JPS646981B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a brake unit that applies braking force to a railway vehicle, and particularly to a brake unit equipped with an automatic clearance adjustment mechanism.

As a conventional brake unit of this type, there is a brake unit disclosed in Japanese Patent Publication No. 50-35992. First, this brake unit will be explained based on FIGS. 8 to 11.
The upper part of the brake lever 3, which is rotatably supported on the frame 2 by the fulcrum pin 1, is connected to a brake cylinder (not shown), so the lower part of the brake lever 3 is rotated when the brake cylinder is operated. As a result, it is rotatably movable in the front and rear directions around the fulcrum pin 1. A two-part bushing 5 is press-fitted into a circular hole 4 formed below the brake lever 3. A spherical recess is formed in each divided portion of the bush 5, and is in spherical contact with a bearing 6 having a spherical outer surface. The bearing 6 is provided with a circular hole 7, and the axis of the circular hole 7 is located at right angles to the axis of the fulcrum pin 1 and below the fulcrum pin 1. In the position shown in FIG. It is in an acute angle relationship with the axis of 4. A sleeve 8 having an internal thread is fitted into the circular hole 7. A push rod 9 having a male thread at its rear end is screwed into the sleeve 8 so as to be relatively movable back and forth. The front end of the push rod 9 is connected to a brake shoe (not shown) whose upper end is rotatably supported by the frame 2 and whose lower end is supported by a pin 10 (not shown). In the brake unit configured as described above, when pressure fluid is supplied to the brake cylinder, the brake lever 3 rotates around the fulcrum pin 1, pushes the sleeve 8, push rod 9, and brake shoe forward, and pushes the brake shoe forward. Press the wheel tread (not shown) located in front of the brake lever to apply the brake, and conversely, when releasing the brake, the pressure fluid in the brake cylinder is discharged, and a return mechanism (not shown) is used to release the brake lever. 3 in the opposite direction around the fulcrum pin 1,
Move the sleeve 8, push rod 9, and brake shoes rearward.

As the braking surface of the brake shoe wears due to repetition of such operations, the amount of forward movement of the push rod 9 increases with each braking operation. Therefore, in order to maintain the same travel distance of the push rod 9 and the piston of the brake cylinder even if the brake shoe wears out and a braking action is subsequently performed, the brake unit is provided with an automatic clearance adjustment mechanism, which will be described in detail below. ing.

This automatic clearance adjustment mechanism consists of a sleeve 8 having a male thread of the push rod 9 and a female thread that engages with the male thread, a ratchet gear 11, a pawl 1,
2 and a drive mechanism that connects the brake lever 3 and the pawl 12.

Since the ratchet gear 11 is fitted around the outer periphery of the sleeve 8, it rotates together with the sleeve 8. Both sides of the ratchet gear 11 are in contact with both walls provided in a groove shape in the clearance adjustment ring 13, and the ring 13
is attached to the sleeve 8 via a pair of sleeve bearings 14 so as to move together with the sleeve 8. As shown in FIG. 9, the claw 12 has one end attached to the pin 1.
5, and both ends of this pin 15 are supported near the left end of a pair of links 16 with a certain distance between them. The middle of this link 16 is pin 17
It is rotatably supported by an arm 18 formed on the gap adjustment ring 13. Near the right end of the pair of links 16, the link 16 connects the upper end of the actuating rod 19 with the pin 20.
It is connected so that it can swing freely. The actuating rod 19 slidably passes through a wear bushing 21 attached to the clearance adjusting ring 13, and the link 16 is centered around the pin 17 by means of a spring 22 fitted onto the actuating rod 19. It is biased to rotate counterclockwise.
Further, the other end of the tooth presser 23, one end of which is fixed through the operating rod 19, is in pressure contact with the ratchet gear 11 to prevent the ratchet gear 11 from freely rotating. The lower part of the operating rod 19 is the main moving rod 2 for adjusting the gap.
It is connected to 4. The main drive rod 24 is rotatably supported by a bell crank lever 25 by a pin 26. Further, a roller 28 is rotatably attached to the bell crank lever 25 by a pin 27.
The contact line 9 becomes the fulcrum of the bell crank lever 25. The gap adjusting roller mounting seat 30 is attached to one side wall of the frame body 2 with bolts 31, and a roller 32 is rotatably supported at the upper end by a pin 33. The roller 32 contacts a circular arc surface 35 formed on the arm 34 of the bell crank lever, and when the lever 25 rotates around the fulcrum formed by the contact line between the roller 28 and the plane 29, the roller 32 rolls along this arc plane.

A cam surface 36 and a claw tip 37 are formed at the lower end of the claw 12, and the lower end of the intermediate portion of the claw 12 is connected to the upper end of a first spring 39 supported by a vertical arm 38 that is the same body as the clearance adjustment ring 13. Therefore, the first spring 39
In this case, the cam surface 36 of the pawl 12 is
Each member of the gap adjustment mechanism is normally forced into the position shown in contact with the two teeth.

Next, the operation of adjusting the gap in the conventional brake unit constructed as described above will be explained.

When the brake lever 3 rotates clockwise about the fulcrum pin 1 when applying the brake, the automatic clearance adjustment mechanism includes the clearance adjustment ring 13, ratchet gear 11, pawl 12, link 16, actuating rod 19, and driving rod 24. moves forward simultaneously when the push rod 9 and sleeve 8 move forward. The roller 32 is in contact with the circular arc surface 35 of the arm 34 of the bell crank lever 25, and is rotatably attached to a mounting seat 30 fixed to the frame 2 with a pin 33. the result,
The rollers 32 and pins 33 cannot move relative to the frame 2. Therefore, the roller 32 is connected to the arm 3 in FIG.
Suppress the leftward movement of 4. Furthermore, the roller 28 contacts a flat surface 29 formed on the gap adjustment ring 13 that moves forward at the same time. Therefore, the roller 32 rotates the bell crank lever 25 clockwise in FIGS. In response to the forward movement of the adjustment ring 13, ratchet gear 11, pawl 12, link 16, operating rod 19, and main driving rod 24, the arm 34 rolls along the circular arc surface 35. Since the bell crank lever 25 is connected to the main drive rod 24 by the pin 26, this clockwise rotation of the bell crank lever 25 moves the main drive rod 24 downward.
This downward movement of the actuating rod 24 pushes the actuating rod 19 downward, and furthermore, this downward movement of the actuating rod 19 causes the link 16 connected by the pin 20 to rotate clockwise in FIG. 9 around the pin 17. Since the pawl 12 is rotatably attached to the other end of the link 16 by a pin 15, clockwise rotation of the link 16 moves the pawl 12 upward in FIG. 9, so that the cam surface 36 of the pawl 12 It slides on the teeth of the ratchet gear 11. This ratchet gear 11 is moved forward by the brake lever 3 2
Sleeve 8 and key 8a supported by split bush 5
It cannot rotate in this state because it is united by the . If the brake shoe wear does not exceed the specified value, the cam surface 36 and the claw tip 37 will pass through the tooth 40 and
0 and the adjacent tooth 41 does not rise enough distance for the nail tip 37 to be located between the tooth 41 and the adjacent tooth 41. As a result, when the brake is released in this state, the pawl 12 returns to its original position by the first spring 39 without causing the ratchet gear 11 to rotate.
The cam surface 36 is maintained in contact with the end of the tooth as it slides along the tooth during braking by pushing counterclockwise in FIG.

However, during braking, the ratchet gear 11
When the brake shoe is sufficiently worn that the pawl tip 37 passes over the outer end of the tooth 41, the pawl tip 37 stops between the teeth 40 and 41. When the pawl tip 37 is in this position, the pawl 12 rotates the ratchet gear 11 and the sleeve 8 by the action of the first spring 39 and then releases the brake. Since the push rod 9 does not rotate as it is connected to the brake shoe and the suspension, the sleeve 8 screwed onto the push rod 9 is unscrewed, thus moving the brake shoe toward the wheel tread and preventing wear of the brake shoe. Close the gap created by

According to the conventional brake unit as mentioned above,
During braking, that is, when the sleeve 8, push rod 9, and automatic clearance adjustment mechanism move forward together in response to the braking force from the brake cylinder, and the brake shoe is pressed against the wheel tread, vehicle vibrations occur. If the relative positional relationship between the wheel and the bogie frame shifts due to the deflection of the shaft spring, the relative position will change due to the fact that the sleeve 8, push rod 9, and automatic clearance adjustment mechanism are attached to the bogie frame. Any misalignment will eventually manifest itself in a misalignment of the gap between the wheel tread and the brake shoe. Therefore, the claw tip 37 in the above explanation passes over one tooth and stops between the teeth 40 and 41 even though the brake shoe is not worn. When the claw tips 37 stop at this position, the sleeve 8 is rotated by releasing the brake, and the push rod 9, that is, the brake shoe, is moved toward the wheel tread to close the gap between the brake shoe and the wheel tread. However, since the gap was filled even though the brake shoes were not worn beyond the specified value, the gap is smaller than the normal setting value. The gap between the brake shoe and the wheel tread affects the stroke of the brake cylinder, the length of the brake lever 3, etc., and if it is too large, it will lead to an increase in the size of the brake unit, a decrease in brake response, and an increase in air consumption. Therefore, it is set to the minimum necessary limit. Therefore, in the conventional brake unit, where the clearance is even smaller than the value set to the minimum necessary value, the brake shoe may be caused to close to the wheel tread due to vibrations during running or deflection of the shaft spring when the vehicle is loaded or empty. It has the disadvantage of coming into contact with

This invention was made in view of the above circumstances, and has a structure in which the automatic gap adjustment is stopped at the same time as the brake shoe comes into contact with the wheel tread and the brake is applied, thereby reducing vibrations and accumulation during driving. The purpose is to always maintain a set gap without being affected by the deflection of the shaft spring when the car is empty.

The present invention is characterized in that, in the conventional brake unit, an adjustment body having an inner hole penetrating in the front-rear direction and receiving the brake cylinder output is provided inside the main body so as to be movable back and forth, and the inner hole of the adjustment body is It is composed of a small diameter inner hole at the rear and a large diameter inner hole in front of it, and the sleeve is fitted into the inner hole of the adjusting body so as to be movable back and forth, and a large diameter part is provided in the middle of the sleeve, and the sleeve has a large diameter. first bevel teeth are formed at the front end of the diameter portion, and a ratchet gear attached to the front end of the adjustment body and movable back and forth integrally with the adjustment body is rotatably fitted to the front of the large diameter portion of the sleeve; A second bevel tooth that meshes with the first bevel tooth is formed at the rear end of the ratchet gear, and the front end thereof is in contact with the stepped portion of the large diameter portion of the sleeve, and the second bevel tooth is formed in the large diameter inner hole of the adjusting body, and the rear end A second spring is attached which is precompressed by contacting the step between the small diameter inner hole and the large diameter inner hole of the adjustment body, and the second spring is precompressed.
The pressing force due to the precompression of the spring is made to correspond to the set braking force, and when the brake cylinder output transmitted to the adjustment body becomes larger than the pressing force due to the precompression, the adjustment body compresses the second spring and releases the sleeve. The first bevel tooth and the second bevel tooth are disengaged from each other when the first bevel tooth and the second bevel tooth are relatively moved forward relative to each other.

Embodiments of the present invention will be described below based on the description of the drawings.

Components common to those of the conventional brake unit will be designated by the same reference numerals and their explanation will be omitted.

First, the first part of this invention shown in FIGS.
An example will be described.

The brake unit of the present invention includes the sleeve 8, push rod 9,
In addition to the ratchet gear 11, the pawl 12, and the first spring 39, an adjustment body 42 is provided in the brake unit body so as to be movable back and forth, and the sleeve 8 is fitted into the inner hole thereof so as to be movable back and forth. The first bevel teeth 43, the first bevel teeth 43
The main components are a second bevel tooth 44 formed on the ratchet tooth 11 that meshes with the ratchet tooth 11, and a second spring 45 that is pre-compressed and installed between the adjustment body 42 and the sleeve 8.

The rear part of the sleeve 8 (on the opposite side from the wheel) is fitted into the circular hole 7 of the bearing 6, and a retaining ring 46 for preventing backward movement of the bearing 6 is provided at the rear end to prevent it from coming off the sleeve 8. It is provided together with a nut 47. This locking nut 47 is connected to a manual rotation mechanism (not shown). Further, in front of the bearing 6 (on the wheel side), a spacer 48 is fitted onto the sleeve 8 so as to be movable back and forth. In the middle of the sleeve 8 located further forward than the spacer 48, a large diameter portion 5 having teeth 49 formed on the outer periphery of the rear end.
0 is formed, and a ratchet gear 11 is rotatably fitted further forward of the large diameter portion 50. The adjustment body 42 has an inner hole 51 penetrating in the front-rear direction, and a sleeve 8 is disposed inside the inner hole 51.
is inserted so that it can move freely back and forth. Furthermore, the adjusting body 4
An arm 52 shown in FIG. 2 provided on the outer periphery of the brake lever 3 is connected to the brake lever 3 so that the adjustment body 42 is movable in the front-back direction but cannot rotate. A small diameter inner hole 5 formed behind the inner hole 51 of the adjustment body 42
3 is fitted with the teeth 49 of the large diameter portion 50, and a second spring 45 externally fitted onto the large diameter portion 50 of the sleeve 8 is fitted into the large diameter inner hole 54 formed in front of the inner hole 51. ing. The rear end of the second spring 45 is connected to the small diameter inner hole 53 and the large diameter inner hole 5 through a sliding washer 55.
4, the front end of which is in contact with the step 56 formed by the sleeve 8, and the stopper 5 as a step provided on the front outer periphery of the sleeve 8.
7 via a sliding washer 58, the pressing force due to the precompression corresponds to the set braking force. Further, the adjustment body 42 is provided with a tooth presser 60 that presses the teeth 49 of the large diameter portion 50 by a spring 59, thereby preventing the sleeve 8 from freely rotating due to vibrations of the vehicle, etc. has been done. A first bevel tooth 43 is formed at the front end of the large diameter portion 50 of the sleeve 8 facing the ratchet gear 11, and a second bevel tooth 44 that meshes with the first bevel tooth 43 is formed at the rear end of the ratchet gear 11. is formed. Furthermore, the ratchet gear 11
is fixed to the adjustment body 42 by a fixing bolt 62 via a retaining plate 61 which is fitted onto the sleeve 8 at its front end so that it can move back and forth around the outer periphery of the sleeve 8 together with the adjustment body 42. . As a result, when the first bevel teeth 43 and the second bevel teeth 44 are not engaged, the ratchet gear 11 independently engages the sleeve 8.
However, forward and backward movement is not possible unless it is integrated with the adjustment body 42. An actuating rod 64 is fitted into a cylindrical hole 63 formed on the side of the adjusting body 42 having a center line perpendicular to the axis of the push rod 9 so as to be vertically movable. At the upper end of this operating rod 64, as shown in FIG.
Since the lower end of the spring 67, the upper end of which is in contact with the spring receiver 66, which is prevented from moving upward by the lower end of the spring 67, is urged downward, the operating rod 64 is urged downward. A pawl link support 69 is fixed to the operating rod 64 by a bolt 68. A claw link 71 whose upper end is rotatably fixed with a pin 70 is provided inside the claw link support 69. Further, inside the pawl link 71, the pawl 12 is rotatably fixed by a pin 72 with the teeth of the pawl 12 facing the ratchet gear 11, and one end side of the pawl 12 and the pawl link are fixed. Between one end of 71,
A spring 73 is provided that biases the upper side of the pawl 12 to rotate in a direction in which it comes into contact with the ratchet gear 11, and further,
Between the other end of the pawl link 71 and the pawl link support 69, there is provided a first spring 39 having a rotational biasing force that exceeds the rotational biasing force of the spring 73, so that the pawl 12 ends up with its lower side It is urged to rotate clockwise in FIG. 3 about pin 72 so as to abut against ratchet gear 11. Further, the adjusting body 42 is adjusted so that the lower side of the pawl 12 does not come into contact with the ratchet gear 11 when the operating rod 64 is urged to the lowest position by the spring 67, that is, when the brake is released. The lower inclined portion 75 of the pawl link 71 on the side of the ratchet gear 11 rides on a roller 74 rotatably fixed inside, and the upper side of the pawl 12 is pushed onto the ratchet gear 11 by the rotational biasing force of the spring 73. A stopper pin 76 is provided inside the adjustment body 42 to prevent rotation of the pawl 12 so as not to come into contact with it.
Further, a roller 78 is rotatably fixed to a protrusion 77 from the adjustment body 42 at the lower end of the operating rod 64 by a pin 79, and a roller 78 is fixed to a lower part of the brake lever 3 below the roller 78. Arm 80 is positioned.

The operation of the first embodiment of the present invention having the above configuration will be explained.

First, manual gap adjustment will be explained. When replacing the brake shoe when the brake is loosened, tighten the retaining nut 4 provided at the rear end of the push rod 9.
7 is rotated via a manual rotation mechanism (not shown). As a result, the sleeve 8 fixed to the locking nut 47 also rotates. At this time, since the downwardly inclined portion 75 of the pawl link 71 rides on the roller 74, the pawl link 71 remains at rest at a position rotated to the opposite side of the ratchet gear 11 about the pin 70, and the pawl 12 is moved by the pin 76. Since the rotation biasing force by the lever spring 73 is blocked, the ratchet gear 11
Since the teeth of the sleeve 8 and the teeth of the claw 12 cannot be engaged with each other, the sleeve 8 can be easily rotated. The pressing of the large diameter portion 50 against the teeth 49 by the biasing force of the spring 59 of the tooth presser 60 does not become a hindrance in most cases. By this rotation of the sleeve 8, a push rod 9 having a male thread screwed into a female thread formed in the sleeve 8 moves in the front and back direction, and therefore a control (not shown) fixed to the tip of the push rod 9 is moved. The gap between the wheels and the wheel tread can be adjusted.

Next, the adjustment by the automatic gap adjustment mechanism will be explained.

First, a description will be given of the operation when the brake is applied when the gap between the brake shoe and the wheel tread is within a set value.

When the lower part of the brake lever 3 is rotated forward about the fulcrum pin 1 by supplying pressure fluid to the brake cylinder, the spacer 48,
Adjustment body 42, second spring 45, sleeve 8, push rod 9
The brake cylinder output is sequentially transmitted to the brake cylinders. Further, the arm 80 fixed below the brake lever 3 is
The actuating rod 64 and the pawl link support 69 fixed to the actuating rod 64 are pushed up via the roller 78. Then, the pawl link 71 rotatably fixed to the pawl link support 69 by a pin 70 also rises, and its downwardly inclined portion 75 also gradually comes off the roller 74. Therefore, the pawl link 71 gradually moves toward the ratchet gear 11 due to the pressing force of the first spring 39.
The pawl 12 rotates until it comes into complete contact with the ratchet gear 11.
As the pawl link 71 moves, the teeth of the pawl 12 slide along the backs of the teeth on the outer periphery of the ratchet gear 11.
The ratchet gear 11 has a second
The bevel teeth 44 mesh with the first bevel teeth 43 formed on the front end of the large diameter portion 50 of the sleeve 8, and the sleeve 8 meshes with the first bevel teeth 43 formed on the large diameter portion 50 of the sleeve 8.
9 is prevented from freely rotating by the tooth retainer 60, so it does not rotate due to the sliding contact with the teeth of the pawl 12. When the brake shoe at the tip of the push rod 9 comes into contact with the wheel tread and the braking force becomes larger than the force of the second spring 45, that is, the adjustment body 42
The brake cylinder output transmitted to the second spring 4
5, the adjustment body 42 is pushed forward from the brake lever 3 via the two-part bush 5, the bearing 6, and the spacer 48, so the second spring 45 is compressed and the spacer 48 finally comes into contact with the rear end of the large diameter portion 50. Since the ratchet gear 11 moves forward together with the adjustment body 42, each tooth of the pawl 12 does not get over one tooth of the ratchet gear 11 due to the spacer 48 coming into contact with the rear end of the large diameter portion 50. As it is, the second bevel teeth 44 and the first bevel teeth 43 are disengaged, and the ratchet gear 11 becomes independently rotatable with respect to the sleeve 8. Therefore, the subsequent movement of the actuating rod 64, that is, the movement of the pawl 12, is caused by the ratchet gear 11.
Since each tooth of the pawl 12 does not pass over one tooth of the ratchet gear 11, the condition is maintained.

Even when the brake is released, the pawl 12 and the ratchet gear 11 move together until the predetermined braking force is restored, that is, until the second bevel tooth 44 and the first bevel tooth 43 engage. In order to do this, as the actuating rod 64 is lowered by the pressing force of the spring 67, that is, the pawl 12 is lowered, the ratchet gear 11 also rotates in the opposite direction. Therefore, the contact position of the ratchet gear 11 and pawl 12 in the state where the second bevel teeth 44 and the first bevel teeth 43 are meshed again is the state where the second bevel teeth 44 and the first bevel teeth 43 are disengaged. The abutment position at , that is, the claw 1
Each tooth of No. 2 is in a position where it does not go over one tooth of the ratchet gear 11. When the actuating rod 64 further descends, the downwardly inclined portion 75 of the pawl link 71 slides against the roller 74 and gradually separates from the ratchet gear 11. Accordingly, the pawl 12 also separates from the ratchet gear 11, so that the clearance can be adjusted. will not be carried out. At this time, the upper part of the pawl 12 is urged toward the ratchet gear 11 by the spring 73, but its rotation is prevented by the pin 76, so the pawl 12
Each tooth of the ratchet gear 11 waits for the next braking action while maintaining a state in which it does not come into contact with each tooth of the ratchet gear 11.

In this way, the rotation of the ratchet gear 11 due to the forward movement of the push rod 9 after the braking force is generated is unrelated to the rotation of the sleeve 8, so no gap adjustment is performed.

The operation when the brake is applied when the gap between the brake shoe and the wheel tread is greater than or equal to a set value will be described.

In this case, since the forward movement distance of the push rod 9 increases compared to the case where it is within the set value, the rotation angle about the lower fulcrum pin 1 of the actuation lever 3 increases, and as a result, the actuation Since the rod 64 and the pawl 12 move upwards, the pawl 12
The tooth passes over one tooth of the ratchet gear 11.
Even when the braking force becomes greater than the force of the second spring 45 and the ratchet gear 11 is able to rotate independently with respect to the sleeve 8, for the same reason as mentioned above, it cannot overcome this one tooth. maintain the same state.

When the brake is released with the teeth of the pawl 12 passing over one tooth of the ratchet gear 11, the actuating rod 64, pawl link support 69, pawl link 71, and pawl 12 are lowered by the force of the spring 67. To,
The ratchet gear 11 is rotated clockwise in FIG. At this time, the ratchet gear 11
Since the bevel teeth 44 and the first bevel teeth 43 are engaged with each other, they are integrated with the sleeve 8, so that the sleeve 8 also rotates in the clockwise direction. However, since the push rod 9, which has a male thread on its outer periphery that engages with the female thread in the sleeve 8, is connected to a brake shoe fixed to a hanging tool (not shown), the push rod 9
does not rotate together with the sleeve 8. Therefore, push rod 9
Since the sleeve 8 is pushed forward by the pitch of the rotated screw relative to the push rod 9, the gap can be adjusted.

In this way, each time the brake shoe wears by the specified value, the push rod 9 is pushed forward of the sleeve 8, and the gap between the brake shoe and the wheel tread is automatically adjusted to the set value. be.

A second embodiment of the invention is shown in FIGS. 5-7.

The difference between this second embodiment and the first embodiment is that, instead of the brake lever 3 rotating around the fulcrum pin 1, a wedge 81 that moves up and down by a brake cylinder (not shown) is used. The sleeve 8, the push rod 9, and the automatic clearance adjustment mechanism are moved back and forth as one, but due to this difference, their configurations are also different, so only the different points will be explained, and other identical configurations will be explained below. The same reference numerals are used to omit the explanation.

A roller 83 is provided on the adjustment body 42, which abuts against the inclined working surface 82 of the wedge 81. The adjusting body 4
2 is formed with a collar portion 84 in which the sleeve 8 is fitted into the center hole. When the braking force exerted by the wedge 81 becomes greater than the force of the second spring 45, the collar portion 84 comes into contact with the rear end of the large diameter portion 50 of the sleeve 8, and the further adjustment body 42 is moved against the sleeve 8. This is to prevent forward movement.
This corresponds to the spacer 48 of the first embodiment. Further, the claw link support 69, the operating rod 64, etc. are the same in structure and function, with the only difference being that they are attached to the adjusting body 42 so as to be movable in the horizontal direction. The roller 78, which is rotatably fixed to the protrusion 77 of the actuating rod 64 from the adjusting body 42 with a pin 79, moves to the inclined guide 85 fixed to the frame of the brake unit (not shown) as the adjusting body 42 moves back and forth. You will be guided.

According to the brake unit of the second embodiment of the present invention having such a configuration, at the start of braking action, as the wedge 81 is lowered by the action of the brake cylinder, it comes into contact with the inclined action surface 82 of the wedge 81. Since the contacting roller 83 is pushed forward, the adjusting body 42 also moves forward at the same time.
As the adjustment body 42 moves forward, the roller 78 of the actuating rod 64 rides on the inclined guide 85, so the actuating rod 64 moves to the right in FIGS. 6 and 7, and the first embodiment Activate the gap adjustment mechanism in exactly the same way. The only difference from the first embodiment is that when the brake is released, the adjustment body 42 is returned to its original rear position by a spring not shown.
All other effects are the same.

As is clear from the above explanation, according to the brake unit of the present invention, in order to release the connection between the ratchet gear 11 and the sleeve 8 when the braking force exceeds a set value, the vibration of the vehicle and the loading Even if the relative positional relationship between the wheels and the bogie frame becomes misaligned due to the deflection of the axle spring when the vehicle is empty, and the gap distance between the wheel tread and the brake shoe becomes large, these It becomes possible to perform accurate gap adjustment without being affected. Therefore, even if the gap between the wheel tread and the brake shoe is set to the minimum necessary, there is no risk that the brake shoe will come into contact with the wheel tread. Furthermore, by setting the gap to the minimum necessary in this way, it is possible to shorten the stroke of the brake cylinder and shorten the length of the brake lever and wedge, resulting in a smaller brake unit and improved brake response. It is possible to obtain the effect of improving air consumption and saving air consumption.

[Brief explanation of drawings]

1 to 4 show a first embodiment of the present invention, in which FIG. 1 is a vertical sectional view of the main part, FIG. 2 is a sectional view taken along the line -- in FIG. 4 is a sectional view taken along the line - of FIG. 3, FIGS. 5 to 7 show a second embodiment of the present invention, and FIG.
6 is a sectional view taken along the - line in FIG. 5, FIG. 7 is a sectional view taken along the - line in FIG. 6, and FIGS. 8 to 11 show a conventional brake unit.
Fig. 8 is a longitudinal sectional view of the main part and a sectional view taken along the - line in Fig. 9;
The figure shows a partially omitted front view in the - line direction of FIG. 9, and FIG. 11 shows a sectional view taken along the line XI--XI of FIG. 10, respectively. 8... Sleeve, 9... Push rod, 11... Ratchet gear, 12... Pawl, 39... First spring, 42
... Adjustment body, 43 ... First bevel teeth, 44 ... Second
Bevel teeth, 45...Second spring, 50...Large diameter portion, 5
1... Inner hole, 53... Small diameter inner hole, 54... Large diameter inner hole, 56... Step portion.

Claims (1)

[Scope of Claims] 1. A sleeve that is rotatably and freely movable back and forth within the main body and moves back and forth upon transmission of brake cylinder output; and a sleeve that is screwed into the sleeve so that it can move back and forth relatively; A push rod that projects forward and is pivotally supported by a hanger and has a brake shoe connected to its front end; a ratchet gear that is fitted around the outer periphery of the sleeve so as to rotate together with the sleeve; , a brake unit comprising a pawl that moves along the teeth on the outer periphery of the ratchet gear, and a first spring that presses the pawl against the teeth on the outer periphery of the ratchet gear, the brake cylinder having an inner hole penetrating in the front-rear direction; An adjusting body for receiving an output is provided in the main body so as to be movable back and forth, and the inner hole of the adjusting body is composed of a small diameter inner hole at the rear and a large diameter inner hole in front of the adjusting body, and the sleeve is inserted into the inner hole of the adjusting body. The sleeve is fitted so as to be movable back and forth, a large diameter portion is provided in the middle of the sleeve, first bevel teeth are formed at the front end of the large diameter portion of the sleeve, and the sleeve is attached to the front end of the adjustment body in front of the large diameter portion of the sleeve. A ratchet gear is rotatably fitted on the outside of the ratchet gear and moves back and forth integrally with the adjusting body, and a second bevel tooth that meshes with the first bevel tooth is formed at the rear end of the ratchet gear, A pre-compressed groove is placed in the large diameter inner hole, with its front end in contact with the stepped portion of the large diameter portion of the sleeve, and its rear end in contact with the stepped portion between the small diameter inner hole and the large diameter inner hole of the adjusting body. 2
A spring is attached, and the pressing force due to the precompression of the second spring is made equivalent to the set braking force, and the brake cylinder output transmitted to the adjustment body becomes larger than the pressing force due to the precompression, so that the adjustment body A brake unit configured such that the first bevel teeth and the second bevel teeth are disengaged when the second spring is compressed and the second spring is moved forward relative to the sleeve.