JPS63225702A - Brake device of hydraulic motor for construction machine - Google Patents

Abstract

PURPOSE:To perform speed control smoothly, by releasing a brake characteristic nearly at the same time when a hydraulic motor generates pressure by which it can start operation against a load and applying the maximum braking action when pressure oil supply to the hydraulic motor is stopped and in the mean time, applying brake force nearly proportional to the oil pressure. CONSTITUTION:When the oil pressure in a pressure chamber reaches a tank pressure, the maximum brake force is applied to the hydraulic motor 1, and the brake force to the motor 1 is released when the oil pressure in the pressure chamber nearly reaches the pressure for running on a flat ground. The magnitude of this brake force is changed continuously, between the maximum and released conditions according to a change of the oil pressure in the pressure chamber. Furthermore, a changeover valve 3 which can switch the pressure chamber to the tank or the high pressure side of the hydraulic motor 1 has a changeover characteristic which can changeover from a neutral position to a changeover position by low oil pressure which is 1/5-1/10 of the pressure for running on a flat ground. By this constitution, the speed control can be performed smoothly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a brake device for a hydraulic motor of a construction machine, and relates to a brake device used for a hydraulic motor such as a hydraulic motor that drives a crawler in a crawler vehicle, for example. .

[Conventional technology]

As disclosed in Japanese Utility Model Publication No. 56-27415, conventional hydraulic motors have been made smaller by combining a hydraulic motor and a speed reducer to make the output of the hydraulic motor low torque and high rotation. As a result, a part of the reducer and the hydraulic motor are arranged on the same axis so that they partially overlap, thereby achieving a reduction in size in the radial and axial directions. A counterbalance valve and a brake brake for controlling the hydraulic motor are provided in the space created by such miniaturization, and can be housed within the width plate of the crawler. A counterbalance valve was used to control this type of hydraulic motor. That is, when the construction vehicle goes down a slope, the counterbalance valve throttles the outlet side of the hydraulic motor to prevent the construction vehicle from running on its own by hydraulically applying a brake. The counterbalance valve is switched by the oil pressure of the main circuit of the hydraulic motor, and throttles the amount of pressure oil discharged from the main circuit of the hydraulic motor. As a result, surge pressure is generated, making equipment more likely to malfunction, and counterbalance valves resonate with their own inherent vibrations and the circuit's natural vibrations (circuit vibrations due to delays in the transmission of hydraulic pressure within the circuit, etc.) This may cause hunting (pulsation in the rotation speed of the hydraulic motor).

Therefore, a technique shown in FIG. 3 (Utility Model Application Publication No. 122801/1983) was proposed. This technology supplies control pressure oil to a brake device 2 provided in a hydraulic motor 1 via a switching valve 3,
Due to the configuration in which the hydraulic motor 1 is controlled by the braking force of the brake device 2, a counterbalance valve is omitted. The operation of this technique will be explained next. When the directional switching valve 4 is operated from the neutral position 4a to the switching position 4b, pressure oil from the pump P is supplied to the hydraulic motor 1 via the main circuit 5.
The oil pressure in the main circuit 5 corresponds to the load acting on the hydraulic motor. In the case of a crawler for construction machinery, this oil pressure activates an inertial body at startup, so it temporarily rises to the set pressure of the circuit, and then becomes the driving pressure. When driving on flat ground, it is 60~B0Kflf42. On the other hand, the main circuit 6 is connected to the tank T via the directional control valve 4. In this way, a hydraulic pressure difference occurs between the main circuits 5 and 6. This oil pressure difference acts on the switching valve 3 provided between the brake circuit 7 and the main circuit 5% 6. Therefore, the switching valve 3 is switched to the switching position 3b, and the brake circuit 7 is connected to the main circuit 5. As a result, pressure oil from the main circuit 5 flows into the hydraulic chamber 2a of the brake device 2, and the brake shoe 2d of the spring brake 2 is moved from the disc 1a provided on the output shaft of the hydraulic motor, facing the spring 2c of the spring brake 2. then release the brake. Note that the pressure at which the switching valve 3 switches is 17% of the driving pressure for driving on flat ground.
~ It's only a fake.

In the above-described operation, when the construction machine runs on flat ground or on a hill, the changeover valve 3 switches due to the pressure difference between the main circuits 5 and 6, so that the brake is loosened. However, when construction machinery goes down a slope,
The hydraulic motor 1 is self-propelled by the weight of the construction machine, and is driven by this self-propulsion. At this time, the pressure difference in the main circuit 5.6 decreases, and when the applied braking force prevents the construction machine from moving on its own, the oil pressure in the main circuit 5 rises again, and the switching valve 3 shifts to the switching position 3b. As a result, the braking force applied to the hydraulic motor 1 is released.

[Problem that the invention seeks to solve]

Conventional technology uses the brake device 2 to allow self-propulsion when going down a slope.
This is prevented by discharging the pressure oil. Therefore, the braking force applied to the construction machine is applied digitally. If the frequency of vibration caused by the brake action matches the unique frequency of the construction machine, resonance occurs, causing a problem of hunting.

An object of the present invention is to enable smooth control of the speed of a hydraulic motor.

[Means for solving problems]

The means of the present invention provides a hydraulic motor for traveling of a construction machine with a honeyflake device, and this spring brake device is provided with a pressure chamber, and this pressure chamber is connected to the high pressure of the main circuit of the hydraulic motor via a switching valve. In the brake device for a hydraulic motor configured to be connected to the side, the spring brake device applies the maximum braking force to the hydraulic motor when the hydraulic pressure in the pressure chamber reaches the tank pressure, and when the hydraulic pressure in the pressure chamber is approximately equal to the tank pressure. The brake force on the hydraulic motor is released when the level running pressure is reached, and the change in the brake force between the maximum and release changes continuously in accordance with the change in the oil pressure in the pressure chamber. The switching valve is an abbreviation for flat running pressure.
It is characterized by having a switching characteristic of switching from a neutral position to a switching position using a low hydraulic pressure.

[Function] The present invention having the above-mentioned technical means changes the operating pressure of the switching valve disposed between the main circuit of the hydraulic motor and the pressure chamber of the spring brake device to the level running hydraulic pressure. Therefore, when the construction machine starts to run on its own and the hydraulic pressure supplied to the main circuit decreases, the brake force increases accordingly. Furthermore, since the braking force is continuously changed during this pressure increase and decrease, the rotation of the hydraulic motor is smoothly controlled.

〔Example〕

The first embodiment will be explained with reference to FIGS. 1(a), (b), (c), and (d). In the description of the embodiment, the same drawing numerals are used for the same parts as in the prior art shown in FIG.

In FIG. 1(a) showing the circuit diagram of this embodiment, a hydraulic motor l is connected to a pump P and a tank T via a main circuit 5.6 and a directional control valve 4. When each of these is connected to a pump P and a tank T, they are rotated by hydraulic pressure from the pump P. The switching valve 4 has a neutral position 4a and switching positions 4b and 4c.

When this directional control valve 4 is in the neutral position 4a (the position shown), the main circuit 5.6 is connected together to the tank T, and when the directional control valve 4 is operated into the switching position 4b or 4C, the main circuit 5.
．． 6 is connected to the pump P and the other to the tank T.

12 is a first brake device, and 11 is a second brake device. The first brake device 12 has a hydraulic chamber 12a connected to the switching valve 3 via the brake circuit 7. The switching valve 3 has a neutral position 3a and switching positions 3b, 3c, and hydraulic pilot sections 3e, 3f are connected to the main circuit 5.6.

For this reason, the switching valve 3 is configured so that the hydraulic pressure difference acting on the hydraulic pilot parts 3e and 3f is a constant value P2 (14 to 1/7 of the running pressure).
), the switch is switched to either the switching position 3b or 3C.

In the second brake device 11, a brake circuit 73 branched from the brake circuit 7 is connected to the pressure chamber 11a,
The brake circuit 7.73 is connected to the tank T when the switching valve 3 is in the neutral position 3a. Note that the spring chambers 12b and llb of the first and second brake devices 12.11 are always connected to the spring T.

Brake force of the first brake device 12 (brake torque F
Kg-m) and the pressure in the hydraulic chamber 12a (PK7f/, 2)
As shown by curve A in FIG. 1(e), when the oil pressure in the pressure chamber 12a reaches approximately the level running pressure P3,
Become completely relaxed. The brake torque F has a value approximately proportional to the pressure P from the maximum brake torque F to complete release. Furthermore, the brake torque F and the stroke S ms of the piston member of the first brake device 12 (the amount of oil in the pressure chamber 12a)
As shown in the straight line A' in Fig. 1(d), as the stroke increases (the amount of oil supplied to the pressure chamber 12a increases), the brake torque F decreases along the straight line A'. do.

In the first brake device 12 having such characteristics, the hydraulic motor 1 acts as a pump when the construction machine goes down a slope, so that the pressure difference in its main circuit is reduced.

Due to this reduction in pressure difference in the main circuit, the first brake device 1
The oil pressure in the second pressure chamber 12a also decreases, and at the same time the stroke of the piston member of the first brake device 12 decreases.
The brake torque F increases, and the free movement of the hydraulic motor 1 is restricted. When the free movement of the hydraulic motor 1 is restricted, the main circuit 5
．． 6 increases, main circuit pressure oil is supplied to the hydraulic chamber 12a of the first spring brake device 12, the stroke S of the piston member increases, and the brake torque F decreases.

Therefore, the braking force applied to the hydraulic motor 1 is relaxed. In this way, the self-propulsion of the hydraulic motor 1 is controlled to an appropriate speed.

The relationship between the brake torque F and the pressure P of the second brake device 11 is such that it changes more rapidly than the characteristic curve A of the first brake device 12, as shown by the straight line in FIG. 1(c). In addition, the brake torque F and the second play device 1
The relationship with the stroke S of the piston member No. 1 is shown in Fig. 1 (
As shown in the straight line opening d), the brake is released almost at the same time as the piston member strokes.

As is clear from the characteristics of the second brake device 11 having such characteristics, the pressure in the main circuit 5 or 6 is P2.
When the brake pedal goes higher, it is released almost at the same time, and when it goes lower, the maximum brake torque is obtained almost at the same time.
It is equipped with a parking brake.

Furthermore, since the brake device 12 having the above-mentioned characteristics replaces a brake device using hydraulic pressure of a counterbalance valve, its maximum brake torque is capable of absorbing inertia acting on a hydraulic motor of a construction machine, etc. As will be described later, it has a structure that can withstand continuous use. On the other hand, the second brake device 11 is used as a parking brake device. That is, since no driving force due to inertia is acting on the hydraulic motor 1 and it is used for parking the hydraulic motor 1, it is not necessary to withstand continuous use, and it is smaller than the first brake device. Anything is fine.

Figure 1(b) C. First and second brake devices 12.11
1 is a cross-sectional view of a hydraulic motor with a reduction gear for driving a crawler of a crawler vehicle, in which a hydraulic motor 1 having a structure shown in FIG. 1 is combined with a reduction gear 20, and this structure will be described below.

1), the reducer 20 includes a hub 21 to which a crawler drive sprocket is attached, and a
an internal gear 22 provided on the rotary shaft 3 of the hydraulic motor l;
an external gear 23 that is supported by an eccentric shaft 28 driven by an eccentric shaft 28 via a bearing and meshes with the internal gear 22;
carrier pin 24 held by a plate 25 fixed to
It consists of Note that the eccentric shaft 28 is supported by a bearing between the plate 25 and a lid 28 provided at the end of the hub 21. The plate 25 is fixed to the housing 35 of the hydraulic motor 1 with bolts 26 and is attached to the housing 35.
Positioning is done by a spigot part 27 provided in the.

The hydraulic motor l is provided with a rotary shaft 37 formed integrally with the eccentric shaft 28 of the speed reducer 20 passing through an inner hole 39 of the housing 35 . A cylinder block 4° having a plurality of cylinders 41 is connected to this rotating shaft 37 by a spline 42. A shoe 43 is provided at the tip of the cylinder 41, and this shoe 43 is attached to the swash plate 44.
It comes into contact with the sliding surface 45 of. A valve plate 47 is provided between the cylinder block 40 and a rear cover 46 provided on the housing 35. Further, the swash plate 44 is provided with a tilting cylinder device 48 above and a fulcrum 49 below.
, the angle of the sliding surface 45 relative to the sliding surface 45 is changed. A stopper 50 is provided in the inner hole 39 of the housing 35, and the upper end 44a of the swash plate 44 comes into contact with the stopper. That is, the swash plate 44 is tilted by the operation of the tilt cylinder device 48 to a position where its upper end 44a abuts the stopper 59.

The first brake device 12 is provided within the rear cover 46 of the housing 35. This first brake device 12 includes a rear lid 46
A piston member 53 is provided in the inner hole 51 of the piston/member 53, and the piston/member 53 and the inner hole 51 form a pressure chamber 12a and a spring chamber 12b. The spring 120 is inserted into the recess 54 provided in the piston member 53, and the spring 120 is inserted into the spring chamber 12b.
It connects. This inner hole 39 is connected to the drain boat D.
Since the spring chamber 12b is connected to the tank T through the spring chamber 12b, the spring chamber 12b is always connected to the tank T. In the figure, 84 and 85 are brake discs. This brake disc 84 is attached to the rear cover 46
It is engaged with the rear lid 46 by a spline 56 provided at the rear lid 46, and is movable in the axial direction.

The brake disc 85 is engaged with the rotating shaft 37 through a spline 57 provided on the rotating shaft 37, and is movable in the axial direction. A plurality of brake discs 84 and 85 are provided alternately. The rear end of this brake disc 84 is in contact with the piston member 53,
The front end has a rear cover 4 facing the piston member 53.
The ring 60 is in contact with a ring 60 which receives a pressing force from a spring 59 installed in a recessed hole 58 provided in the ring 6 . That is, the brake discs 85 and 84 are arranged alternately, and the brake discs 84 are arranged at both ends of the alternately arranged brake disc bodies.

The second brake device 11 is provided in the housing 35. A large-diameter inner hole 62 having a larger diameter than the inner hole 39, and this large-diameter inner hole 6
a piston member 66 having a large diameter portion 64 and a medium diameter portion 65 that are slidably fitted into a medium diameter inner hole 63 having a smaller diameter than the inner hole 39 and a diameter larger than the inner hole 39; Medium diameter inner hole 63
The brake disc 68 is connected to the cylinder block 40 by a spline 67 installed in the cylinder block 40 and is movable in the axial direction.

The piston member 66 has a bottle 7 inserted into both a recess 69 of the rear lid 46 and a recess 70 provided in the piston/member 66.
1 is connected to the rear cover 46 so as not to rotate.

A pressure chamber 11 a communicates with the recess 70 via a throttle 72 .

Further, the pressure chamber 12a of the first brake device 12 is located in the recess 69.
are communicated via passage 73. The pin 71 has a passage 74 inside thereof. Therefore, pressure chamber 1
1a rises and falls at the same time as the pressure in the pressure chamber 12a.

Although the piston member 66 is not shown, a spring 12e (shown in FIG. 1(a)) is provided between the rear lid 46 and the piston member 66. A chamber 11b is formed, and this spring chamber 11b communicates from the drain port D to the tank T.

Next, the operation of the first embodiment will be explained. Figure 1(a)
When the directional switching valve 4 is operated to the switching position 4b, the pump P is connected to the main circuit 5 via the load check valve C while the unload circuit is cut off, and the main circuit 6 is connected to the tank T. Ru. Therefore, pressure oil is supplied to the hydraulic motor 1. The pressure of this pressure oil increases in accordance with the load acting on the hydraulic motor l. For example, when driving on flat ground it is 60-7.
It becomes 0Kg/cm2. When the oil pressure in the main circuit 5 increases,
The pressure difference between the main circuit 6 and the main circuit 6 increases. This pressure difference is 1
When the temperature reaches approximately 0 to 15"f/cIn2 (P2), the switching valve 3 switches to the switching position 3b. Therefore, the main circuit 5 is connected to both the hydraulic chambers 12a%ll& of the first and second brake devices 12.11. Pressure oil acts via the brake circuit 7.73.By means of this oil pressure, the second brake device 11 is released as shown in its characteristic diagram.However, the first brake device 12 does not brake the hydraulic motor 1. In addition, the hydraulic motor 1 does not start when the pressure difference (pressure in the main circuit 5) is around P2. Therefore, the oil pressure in the main circuit 5 increases, and the pressure corresponding to the load acting on the hydraulic motor 1 increases. When the pressure reaches P3, it starts to start.Since this pressure drives the inertial body, it is higher than the running pressure P3.When this hydraulic pressure acts on the hydraulic chamber 12a of the first brake device 12, the brake force is completely relieved. and the hydraulic motor l starts operating.

The above-mentioned effects apply when the construction machine runs on level ground. Furthermore, when the construction machine climbs a slope, the oil pressure in the main circuit 5 increases by the amount required to climb the slope, similar to the above-described case of running on flat ground. However, when the construction machine goes down a slope, the hydraulic motor 1 is driven by the weight of the construction machine. Therefore, the oil pressure in the main circuit 5 begins to decrease. In response to this decrease in oil pressure, the pressure in the hydraulic chambers 12a111a of the first and second brake devices 12.11 decreases. This decrease in pressure causes the first brake device 12 to apply a brake to the hydraulic motor 1 in accordance with the decrease in pressure, as shown by straight line A in FIG. 1(c). Note that when the hydraulic motor l is driven,
Since the first brake device 12 is activated, the oil pressure in the main circuit 5.6 does not drop to the extent that the second brake device 11 is activated.

Next, when the work on the construction machine is finished and the directional switching valve 4 is returned to the neutral position 4a, the main circuit 5.6 is connected to the tank T, so the switching valve 3 returns to the neutral position 3a, and the first brake 12. The oil pressure in the pressure chamber 12, ll& of 11 becomes the evening pressure. For this reason, the hydraulic motor 1 has a first motor. A braking force from the second brake device 12.11 is applied, causing the construction machine to knock.

The above is a circuit description based on FIG. 1(a).

Next, the operation will be explained based on FIG. 1(b). When the directional control valve 4 shown in FIG. Or it switches to 3C and pressure oil is supplied to the brake circuit 7.73.

The pressure oil supplied to the main circuit 5 is transferred from the valve plate 47 to the cylinder via a passage in the rear lid 46 (not shown, but a passage connected to the main circuit 5.6 is provided in the rear lid 46). Approximately half of the cylinders 41 of the block 40 are supplied, and the other approximately half of the cylinders 41 are connected to the main circuit 6 through a valve plate 47 .

Pressure oil from the switching valve 3 passes through the passage 7 of the rear cover 46 to the first
It acts on the hydraulic chamber 12a of the brake device 12, and simultaneously acts on the hydraulic chamber 11a of the second brake device 11 via the passage 73. Therefore, as described above, when the oil pressure in the main circuit 5 reaches the predetermined oil pressure P3, the first and second pressure devices 1
2.11 brake is released and cylinder block 40
is rotated by the reaction force of the piston 41a. Hydraulic motor 1
The rotation is performed by an eccentric shaft 28 formed integrally with the rotation shaft 37.
transmitted to. Since the eccentric shaft 28 causes the external gear 23 to revolve, the knob 21 rotates.

In the above-described operation, when the construction machine starts to run on its own, a load acts on the reducer 20 in the same direction as the rotational direction of the hydraulic motor, so that rotational force is applied to the hydraulic motor l. Therefore, the oil pressure in the main circuit 5 decreases. This decrease in oil pressure causes the first
, hydraulic chamber '2 a, 11 of the second brake device 12.11
The oil pressure at a also decreases. If this reduction has not reached the predetermined value P2, the second braking device 11 remains relaxed. However, the second brake device 12 causes the pressing force of the spring 120 to act on the brake disc 54.55 via the piston member 53, and the spring 59 acts against this pressing force.
The pressing force acts through the ring 60. Therefore, even if the amount of oil in the pressure chamber 12a of the first brake device 12 decreases, the braking force gradually decreases. Furthermore, by using a plurality of brake discs 84 and 85, the brake torque is increased. Therefore, when construction machinery begins to run on its own,
The self-propulsion is prevented by the decrease of the oil pressure in the main circuit 5 or 6, which applies a brake to the hydraulic motor 1 accordingly.

Next, when the directional switching valve 4 is operated to the neutral position, the main circuit 5.6 is connected to the tank T, so that the switching valve 3 returns to the neutral position 3a. By returning the switching valve 3 to the neutral position 3a, the brake circuit 7 is connected to the tank T, so that the first and second brake devices 12.11
apply the brakes.

Next, a second embodiment will be explained with reference to FIG.

In this embodiment, the first embodiment has the first and second brake devices 1 and 1.
2.11 is controlled by one switching valve 3, whereas the first
The difference is that the second brake device 12.11 is controlled by each of the switching valves 3.13.

The operation of this embodiment is almost the same as that of the first embodiment. That is, when the directional switching valve 4 is operated to any switching position, a pressure difference is generated between the main circuits 5.6, and the switching valve 3.13 is actuated by this pressure difference. This switching valve 3.13
When the main circuit is activated, the first and second brake devices 12.11
The brake force applied to the hydraulic motor 1 is released. When the hydraulic motor 1 enters a self-propelled state while being driven, the oil pressure in the main circuit 5.6 decreases, so the first brake device 12 applies a braking force to the hydraulic motor 1. Therefore, the self-propulsion of the hydraulic motor 1 is controlled to an appropriate speed.

Although the characteristics (pressure-brake torque characteristics) of the first brake device 12 are shown in FIG. 1(c), the characteristics are not limited to those shown in FIG. It may be something like the one shown.

Hereinafter, the first brake device 12e having this characteristic will be described in FIG.
This is explained by e).

The position of the first brake device 12e shown in FIG. 1(e) is as follows:
This shows a state in which pressure oil is supplied to the pressure chamber 12a, the piston member 53 is in contact with the rear cover 46a, and the brake is released. That is, when the piston/member 53 is in the position shown in FIG. 1(e), the pressure chamber 12
The oil pressure of a is P3Kg/cfn2 (60~80”/,
, p (hydraulic pressure when traveling on flat ground), and the braking force is O as shown in FIG. 1(f).

Now, as described above, when driving on a flat road, the directional control valve 4
When it is operated to the neutral position, supply and discharge of pressure oil to the hydraulic motor 1 is cut off, and the main circuit 5.6 is connected to the tank T, so that the oil pressure in the pressure chamber 12a also decreases.

Then, the piston member 53 is pressed by the spring 12C and presses the brake disc 84%85. ring 6 at the same time
0, the pressing force of spring 59 acts against spring 120. (The pressing force of the spring 59 is set to a value weaker than that of the spring 12c.) At this time, a braking force corresponding to the pressing force of the spring 59 acts on the rotating shaft 37. The distance between this ring 60 and the inner end 61 of the casing 46 is ΔL. In addition, the brake circuit 7e that connects the pressure chamber 12a and the main circuits 5 and 6 has a throttle υ12d (this throttle,
912d may be configured as a check valve seal, as shown in FIG. 1(e). ) is provided. Therefore, main circuit 5.
6 is connected to the tank T, and a braking force corresponding to the pressing force of the spring 59 is applied until the ring 60 hits the inner end 61 of the casing. In other words, in FIG. 1(f),
A braking force shown by the curve (A") acts on the shaft 37.

Next, when the ring 60 comes into contact with the end 61 of the casing, a braking force corresponding to the pressing force of the spring 12c (braking force of the mouth Y' acts on the shaft 37. 1 According to the brake device 12e, FIG. 1(f)
As shown in , a weak brake of 1 is applied for time t1,
After that, as shown in (), a large braking force (corresponding to parking brake force) is applied.

As described above, the first brake device 12e has two parts: a dynamic brake part shown by diagonal lines (c) in FIG. 1(f), and a static brake part shown by (b) ". It also has the function of a second brake device. Therefore, if necessary, please refer to Figure 1 (a)
), in the embodiment shown in FIG.
1 may be omitted.

〔Effect of the invention〕

As explained above, the present invention is configured to control the self-propulsion of a hydraulic motor using a brake device, and the characteristics of this brake device are adjusted almost immediately when the hydraulic motor reaches a pressure for starting a load. When the brake is released and the supply of pressure oil to the hydraulic motor is stopped, the maximum braking force is generated and the braking force is approximately proportional to the hydraulic pressure during that time, so the speed of the hydraulic motor can be controlled smoothly. It has the effect of

[Brief explanation of drawings]

FIG. 1(a) is a hydraulic circuit diagram of the first embodiment of the present invention, FIG. Torque characteristic diagram,
Figure 1(d) shows the stroke of the brake device of the same example.
Brake torque characteristic diagram, FIG. 1(e) is an enlarged cross-sectional view of the main part of another embodiment with different characteristics of the first brake device, and FIG. 1(f) is a diagram of other embodiments shown in FIG. 1(e). A pressure (and time)-brake torque characteristic diagram of the first brake device 12e of the embodiment, FIG. 2 is a hydraulic circuit diagram of the second embodiment of the present invention, and FIG. 3 is a hydraulic pressure of the brake device of a conventional hydraulic motor. It is a circuit diagram. l...Hydraulic motor, 3.13...Switching valve, 5.6.
...Main circuit, 11...Second brake device (spring brake device), 12.12e...First brake device (spring brake device), T...Event/return.

Claims (1)

[Claims] (1) A spring brake device is provided on the hydraulic motor for traveling of the construction machine, and this spring brake device is provided with a pressure chamber, and this pressure chamber is connected to a tank or the high pressure side of the main circuit of the hydraulic motor via a switching valve. In the brake device for a hydraulic motor configured as above, the spring brake device applies the maximum braking force to the hydraulic motor when the hydraulic pressure in the pressure chamber reaches the tank pressure, and the spring brake device applies the maximum braking force to the hydraulic motor when the hydraulic pressure in the pressure chamber reaches approximately the level running pressure. The brake force applied to the hydraulic motor is released when the brake force is reached, and the change in the brake force between the maximum and release changes continuously in accordance with the change in the oil pressure in the pressure chamber. The switching valve is approximately 1/5 to 1/1 of the level running pressure.
1. A brake device for a hydraulic motor for driving a construction machine, characterized in that the brake device has a switching characteristic of switching from a neutral position to a switching position with a low oil pressure of 0.