JP2000265770A - Drive mechanism for construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide accurate synchronous rotation by connecting hydraulic motors in series and compensating internal leakage through a refilling circuit and also to enable switching over an arbitrary hydraulic motor easily to an independent drive by the operation of a changeover valve. SOLUTION: A going route 18 of oil pressure is connected from a hydraulic pump P to an inlet oil route 2a of a hydraulic oil motor 2 through transfer valves 20, 13, an inlet circuit 22 is connected from an outlet oil route 2b to an inlet oil route 3a of a hydraulic motor 3 through a transfer valve 17, and an internal leak of oil pressure is compensated through the refilling circuit comprising a check valve 11, a variable throttle valve 10 and a shut-off valve 12. And the rotating direction of the hydraulic motors 2, 3 making synchronous rotation is switched by the transfer valve 20. Also, if the transfer valve 17 is transferred and the shut-off valve 12 of the refilling circuit 9 is turned off, only the hydraulic motor 2 is driven independently and, if the transfer valve 13 is transferred in this state, only the hydraulic motor 3 is driven independently. Thus, the hydraulic motors 2, 3 is able to make synchronous rotation accurately and can be easily switched to an independent drive.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive mechanism such as an earth auger, a lift or a casing which is operated by a drive mechanism comprising a hydraulic motor.

[0002]

2. Description of the Related Art As shown in FIG. 5, an earth auger 4 and a casing 5 which are a kind of construction machine for excavating underground are connected to separate hydraulic motors 2 and 3, respectively, and each of them is driven in synchronization. Alternatively, there is a case where a single drive is performed. However, conventionally, there is no simple method or device for switching between the two drives. In particular, when raising and lowering the earth auger 4 and the casing 5 separately along the leader 1, the lift 6 operated by the hydraulic motors 2, 3 (the same reference numerals are used for the following description). , 7 are used, there are cases where it is necessary for the elevators 6, 7 to synchronize and elevate at the same time, or to elevate and lower independently, respectively. A simple method and device for precisely synchronizing or independently driving them are required. There was no.

In order to rotate the hydraulic motors 2 and 3 at a high speed and perform a synchronous operation, a hydraulic source, the hydraulic motors 2 and 3 and a hydraulic circuit returning to the tank are often connected in series.
In the conventional series circuit, each hydraulic motor 2, 3
It was difficult to operate the tuning.

The conventional series circuit will be described with reference to FIG. 1 showing an embodiment of the present invention.
Hydraulic circuit from the first hydraulic motor 2 inlet oil passage 2a
And an outlet oil passage 2b of the first hydraulic motor 2 is connected to an inlet oil passage 3 of the second hydraulic motor 3 through circuits 21 and 22.
a, the outlet oil passage 3b of the second hydraulic motor 3 is connected to the tank T, whereby the first and second hydraulic motors 2, 3 connect the hydraulic pump P and the tank T in series. The connection is established by the hydraulic circuit 8, and a rotation speed matching the flow speed of the pressure oil can be obtained.

However, when a plurality of hydraulic motors are connected by a serial hydraulic circuit as described above, the hydraulic motor always has a problem of internal leakage of pressure oil (internal leakage).

[0006] Explaining with a specific example, for example, when the volume of the hydraulic motor is 100 cc, if 100 liters of pressure oil is supplied from the hydraulic pump side, the theoretical value of the hydraulic motor will be 1000 revolutions / minute. However, hydraulic motors always have an internal leak, and it is generally said that there is an oil leak of 0.5 to 5.0 liters per minute. Assuming that the internal leak is 2 liters per minute,
The pressure oil supplied to the first hydraulic motor 2 is 100-2 =
It becomes 98 liters, and the rotation speed of the first hydraulic motor 2 becomes 980 rotations / minute. Similarly, the pressure oil supplied to the second hydraulic motor 3 is 98-2 = 96 liters,
The rotation speed of the hydraulic motor 3 is 960 rotations / minute. Therefore, there is a difference of 20 revolutions per minute between the first hydraulic motor 2 and the second hydraulic motor 3, which results in the earth auger 4 connected to these hydraulic motors 2, 3. And the rotation speed of the casing 5 changes, which causes a reduction in cutting efficiency. Elevators 6,7
When the rotation speed of the upper hydraulic motor 2 is higher than that of the lower hydraulic motor 3 among the hydraulic motors 2 and 3 used in the above, the upper elevator 6 is moved downward by the lower elevator It may cause an accident of collision.

[0007]

SUMMARY OF THE INVENTION It is a main object of the present invention to eliminate the above-mentioned disadvantages when a plurality of hydraulic motors are used as drive sources for construction equipment.

[0008]

Means for Solving the Problems To solve the above problems, the invention according to claim 1 comprises a plurality of hydraulic motors 2, 3 as indicated by reference numerals shown in the drawings. In a drive mechanism of a construction machine device in which each hydraulic motor 2, 3 is a drive source of a construction machine 4, 5, or 6, 7, respectively, each hydraulic motor 2, 3 is sequentially operated from a hydraulic oil source P by a hydraulic circuit 8 in series. Each hydraulic motor 3 except for the hydraulic motor 2 which is connected and directly connected to the pressure oil source P
Are connected to the supply circuit 9 branched from the pressure oil source P, respectively.
Each of the hydraulic motors 2 and 3 adopts a configuration adapted to be simultaneously driven in the same direction.

Further, in the invention according to claim 2, the variable throttle valve 10 for adjusting the supply amount of the pressure oil passing through the circuit 9 is interposed in the supply circuit 9. It has a configuration.

[0010] In the invention according to claim 3, the hydraulic motors 2 and 3 comprise a plurality of hydraulic motors 2 and 3 respectively.
In the drive mechanism of the construction machine, which is the drive source of the construction machine 4, 5 or 6, 7, respectively, the hydraulic motors 2, 3 are sequentially connected from the hydraulic oil source P by a serial hydraulic circuit 8, Each hydraulic motor 3 except for the hydraulic motor 2 directly connected to P is connected to a supply circuit 9 branched from the pressure oil source P so that the hydraulic motors 2 and 3 are simultaneously driven in the same direction. A simultaneous drive / single drive switching circuit 16 for switching to one of the simultaneous drive circuit 14 and the single drive circuit 15 in which each of the hydraulic motors 2 and 3 is driven independently. This configuration is adopted.

Further, in the invention according to claim 4, the simultaneous drive / single drive switching circuit 16 selects one of the simultaneous drive / single drive switching valve 17 and each of the hydraulic motors. The one-drive switching valve (13) is provided.

According to the fifth aspect of the present invention, a variable throttle valve 10 for adjusting the supply amount of the pressure oil passing through the supply circuit 9 flows through the supply circuit 9 in only one direction. And a shut-off valve for turning on and off the flow of pressure oil.

[0013]

According to the first aspect of the present invention, the construction machine
Since the plurality of hydraulic motors 2 and 3 used as the drive sources 5 or 6 and 7 are connected sequentially from the hydraulic oil source P by the hydraulic circuit 8 in series, it is necessary to obtain a rotational speed corresponding to the flow velocity of the hydraulic oil. Can be.

Each of the plurality of hydraulic motors 2 and 3 except for the hydraulic motor 2 directly connected to the pressure oil source P is connected to a supply circuit 9 branched from the pressure oil source P. Therefore, even if there is an internal leak of hydraulic oil in each hydraulic motor 3, the hydraulic oil is constantly supplied to each hydraulic motor 3 from the supply circuit 9, so that the internal leak is compensated and the pressure to each hydraulic motor 3 is increased. The oil supply is not reduced, and thus the rotational speed of each hydraulic motor 3 is not reduced, so that the plurality of hydraulic motors 2 and 3 rotate exactly in synchronization with each other, and the hydraulic motors 2 and 3 do not rotate. Can be driven at an accurate speed, and a stable and efficient cutting operation can be performed.

According to the second aspect of the present invention, in order to accurately adjust the amount of hydraulic oil supplied to each of the hydraulic motors 2 and 3, the variable throttle valve 10 provided in the supply circuit 9 is operated. As a result, the hydraulic motors 2 and 3 can be maintained at exactly the same speed as each other.

According to the third aspect of the invention, the same effect as the first aspect of the invention can be exhibited, and each of the construction machines 4, 5 or 6, 7 can be used in accordance with the working application. Hydraulic motors 2 and 3 can be driven simultaneously in the same direction, each hydraulic motor 2 and 3 can be driven independently, or can be instantly switched to one of the operating states. be able to.

According to the third aspect of the present invention, both the simultaneous driving of the hydraulic motors in the same direction and the independent driving of one of the hydraulic motors can be achieved by supplying the hydraulic oil from the single hydraulic oil source P. The configuration is very simple.

Further, in the invention according to claim 4, a simultaneous drive circuit 14 for simultaneously driving the hydraulic motors in the same direction, and a single drive circuit 1 for independently driving one of the hydraulic motors.
5, the simultaneous drive / single drive switching circuit 16 has a simple configuration of the simultaneous drive / single drive switching valve 17 and the alternative drive switching valve 13, and can be manufactured at low cost.

According to the fifth aspect of the present invention, in order to accurately adjust the amount of hydraulic oil supplied to each of the hydraulic motors 2 and 3, the variable throttle valve 10 provided in the supply circuit 9 is operated. Since the check valve 11 and the shut-off valve 12 are interposed in the supply circuit 9, the hydraulic motors 2, 2 are operated by operating the simultaneous drive / single drive switching valve 17 and the alternative drive switching valve 13. Switching between the same-direction simultaneous drive 3 and the independent drive of any one of the hydraulic motors 2 and 3 can be achieved by a simple circuit configuration.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an upper hydraulic motor 2 as a drive source of an upper elevator 6 (FIG. 5) and a lower elevator. 7 (FIG. 5) shows a series hydraulic circuit 8 for simultaneously driving the lower hydraulic motor 3 as a drive source in the same direction, that is, counterclockwise as indicated by an arrow. In the state shown in the figure, the circuit shown by the bold line is in principle
8 and a circuit indicated by a thin line indicates the pressure oil return path 19. That is, the rotation direction switching valve 20 and the alternative drive switching valve 13 are interposed in the pressure oil forward path 18 connected to the hydraulic pump P serving as the pressure oil source. An outlet circuit 21 connected to an inlet oil passage 2a of the upper hydraulic motor 2 and coming out of an outlet oil passage 2b of the hydraulic motor 2, and an inlet circuit 2 connected to an inlet oil passage 3a of the lower hydraulic motor 3
2 is connected by a simultaneous drive / single drive switching valve 17, an outlet oil passage 3 b of the lower hydraulic motor 3 is connected to a pressure oil return passage 19, and is connected to a tank via an alternative drive switching valve 13 and a rotation direction switching valve 20. Connected to T. The circuit connecting the simultaneous drive / single drive switching valve 17 and the alternative drive switching valve 13 constitutes a simultaneous drive / single drive switching circuit 16 for switching between simultaneous drive and single drive as described later. On the downstream side of the pressure oil outward path 18, the outward path 18 and the upstream side of the inlet circuit 21 of the lower hydraulic motor 3 are connected to the supply circuit 9.
(9A), and a check valve 11 is connected to the supply circuit 9A.
A, a variable throttle valve 10A, and a shutoff valve 12A are interposed. The outlet circuit 21 of the upper hydraulic motor 2
And the upstream side of the hydraulic oil return path 19 of the lower hydraulic motor 3 are also connected by the supply circuit 9 (9B).

Therefore, the pressure oil discharged from the pressure oil source P is supplied to the port C of the rotation direction switching valve 20 and the port T of the alternative drive switching valve 13.
To the inlet oil passage 2a of the upper hydraulic motor 2 from the pressure oil outward path 18 and the outlet oil passage 2 of the upper hydraulic motor 2.
b from the outlet oil passage 2b through the outlet circuit 21 and from the port M of the switching valve 17 of the simultaneous drive / single drive switching circuit 16 to the lower hydraulic motor 3 through the inlet circuit 22 of the lower hydraulic motor 3. The hydraulic oil that reaches the inlet oil passage 3a and exits from the outlet oil passage 3b of the hydraulic motor 3 passes through the hydraulic oil return passage 19, passes through the port J of the alternative drive switching valve 13, and passes through the port D of the rotation direction switching valve 20. And returns to the tank T. That is, the upper and lower hydraulic motors 2 and 3 are connected in series with the hydraulic circuit 8.
, It is possible to obtain a rotation speed according to the flow speed of the pressure oil.

Then, as described above, the pressure oil sent from the hydraulic pump P to the pressure oil forward path 18 also enters the supply circuit 9 (9A). That is, since both the check valve 11A and the shutoff valve 12A of the supply circuit 9A are in a flowable state, a pressure oil having a flow rate corresponding to the throttle amount of the variable throttle valve 10A passes through the supply circuit 9A from the inlet circuit 22. Lower hydraulic motor 3
To replenish the decrease in the amount of hydraulic oil to the lower hydraulic motor 3 due to oil leakage in the circuit leading to the hydraulic motor 3 or in the upper hydraulic motor 2 by the amount of hydraulic oil from the supply circuit 9A. In this way, the rotational speeds of the upper hydraulic motor 2 and the lower hydraulic motor 3 can be maintained in synchronism. In particular, the exact amount of pressurized oil supplied to the lower hydraulic motor 3 is determined by the supply circuit 9A. It can be adjusted accurately by the variable throttle valve 10A. In this case, the supply circuit 9 connected between the outlet circuit 21 and the pressure oil return path 19
In (9B), since the shut-off valve 12B is off, no pressure oil flows into the supply circuit 9 (9B).

FIG. 2 is a circuit diagram when the upper and lower hydraulic motors 2 and 3 are rotated in the clockwise direction as shown in the figure, and when the rotation direction switching valve 20 is switched, both hydraulic motors 2 and 3 are switched. 1, the circuit shown by the thick line is the hydraulic oil forward path 19, the circuit shown by the thin line is the hydraulic oil return path 18, and both the upper and lower hydraulic motors 2, 3 are different from the circuit shown in FIG. Inlet oil passages 2a, 3a
It can be seen from the circuit diagram that the outlet oil passages 2b and 3b serve as an outlet oil passage and an inlet oil passage, respectively, and the inlet circuit 22 and the outlet circuit 21 serve as an outlet circuit and an inlet circuit, respectively. Accordingly, the pressure oil discharged from the pressure oil source P enters the lower hydraulic motor 3 from the port B of the rotation direction switching valve 20 through the port J of the alternative drive switching valve 13 and the pressure oil outward path 19, 3a is simultaneously driven from the outlet circuit 22.
After exiting the port M of the switching valve 17 of the single drive switching circuit 16 and reaching the upper hydraulic motor 2 via the inlet circuit 21, the hydraulic oil discharged from the hydraulic motor 2 passes through the hydraulic oil return path 18 and is selectively driven. From the port T of the switching valve 13 to the rotation direction switching valve 20
And returns to the tank T through the port A.

Then, as described above, the pressure oil sent to the pressure oil forward path 19 also enters the supply circuit 9 (9B). That is, the check valve 11B and the shut-off valve 12 of the supply circuit 9B
Since both B are in a flowable state, pressure oil having a flow rate corresponding to the throttle amount of the variable throttle valve 10B enters the upper hydraulic motor 2 through the replenishing circuit 9B. The decrease in the amount of hydraulic oil to the upper hydraulic motor 2 due to oil leakage in the upper hydraulic motor 3 is replenished by the amount of hydraulic oil from the supply circuit 9B, whereby the lower hydraulic motor 3 and the upper hydraulic oil are replenished. The rotation speed with the motor 2 can be maintained in synchronization. In particular, the exact amount of hydraulic pressure supplied to the upper hydraulic motor 2 can be accurately adjusted by the variable throttle valve 10B of the supply circuit 9B. In this case, since the shutoff valve 12A of the supply circuit 9A connected between the outlet circuit 22 and the pressure oil return path 18 is off, the pressure oil does not flow into the supply circuit 9A.

As described above, when the upper hydraulic motor 2 and the lower hydraulic motor 3 are accurately driven in synchronization in the same direction and driven to rotate, for example, the upper and lower elevators 6 and 7 shown in FIG. It is possible to move up and down exactly in synchronization, and there is no collision between the elevators 6 and 7 during the up and down movement. Also, when the earth auger 4 and the casing 5 are driven by separate hydraulic motors 2 and 3, respectively, the two can be precisely synchronized and rotated in the same direction to increase the excavating ability.

FIGS. 3 and 4 show the upper hydraulic motor 2.
Alternatively, FIG. 3 shows a circuit in which only one of the lower hydraulic motors 3 is rotationally driven, and FIG. 3 shows a circuit in which only the upper hydraulic motor 2 is rotationally driven. That is, this switching is performed by operating the switching valve 17 of the simultaneous drive / single drive circuit 16 as shown in the figure, and the shut-off valves 12A, 1 of both supply circuits 9A, 9B.
2B may be turned off. However, in the supply circuit 9B, even if the shut-off valve 12B is on, the check valve 1
Distribution is blocked at 1B. As a result, a circuit indicated by a bold line reaching the upper hydraulic motor 2 indicates the pressure oil forward path 18. That is, the pressure oil that has flowed out of the port C of the rotation direction switching valve 20 passes through the pressure oil outward path 18 through the port I of the alternative drive switching valve 13, and from the inlet oil path 2 a of the upper hydraulic motor 2 to the hydraulic motor 2. The hydraulic oil which enters and exits from the outlet oil passage 2b of the hydraulic motor 2 passes through the port O of the simultaneous drive / single drive switching valve 17 from the outlet circuit 21 and enters the port J of the alternative drive switching valve 13 to switch the rotation direction. From port D of valve 20 to tank T
Is returned to. The supply circuit 9A connected to the pressure oil forward path 18 has a shut-off valve 12A in an off state, so that no pressure oil flows into the supply circuit 9A, and the supply circuit 9B connected to the outlet circuit 21. Is also turned off by the check valve 11B or the shut-off valve 12B, so that no pressure oil flows into the supply circuit 9B from the outlet circuit 21.

The lower hydraulic motor 3 is stopped because it is shut off by the alternate drive switching valve 13 and the switching valve 17 of the simultaneous drive / single drive switching circuit 16.

FIG. 4 shows a circuit for driving only the lower hydraulic motor 3 to rotate. In this switching, the switching valve 17 of the simultaneous drive / single drive switching circuit 16 is located at the same position as shown in FIG. 3, and only the alternative drive switching valve 13 is switched as shown in FIG. Supply circuit 9
The shutoff valves 12A and 12B of A and 9B may be turned off. However, in the supply circuit 9A, even when the shutoff valve 12A is on, the flow is blocked by the check valve 11A. As a result, a circuit indicated by a thick line reaching the lower hydraulic motor 3 indicates the pressure oil forward path 19. That is, the pressure oil that has flowed out of the port C of the rotation direction switching valve 20 is supplied to the alternative drive switching valve 1.
3, through the port G, through the pressure oil outward path 19, enter the hydraulic motor 3 from the inlet oil path 3b of the lower hydraulic motor 3,
Hydraulic oil flowing out of the outlet oil passage 3a of the hydraulic motor 3 enters the port H of the alternative drive switching valve 13 from the outlet circuit 22 (at this point, simultaneous drive / single drive switching is performed as in the outlet circuit 21 of FIG. 3). Does not pass through the valve 17), the rotation direction switching valve 20
Is returned to the tank T from the port D. The replenishment circuit 9B connected to the pressure oil outward path 19 includes the shut-off valve 1
Since 2B is in the off state, no pressure oil flows into the supply circuit 9B, and the supply circuit 9A connected to the outlet circuit 22 is also in the off state by the check valve 11A or the shutoff valve 12A. No pressure oil flows into the supply circuit 9A from the outlet circuit 22.

As shown in FIGS. 3 and 4, when only one of the upper hydraulic motor 2 and the lower hydraulic motor 3 is driven independently, a hydraulic pump serving as a hydraulic oil source P is required. However, in the present invention, since each hydraulic motor 2 and 3 can be driven by one hydraulic pump, it is possible to manufacture the motor at low cost as a matter of course.

Further, as shown in FIG. 5, for example, only the earth auger 4 or the casing 5 attached to the elevator is stopped at a position where one of the upper elevator 6 and the lower elevator 7 is stopped. It can be easily applied when needed.

[0031]

According to the first aspect of the present invention, the plurality of hydraulic motors used as the drive source of the construction machine are sequentially connected from the hydraulic oil source by a serial hydraulic circuit.
It is possible to obtain a high rotation speed according to the flow speed of the pressure oil.

Each of the plurality of hydraulic motors, excluding the hydraulic motor directly connected to the hydraulic oil source, is connected to a supply circuit branched from the hydraulic oil source. Even if there is an internal leak of pressure oil, the supply oil is constantly supplied to each hydraulic motor from the supply circuit, so there is no need to compensate for the internal leak and reduce the supply of hydraulic oil to each hydraulic motor. Does not reduce the rotational speed of each hydraulic motor, so that multiple hydraulic motors can rotate precisely in synchronism with each other and drive the construction machine independently connected to each hydraulic motor at the correct speed. In addition, stable and efficient cutting work can be performed.

In the invention according to the second aspect, in order to accurately adjust the amount of pressure oil supplied to each hydraulic motor, a variable throttle valve provided in a supply circuit may be operated.
This allows the hydraulic motors to be maintained at exactly the same speed as one another.

According to the third aspect of the present invention, the same effects as those of the first aspect of the invention can be exhibited, and the hydraulic motors can be simultaneously driven in the same direction according to the working application of the construction machine. Since it can be driven, each hydraulic motor can be driven independently, or can be immediately switched to one of the operating states, on-site construction can be performed efficiently.

In the invention according to claim 3, both the simultaneous driving of the hydraulic motors in the same direction and the independent driving of any one of the hydraulic motors are both achieved by supplying hydraulic oil from a single hydraulic oil source. The configuration is very simple.

Further, in the invention according to the fourth aspect, there is provided a simultaneous drive circuit for simultaneously driving the respective hydraulic motors in the same direction and a single drive circuit for individually driving one of the hydraulic motors. Since the simultaneous drive / single drive switching circuit has a simple configuration of the simultaneous drive / single drive switching valve and the alternative drive switching valve, it can be manufactured at low cost.

In the invention according to claim 5, in order to accurately adjust the amount of pressure oil supplied to each hydraulic motor, a variable throttle valve provided in a supply circuit may be operated.
In addition, since a check valve and a shut-off valve are interposed in the replenishment circuit, simultaneous driving of each hydraulic motor in the same direction by operating a simultaneous drive / single drive switching valve and independent driving of any one of the hydraulic motors can be performed. Can be achieved by a simple circuit configuration.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram showing one embodiment of the present invention.

FIG. 2 is a hydraulic circuit diagram showing the same operation state.

FIG. 3 is a hydraulic circuit diagram showing another operation state.

FIG. 4 is a hydraulic circuit diagram showing another operation state.

FIG. 5 is an external view of an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 8 Series hydraulic circuit 9 Supply circuit 9 10 Variable throttle valve 11 Check valve 12 Shut-off valve 14 Simultaneous drive circuit 15 Individual drive circuit 16 Simultaneous drive / single drive switching circuit 17 Simultaneous drive / single drive switching valve 18 Pressure oil forward path 19 Pressure oil return path 20 Rotational direction switching valve 21 Outlet circuit 22 Inlet circuit

Claims (5)

[Claims] 1. A construction machine drive mechanism comprising a plurality of hydraulic motors, each hydraulic motor being a drive source of a construction machine, wherein each hydraulic motor is sequentially connected from a hydraulic oil source by a series hydraulic circuit. Except for the hydraulic motor directly connected to the pressure oil source, each hydraulic motor is connected to a supply circuit branched from the pressure oil source, and each hydraulic motor is driven simultaneously in the same direction. Drive mechanism. 2. A drive mechanism for a construction machine according to claim 1, wherein a variable throttle valve for adjusting a supply amount of the pressure oil passing through the supply circuit is interposed in the supply circuit. 3. A construction machine drive mechanism comprising a plurality of hydraulic motors, each hydraulic motor being a drive source of the construction machine, wherein each hydraulic motor is sequentially connected from a hydraulic oil source by a serial hydraulic circuit. Except for the hydraulic motor that is directly connected to the pressure oil source, each hydraulic motor is connected to a supply circuit that branches off from the pressure oil source, and each hydraulic motor is driven simultaneously in the same direction. A drive mechanism for a construction machine having a simultaneous drive / single drive switching circuit for switching to one of a circuit and a single drive circuit in which each hydraulic motor is driven independently. 4. The simultaneous drive / single drive switching circuit comprises a simultaneous drive / single drive switching valve and an alternative drive switching valve for selectively driving one of the hydraulic motors.
The drive mechanism of the construction machine according to the above. 5. A variable throttle valve for adjusting a supply amount of the pressure oil passing through the supply circuit, a check valve for allowing the pressure oil to flow only in one direction, and a flow of the pressure oil on / off. 5. The drive mechanism for a construction machine according to claim 4, wherein the drive mechanism includes a shut-off valve.