JPH053519Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a brake device that is capable of switching to a manual brake in a construction machine or the like equipped with a hydraulically assisted brake.

[Prior Art] For example, when braking a winch drum in a large crane or the like, a manual brake using pedal force not only requires a large pedal force when carrying a heavy load, but also cannot hold the load stably. Therefore,
As shown in Fig. 3, when the foot brake a is depressed, the pressure reducing valve d is operated via the rod b and lever c, and the pressure oil discharged from the pressure reducing valve d causes the piston f of the assist cylinder e to protrude and link The brake band g is configured to tighten the drum h via the brake band g and the rod.

As a result, the pressure reducing valve d and the assist cylinder e
This combination doubles the pedal effort, making it possible to stably brake a heavy load with a light pedal effort.

[Problem that the invention aims to solve] However, although this kind of assist brake is good for heavy loads, it does not convey the feeling of braking when the load is light, so even a slight pedal force may cause the brakes to fail. There are problems such as being too powerful and receiving shocks.

[Means for Solving the Problems] The present invention was made with the purpose of solving the above-mentioned problems and enabling easy, safe, and reliable braking for both heavy loads and light loads. It comprises a brake band 2 for braking the rotatable drum 1, a lever 3 whose intermediate portion is pivotally supported by a fixed object 36 and whose one end is connected to the brake band 2, and a rotatably supported shaft. 6, a lever 7 whose intermediate portion is fixed to the shaft 6 and whose one end is connected to the other end of the lever 3 via a link rod 9;
An assist cylinder 25 with a piston rod 27 connected to the other end of the lever 7, and a pair of levers 12, 1 which have arm portions 15, 16 at one end and leg portions 13, 18 at the other end and are arranged opposite to each other.
X-shaped paired lever 3 with 3 pivoted at its intermediate portion
7, a pressure reducing valve 17 provided so that the spool 33 is switched to the communicating position when the arms 15 and 16 of the X-type pair lever 37 approach, and one end of which is fixed to the shaft 6 and the other end of which is a link rod. A lever 8 is connected to the leg portion 13 of the lever 11 via a lever 14, a brake pedal 19 is fixed to a rotating shaft 20, and one end is fixed to the rotating shaft 20 and the other end is connected to the lever 11 via a link rod 22. A lever 21 connected to the leg portion 18 of the lever 12 and a switching valve 24
The present invention relates to a brake device for a construction machine or the like, characterized in that it has a conduit 23 that connects the pressure reducing valve 17 and the assist cylinder 25.

[Function] When the load is heavy, the switching valve can be manually switched to apply braking via the assist brake, and when the load is light, the switching valve can be switched to directly apply manual braking using pedal force without using the assist brake. can be braked.

[Example] Hereinafter, an example of the present invention will be described based on the drawings.

Figures 1 and 2 are an embodiment of the present invention,
A brake band 2 arranged to be wrapped around a rotatable drum 1 can be tightened and loosened by a lever 3, and a lever 7 is attached to a shaft 6 whose both ends are rotatably supported by brackets 4 and 5. 8 are fixed to each other so that one lever 7 is parallel to the middle part and the other lever 8 is fixed to the end part, and the end part of the lever 7 on the side where the other lever 8 is located and the end part of the lever 3 are fixed to each other. are connected by a link rod 9.

The end of the lever 8 and the leg 13 of one lever 11 of the pair of levers 11, 12 which are pivotally connected in an X-shape by a pin 10 are connected by a link rod 14, and the arms of the pair of levers 11, 12 are connected by a link rod 14. Part 15,
A pressure reducing valve 17 between 16 and 16 is provided, and a leg 18 of the lever 12 and a lever 21 fixed to a rotating shaft 20 of a foot brake pedal 19 are connected by a link rod 22. The pressure reducing valve 17 can be operated by opening and closing 15 and 16.

One end of the pipe line 23 is connected to the discharge hole of the pressure reducing valve 17, and the other end of the pipe line 23 is connected to the piston head 26 side of the assist cylinder 25. A switching valve 24 is connected to the end opposite to the side to which the link rod 9 is connected, and is further provided in the middle of the pipe line 23.
is provided, and the pressure reducing valve 1 of the pipe line 23 is manually switched.
The assist cylinder 25 side can be opened while the 7 side can be shut off.

In the figure, 28 is the spool of the pressure reducing valve 17, 29 is the pressure side oil pipe of the pressure reducing valve 17, 30 is the return oil pipe of the pressure reducing valve, 31 is the link rod, 32 is the spring, 3
5 indicates a spacer.

With the above configuration, in the case of heavy loads,
When the switching valve 24 is manually switched as shown in FIG. 2, by lightly stepping on the foot brake pedal 19, the lever 21 rotates together with the rotating shaft 20, and the link rod 22 moves in the direction of the pedal 19 (in the direction of the arrow). Move, a pair of X-shaped levers 1
The leg portions 13 and 18 of No. 1 and 12 open, the arm portions 15 and 16 close, and the spool 33 of the pressure reducing valve 17 opens.
is pushed in, the pressure reducing valve 17 is switched from the state shown in FIG.
3 to the piston head 26 of the assist cylinder 25, the piston rod 27 is projected, the lever 7 rotates together with the shaft 6, the link rod 9 moves toward the assist cylinder 25, and the brake band 2 is wrapped around the drum 1. It is tightened.

As a result, strong braking force can be obtained with a small amount of pedal effort.

In the case of a light load, if the switching valve 24 is manually switched from the position shown in FIG. 2, the pressure oil supplied from the pressure reducing valve 17 to the assist cylinder 25 will be cut off, and even if the pressure reducing valve 17 is switched from the position shown in FIG. 27 is not outstanding. Therefore, when the foot brake pedal 17 is depressed, the link rod 22 moves in the direction of the arrow as described above, and the leg 1 of the lever 12
8 rotates around the pin 10 in the opening direction, the arm portion 16 of the lever 12 rotates in the opening direction, and the spool 33 is pushed in, but the link rod 31 and the spacer 35 become fixed at a certain pushing amount. By increasing the pedaling force, the entire pressure reducing valve 17 rotates counterclockwise in FIG. 1, and the arm portion 15 and leg portion 13 of the other lever 11 also rotate in the same direction. The link rod 14 connected to the leg portion 13 is also on the foot brake pedal 19 side (in the direction of the arrow)
The lever 8, shaft 6, and lever 7 rotate together to tighten the brake band 2 around the drum 1. At this time, the oil in the assist cylinder 25 returns to the oil tank 34 via the switching valve 24 switched from FIG. 2, and the piston rod 27 of the assist cylinder 25 can be pushed.

Thereby, braking force can be applied directly by the pedal force of the foot brake pedal 19 without going through the assist cylinder 25.

It should be noted that the brake device of the present invention is not limited to the above-described embodiments, and it goes without saying that various changes can be made without departing from the gist of the present invention.

[Effects of the invention] As explained above, according to the brake device of the invention, the assist brake and manual brake are switchable, so when the load is heavy, the assist brake can be used to apply a strong braking force with a light pedaling force. In addition, when the load is light, the switching valve allows a braking force proportional to the pedal force to be obtained as a manual brake, and the foot brake pedal can be operated while checking the effectiveness of the brake. Therefore, it is possible to easily, safely, and reliably brake a large crane or the like under both heavy loads and light loads.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of one embodiment of the brake device of the present invention, FIG. 2 is a detailed diagram of the hydraulic circuit in FIG. 1, and FIG. 3 is an explanatory diagram showing an example of a conventional assist brake device. 1 is the drum, 2 is the brake band, 6 is the shaft,
7, 8, 11, 12 are levers, 13, 18 are legs, 15, 16 are arms, 17 is a pressure reducing valve, 19
24 is a foot brake pedal, 24 is a switching valve, 25 is an assist cylinder, 29 is a pressure side oil pipe, and 30 is a return oil pipe.

Claims (1)

[Scope of utility model registration request] A brake band 2 for braking a rotatable drum 1 includes a lever 3 whose intermediate portion is pivotally supported by a fixed object 36 and one end connected to the brake band 2, and a shaft 6 rotatably supported. A lever 7 whose intermediate portion is fixed to the shaft 6 and whose one end is connected to the other end of the lever 3 via a link rod 9; an assist cylinder 25 whose piston rod 27 is connected to the other end of the lever 7; Arm part 1
5 and 16, and a pair of levers 12 and 13 having leg portions 13 and 18 at the other end and arranged opposite to each other.
An X-shaped twin lever 37 that is pivoted at its intermediate portion.
and a pressure reducing valve 17 which is provided so that the spool 33 is switched to the communicating position when the arm portions 15 and 16 of the X-shaped pair lever 37 approach, and one end of which is fixed to the shaft 6 and the other end of which is a link rod. A lever 8 is connected to the leg portion 13 of the lever 11 via a lever 14, a brake pedal 19 is fixed to a rotating shaft 20, and one end is fixed to the rotating shaft 20 and the other end is connected to the lever 11 via a link rod 22. A lever 21 connected to the leg portion 18 of the lever 12 and a switching valve 24
A brake device for construction machinery, etc., comprising: a conduit 23 connecting the pressure reducing valve 17 and the assist cylinder 25.