JP2583758Y2 - Crane parking brake device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile crane having a parking brake only on a rear wheel, and more particularly to a parking brake device for a mobile crane.

[0002]

2. Description of the Related Art FIG. 1 shows a crane truck.
A telescopic boom 2 is attached to the body 1 so as to be able to move up and down, and a first shaft 3, a second shaft 4, a third shaft 5, and a fourth shaft 6 are provided sequentially from the front of the body 1. In the normal running, the third shaft 5 and the fourth shaft 6 are driven to perform so-called rear-wheel drive running. When the vehicle escapes from a soft ground, a front clutch (not shown) is connected so that the first shaft 3 and the second shaft 4 can be driven at the same time. ing.

The first shaft 3 and the second shaft 4 have front wheels 7,
7, 7, 7 are attached, and the rear wheels 8, 8, 8, 8 are attached to the third shaft 5 and the fourth shaft. Although not shown, an air-hydraulic conversion type disc brake is mounted on the front wheel 7 and a drum brake is mounted on the rear wheel 8. The drum brake of the rear wheel 8 has a built-in spring and is used as a parking brake.

Further, outrigger jacks 9, 9 and 10, 10 are provided on both left and right sides of the machine body 1 to improve the stability of the machine body during crane work. In the case of work on an inclined ground as shown in FIG. 2, the extension of the front and rear outrigger jacks 9 and 10 is made different, and the body 1 is kept horizontal.

[0005]

[Problems to be solved by the invention] Conventional crane trucks
Only the rear wheel 8 is provided with a parking brake. Therefore,
On a slope as shown in FIG. 2, when the front outrigger jack 9 is contracted first and the front wheel 7 is grounded,
Since the brake is not applied to the front wheel 7, the body 1 is supported only by the rear outrigger jack 10. Therefore, when the front wheel 7 rotates freely, the support of the rear outrigger jack 10 is released, and there is a risk that the aircraft 1 may run backward.

In order to prevent such a danger, it is conceivable to mount a spring-type drum brake on the front wheel 7, but there is a problem that the braking force during traveling is lower than that of the disk brake. It is also possible to provide a parking brake in the middle of the drive system of the front wheels 7, for example, at the front propeller shaft, but it requires a dedicated brake device, which is expensive.

Therefore, when a crane vehicle having a parking brake on only the rear wheels is parked, there is a technical problem to be solved in order to apply a braking force to the front wheels and to improve safety. Therefore, the present invention aims to solve this problem.

[0008]

SUMMARY OF THE INVENTION The present invention has been proposed in order to achieve the above-mentioned object, and in a crane vehicle having a parking brake only on the rear wheel, a circuit opened and closed by a service brake valve is provided. A circuit that opens and closes with a solenoid valve is provided, both circuits are connected to a circuit that operates the front brake by a shuttle valve, a means for operating the solenoid valve is provided with a front brake switch and an indicator lamp, and the solenoid valve is opened. When the front brake is activated ,
Alternatively, the service brake valve is opened and the front
An object of the present invention is to provide a parking brake device for a crane truck configured to turn on an indicator lamp when a brake is actuated .

[0009]

After the crane work on the slope is completed, the front brake switch is turned on before the front outrigger jack is contracted to ground the front wheels. When this is the case, the solenoid valve is opened and pressure is led via the shuttle valve to the circuit that activates the front brake. Therefore, the front wheel is also braked.

Therefore, even when only the front wheels are grounded while the rear wheels are floating above the ground, the front wheels do not rotate freely and the body can be prevented from escaping.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a crane truck, and a description overlapping with that of the prior art will be omitted. FIG. 3 shows a drive system for the front wheels 7 and the rear wheels 8, wherein the power of the engine 11 is shifted by the transmission 12 and distributed to the front and rear by the transfer 13.
During normal traveling, the front clutches 14 and 15 are disengaged, and the transfer propeller shaft 1
Power is transmitted to the third shaft 5 and the fourth shaft 6 via the drive shaft 6 to drive the left and right rear wheels 8,8,8,8.

On the other hand, when the crane vehicle escapes from a soft ground, the front clutches 14 and 15 are engaged, and the second shaft 4 and the first shaft 4 are transferred from the transfer 13 via the front propeller shafts 17 and 18. 3 is transmitted to drive the left and right front wheels 7, 7, 7, 7. Thus, both the front wheel 7 and the rear wheel 8 are driven and can easily escape from a soft ground. Air hydraulic pressure conversion type disc brakes 19 and 20 are mounted on the first shaft 3 and the second shaft 4, respectively, to enhance the braking force during traveling, and to improve the third shaft 5 and the fourth shaft 4. Drum brakes 21 and 22 are mounted on the shaft 6, respectively. A spring is built in the drum brakes 21 and 22 and used as a parking brake.

FIG. 4 shows an air circuit of the brake device, in which high-pressure air generated by an air compressor 23 is distributed by a distribution valve 24 and air tanks 25, 26, 27, 28,
Is stored in An air circuit 30 opened and closed by a service brake valve 29 from an air tank 25 and an air circuit 32 opened and closed by an electromagnetic valve 31 are provided in a branched manner. Both air circuits 30 and 32 are connected to one front brake via a shuttle valve 33. Is connected to an air circuit 34 for operating the. The air circuit 34 is provided with an air booster 35 and a pressure switch 36.

Similarly, an air circuit 37 opened and closed by the service brake valve 29 from the air tank 26.
And an air circuit 39 which is opened and closed by an electromagnetic valve 38 is provided in a branched manner.
0 is connected to an air circuit 41 for operating the other front brake. The air circuit 41 is provided with an air booster 42 and a pressure switch 43.

When the service brake valve 29 is depressed to stop the body 1 during traveling of the crane truck, at this time, the spools of the solenoid valves 31 and 38 are respectively 31a and 3a.
8a, the air tank 2 is in the closed state.
The air of 5 and 26 passes through the service brake valve 29 and is led out to the air circuits 30 and 37. Here, the solenoid valve 3
Shuttle valves 33, 40 are closed because 1, 38 are closed.
As a result, the air in the air circuits 30 and 37 is selected to have a high pressure and is introduced into the air circuits 34 and 41 to pressurize the air boosters 35 and 42 so that the disc brake cylinder 44 provided on the first shaft 3 and the second shaft 4 The pressure oil is led out to the disc brake cylinder 45 provided at the, and the disc brakes 19, 20 of the front wheels 7, 7 operate.

At the same time, the air in the air circuits 34 and 41 is led out to the pilot port 46a of the relay valve 46. In that case, an air secondary pressure equal to the pilot pressure is applied to the air chamber 47 of the brake chamber 47 provided on the third shaft 5.
a, and is led out to an air chamber 48a of a brake chamber 48 provided on the fourth shaft 6, and the other relay valve 4
9 is also led out to the pilot port 49a. Air chamber 47a of brake chamber 47 and brake chamber 4
When the air is drawn into the air chamber 48a of the rear wheel 8, the brake shoe is pressed against the drum, and the drum brakes 2 of the rear wheels 8, 8 are driven.
1 and 22 operate.

When the other relay valve 49 operates, a secondary pressure equal to the pilot pressure is applied to the brake chamber 4.
7 and an air chamber 48b of the brake chamber 48, and the parking spring 47 built therein.
The spring pressures of c and 48c are reduced to prevent the wedge mechanisms of the drum brakes 21 and 22 from being overloaded. Note that reference numeral 50
Is a parking brake valve, and 51 is a pressure switch.

FIG. 5 shows an electric circuit of the brake device. A front brake switch 52 and a front brake indicator lamp 53 provided in a cab are connected in parallel. The solenoid 31c of the solenoid valve 31 of the air circuit is connected in series to the front brake switch 52.
The solenoid 38c of the solenoid valve 38 is connected in parallel with 1c. Further, a contact of a pressure switch 36 of an air circuit is connected in series to the front brake display lamp 53, and a contact of a pressure switch 43 is connected in parallel with the contact of the pressure switch 36.

FIG. 6 shows a control box for operating the outrigger jack. In addition to the control switches 54 of the front and rear outrigger jacks 9 and 10 shown in FIG. When the parking brake valve 50 shown in FIG. 4 is operated to hold the machine body 1 in a stopped state when the crane truck stops, the air pressure of the pilot port 49a of the relay valve 49 decreases, and the brake chambers 47, 48 The air in the respective air chambers 47b and 48b escapes. The spring 47 built in the brake chambers 47 and 48
drum brakes 21 and 22 by the spring pressures of c and 48c.
Operates, and the brakes are applied to the rear wheels 8,8.

At this time, when the front brake switch 52 is turned on, the solenoids 31c and 38c are turned on, and the spool of the solenoid valve 31 moves from the position of 31a to 31b.
And the spool of the solenoid valve 38 switches from the position 38a to the position 38b. Since the service brake valve 29 is not depressed because the vehicle is parked, the air in the air tanks 25 and 26 is supplied to the air circuits 32 and 3.
9 is derived. Now, since the solenoid valves 31 and 38 are opened and the service brake valve 29 is not operated, the air circuit 3 is controlled by the shuttle valves 33 and 40.
The high pressure of the air 2, 39 is selected and introduced into the air circuits 34, 41, and the air boosters 35, 42 are pressurized to release the pressure oil to the disk brake cylinders 44, 45,
The disc brakes 19, 20 of the front wheels 7, 7 operate.

When the crane truck is parked, the rear wheels 8, 8
And the disc brakes 19 and 20 of the front wheels 7, 7 are also operated at the same time,
The body 1 surely holds the stopped state. Since air is led out to the air circuits 34 and 41, the pressure switches 36 and
43 is turned on, the respective contacts connected to the front brake display lamp 53 shown in FIG. 5 are turned on, the front brake display lamp 53 is lit, and the disc brakes 19, 20 of the front wheels 7, 7 are in the operating state. Inform. still,
Even when only one of the disc brakes 19 or 20 is operated, a sufficient braking force can be obtained.
When one of the pressure switches 36 or 43 is turned on, the front brake display lamp 53 is illuminated.

Thus, when performing a crane operation on a slope as shown in FIG. 2, the parking brake valve 50 is operated and the front brake switch 52 is operated.
Turn on. At that time, the brakes are applied to all the front wheels 7 and the rear wheels 8. Therefore, even if the front outrigger jack 9 is contracted first and the front wheel 7 is brought into contact with the ground after the crane operation is completed, the front wheel 7 can rotate freely because the braking force is applied to the front wheel 7. Not,
The body 1 is stably supported by the front wheels 7 and the outrigger jack 10 at the rear.

The present invention can be variously modified without departing from the spirit of the present invention, and it goes without saying that the present invention extends to the modified one.

[0024]

According to the present invention, as described in detail in the above-described embodiment, when a front brake switch is turned on when a crane vehicle having a parking brake on only the rear wheels is parked, the front wheels are also controlled. The power works and can be confirmed by turning on the display lamp. Therefore, when the outrigger jack is contracted after performing the crane work on the slope, the front wheel does not rotate freely when the ground touches the ground, and there is no danger of the aircraft being stably supported and escaping.

Also, since a simple configuration is provided without newly providing a dedicated brake device, safety can be improved at low cost.

[Brief description of the drawings]

FIG. 1 is a side view of a crane truck.

FIG. 2 is a side view of the crane on a slope.

FIG. 3 is an explanatory diagram showing a drive system for front wheels and rear wheels.

FIG. 4 is an air circuit diagram of the brake device.

FIG. 5 is an electric circuit diagram of the brake device.

FIG. 6 is a front view of a control box for operating an outrigger jack.

[Explanation of symbols]

 7 Front wheel 8 Rear wheel 19,20 Disc brake 21,22 Drum brake 29 Service brake valve 30,32,34 Air circuit 31,38 Solenoid valve 33,40 Shuttle valve 37,39,41 Air circuit 52 Front brake switch 53 Front brake Indicator lamp

Claims (1)

(57) [Scope of request for utility model registration] 1. A crane vehicle equipped with a parking brake only on the rear wheels, a circuit for opening and closing by a service brake valve and a circuit for opening and closing by a solenoid valve are provided. A front brake switch and an indicator lamp are provided on the means for operating the solenoid valve connected by a valve, and when the solenoid valve is opened and the front brake is actuated ,
When the key valve is released and the front brake is activated
Parking brake system of the crane truck tree which is characterized by being configured such that the display lamp is turned on.