JP5215338B2 - Gate lock circuit for construction machinery - Google Patents

Description

  The present invention relates to a gate lock circuit of a construction machine that is preferably used to ensure operational safety in a construction machine such as a hydraulic excavator.

  Generally, a construction machine such as a hydraulic excavator is provided with a gate lock lever in the vicinity of a driver's seat. The gate lock lever is manually tilted when the operator gets on and off the driver's seat. Thus, the gate lock switch is switched to open and close, and the operation and stop of the entire hydraulic circuit are controlled by the gate lock switch (see, for example, Patent Documents 1 and 2).

  The hydraulic circuit of the construction machine according to this type of prior art is provided with a gate lock control valve in the middle of the pilot pipeline, and the gate lock control valve is a work system when the gate lock switch is opened, By stopping the supply of pilot pressure oil from the hydraulic pump to all directional control valves including the traveling system and holding each directional control valve in the neutral position, all hydraulic actuators including the working system and traveling system are controlled. Keep it stopped.

  On the other hand, when the gate lock switch is closed by the operation of the gate lock lever, the gate lock control valve is excited and switched by energization, and the pilot pressure oil is applied to each direction control valve including the working system and the traveling system. Allow supply. For this reason, when any one of the directional control valves is switched from the neutral position by the supply of the pilot pressure oil, the pressure oil from the hydraulic pump is supplied to either the working system or the traveling system hydraulic actuator. The actuator operates.

JP-A-4-30032 JP 2006-233615 A

  By the way, in the above-described prior art, the gate lock control valve provided in the middle of the pilot pipeline is configured by a single solenoid valve, and this solenoid valve is used for all directional control valves and hydraulic actuators including the working system and the traveling system. Since it is configured to control the supply and stop of pressure oil, the following problems are feared with conventional hydraulic excavators.

  That is, even when the gate lock switch is turned on (closed), if the energization (excitation) to the gate lock control valve is canceled due to a failure of the electrical system such as disconnection, the working hydraulic actuator is In some cases, the traveling hydraulic actuator is also stopped.

  For this reason, for example, when work such as quickly moving a vehicle such as a hydraulic excavator is necessary, measures such as moving using another work vehicle parked at the site are taken. There is a problem that it causes a reduction in work efficiency on site.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to control the operation of a traveling hydraulic actuator even when the working hydraulic actuator is stopped, for example. It is an object of the present invention to provide a gate lock circuit for a construction machine that can be used.

  In order to solve the above-described problem, the present invention provides a hydraulic actuator for a work system that drives a working device by being supplied with pressure oil from a hydraulic pump, and by supplying pressure oil from the hydraulic pump. A hydraulic actuator for a traveling system that drives the vehicle to travel, a gate lock switch that is provided in the vicinity of a driver's seat and is switched by an operator's operation, and the hydraulic oil for the working system and the traveling system hydraulic actuator according to the switching of the gate lock switch The present invention is applied to a gate lock circuit of a construction machine including a gate lock control valve for controlling supply and stop.

  A feature of the configuration adopted by the invention of claim 1 is that the gate lock control valve is a work system electromagnetic valve that controls supply and stop of pressure oil to the hydraulic actuator of the work system according to switching of the gate lock switch; The working system solenoid valve includes a traveling system solenoid valve that is connected in parallel to the power source and controls supply and stop of pressure oil to the traveling system hydraulic actuator according to switching of the gate lock switch. It is in.

  According to a second aspect of the present invention, when the gate lock switch is opened between any one or both of the working system solenoid valve and the traveling system solenoid valve and the power source. An operation switch for controlling supply and stop of the pressure oil by switching the electromagnetic valve by an operator's operation is provided.

  According to a third aspect of the present invention, there is provided a notification device that notifies when the electromagnetic valve is switched by the operation switch.

  According to a fourth aspect of the present invention, the operation switch is operated when the vehicle is moved, and the traveling solenoid valve can be controlled even when the gate lock switch is opened. .

  According to a fifth aspect of the present invention, between one or both of the working system solenoid valve and the traveling system solenoid valve and the power source, the power source is opened and closed according to the switching of the gate lock switch. The relay is provided.

  According to a sixth aspect of the present invention, the relay includes a relay coil connected to the power source via the gate lock switch, and a movable contact that is closed and opened according to energization or non-energization of the relay coil. One or both of the working system solenoid valve and the traveling system solenoid valve are connected in accordance with switching of the movable contact of the relay.

  As described above, according to the first aspect of the present invention, the gate lock control valve is constituted by the working system solenoid valve and the traveling system solenoid valve, and these solenoid valves are connected in parallel to the power source. Even if energization is canceled due to an accident such as disconnection of the work system solenoid valve, this influence can be prevented from reaching the travel system solenoid valve. The traveling system solenoid valve can be energized without being affected by the work system, and the supply and stop of pressure oil to the traveling system hydraulic actuator can be controlled according to the switching of the gate lock switch. .

  For this reason, for example, in a construction machine such as a hydraulic excavator, even when the working hydraulic actuator is stopped due to a failure of the electrical system or the like, it is possible to ensure operation control for the traveling hydraulic actuator, Thereby, a vehicle can be moved quickly. Therefore, it is possible to eliminate the situation where the construction machine is left at the work site, and it is possible to prevent a decrease in work efficiency at the work site.

  Further, the invention of claim 2 can be applied to the travel system hydraulic actuator by switching the travel system solenoid valve, for example, by the operator arbitrarily operating the operation switch even when the gate lock switch is opened (OFF operation). Supply and stop of the pressure oil can be controlled, and the working system solenoid valve and / or the traveling system solenoid valve can be switched only by operating the operation switch.

  According to the invention of claim 3, when the operator closes the operation switch (ON operation), at least one of the solenoid valves can be switched by this, and the notification device is operated to switch the solenoid valve. Can be notified by means such as an alarm buzzer, an alarm lamp, voice synthesis or a display.

  According to the invention of claim 4, when a vehicle such as a hydraulic excavator is moved urgently, the traveling system electromagnetic valve can be excited by the operator performing an operation switch. It is possible to control the supply and stop of pressure oil to the.

  The invention according to claim 5 controls the energization and release of at least one of the working system solenoid valve and the traveling system solenoid valve by the relay that is opened and closed according to the switching of the gate lock switch. The other solenoid valve can be energized and released by opening and closing the gate lock switch. In addition, it is possible to control energization and release to both solenoid valves by the relay.

  Furthermore, according to the invention of claim 6, either one or both of the working system solenoid valve and the traveling system solenoid valve can be connected to the power source in accordance with the switching of the movable contact of the relay. Alternatively, energization and release of both solenoid valves can be controlled.

1 is a front view showing a small hydraulic excavator equipped with a gate lock circuit according to a first embodiment of the present invention. FIG. 2 is an enlarged perspective view showing a driver's seat, an operation lever, a gate lock lever and the like provided in the cab in FIG. 1. 1 is a hydraulic circuit diagram of a working system and a traveling system showing a gate lock circuit according to a first embodiment. It is a circuit diagram which expands and shows the gate lock switch, relay, electromagnetic valve, etc. in FIG. It is a circuit diagram which shows the gate lock circuit by 2nd Embodiment. It is a circuit diagram which shows the gate lock circuit by 3rd Embodiment. It is a circuit diagram which shows the gate lock circuit by 4th Embodiment. It is a circuit diagram which shows the gate lock circuit by 5th Embodiment. It is a circuit diagram which shows the gate lock circuit by 6th Embodiment.

  Hereinafter, a case where a gate lock circuit of a construction machine according to an embodiment of the present invention is applied to a small hydraulic excavator will be described as an example and described in detail with reference to the accompanying drawings.

  1 to 4 show a first embodiment of the present invention. In the figure, 1 is a small hydraulic excavator used for excavation work of earth and sand. The hydraulic excavator 1 is a self-propelled crawler-type lower traveling body 2, and is mounted on the lower traveling body 2 through a turning device 3 so as to be capable of turning. The main body 4 and a work device 5 provided so as to be able to move up and down on the front side of the upper swing body 4 are roughly configured.

  Here, the working device 5 is configured as a swing post type working device, for example, a swing post 5A, a boom 5B, an arm 5C, a bucket 5D as a working tool, a swing cylinder (not shown), a boom cylinder 5E, an arm cylinder. 5F, bucket cylinder 5G, etc. are provided. The upper swing body 4 includes a swing frame 6, an exterior cover 7, a cab 8, a counterweight 9, and the like which will be described later.

  Reference numeral 6 denotes a revolving frame of the upper revolving unit 4, and the revolving frame 6 is attached on the lower traveling unit 2 via the revolving device 3. The revolving frame 6 is provided with a counterweight 9 and an engine 16 described later on the rear side, and a cab 8 described later on the left front side. Further, the revolving frame 6 is provided with an exterior cover 7 positioned between the cab 8 and the counterweight 9, and this exterior cover 7, together with the revolving frame 6, the cab 8 and the counterweight 9, mounts the engine 16 and the like. A space to be accommodated inside is defined.

  Reference numeral 8 denotes a cab mounted on the left front side of the revolving frame 6, and the cab 8 defines an operator cab in which an operator is boarded. As shown in FIG. 2, a driver's seat 10, left and right operation lever devices 11, 12, travel levers / pedals 13, 14, a gate lock lever 15, and the like are disposed inside the cab 8. Yes. The cab 8 is provided with an entrance 8A for an operator to get on and off, and the entrance 8A is opened and closed by a door 8B shown in FIG.

  Reference numeral 9 denotes a counterweight that constitutes a part of the upper swing body 4. The counterweight 9 is positioned on the rear side of the engine 16, which will be described later, and is attached to the rear end of the swing frame 6. It is a balance. Further, the rear surface side of the counterweight 9 is formed in an arc shape so that the turning radius of the upper turning body 4 is small.

  A driver's seat 10 is provided in the cab 8 of the upper swing body 4, and is seated by an operator who operates the hydraulic excavator 1. Further, on the left and right sides of the driver's seat 10, operating system operating lever devices 11 and 12 for operating the turning device 3 and the working device 5 are arranged. The left operation lever device 11 includes a console 11B provided with a left operation lever 11A, a switch, a display (not shown), and the like.

  The right operating lever device 12 includes a console 12B provided with a right operating lever 12A, a switch, a display, and the like. Here, for example, pressure-reducing valve type pilot valves (only one pilot valve 31 is shown in FIG. 3) are provided in the consoles 11B and 12B of the operating lever devices 11 and 12, and these pilot valves are operated by operating levers. Pilot pressure oil is supplied to each directional control valve (only one directional control valve 30 is shown in FIG. 3) by the tilting operation of 11A and 12A.

  Reference numerals 13 and 14 denote left and right traveling lever pedals which are positioned on the front side of the driver's seat 10 and are provided on the floor 8C of the cab 8, and the left and right traveling lever pedals 13 and 14 are provided on the driver's seat. The operator seated in 10 is stepped with both feet or manually operated with both hands, and is tilted to perform a traveling operation by the lower traveling body 2.

  Reference numeral 15 denotes a gate lock lever provided on the lower side of the left operating lever device 11. The gate lock lever 15 has a blocking position extending forward from the left operating lever device 11 as shown in FIG. It is rotated upward and downward between the opening position lifted above the blocking position. That is, when the operator gets into the cab 8 from the entrance / exit 8A, the gate lock lever 15 is rotated to the shut-off position so as to shut off the entrance / exit 8A, and when the operator gets out of the entrance / exit 8A, It is lifted up to the open position for ease.

  Therefore, until the operator gets on and off the driver's seat 10, the gate lock lever 15 is in the open position where it is lifted upward. At this time, the gate lock switch 38 described later is opened and the operation of the work device 5 is prohibited. At the same time, the traveling operation by the lower traveling body 2 is also prohibited. When the operator gets into the driver's seat 10, the gate lock lever 15 is turned downward to enter the blocking position. At this time, the gate lock switch 38 described later is closed, so that the prohibition of the operation of the work device 5 is released. In addition, the prohibition of the traveling operation by the lower traveling body 2 is also released.

  Reference numeral 16 denotes an engine as a prime mover disposed on the rear side of the revolving frame 6. Since the engine 16 is mounted on the small hydraulic excavator 1, for example, a small diesel engine is used. Further, the engine 16 is provided with a starter 17 for starting the engine 16 and an alternator 18 as a generator as shown in FIG.

  Reference numeral 19 denotes a main hydraulic pump which is rotationally driven by the engine 16, and the hydraulic pump 19 constitutes a main hydraulic source together with a tank 20 (see FIG. 3). The hydraulic pump 19 is rotationally driven by the engine 16 together with the pilot pump 21, and the pilot pump 21 constitutes a pilot hydraulic power source together with the tank 20. The hydraulic pump 19 discharges pressure oil toward the discharge line 22 as shown in FIG. 3, and the pilot pump 21 discharges pilot pressure oil toward the pilot line 23.

  Here, the discharge pipe 22 has first and second branch pipes 22A and 22B branched from a midway portion as shown in FIG. The first branch conduit 22A is a directional control valve (not shown) different from the directional control valve 30 described later with respect to a hydraulic actuator (not shown) of a working system other than the hydraulic cylinder 28 described later. Supply the pressure oil through. Further, the second branch conduit 22B is a directional control valve (not shown) different from the directional control valve 35 described later with respect to a hydraulic actuator (not shown) of a traveling system other than the traveling motor 33 described later. ) Through which pressure oil is supplied.

  Reference numerals 24 and 25 denote relief valves. Of these, the relief valve 24 constitutes a high-pressure relief valve and is connected between the discharge line 22 and the return line 26. The relief valve 24 sets the maximum discharge pressure of the pressure oil by the main hydraulic pump 19 and returns the excess pressure beyond this to the tank 20 side via the pipeline 26. The relief valve 25 constitutes a low-pressure relief valve and is connected between the pilot pressure oil return line 27 and the pilot line 23. The relief valve 25 sets a maximum discharge pressure of the pilot pump 21 and relieves an excess pressure higher than this to the tank 20 side via a conduit 27.

  Reference numeral 28 denotes a working hydraulic cylinder that constitutes a working hydraulic actuator. This hydraulic cylinder 28 is, for example, a swing cylinder (not shown), a boom cylinder 5E, an arm cylinder 5F, or a bucket cylinder of the working device 5 shown in FIG. Any one of 5G and the like is configured. The hydraulic cylinder 28 has oil chambers 28A and 28B, a rod 28C and the like as shown in FIG. 3, and this rod 28C is expanded and contracted by the pressure oil supplied to and discharged from the oil chambers 28A and 28B. is there.

  The hydraulic excavator 1 generally includes a swing hydraulic motor (not shown) as a working hydraulic actuator in addition to a swing cylinder (not shown), a boom cylinder 5E, an arm cylinder 5F, and a bucket cylinder 5G. Is provided. However, in the hydraulic circuit shown in FIG. 3, a hydraulic cylinder 28 is shown as a representative example of a plurality of working system hydraulic actuators in order to simplify the description.

  Reference numerals 29A and 29B denote a pair of hydraulic conduits connected to the oil chambers 28A and 28B of the hydraulic cylinder 28. The hydraulic conduits 29A and 29B are configured by hydraulic piping such as a flexible hose, for example. The hydraulic lines 29A and 29B supply and discharge the pressure oil supplied from the hydraulic pump 19 via the discharge line 22 to the oil chambers 28A and 28B of the hydraulic cylinder 28 via the directional control valve 30 described later. Thus, the rod 28C of the hydraulic cylinder 28 is expanded and contracted.

  Reference numeral 30 denotes a directional control valve for the hydraulic cylinder 28. The directional control valve 30 is constituted by, for example, a 6-port, 3-position hydraulic pilot type directional control valve, and a pair of hydraulic pilot portions 30A, 30B on the left and right sides. Is provided. The hydraulic pilot portions 30A and 30B are supplied with pilot pressure oil from a pilot valve 31 described later, whereby the directional control valve 30 is switched from the neutral position (c) to the left and right switching positions (a), ( It can be switched to any of b).

  Here, when the directional control valve 30 is switched from the neutral position (c) to the switching position (a), the pressure oil from the hydraulic pump 19 is supplied to the oil in the hydraulic cylinder 28 via the discharge line 22 and the hydraulic line 29A. The return oil supplied to the chamber 28A and returned from the oil chamber 28B is returned to the tank 20 via the hydraulic line 29B and the return line 26. Thereby, the hydraulic cylinder 28 is driven in the direction in which the rod 28C extends.

  When the directional control valve 30 is switched from the neutral position (c) to the switching position (b), the pressure oil from the hydraulic pump 19 is supplied to the oil chamber of the hydraulic cylinder 28 via the discharge line 22 and the hydraulic line 29B. The return oil from the oil chamber 28A is returned to the tank 20 via the hydraulic line 29A and the return line 26. Thereby, the hydraulic cylinder 28 is driven in a direction in which the rod 28C is contracted.

  Reference numeral 31 is a working system pressure reducing valve type pilot valve (hereinafter referred to as a pilot valve 31) for remotely operating the hydraulic cylinder 28. The working system pilot valve 31 is, for example, the console 11B of the operating lever devices 11 and 12 shown in FIG. , 12B and accommodated in one of them, and the pilot pressure oil is supplied to the direction control valve 30 when the operator tilts the operation lever 11A or 12A.

  Here, the working system pilot valve 31 has a pump port connected to a pilot pressure conduit 32, and the pilot pressure conduit 32 is connected to a pilot line 23 (pilot pump 21 through a working system electromagnetic valve 43 described later. ) And the return pipe line 27 (tank 20). Further, the tank port of the pilot valve 31 is always connected to the tank 20 via the return pipe line 27. On the other hand, the output port of the pilot valve 31 is connected to the hydraulic pilot portions 30A and 30B of the direction control valve 30 via the pilot lines 31A and 31B.

  When the operator tilts the operation lever 11A (or the operation lever 12A), the working pilot valve 31 supplies pilot pressure oil corresponding to the operation amount through the pilot lines 31A and 31B to the direction control valve 30. To the hydraulic pilot parts 30A and 30B. Thereby, the direction control valve 30 is switched from the neutral position (c) shown in FIG. 3 to one of the switching positions (a) and (b).

  Further, the pilot pressure conduit 32 has a pilot pressure conduit 32A branched from a midpoint as shown in FIG. 3, and this pilot pressure conduit 32A is a pilot valve (not shown) of a working system other than the pilot valve 31. The pilot pressure oil is guided through a work system electromagnetic valve 43 described later. Note that the pilot valves other than the pilot valve 31 are also provided in the consoles 11B and 12B of the operating lever devices 11 and 12 shown in FIG. 2, for example, and the operator operates the tilting lever 11A or 12A. By doing so, the pilot pressure oil is supplied to the direction control valve (not shown) of the working system.

  Reference numeral 33 denotes a traveling hydraulic motor (hereinafter referred to as a traveling motor 33) that constitutes a traveling system hydraulic actuator. The traveling motor 33 includes, for example, left and right left and right sensors provided in the lower traveling body 2 shown in FIG. It constitutes one of the traveling motors. That is, the lower traveling body 2 of the hydraulic excavator 1 is generally provided with left and right traveling motors and the like as traveling system hydraulic actuators. However, in the hydraulic circuit shown in FIG. 3, a traveling motor 33 is shown as a representative example of a plurality of traveling hydraulic actuators in order to simplify the description.

  Reference numerals 34A and 34B denote a pair of hydraulic pipes connected to the pressure oil supply / discharge port of the traveling motor 33, and the hydraulic pipes 34A and 34B are constituted by a hydraulic pipe such as a flexible hose, for example. . The hydraulic lines 34A and 34B supply and discharge the pressure oil supplied from the hydraulic pump 19 via the discharge line 22 to the traveling motor 33 via a directional control valve 35, which will be described later. 33 is rotationally driven.

  Reference numeral 35 denotes a directional control valve for the travel motor 33. The directional control valve 35 is constituted by, for example, a 6-port 3-position hydraulic pilot type directional control valve, and a pair of hydraulic pilot portions 35A, 35B is provided. The hydraulic pilot portions 35A and 35B are supplied with pilot pressure oil from a pilot valve 36, which will be described later, whereby the directional control valve 35 is switched from the neutral position (c) to the left and right switching positions (a), ( It can be switched to any of b).

  Here, when the directional control valve 35 is switched from the neutral position (c) to the switching position (a), the pressure oil from the hydraulic pump 19 is transferred to the travel motor 33 via the discharge line 22 and the hydraulic line 34A. The supplied return oil from the traveling motor 33 is returned to the tank 20 via the hydraulic line 34 </ b> B and the return line 26. Thus, the traveling motor 33 is rotationally driven in one direction (for example, the forward direction of the vehicle).

  When the directional control valve 35 is switched from the neutral position (c) to the switching position (b), the pressure oil from the hydraulic pump 19 is supplied to the traveling motor 33 via the discharge pipe 22 and the hydraulic pipe 34B. Then, the return oil is returned to the tank 20 via the hydraulic line 34A and the return line 26. As a result, the traveling motor 33 is rotationally driven in the other direction (for example, the reverse direction of the vehicle).

  Reference numeral 36 denotes a traveling system pressure reducing valve type pilot valve (hereinafter referred to as a pilot valve 36) for remotely operating the traveling motor 33. The traveling system pilot valve 36 is, for example, below the floor 8C of the cab 8 shown in FIG. A pilot pressure oil is supplied to the directional control valve 35 by an operator tilting one of the left and right traveling lever pedals 13 and 14.

  Here, the pilot port 36 of the traveling system is connected at its pump port to a pilot pressure conduit 37, and the pilot pressure conduit 37 is connected to the pilot line 23 (pilot pump 21 via a traveling system electromagnetic valve 44 described later. ) And the return pipe line 27 (tank 20). Further, the tank port of the pilot valve 36 is always connected to the tank 20 via the return pipe line 27. On the other hand, the output port of the pilot valve 36 is connected to the hydraulic pilot portions 35A and 35B of the direction control valve 35 via pilot pipes 36A and 36B.

  When the operator operates the travel lever pedal 13 (or travel lever pedal 14), the traveling system pilot valve 36 controls the direction of pilot pressure oil corresponding to the amount of operation through the pilot pipelines 36A and 36B. It supplies to the hydraulic pilot parts 35A and 35B of the valve 35. Thereby, the direction control valve 35 is switched from the neutral position (c) shown in FIG. 3 to one of the switching positions (a) and (b).

  Further, as shown in FIG. 3, the pilot pressure conduit 37 has a pilot pressure conduit 37A branched from an intermediate portion, and this pilot pressure conduit 37A is a pilot valve (not shown) of a traveling system other than the pilot valve 36. The pilot pressure oil is guided through a traveling electromagnetic valve 44 described later.

  Reference numeral 38 denotes a gate lock switch provided in the vicinity of the driver's seat 10, and the gate lock switch 38 is opened and closed by rotating the gate lock lever 15 as shown in FIGS. 3 and 4. That is, the gate lock switch 38 is opened when the gate lock lever 15 is lifted upward to the open position as described above, and is closed when the gate lock lever 15 is turned downward to the blocking position. It is made.

  Reference numeral 39 denotes a battery as a power source. The battery 39 is connected to a gate lock control valve (that is, a work system solenoid valve 43, a travel system solenoid valve 44, which will be described later) according to switching of the gate lock switch 38 as shown in FIGS. ) Is turned on and off.

  Reference numeral 40 denotes a lead wire connected to the positive side of the battery 39, and the lead wire 40 is provided between the one terminal of the gate lock switch 38 and the battery 39 as shown in FIG. A wiring part 40A, a second wiring part 40B provided between the other terminal of the gate lock switch 38 and a relay coil 42A, which will be described later, and a branching operation from the middle of the second wiring part 40B. And a third wiring portion 40 </ b> C connected to the system solenoid valve 43.

  Reference numeral 41 denotes another lead wire connected to the positive side of the battery 39 together with the wiring portion 40A of the lead wire 40. Here, the lead wires 40 and 41 are connected to the battery 39 so as to be parallel to each other. As shown in FIG. 4, the lead wire 41 includes a first wiring part 41A provided between a common terminal 42C of a relay 42, which will be described later, and a battery 39, a switching terminal 42E, which is described later, and a traveling system electromagnetic wave. And a second wiring portion 41B provided in connection with the valve 44.

  Reference numeral 42 denotes a relay (relay) provided between a travel system electromagnetic valve 44 and a battery 39, which will be described later. The relay 42 is connected to the battery via wiring portions 40A and 40B of the lead wire 40 as shown in FIG. 39, a relay coil 42A connected to the relay coil 42, a movable contact 42B that is closed and opened according to energization (excitation) and non-energization (demagnetization) to the relay coil 42A, and a common located on the base end side of the movable contact 42B It includes a terminal 42C, first and second switching terminals 42D and 42E to which the front end side of the movable contact 42B is switchably connected, and a back electromotive force preventing diode 42F connected in parallel to the relay coil 42A. Has been.

  Here, in the relay 42, the common terminal 42 </ b> C is always connected to the battery 39 via the first wiring portion 41 </ b> A of the lead wire 41. The movable contact 42B of the relay 42 is kept in the open state by contacting the first switching terminal 42D until the relay coil 42A is energized. On the other hand, the movable contact 42B is closed when it switches from the first switching terminal 42D and contacts the second switching terminal 42E.

  That is, when the gate lock switch 38 is closed (ON operation), the relay 42 is closed when the relay coil 42A is energized (excited) so that the movable contact 42B contacts the switching terminal 42E. . As a result, power is supplied from the battery 39 to the work system solenoid valve 43 and the travel system solenoid valve 44, which will be described later, via the lead wires 40 and 41, respectively, from the initial position (d) shown in FIGS. Switch to excitation position (e).

  When the gate lock switch 38 is opened, the energization (excitation) from the battery 39 to the relay coil 42A of the relay 42 is released, so the movable contact 42B of the relay 42 moves (contacts) toward the switching terminal 42D. Return to the open position. As a result, the work system solenoid valve 43 and the travel system solenoid valve 44, which will be described later, are de-energized from the battery 39 via the lead wires 40 and 41, so that the initial positions (d) shown in FIGS. ).

  43 is a work system solenoid valve that constitutes a gate lock control valve together with a travel system solenoid valve 44, which will be described later. The work system solenoid valve 43 includes wiring sections 40A to 40C of a lead wire 40 and a gate lock switch as shown in FIG. When the gate lock switch 38 is closed, the initial position (d) is switched to the excitation position (e). The work system solenoid valve 43 is connected to the pump port of the work system pilot valve 31 via a pilot pressure conduit 32.

  While the work system electromagnetic valve 43 is in the initial position (d), the pilot pressure conduit 32 is connected to the tank 20 via the return conduit 27, and the pilot pressure conduit 32 is in the tank pressure (low pressure) state. Retained. For this reason, the pilot pressure oil is not supplied to the pilot pipe lines 31A and 31B even if the operation system pilot valve 31 tilts the operation lever 11A (12B), and the operation direction control valve 30 is in the neutral position. It remains held in (c).

  On the other hand, when the work system solenoid valve 43 is switched from the initial position (d) to the excitation position (e) by closing the gate lock switch 38, the pilot pressure conduit 32 is connected to the pilot pump 21 via the pilot conduit 23. For example, pilot pressure oil set by the relief valve 25 is supplied to the pilot pressure conduit 32. Therefore, the working system pilot valve 31 can supply pilot pressure oil to the pilot pipe lines 31A and 31B when the operation lever 11A (12B) is tilted, and the working system direction control valve 30 is provided. It is possible to switch from the neutral position (c) to either the switching position (a) or (b).

  44 is a travel system solenoid valve that constitutes a gate lock control valve together with the work system solenoid valve 43. The travel system solenoid valve 44 is composed of wiring portions 41A and 41B of a lead wire 41 and a movable contact 42B of a relay 42 as shown in FIG. The work system solenoid valve 43 is connected in parallel to the battery 39 by a relay 42. The traveling system solenoid valve 44 is connected to the pump port of the traveling system pilot valve 36 via a pilot pressure conduit 37.

  While the traveling system solenoid valve 44 is in the initial position (d), the pilot pressure conduit 37 is connected to the tank 20 via the return conduit 27, and the pilot pressure conduit 37 is in the tank pressure (low pressure) state. Retained. Therefore, even if the traveling pilot valve 36 tilts the traveling lever / pedal 13 (14), the pilot pressure oil is not supplied to the pilot pipelines 36A and 36B, and the traveling direction control valve 35 It remains held in the neutral position (c).

  On the other hand, when the movable contact 42B of the relay 42 is closed by closing the gate lock switch 38, the traveling system electromagnetic valve 44 is energized from the battery 39 to change from the initial position (d) to the excitation position (e). Switched. Thereby, the pilot pressure conduit 37 is connected to the pilot pump 21 via the pilot conduit 23, and the pilot pressure oil set by, for example, the relief valve 25 is supplied to the pilot pressure conduit 32. Therefore, the traveling pilot valve 36 can supply pilot pressure oil to the pilot pipes 36A and 36B when the traveling lever / pedal 13 (14) is tilted. 35 can be switched from the neutral position (c) to either the switching position (a) or (b).

  The gate lock circuit mounted on the small excavator 1 according to the present embodiment has the above-described configuration, and the operation thereof will be described next.

  First, the operator of the hydraulic excavator 1 gets on the cab 8 of the upper swing body 4 and rotates the gate lock lever 15 to the lower blocking position while sitting on the driver's seat 10. As a result, the gate lock switch 38 shown in FIG. 3 is closed, and the work system solenoid valve 43 is supplied with power from the battery 39 via the wiring portions 40A to 40C of the lead wire 40 and the gate lock switch 38. The position (d) is switched to the excitation position (e).

  When the working solenoid valve 43 is switched from the initial position (d) to the excitation position (e), the pilot pressure conduit 32 is connected to the pilot pump 21 via the pilot conduit 23, and the pilot pressure conduit 32 is connected to the pilot pressure conduit 32. For example, pilot pressure oil set by the relief valve 25 is supplied. Therefore, the pilot pressure oil corresponding to the tilting operation of the operation lever 11A (12B) is supplied from the working pilot valve 31 to the hydraulic pilot portions 30A and 30B of the direction control valve 30 via the pilot pipe lines 31A and 31B. The directional control valve 30 of the working system can be switched from the neutral position (c) to any one of the switching positions (a) and (b).

  As described above, when the directional control valve 30 of the work system is switched from the neutral position (c) to any one of the switching positions (a) and (b), the pressure supplied from the hydraulic pump 19 via the discharge line 22 is changed. Since oil is supplied to and discharged from the oil chambers 28A and 28B of the hydraulic cylinder 28 via the direction control valve 30 and the hydraulic pipes 29A and 29B, the rod 28C of the hydraulic cylinder 28 can be driven in the expansion and contraction direction. 5 can perform excavation work such as earth and sand.

  Further, the relay 42 connected to the battery 39 via the lead wire 41 closes the movable contact 42B when the relay coil 42A is excited by closing the gate lock switch 38. For this reason, the traveling system electromagnetic valve 44 is switched from the initial position (d) to the excitation position (e) by being energized from the battery 39 via the wiring portions 41A and 41B of the lead wire 41.

  Thereby, the pilot pressure conduit 37 is connected to the pilot pump 21 via the pilot conduit 23, and the pilot pressure oil set by, for example, the relief valve 25 is supplied to the pilot pressure conduit 32. Therefore, the pilot pressure oil corresponding to the tilting operation of the travel lever / pedal 13 (14) is supplied from the travel system pilot valve 36 via the pilot lines 36A, 36B to the hydraulic pilot portions 35A, 35A of the direction control valve 35. 35B, the direction control valve 35 of the traveling system can be switched from the neutral position (c) to any one of the switching positions (a) and (b).

  When the directional control valve 35 of the traveling system is switched from the neutral position (c) to any one of the switching positions (a) and (b), the pressure oil supplied from the hydraulic pump 19 via the discharge conduit 22 is supplied. Since the traveling motor 33 is supplied to and discharged from the direction control valve 35 and the hydraulic pipes 34A and 34B, the traveling motor 33 can be driven to rotate, whereby the lower traveling body 2 can be moved forward or backward. it can.

  On the other hand, when the operator leaves the driver's seat 10 and gets off from the boarding opening 8A of the cab 8, the gate lock lever 15 is rotated to the upper opening position. Thereby, the gate lock switch 38 shown in FIG. 3 is opened, and the work system electromagnetic valve 43 is cut off from the battery 39 through the wiring portions 40A to 40C of the lead wire 40, so that the excitation position (e) To the initial position (d).

  Then, when the work system electromagnetic valve 43 returns to the initial position (d), the pilot pressure conduit 32 is connected to the tank 20 via the return conduit 27, so the pressure in the pilot pressure conduit 32 is, for example, It will drop to a pressure close to the tank pressure. Therefore, even if the operating system pilot valve 31 tilts the operating lever 11A (12B), no pilot pressure oil is generated on the pilot pipe lines 31A and 31B, and the working system direction control valve 30 is neutral. The supply of the pressure oil to the hydraulic cylinder 28 can be stopped while being held at the position (c).

  Further, in the relay 42 connected to the battery 39 via the lead wire 41, the relay coil 42A is demagnetized by opening the gate lock switch 38, so that the movable contact 42B is opened. The energization from the battery 39 via the lead wire 41 is released, and the excitation position (e) returns to the initial position (d).

  As a result, the pilot pressure conduit 37 is connected to the tank 20 via the return line 27, so that pilot pressure oil is not supplied from the traveling system pilot valve 36 via the pilot lines 36A and 36B. The directional control valve 35 of the traveling system is held at the neutral position (c), and the supply of pressure oil to the traveling motor 33 is also stopped.

  By the way, even when the gate lock switch 38 is turned ON (closed) by the gate lock lever 15, the energization (excitation) to the work system electromagnetic valve 43 is canceled due to a failure of the electrical system such as disconnection. Then, the work system electromagnetic valve 43 returns to the initial position (d), the pressure in the pilot pressure conduit 32 decreases, the work system direction control valve 30 returns to the neutral position (c), and the pressure to the hydraulic cylinder 28 is reduced. Oil supply will also be stopped.

  However, according to the present embodiment, the relay 42 is provided between the wiring portion 41A, 41B of the lead wire 41 between the battery 39 as the power source and the traveling system electromagnetic valve 44, and the relay 42 The work system solenoid valve 43 and the travel system solenoid valve 44 are connected in parallel to the battery 39.

  Thereby, even if the working system solenoid valve 43 is deenergized due to disconnection or the like and the work system solenoid valve 43 malfunctions, this influence can be prevented from reaching the traveling system solenoid valve 44. The traveling electromagnetic valve 44 can be energized as long as the gate lock switch 38 is closed, and the traveling electromagnetic valve 44 is switched from the initial position (d) to the excitation position (e). be able to.

  For this reason, the pilot pressure oil corresponding to the tilting operation of the travel lever / pedal 13 (14) is supplied from the travel system pilot valve 36 via the pilot lines 36A, 36B to the hydraulic pilot portions 35A, 35A of the directional control valve 35. 35B, the directional control valve 35 of the traveling system can be switched from the neutral position (c) to any one of the switching positions (a) and (b), and the supply and stop of the pressure oil to the traveling motor 33 can be performed. It can be controlled according to the switching of the gate lock switch 38.

  Therefore, according to the present embodiment, even if a situation occurs in which the hydraulic cylinder 28 of the work system is stopped due to a failure of the electrical system or the like, this influence extends to the hydraulic actuator or the like of the traveling system. It is possible to prevent this, and it is possible to secure drive control for the traveling motor 33 (traveling hydraulic actuator), and it is possible to quickly move the vehicle in response to a request to move it urgently.

  As a result, it is possible to eliminate a situation in which the operation control of the traveling system cannot be performed due to the failure of the work system, and it is possible to improve the work efficiency at the site.

  Next, FIG. 5 shows a second embodiment of the present invention. The feature of this embodiment is that an operation switch is provided between at least one of the working system solenoid valve and the traveling system solenoid valve and the power source. And the electromagnetic valve can be switched by the operation switch even when the gate lock switch is opened. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  In the figure, reference numeral 51 denotes an operation switch employed in the present embodiment. The operation switch 51 is located between the movable contact 42B (switching terminal 42D) side of the relay 42 and the intermediate position of the second wiring portion 41B of the lead wire 41. They are connected via a detour wiring 52 therebetween. Here, the bypass wiring 52 includes a first wiring portion 52A provided between the switching terminal 42D of the relay 42 and one terminal of the operation switch 51, and the other terminal of the operation switch 51 and the second wiring. The second wiring portion 52B is provided so as to be connected to the middle position of the portion 41B.

  The first wiring portion 52A of the bypass wiring 52 is connected to the battery 39 via the first wiring portion 41A of the lead wire 41 when the movable contact 42B of the relay 42 is opened and is in contact with the switching terminal 42D. When the movable contact 42B of the relay 42 is closed by contacting the switching terminal 42E, it is disconnected from the first wiring portion 41A (battery 39) of the lead wire 41.

  Further, the operation switch 51 is arbitrarily pressed by an operator or the like and electrically connects between the wiring portions 52A and 52B of the bypass wiring 52 when closed. The operation switch 51 is automatically opened when the pressing operation by the operator is released, and cuts off between the wiring portions 52A and 52B of the bypass wiring 52.

  Thus, also in the present embodiment configured as described above, the same effect as in the first embodiment can be obtained. In particular, according to the second embodiment, even when the gate lock switch 38 is opened (OFF operation), the operator can arbitrarily operate the operation switch 51 to obtain the following effects. be able to.

  That is, when the operator arbitrarily operates the operation switch 51 while the gate lock switch 38 is opened, the movable contact 42B of the relay 42 in the opened state is connected via the bypass wiring 52 and the operation switch 51. Are connected to the second wiring portion 41B of the lead wire 41. As a result, the current from the battery 39 flows to the traveling system electromagnetic valve 44 via the lead wire 41, the bypass wiring 52, etc., and the traveling system electromagnetic valve 44 can be switched from the initial position (d) to the excitation position (e). it can.

  Therefore, according to the second embodiment, even when the gate lock switch 38 is opened (OFF operation), the operator arbitrarily operates the operation switch 51 to switch the traveling system solenoid valve 44. It is possible to control the supply and stop of the pressure oil to the traveling motor 33 (traveling hydraulic actuator).

  For this reason, if the excitation of the work system solenoid valve 43 expires or is canceled for some reason apart from the failure on the work system solenoid valve 43 side or the operator's intention, a failure or the like further occurs on the gate lock switch 38 side. Even in such a case, the operator can arbitrarily switch the traveling system solenoid valve 44 by operating the operation switch 51 as an urgent movement switch, and the vehicle can be moved quickly in response to a request to move urgently. Can be made. And if operation of the operation switch 51 is cancelled | released, driving | running | working of a vehicle can be stopped automatically.

  Next, FIG. 6 shows a third embodiment of the present invention, and the feature of the present embodiment is that it is configured to have a notification device that notifies when a solenoid valve is switched by an operation switch. It is in. In the third embodiment, the same components as those in the second embodiment described above are denoted by the same reference numerals, and description thereof is omitted.

  In the figure, 61 is an alarm buzzer as a notification device adopted in the present embodiment, and the alarm buzzer 61 is connected in the middle of the second wiring portion 52B in the detour wiring 52 described in the second embodiment. Has been. For this reason, when the operator performs an operation of pressing down the operation switch 51 while the gate lock switch 38 is opened, the alarm buzzer 61 is energized from the battery 39 and the traveling system electromagnetic valve 44 is switched. Is done.

  The alarm buzzer 61 indicates that the hydraulic excavator 1 is moved urgently when the traveling electromagnetic valve 44 is switched by the operation switch 51 with the gate lock switch 38 opened. Can be notified.

  Thus, in the present embodiment configured as described above, the same effects as those of the second embodiment can be obtained. In particular, according to the third embodiment, when the operator operates the operation switch 51 with the gate lock switch 38 opened, this can be notified by the alarm buzzer 61. In addition, since the alarm buzzer 61 is activated when the operation switch 51 is operated, it is possible to avoid undue operation of the operation switch 51 in a state of no urgency.

  Next, FIG. 7 shows a fourth embodiment of the present invention. The feature of this embodiment is that a working system solenoid valve and a traveling system solenoid valve are connected in parallel on the movable contact side of the relay. It is in that. Note that in the fourth embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and description thereof is omitted.

  In the figure, reference numeral 71 denotes a lead wire connected to the positive side of the battery 39, and the lead wire 71 is connected to one terminal of the gate lock switch 38 and the battery 39 and is connected to the first wiring portion 71 </ b> A. And a second wiring portion 71B provided to be connected between the other terminal of the gate lock switch 38 and the relay coil 42A of the relay 42.

  Reference numeral 72 denotes another lead wire that is connected to the positive side of the battery 39 together with the wiring portion 71A of the lead wire 71. Here, the lead wires 71 and 72 are connected to the battery 39 so as to be in parallel with each other. The lead wire 72 is connected between the first wiring portion 72A provided between the common terminal 42C of the relay 42 and the battery 39, and between the switching terminal 42E and the work system solenoid valve 43. Second wiring portion 72B provided, and a third wiring portion 72C provided between switching terminal 42E and traveling system solenoid valve 44 so as to be in parallel with second wiring portion 72B. It is configured.

  Thus, also in the present embodiment configured as described above, the movable contact 42B of the relay 42 can be similarly opened and closed in accordance with the opening and closing of the gate lock switch 38, and the first embodiment. The same effect can be obtained. In particular, in the present embodiment, when the movable contact 42B of the relay 42 is closed, the work is performed via the second and third wiring portions 72B and 72C connected to the switching terminal 42E so as to form a parallel relationship with each other. The system solenoid valve 43 and the travel system solenoid valve 44 can be switched together.

  Even if the work system solenoid valve 43 is stopped due to a failure of the electrical system, the travel system solenoid valve 44 can ensure drive control for the travel motor 33 and move it urgently. The vehicle can be moved quickly in response to such a request. Thereby, the situation of leaving the excavator 1 at the work site can be solved, and the work efficiency and the like at the site can be improved.

  Next, FIG. 8 shows a fifth embodiment of the present invention. The feature of this embodiment is that an operation switch is provided between the work system solenoid valve, the travel system solenoid valve and the power source, and the gate lock switch is installed. It is in a configuration in which both solenoid valves can be switched by an operation switch even when opened. In the fifth embodiment, the same components as those in the above-described fourth embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  In the figure, reference numeral 81 denotes an operation switch employed in the present embodiment. The operation switch 81 is located between the movable contact 42B (switching terminal 42D) side of the relay 42 and the midway position of the third wiring portion 72C of the lead wire 72. They are connected to each other via a bypass wiring 82. Here, the bypass wiring 82 is connected between the switching terminal 42D of the relay 42 and one terminal of the operation switch 81, and the other terminal of the operation switch 81 and the third wiring. The second wiring portion 82B is provided so as to be connected to the middle position of the portion 72C.

  The first wiring portion 82A of the bypass wiring 82 is connected to the battery 39 via the first wiring portion 72A of the lead wire 72 when the movable contact 42B of the relay 42 is opened and is in contact with the switching terminal 42D. When the movable contact 42B of the relay 42 contacts the switching terminal 42E and is closed, the relay 42 is disconnected from the first wiring portion 72A (battery 39) of the lead wire 72.

  The operation switch 81 is arbitrarily pressed by an operator or the like, and electrically connects between the wiring portions 82A and 82B of the bypass wiring 82 when closed. The operation switch 81 is automatically opened when the pressing operation by the operator is released, and cuts off between the wiring portions 82A and 82B of the bypass wiring 82.

  Thus, the present embodiment configured as described above can achieve the same effects as those of the fourth embodiment. In particular, according to the fifth embodiment, even when the gate lock switch 38 is opened (OFF operation), the operator can arbitrarily operate the operation switch 81 to move the relay 42 in the opened state. The contact 42 </ b> B is connected to the third wiring portion 72 </ b> C of the lead wire 72 via the bypass wiring 82 and the operation switch 81.

  As a result, the current from the battery 39 flows to the traveling system electromagnetic valve 44 via the lead wire 72, the bypass wiring 82, etc., and the traveling system electromagnetic valve 44 can be switched from the initial position (d) to the excitation position (e). it can. Further, when the operation switch 81 is operated, the current from the battery 39 also flows to the work system electromagnetic valve 43 via the wiring portion 72A, the bypass wiring 82, the wiring portion 72B, and the like of the lead wire 72. As long as the operation switch 81 is operated, the initial position (d) can be switched to the excitation position (e).

  Therefore, even when a failure or the like occurs on the gate lock switch 38 side, the operator arbitrarily operates the operation switch 81 as a switch for urgent movement to switch both the work system solenoid valve 43 and the travel system solenoid valve 44. be able to. Further, even if a failure occurs on the work system solenoid valve 43 side or the excitation of the work system solenoid valve 43 is deactivated or released for some reason apart from the operator's intention, this influence is caused by the traveling system solenoid valve 44. The vehicle can be moved quickly in response to a request to move it urgently. And if operation of the operation switch 81 is cancelled | released, driving | running | working of a vehicle can be stopped automatically.

  Next, FIG. 9 shows a sixth embodiment of the present invention. The feature of the present embodiment is that a configuration is provided in which a notification device is provided to notify when a solenoid valve is switched by an operation switch. is there. In the sixth embodiment, the same components as those in the fifth embodiment described above are denoted by the same reference numerals, and description thereof is omitted.

  In the figure, 91 is an alarm buzzer as a notification device employed in the present embodiment, and the alarm buzzer 91 is connected in the middle of the second wiring portion 82B of the detour wiring 82 described in the fifth embodiment. Has been. For this reason, when the operator performs an operation of pressing down the operation switch 81 while the gate lock switch 38 is opened, the alarm buzzer 91 is energized from the battery 39 and the traveling system electromagnetic valve 44 is switched. Is done.

  The alarm buzzer 91 indicates that the hydraulic excavator 1 is moved urgently when the traveling electromagnetic valve 44 is switched by the operation switch 81 with the gate lock switch 38 opened. Can be notified.

  Thus, the present embodiment configured as described above can achieve the same effects as those of the fifth embodiment. In particular, according to the sixth embodiment, when the operator operates the operation switch 81 with the gate lock switch 38 opened, this can be notified by the alarm buzzer 91 and the urgency. Unnecessary operation of the operation switch 81 in the absence of the operation can be avoided.

  In the third and sixth embodiments, the case where the alarm buzzers 61 and 91 are used as the notification device has been described as an example. However, the present invention is not limited to this, and the notification device may be configured by means such as an alarm lamp, a voice synthesizer, or a display.

  Further, in each of the above-described embodiments, the case where the gate lock circuit is mounted on the small hydraulic excavator 1 has been described as an example. However, the gate lock circuit according to the present invention is not limited to this. For example, a construction machine such as a hydraulic excavator, a wheel loader, a forklift, or a hydraulic crane having a wheel-type lower traveling body, or a hydraulic working machine other than the construction machine. It can also be widely applied to.

DESCRIPTION OF SYMBOLS 1 Hydraulic excavator 2 Lower traveling body 3 Turning device 4 Upper turning body 5 Working device 6 Turning frame (frame)
8 Cab (cab)
DESCRIPTION OF SYMBOLS 15 Gate lock lever 16 Engine 19 Hydraulic pump 20 Tank 21 Pilot pump 22 Discharge line 23, 31A, 31B, 36A, 36B Pilot line 24, 25 Relief valve 26, 27 Return line 28 Hydraulic cylinder (work system hydraulic actuator) )
30, 35 Directional control valve 31 Working system pilot valve 32, 37 Pilot pressure conduit 33 Traveling motor (traveling hydraulic actuator)
36 Pilot valve for traveling system 38 Gate lock switch 39 Battery (power supply)
40, 41, 71, 72 Lead wire 42 Relay 42A Relay coil 42B Movable contact 43 Work system solenoid valve (gate lock control valve)
44 Traveling solenoid valve (gate lock control valve)
51, 81 Operation switch 52, 82 Detour wiring 61, 91 Alarm buzzer (notification device)

Claims (6)

A hydraulic actuator for a work system that drives a working device by being supplied with pressure oil from a hydraulic pump, a hydraulic actuator for a travel system that drives a vehicle by being supplied with pressure oil from the hydraulic pump, and an operation A gate lock switch provided in the vicinity of the seat and switched by an operator's operation; and a gate lock control valve for controlling supply and stop of pressure oil to the hydraulic actuators of the working system and the traveling system according to the switching of the gate lock switch. In the construction equipment gate lock circuit,
The gate lock control valve is connected in parallel to a work system solenoid valve for controlling the supply and stop of pressure oil to the work system hydraulic actuator according to the switching of the gate lock switch, and the work system solenoid valve is connected in parallel to the power source And a traveling system electromagnetic valve that controls supply and stop of pressure oil to the hydraulic actuator of the traveling system in accordance with switching of the gate lock switch.   Even when one of the working system solenoid valve and the traveling system solenoid valve or both solenoid valves and the power source is open, the solenoid valve is switched by an operator operation even when the gate lock switch is opened. 2. The gate lock circuit for a construction machine according to claim 1, further comprising an operation switch for controlling supply and stop of the pressure oil.   The gate lock circuit for a construction machine according to claim 2, further comprising a notification device that notifies when the electromagnetic valve is switched by the operation switch.   The construction machine according to claim 2 or 3, wherein the operation switch is operated when the vehicle is moved, and the traveling electromagnetic valve can be controlled even when the gate lock switch is opened. Gate lock circuit.   A relay that is opened and closed according to switching of the gate lock switch is provided between one or both of the working system solenoid valve and the travel system solenoid valve and the power source. A gate lock circuit for a construction machine according to 2, 3 or 4.   The relay includes a relay coil connected to the power supply via the gate lock switch, and a movable contact that is closed and opened in accordance with energization and non-energization of the relay coil, and the working system solenoid valve; 6. The gate lock circuit for a construction machine according to claim 5, wherein one or both of the traveling system solenoid valves are connected in accordance with switching of the movable contact of the relay.

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