JPH0649556U - Drive control circuit for cargo handling equipment - Google Patents

Abstract

(57) [Summary] [Purpose] To reduce the number of parts. [Structure] Each cylinder 34, 35 by means of automatic stop means 44
Automatically stops the cylinders 34 and 3 that have been stopped.
5, when the restarting means 45 restarts the main control valves 36, 37 in the restart direction control circuit section 46.
It is specified which end of the spool the fluid should be supplied to, and the fluid is supplied to the spool end designated by the single electromagnetic proportional control valve 67. [Effect] It is not necessary to provide a solenoid valve or the like at each spool end.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a drive control circuit for a cargo handling device having an arm, a boom, and the like.

[0002]

[Prior art]

 Generally, in the ultra-small swing hydraulic excavator, the operation limit range and operation position of the cargo handling device are automatically controlled. These controls are performed automatically in order to prevent the cargo handling equipment from interfering with the operator's cab (canopy, cab). Otherwise, the operation will be complicated and only a skilled worker can operate it, for two reasons.

FIG. 5 is a diagram showing a hydraulic circuit of a conventional hydraulic excavator. In FIG. 5, 1, 2 and 3 are potentiometers, 4 is a first boom, 5 is a second boom, 6 is a third boom, 7 is an arm, 8 is a bucket, 9 is a boom cylinder, 10 is an arm cylinder, Reference numerals 11 and 12 are main control valves, 13 and 14 are pumps, 15 and 16 are solenoid valves, 17 and 18 are solenoid proportional control valves, 19 and 20 are pilot valves, 21 is a pump, 22 is a control unit (microcomputer), 23 is a tank. The solid lines in FIG. 5 indicate hydraulic circuits, and the broken lines indicate electric circuits.

Here, the main control valves 11 and 12 are controlled by the solenoid valves 15 and 16 or the solenoid proportional control valves 17 and 18 arranged between the main control valves 11 and 12, respectively.

The valve positions of the solenoid valves 15, 16 and the solenoid proportional control valves 17, 18 are switched by the potentiometers 1, 2, 3 attached to the connecting pins of the booms 4, 5, 6, the arm 7, etc. The signal is calculated by the control unit 22, and the calculation is performed based on the result.

In FIG. 5, a, b, c and d are terminals for transmitting signals from the control unit 22 to the solenoid valves 15 and 16 and the solenoid proportional control valves 17 and 18, respectively.

[0007]

[Problems to be solved by the device]

 Conventionally, when the bucket 8 is stopped outside the operation limit range, it is not possible to determine to which end of the spool of each main control valve 11, 12 the fluid should be supplied when restarting next. , The worker was going by himself.

Then, the solenoid valves 15 and 16 or the solenoid proportional control valves 17 and 18 are connected to the respective main control valves 11 and 12 in the control direction (that is, both ends). Therefore, a plurality of solenoid valves 15 and 16 and solenoid proportional control valves 17 and 18 are required.

Specifically, as shown in FIG. 5, an electromagnetic proportional control valve 18 is used for raising the booms 4, 5, 6 and an electromagnetic proportional control valve 17 is used for lowering the booms 4, 5, 6. The solenoid valve 15 is driven to move the arm 7 downward to excavate, and the electromagnetic valve 16 is driven to move the arm 7 upward to load. That is, when performing these four types of control, at least four electromagnetic valves and electromagnetic proportional control valves were required.

However, the solenoid valve and the solenoid proportional control valve are generally expensive, and the above configuration requires many of these parts, which causes a cost increase.

The present invention has been made in view of the above problems, and an object thereof is to provide a drive control circuit of a cargo handling apparatus capable of reducing the number of solenoid valves and solenoid proportional control valves.

[0012]

[Means for Solving the Problems]

 As shown in FIGS. 1 and 2, the problem solving means according to the present invention includes a bucket 31, an arm 32, booms 33a and 33b, an arm cylinder 34 that tilts the arm 32, and a boom cylinder 35 that tilts the booms 33a and 33b. A drive control circuit for driving and controlling a cargo handling apparatus including: a main control valve for arm 36 and a main control valve for boom 37, which supply pressurized oil to each of the cylinders 34, 35 to drive the same, and the arm. Pilot control valve 38 connected in parallel to both ends of the spool of the main control valve 36 for boom, boom pilot valve 39 connected in parallel to both ends of spool of the main control valve 37 of boom, and each pilot valve 38, 39 through the main control valves A single pump 41 for supplying fluid to the spool ends of 36, 37, position detecting means 42 for detecting the positions of the bucket 31, the booms 33a, 33b and the arm 32, and position detecting means 42 for detecting the position. When the position of the bucket 31 or the like is out of the desired limit range, fluid is supplied from the pilot valves 38, 39 to one end of the spool of each main control valve 36, 37 to switch it to neutral. , An automatic stop means 44 for automatically stopping the respective cylinders 34, 35, and a main control valve 36 for receiving a restart signal from an operator in a state where the respective cylinders 34, 35 are stopped outside the limit range. , 37 to supply fluid to one end of the spool and switch it to restart the stopped cylinders 34, 35 again. 45, and a restart direction control circuit section 46 for controlling which end of the spool of the main control valves 36, 37 should be supplied with fluid at the time of restarting. The restart direction control circuit section 46 is provided with a restart direction detection section 70 for detecting which end of the spool of each main control valve 36, 37 the fluid has been supplied before the stop, and the restart direction detection section 70. Based on the detection result of the starting direction detection unit 70, the pilot pressure at the spool ends of the main control valves 36, 37 to which the fluid was supplied before the stop was weakened to the insensitive level from the stop to the restart. Based on the detection result of the electromagnetic proportional control valve 67 that holds the pressure and the restart direction detection unit 70, the main control valves 36 and 37 to which the fluid was supplied before the stop. The pilot pressure of the spool end of the opposite side and the spool end opposite to the spool end is provided with a pressure increasing designation section 77 for instructing to increase the pressure at the time of restart, and the electromagnetic proportional control valve 67 includes the pilot valves 38 and 39 and the pump. 41 and the restart direction detection unit 70. The restart direction detection unit 70 determines whether the pilot pressure after stopping one end of the spool of the arm main control valve 36 is at the insensitive level. A first pressure switch 71 for detecting whether or not the second pressure switch 72 for detecting whether or not the pilot pressure after stopping the other end of the spool of the arm main control valve 36 is at a dead body level; Pressure for detecting whether or not the pilot pressure after stopping one end of the spool of the main control valve 37 for vehicle is at the insensitive level The switch 73 and a fourth pressure switch 74 for detecting whether or not the pilot pressure after stopping the other end of the spool of the boom main control valve 37 is at the insensitive level.

[0013]

[Action]

 In the problem solving means according to claim 1, when the position of the bucket 31 or the like goes out of the limit range, the automatic stop means 44 detects the spool of each main control valve 36, 37 based on the position detection result of the position detection means 42. Fluid is supplied from one of the pilot valves 38 and 39 to one end of the cylinder to automatically stop each of the cylinders 34 and 35.

At this time, the restart direction control circuit unit 46 causes the fluid to be supplied to either end of the spool of each main control valve 36, 37 when restarting from the stopped state of each cylinder 34, 35. Control what you do.

Specifically, for example, in claim 2, each pilot valve 38, 39 is kept in the same state as before the stop even after the stop, and the pilot valve 38, 39 is not changed to the main control valve 36, 39. The pilot pressure of the fluid supplied to the spool end of 37 is weakened to the insensitive body level by the electromagnetic proportional control valve 67 and maintained at a low pressure. Then, it is possible to record which spool end of the main control valve 36 or 37 the pilot pressure for limiting was applied before the stop. The pilot pressure at each spool end at this time is detected by the pressure switches 71, 72, 73, 74.

After that, when the restart signal is transmitted from the worker, the pressure increase designating section 77 causes the spool pressure of any one of the spool ends to be detected based on the pilot pressure detection results of the pressure switches 71, 72, 73 and 74. Determine whether the pilot pressure is at the dead level and specify the spool end on the opposite side. Then, the restarting means 45 supplies the fluid to the designated spool end to restart the stopped cylinders 34 and 35.

[0017]

【Example】

 The present invention is a method for setting an operation limit range such as height and depth of a cargo handling device in an ultra-small swing hydraulic excavator, and performing automatic control in accordance with the limit range. By using pilot pressure, a single solenoid proportional control valve and multiple hydraulic switches are used. This will be described in detail below.

As shown in FIG. 1, a cargo handling device according to an embodiment of the present invention is an attachment such as a power shovel or a backhoe, and includes a bucket 31, an arm 32, booms 33a and 33b, and an arm that tilts the arm 32. This is a general one including a cylinder 34 and a boom cylinder 35 that tilts the booms 33a and 33b.

As shown in FIGS. 1 and 2, the drive control circuit of this embodiment includes an arm main control valve 36, a boom main control valve 37, an arm pilot valve 38, and a boom pilot valve. 39, a pump 41, a position detecting means 42 for detecting the position of the bucket 31 and the like of the cargo handling device, and the cylinders 34 and 35 are automatically operated when the positions of the bucket 31 and the like are outside a desired limit range. The automatic stop means 44 for stopping the cylinders and the restart means 45 for restarting the stopped cylinders 34, 35 are provided.

As shown in FIG. 1, the arm main control valve 36 and the boom main control valve 37 have a first position for supplying the fluid from the pumps 41a and 41b in the cylinder extending direction and a cylinder contraction as in the conventional case. It is a switching valve having three positions, a second position for supplying the fluid in the direction and a neutral position for cutting the fluid from the pumps 41a and 41b.

The pilot valves 38 and 39 are connected in parallel to both ends of the spools of the main control valves 36 and 37, respectively, and can be switched on / off (open / close). In FIG. 1, 51 and 52 are pilot valves for driving and controlling other attachments, and their configurations are the same as those of the pilot valves 38 and 39. Then, one end of each of the pilot valves 38, 39, 51, 52 is joined at the joining point Pi, and each of the other terminals thereof is joined to the tank 53.

The pump 41 is a single pump that supplies fluid to the spool ends of the main control valves 36 and 37 through the pilot valves 38 and 39, respectively. Is connected to the confluence point Pi. In FIG. 1, 54 is a pressure reducing valve and T is a tank.

As shown in FIG. 2, the position detecting means 42 includes a potentiometer 55 for detecting the tilting positions of the arm 32 and the booms 33 a, 33 b, and the position of the bucket 31 and the arm 32 based on the detection result of the potentiometer 55. And a computing unit 56 for computing the tip positions of the booms 33a and 33b, which periodically repeat the detecting operation or the computing operation at regular time intervals.

As shown in FIG. 2, the automatic stop means 44 includes a limit range storage unit 61 for storing the limit range of the bucket 31 and the like, and a limit range input unit 62 for inputting the limit range to the limit range storage unit 61. The position comparison unit 63 that compares the limit range stored in the limit range storage unit 61 with the position of the bucket 31 or the like detected by the position detection means 42, and the comparison result in the position comparison unit 63. Based on the above, the switching unit 64 switches the pilot valves 38 and 39 when the position of the bucket 31 or the like is out of the limit range.

The limit range stored in the limit range storage unit 61 is such that each part of the cargo handling apparatus such as the position of the bucket 31, the tip position of the arm 32, and the tip positions of the booms 33a and 33b can be physically moved. The absolute limit range for storing the position, that is, the range in which the position that interferes with the driver's cab (canopy, cab) of the vehicle, the position where the vehicle is not stable, etc. are removed, and the limit range input unit 62 are stored. A range that satisfies both the specified limit range specified by the operator is set.

The limited range input section 62 is for inputting only a designated limited range out of the limited ranges stored in the limited range storage section 61. For example, as shown in FIG. 3, a keyboard 65 and a display section are provided. A control panel equipped with 66 is used. Alternatively, a teaching part (not shown) of the cargo handling device may be used as the restricted range input part 62.

The position comparison unit 63 outputs an alarm signal when the position of the bucket 31 or the like detected by the position detection unit 42 is outside the limit range stored in the limit range storage unit 61.

As shown in FIG. 2, when the switching unit 64 receives an alarm signal from the position comparison unit 63, the switching unit 64 switches on the pilot valves 38 and 39 to turn on the fluid from the pump 41. Supplying to the spool ends of the control valves 36 and 37, the main control valves 36 and 37 are switched to the neutral position, and the cylinders 34 and 35 are stopped.

Here, the fluid pressure for switching the main control valves 36, 37 (hereinafter referred to as pilot pressure) is as shown in FIG. 4 when the main control valves 36, 37 are switched to the neutral position. Suppose P ₃ is required. Therefore, it is necessary to adjust the pilot pressure so that only P _{3 is} secured. Therefore, as shown in FIG. 1, as a pilot pressure adjusting mechanism of the switching section 64, an electromagnetic ratio control valve 67 is provided between the pressure reducing valve 54 of the pump 41 and the confluence point Pi of the pilot valves 38, 39, 51 and 52. Is intervening. Then, the fluid pressure outputted from the solenoid proportional control valve 67, while at least the switching unit 64 is operated, is set to P ₃ or more as shown in FIG.

Even after the operation of the switching unit 64 is completed and the main control valves 36 and 37 are switched to the neutral position, if the pilot pressure is continuously applied to the spool ends, the main control valves 36 and 37 will be turned on. It switches in the opposite direction. This is extremely dangerous because the cylinders 34 and 35 may operate in the opposite direction even though the operator does not want to restart. Therefore, in order to prevent such a situation, after the main control valves 36 and 37 are switched to the neutral position, the fluid pressure from the electromagnetic proportional control valve 67 is less than P ₃ shown in FIG. 4 (insensitive level). Control to reduce pressure to.

The adjustment of the fluid pressure of the electromagnetic proportional control valve 67 is performed by the switching operation of the pressure switches 71, 72, 73, 74 of the restart direction detection unit 70, which will be described later, to determine whether or not the fluid pressure is appropriate. Be adjusted.

As shown in FIG. 2, the restarting means 45 includes a signal transmitting section 75 for transmitting a restarting signal by an operator, and a restarting signal as described above when the restarting signal is received by the signal transmitting section 75. 4. The pressure increasing portion 76 that increases the fluid pressure of the electromagnetic proportional control valve 67, which has been reduced to less than P ₃ during 4 again, to P ₃ or more, and each main control when restarting from the stopped state of each of the cylinders 34 and 35. The restart direction control circuit section 46 controls which end of the spool of each of the valves 36 and 37 should be increased in pilot pressure.

As shown in FIG. 2, the restart direction control circuit section 46 is supplied to the electromagnetic proportional control valve 67 and to which end of the spool of each main control valve 36, 37 the fluid is supplied at the time of stop. Based on the detection result of the restart direction detecting unit 70, and an increase in designating which spool end of the main control valve 36 or 37 should be pressure-increase at the time of restart. It is composed of a pressure designating unit 77.

As described above, the electromagnetic proportional control valve 67 reduces the fluid pressure to less than P ₃ (insensitive level) after the operation of the switching unit 64, as shown in FIG. Since 71, 72, 73, and 74 operate only when P ₁ or more, the pressure is reduced to P ₂ , which is an intermediate value between P ₁ and P ₃ , until the switching unit 64 is restarted after the operation. Retained. As a result, while the cylinders 34, 35 are stopped, the main control valves 36, 37 are not switched (insensitive body) and the pressure switches 71, 72, 73, 74 are turned on.

The restart direction detection unit 70 detects whether the pilot pressure after stopping one end of the spool of the arm main control valve 36 is at the insensitive level, and the first pressure switch 71 and the arm. Second control switch 72 for detecting whether or not the pilot pressure after stopping the other end of the spool of the main control valve 36 for operation is at the insensitive level, and after stopping one end of the spool of the boom main control valve 37 Detects whether the pilot pressure is at the dead level or not. Detects whether the pilot pressure after stopping the third pressure switch 73 and the other end of the spool of the boom main control valve 37 is at the dead level. And a fourth pressure switch 74.

Each of the pressure switches 71, 72, 73, 74 outputs a signal for indicating the operating direction of the cargo handling device, and is turned on when the pilot pressure is P ₁ or more as shown in FIG. The state is entered and current flows.

The pressure increase designating unit 77 receives the current from the pressure switches 71, 72, 73, 74 when any of the pressure switches 71, 72, 73, 74 is in the ON state, and After determining whether the pilot pressure at the spool end is at the dead level (that is, which spool end was supplied with fluid before the stop), the main control valves 36, 37 at the dead level are determined. The spool end opposite to the spool end is designated and the designated signal is transmitted to the pressure booster 76.

The calculation unit 56 of the position detection unit 42, the limited range storage unit 61 of the automatic stop unit 44, the position comparison unit 63, the switching unit 64, the pressure increasing unit 76 of the restarting unit 45, and the restart direction control. The pressure boosting unit 76 of the circuit unit 46 is a program incorporated in a micro computer chip 81 having a ROM, a RAM and a CPU.

In the above-described configuration, first, the operation limit positions of the bucket 31, the arm 32, and the booms 33a and 33b are stored in advance in the limit range storage unit 61 of the automatic stop means 44. At this time, a numerical value is input from the keyboard 65 of the limited range input unit 62.

When the cargo handling device is driven, the fluid (pressure oil) discharged from the pump 41 is reduced to a predetermined pressure by the pressure reducing valve 54, and is supplied to the pilot valves 38, 39 via the electromagnetic proportional control valve 67.

Here, the operator opens and closes the pilot valves 38 and 39 by a predetermined operation to operate the main control valves 36 and 37, sending fluid to the cylinders 34 and 35, and to the arm 32 and the boom. Move 33a and 33b respectively.

The pressure switches 71, 72, 73, 74 always detect the excavation work by the arm 32, the loading work on the truck, and the ascent and descent of the booms 33a, 33b. Further, tilting of the arm 32 and the booms 33a and 33b is detected by the potentiometer 55 of the position detecting means 42, and is calculated by the calculator 56. At this time, the position of the tip of the sword of the bucket 31 is also calculated.

Here, for example, when it is desired to raise the booms 33 a and 33 b, the fluid from the pump 41 passes through the pressure reducing valve 54, the electromagnetic proportional control valve 67, the pilot valve 39, and activates the main control valve 37. , Fluid is supplied to the tail side of the cylinder 35.

When the position of any member of the cargo handling device, for example, the bucket 31 comes out of the limit range, the position of the bucket 31 calculated by the calculation unit 56 of the position detection means 42 and the limit range storage unit 61 in advance. The position comparison unit 63 compares the limit range stored in the position comparison unit 63, the electromagnetic proportional control valve 67 is operated by a command from the switching unit 64, and the main control valve 37 is switched to neutral by adjusting the pilot pressure. The cylinders 34 and 35 are stopped, and the cargo handling device is automatically stopped.

When the operator wants to restart the cargo handling apparatus, the operator sends a restart signal from the signal transmitter 75 of the restart means 45, and the pressure booster 76 causes the fluid amount of the electromagnetic proportional control valve 67 to be increased. Adjust.

At this time, the cargo handling device must operate in the direction opposite to the direction in which it operated before the stop, that is, in the case where it stopped in the ascending position, it lowered the booms 33a and 33b.

Also, when the arm 32 stops during excavation and loading, it must be restarted in the direction opposite to that before the stop.

Therefore, in this embodiment, the restart direction control circuit section 46 controls which end of the spool of each main control valve 36, 37 should be supplied with fluid.

Here, the restart direction control principle at the time of restart will be described in detail.

FIG. 4 shows the relationship between the pilot pressure of the main control valves 36 and 37 and the spool stroke.

When the pilot pressures are P ₁ , P ₂ , and P ₃ , the strokes of the spools of the main control valves 36 and 37 are S ₁ , S ₂ , and S ₃ , respectively.

When the pilot pressure reaches P ₃ , the arm 32 or the booms 33a, 33b corresponding to the valves 36, 37 start moving. Further, if it is less than P ₃ , the arm 32 or the booms 33a and 33b do not move (insensitive body).

When the bucket 31 or the like stops outside the limit range by using this dead body, the electromagnetic ratio control valve 67 lowers the pilot pressure to P ₂ (dead body level) to maintain the reduced pressure.

Further, since the pressure switches 71, 72, 73, 74 can be operated by the pilot pressure P ₁ , they will of course be operated by P ₂ . Therefore, at the time of restart, the pressure sensitive switches 71, 72, 73, 74 detect the insensitive body level, and the pressure intensifying section 77 supplies fluid to the spool ends of any of the main control valves 36, 37 at the time of stop. Determine if it was done. Then, by designating the spool end on the opposite side to the spool end to which the fluid was supplied before the stop, the pressure booster 76 switches on (open) the desired pilot valves 38, 39, and at the same time, the electromagnetic proportional control valve. 67 is switched, the pilot pressure is increased to P ₃ or more, and the bucket 31 and the like are operated in the direction opposite to that before the stop.

That is, when the cargo handling device stops outside the limit range, the pilot pressure is not set to 0 kgf / cm ² but is kept low at the pilot pressure P _{2 at} which the cargo handling device does not operate, and the pilot valve 38 , 39 is restarted, the restart direction is controlled by operating the pressure switch.

In the drive control circuit of such a cargo handling apparatus, as long as the restart direction control circuit section 46 controls the fluid supply direction, a single valve is not required to be provided in each direction. Fluid can be supplied using the electromagnetic proportional control valve 67, and the number of parts can be reduced compared to the conventional case. Therefore, parts cost can be reduced.

It should be noted that the present invention is not limited to the above embodiment, and it goes without saying that many modifications and changes can be made to the above embodiment within the scope of the present invention.

For example, in the above embodiment, the pressure switches 71, 72, 73, 74 were used as one component of the restart direction control circuit unit 46, but a signal for notifying the operating direction of the cargo handling device is transmitted. Any device may be used as long as it is a mechanical switch that controls the operating direction by the movement of the operating lever.

[0059]

[Effect of device]

 As is apparent from the above description, according to claims 1 and 2 of the present invention, the position detecting means for detecting the position of the bucket and the like, and the automatic stop for each cylinder based on the detection result of the position detecting means By providing a stopping means and a restarting means for restarting each stopped cylinder, if the restarting means is supplied with fluid to either end of the spool of each main control valve at the time of restarting Since a restart direction control circuit section is provided to control whether or not it is good, if the restart direction control circuit section is used to control the fluid supply direction, it is not necessary to provide solenoid valves etc. at each spool end one by one. The electromagnetic proportional control valve can be used to supply fluid, and the number of parts can be reduced compared to the conventional model. Therefore, there is an excellent effect that the cost of parts can be saved.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing a cargo handling apparatus and a drive control circuit thereof according to an embodiment of the present invention.

FIG. 2 is a circuit configuration diagram showing a drive control circuit according to an embodiment of the present invention.

FIG. 3 is a diagram showing a limited range input unit of automatic stop means.

FIG. 4 is a diagram showing the relationship between pilot pressure at the spool end of the main control valve and spool stroke.

FIG. 5 is an overall configuration diagram showing a conventional cargo handling device and its drive control circuit.

[Explanation of symbols]

 31 Bucket 32 Arms 33a and 33b Boom 34 Arm Cylinder 35 Boom Cylinder 36 Main Control Valve for Arm 37 Main Control Valve for Boom 38 Pilot Valve for Arm 39 Boom Pilot Valve 41 Pump 42 Position Detection Means 44 Automatic Stop Means 45 Restart Means 46 Restart Direction Control Circuit 67 Electromagnetic Proportional Control Valve 71-74 Pressure Switch 77 Pressure Increase Designator

Claims (2)

[Scope of utility model registration request] 1. A drive control circuit for driving and controlling a cargo handling device comprising a bucket, an arm, a boom, an arm cylinder for tilting the arm, and a boom cylinder for tilting the boom, wherein a pressure control circuit is provided for each cylinder. The arm main control valve and the boom main control valve that supply oil to drive the oil, the arm pilot valve connected in parallel to both ends of the spool of the arm main control valve, and the boom main control valve A boom pilot valve connected in parallel to both ends of the spool, a single pump that supplies fluid to the spool end of each main control valve through each pilot valve, and detects the positions of the bucket, boom, and arm Position detecting means and the position detecting means When the detected position of the bucket etc. is out of the desired limit range, fluid is supplied from each pilot valve to one end of the spool of each main control valve to switch it to neutral, and each cylinder is automatically stopped. In the state where each cylinder is stopped outside the limit range,
And a restart means for supplying fluid to one end of the spool of each main control valve to switch the fluid and restarting each stopped cylinder when the operator gives a restart signal. Is provided with a restart direction control circuit section for controlling which end of the spool of the main control valve should be supplied with fluid at the time of restart, and the restart direction control circuit section is provided before the stop. Based on the restart direction detection unit that detects which end of the spool of each main control valve the fluid was supplied, and the detection result of the restart direction detection unit, the fluid is supplied before the stop. The pilot pressure at the spool end of the main control valve was
Based on the electromagnetic proportional control valve that maintains a weak pressure at the insensitive level, and the spool end on the side opposite to the spool end of the main control valve to which fluid was supplied before the stop, based on the detection result of the restart direction detection unit. The pilot pressure is provided with a pressure increase designation unit for increasing the pressure at the time of restart, and the electromagnetic proportional control valve is provided in series and singly between the pilot valves and the pump. A drive control circuit of a characteristic cargo handling device. 2. The restart direction detection unit according to claim 1, wherein the first pressure switch detects whether or not the pilot pressure after stopping one end of the spool of the arm main control valve is at the dead body level. The second pressure switch that detects whether the pilot pressure after stopping the other end of the arm main control valve spool is at the dead level or the pilot pressure after stopping one end of the boom main control valve spool A third pressure switch that detects whether it is at the dead level or a fourth pressure switch that detects whether the pilot pressure after the other end of the spool of the boom main control valve has stopped is at the dead level. A drive control circuit for a cargo handling device, comprising: