registered when all planned equipment, such as the crane device 21, is mounted on the general-purpose truck 20. These parameters are measured after the outrigger device 33 is extended outward to the left and right and it is confirmed that the crane device 21 is in a usable state. The first tilt angle θ1 is measured by the tilt angle detector 13 installed on the loaded truck crane 10. The rear wheel reaction force F1 is measured by placing the rear wheel 23 on a load measuring device. Note that if a load detector or the like is installed on the axle of the rear wheel 23, the detected value from the load detector can also be used for the rear wheel reaction force F1.

As shown in FIG. 5, the first tilt angle θ1 is defined such that the horizontal axis passing through the intersection of the top surface of the vehicle frame 29 and the front-to-rear center of the base 30 is 0° when the loaded truck crane 10 is viewed from the left, and the direction in which the top surface of the vehicle frame 29 rotates clockwise from that point is a positive value.

Next, the second tilt angle θ2 in the state shown in FIG. 5(B) is registered. As with the first tilt angle θ1, the detected value for this second tilt angle θ2 is registered when all planned equipment, such as the crane device 21, is attached to the general-purpose truck 20. This second tilt angle θ2 is measured when the outrigger device 33 is stored and the loaded truck crane 10 is ready to travel. As with the first tilt angle θ1, the second tilt angle θ2 is measured by the tilt angle detector 13 installed on the loaded truck crane 10, and is defined so that the direction in which the top surface of the vehicle frame 29 rotates clockwise when the loaded truck crane 10 is viewed from the left is a positive value.

Next, the reaction force F2 applied to the rear wheel 23 of the loaded truck crane 10 when the boom 32 of the crane device 21 is located in the forward area as shown in FIG. 5(C) is calculated using the inclination angle of the inclination angle detector 13. Specifically, in the state shown in FIG. 5(C), the third inclination angle θ3 of the inclination angle detector 13 is detected, and the reaction force F2 in the working state in the forward area is calculated using the following equation 1. Note that FIG. 5(C) shows a state in which there is no load on the loading platform 28, but there is no problem if the third inclination angle θ3 is detected in a state in which there is a load. In particular, this specification describes the case in which the boom 32 is located in the forward area, but when there is a load on the loading platform 28, the third inclination angle θ becomes large, and the working capacity in the forward area can be increased, so it is important that the third inclination angle θ3 is used in a state in which there is a load. Like the first tilt angle θ1 and the second tilt angle θ2, the third tilt angle θ3 is defined so that the direction in which the top surface of the vehicle frame 29 rotates clockwise when the loaded truck crane 10 is viewed from the left is a positive value.

(Equation 1)
F2=F1+k×L×sin((θ3-θ2)-θ1))

k: spring constant of the chassis of the rear wheels 23;
L: The distance in a plan view between the front-to-rear center of the outrigger device 33 provided on the loading truck crane 10 and the front-to-rear center of the rear wheels 23.
θ1: First tilt angle The tilt angle of the crane device 21 in the working state at the stored position.
θ2: Second tilt angle. The tilt angle when the loading truck crane 10 is in a travelable state.
θ3: Third inclination angle The inclination angle in the working state in the front region.

When the reaction force F2 calculated by this formula becomes smaller than a predetermined threshold value Ft, the control device 12 activates at least one of the functions of restricting the operation of the crane device 21 or activating the alarm 14.

The reaction force F2 of the rear wheels 23 when the boom 32 of the crane device 21 is located in the forward area is calculated from the tilt signal, so that the value of the reaction force F2 applied to the rear wheels 23 can be obtained with high accuracy.

Since the reaction force F2 is calculated using a predetermined formula, the value of the reaction force F2 applied to the rear wheel 23 can be obtained with greater accuracy.

(Operation flow)
6 shows an operation flow diagram of the loaded truck crane 10 according to this embodiment. The control device 12 of the loaded truck crane 10 first acquires information on the rotation angle of the boom 32 from the boom rotation angle detector 16 in step 01 (hereinafter referred to as S01).

In S02, the control device 12 determines whether the boom 32 is located in the forward region. If the control device 12 determines that the boom 32 is not located in the forward region, the boom 32 is located in the side region or rear region, and the control device 12 performs normal operation in the side region or rear region.

If in S02 the control device 12 determines that it is located in the forward area, the boom 32 is located in the forward area, so the control device 12 proceeds to S03.

In S03, the control device 12 acquires the value of the third tilt angle θ3 from the tilt angle detector 13. In S04, the control device 12 calculates the reaction force F2 of the rear wheel 23 using the third tilt angle θ3, and if the control device 12 determines that the value of this reaction force F2 is equal to or less than the threshold value Ft, the control device 12 proceeds to S05.

In S05, the control device 12 restricts the operation of the crane device 21 in the forward area using the boom hoisting control valve 47c, etc. Specifically, it stops the hoisting operation of the boom 32, or stops the rotation operation of the boom 32. The control device 12 may also restrict operation by slowing down the speed of these operations. In addition to this operation restriction, the control device 12 activates the alarm 14 to notify the user of the loaded truck crane 10 that operation restrictions have been applied in the forward area. It may also activate only the alarm 14.

If in S04 the control device 12 determines that the numerical value of the reaction force F2 is greater than the threshold value Ft, in S05 the control device 12 does not restrict the operation of the crane device 21 in the forward area.

When the boom 32 of the crane device 21 is in the forward area, the control device 12 activates a function to restrict the operation of the crane device 21 based on the tilt signal from the tilt angle detector 13, thereby preventing excessive restrictions on the work capacity in the forward area. This makes it possible to maximize the capacity of the crane device 21 while ensuring the safety of the work. In addition, because the tilt angle detector 13 is used, the mechanism of the loaded truck crane 10 is not limited to cases where it has a rear jack, etc.

Other Embodiments
In the first embodiment, the reaction force F2 is calculated from the third tilt angle θ3 of the tilt angle detector 13, but the control method using the third tilt angle θ3 of the tilt angle detector 13 is not limited to this. For example, it is also possible to make the control device 12 activate a predetermined function when the value of the third tilt angle θ3 becomes smaller than a predetermined value.

The concept of the present invention can be applied not only to a loaded truck crane 10 in which the crane device 21 is provided between the driver's cab 27 and the bed 28 of a general-purpose truck 20, but also to a loaded truck crane 10 in which the crane device 21 is provided on the rear side of the bed 28. In this case, when the boom constituting the crane device 21 is in the rear area, at least one of the functions of restricting the operation of the crane device 21 or the function of activating an alarm is activated based on the tilt signal.

REFERENCE SIGNS LIST 10 Loading truck crane 12 Control device 13 Tilt angle detector 14 Alarm 21 Crane device 23 Rear wheel 27 Cab 28 Cargo platform 32 Boom 33 Outrigger device

Claims (5)

A loading truck crane having a loading platform and a crane device,
a tilt angle detector for measuring the tilt angle of the vehicle body of the loading truck crane;
a control device that receives a tilt signal from the tilt angle detector;
An alarm connected to the control device;
is provided,
The control device, when a boom constituting the crane apparatus is located in a front area, activates at least one of a function of restricting the operation of the crane apparatus or a function of activating the alarm based on the tilt signal.
A loaded truck crane characterized by the above. The tilt angle detector is
The crane apparatus is provided with:
2. The loading truck crane according to claim 1. The tilt angle detector is
The control device is provided inside a housing thereof.
2. The loading truck crane according to claim 1. The control device includes:
Calculating a reaction force applied to a rear wheel of the loaded truck crane when a boom of the crane device of the loaded truck crane is located in a forward area from the tilt signal;
When the reaction force becomes equal to or less than a predetermined value, at least one of a function of restricting the operation of the crane apparatus and a function of activating the alarm is activated.
4. The loading truck crane according to claim 1, wherein the loader is a cam. The control device includes:
The reaction force is expressed as F1 + k × L × sin((θ3 - θ2) - θ1)).
(F1: reaction force of the rear wheel in a working state in the storage position of the crane device,
k: spring constant of the rear wheel chassis,
L: the distance in a plan view between the front-rear center of the outrigger device provided on the loading truck crane and the front-rear center of the rear wheel,
θ1: inclination angle in a working state at the stored position of the crane device,
θ2: the inclination angle of the loading truck crane in a travelable state,
θ3: inclination angle in the working state in the front area),
5. The loading truck crane according to claim 4.