JPS5919146Y2 - Braking gap automatic adjustment device for mechanical drum brakes - Google Patents

Description

[Detailed Description of the Invention] The present invention has a cam collar that is slidably fitted in the direction of the cam shaft, and the end of the shoe web comes into contact with the cam part of the cam member that expands the brake shoes by rotating the brake arm. Automatic braking gap for mechanical drum brakes in which the cam collar is moved in the direction of the cam shaft and moved in the direction of shoe expansion by the screw action of the operating member screwed onto the cam member to expand the brake shoes and adjust the braking gap. This adjustment device has a cam part of a cam member that has a surface facing the free end of the shoe web that is longer than the wall thickness of the free end of the shoe web, and the head of the actuating member that pushes the cam collar is attached to the front end of the cam part. It is characterized by being brought into contact with a surface to restrict the movement of the actuating member and set the limit value for braking gap adjustment, and its purpose is to:
This prevents the actuating member that pushes the cam collar to adjust the braking gap from coming into contact with the free end of the shoe web and interfering with the expansion of the brake shoes when the adjustment is completed, thereby preventing the actuating member from interfering with braking. This prevents the rotating adjustment gear from being pushed out from the cam member by the screw movement of the operating member, preventing damage or breakage to the adjustment mechanism, and furthermore, the stroke of the brake lever or brake pedal cannot be increased after the lining wears out. To provide an automatic braking gap adjustment device for a mechanical drum brake that notifies the time of replacing brake shoes.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

Inside the back plate 1, there is a pair of brake shoes 2.
, 2' are provided with their base ends 2a, 2a' pivotally supported on the anchor pin 3, and this brake shoe 2゜2' has a U-shaped shoe return spring 4 whose intermediate portion 4a is supported on the anchor pin 3. is always biased in the direction of proximity.

The cam member 5 consists of a large-diameter cam portion 5a, a mounting shaft portion 5b, and a serration shaft portion 5C.
.

2b' through the back plate 1 through the washer 6, and connects the cam portion 5a to both shoe web free end portions 2b.
, 2b', a mounting shaft portion 5b is rotatably provided on the back plate 1, and a grease reservoir 5d formed in the mounting shaft portion 5b is filled with grease so that the cam member 5 can rotate smoothly. I have to.

The brake arm 7 is fixed to the serration shaft portion 5C of the cam member 5 that projects outside the back plate 1, and is rotated by the brake operation wire 8 to rotate the cam member 5.

The cam portion 5a of the cam member 5 has a shoe web free end portion 2b.
, 2b' and cut out the free end portions 2b, 2b'.
Opposing surfaces 5e and 5e' facing each other are formed,
The length 11 of these facing surfaces 5e, 5e' is longer than the wall thickness 12 of the shoe web free end portions 2b, 2b'.

Cam collar grooves 9, 9' are formed in the shoe pushing portions of these opposing surfaces 5e, 5e' at vertically symmetrical positions, sandwiching the operating member insertion hole 10, in a direction perpendicular to the opposing surfaces 5e, 5e'. There is.

The bottom of this cam collar groove 9.9' is tapered,
The cam portion 5a slopes and becomes deeper from the rear end to the tip.
At the distal ends, the actuating member insertion hole 10 is sandwiched between the actuating member insertion holes 10 and the actuating member insertion holes 10 are interposed therebetween.

The actuating member 11 has a right-handed thread 11b formed at the end of the shaft portion 11a, which is inserted into the actuating member insertion hole 10, and the female thread 10 is inserted into the actuating member insertion hole 10.
A is screwed into the cam member 5, and its head 11C abuts via a washer 13 against a pair of cam collars 12 and 12' fitted in the cam collar grooves 9 and 9'. .

Then, the actuating member 11 engages the flat plate portion 14b at the tip of the shaft portion 14a of the adjusting gear 14 inserted into the cam member 5 from the opposite side with the slotted groove 11d of the actuating member 11. As it rotates, it rotates integrally and is screwed into the cam member 5, and when the adjustment is completed, the head 11C comes into contact with the front end surface 5f of the cam part 5a via the washer 13, and its movement is restricted. This is the limit value for braking clearance adjustment.

The column collars 12, 12' are formed in the shape of a right triangle with a plate shape, and the slopes 12a, 12a' thereof abut against the bottom tapered surfaces 9a, 9a' of the cam collar grooves 9, 9',
The vertical surfaces 12b, 12b' are the shoe web free ends 2b, 2
b', rotates together with the cam member 5, and is pushed by the screwing of the actuating member 11 and moves in the cam axis direction,
This causes the brake shoes 2, 2' to protrude from the opposing surfaces 5e, 5e' of the cam portion 5b and to spread out.

A partition wall 15 is provided on the outside of the back plate 1 so as to cover the mounting portion of the brake arm 7, and the cam shaft 5g of the cam member 5 projects from the partition wall 15 via a seal member 16.

One end of the dust cover 17 is fitted into the accelerator shaft boss 19 via a seal member 18, and the other end is tightened and fixed to the partition wall 15 at two locations with screws 20, so as to cover the top of the partition wall 15.

The stopper lever 21 has a large diameter hole 21 bored at one end.
a and a small diameter hole 21 drilled at the other end b and an elastic claw portion 21
C, the large diameter hole 21a is inserted into the camshaft 5g, the other end is inserted between the partition wall 15 and the dust cover 17, and the screw 20 is inserted into the small diameter hole 21b so that it is aligned with the camshaft 5g. Fixed.

The tip of the elastic claw portion 21C is connected to the adjustment gear 14.
The teeth 14C mesh with each other so as to restrict the rotation of the adjustment gear 14 when the brake arm 7 is pulled in the operating direction of direction A in FIG.

The adjustment lever 22 has a fitting hole 22a in the center, and a camshaft pressure contact piece 22b is formed on the inner peripheral surface of the fitting hole 22a by bending it in the opposite direction to the fitting direction. .

This adjustment lever 22 has a camshaft pressing piece 22 attached to a chamfered portion 5h formed in the axial direction of the camshaft 5g.
b is fitted by pressure contact engagement, and its elastic claw portion 22
C meshes with the teeth 14C of the adjustment gear 14 from the periphery, and rotates together with the cam member 5 as the brake arm 7 rotates in the operating direction, and when the linings 2C and 2C' wear a predetermined amount, the next gear of the adjustment gear 14 When the brake lever 7 returns, the adjustment gear 14 is rotated to advance one tooth, and the elastic claw portion 21 of the stopper lever 21 is engaged with the tooth 14C of the stopper lever 21.
C meshes with the next tooth 14C of the adjustment gear 14, and the adjustment action is completed.

Next, the operation of this embodiment will be explained.

When braking is performed by operating the brake lever or brake pedal, the brake arm 7 is rotated in the direction A in FIGS. 1 and 2 by the brake operation wire 8.
As the brake arm 7 rotates, the cam member 5 integrally rotates counterclockwise as shown in FIG.
' is opened, whereby the brake shoes 2, 2' expand against the shoe return spring 4, and the linings 2C, 2' are expanded against the shoe return spring 4.
Braking is performed by pressing C' against the inner peripheral surface of a brake drum (not shown).

If the linings 2C, 2C' are worn out by this braking action and a braking gap of more than a set value is created between the inner peripheral surface of the brake drum and the surface of the linings 2C, 2C', the cam member 5 and cam collar 12, which rotate together during braking, .12', operating member 11 adjustment lever 22 and adjustment gear 1
However, since the rotation of the adjustment gear 14 is restricted by the elastic claw portion 21C of the stopper lever 21, the rotation amount of the cam member 5 and the cam collar 12.1 increases.
2', only the adjustment lever 22 is rotated by the increase in its braking gap.

As a result, the adjustment gear 14 and the actuating member 11 rotate integrally, and the elastic claw portion 22C of the adjustment lever 22 passes over one tooth of the adjust gear 14 and meshes with the next tooth 14C, and the actuating member 11 is the third
In the figure, it is screwed into the cam member 5 and moved to the left, and the cam collar 12.12' is pushed toward the back plate 1 by the head 11C of the actuating member 11.

As a result, the cam collar 12, 12' is connected to the cam collar groove 9,
9' in the axial direction and the opposing surface 5 of the cam portion 5a.
e and 5e' protrude in the shoe expansion direction, and expand the shoe web free ends 2b and 2b' to adjust the braking gap.

Then, when the braking operation is released, the brake arm 7, cam member 5, cam collar 12, 12', adjustment gear 1
4. The adjustment lever 22 and the actuating member 11 rotate together in the direction B in FIGS. 1 and 2.

At this time, the adjustment gear 14 is reliably rotated together with the cam member 5 by the adjustment lever 22, and thereby,
The elastic claw portion 21C of the stopper lever 21 passes over one tooth of the adjustment gear 14 and meshes with the next tooth 14C, completing the adjustment and returning to the original initial position.

In this way, as the linings 2c and 2c' wear out, the adjustment gear 14 rotates, and the elastic claw part 21C of the stopper lever 21 and the elastic claw part 2 of the adjustment lever 22 rotate.
2C successively mesh with the teeth 14C of the adjustment gear 14, and the cam collar 12.12' protrudes in the shoe expansion direction to automatically adjust the braking gap so that it is always constant.

When the linings 2c, 2c' reach their wear limit, the head 11C of the actuating member 11 comes into contact with the front end surface 5f of the cam part 5a via the washer 13, and the actuating member 11
This restricts the screwing in of the shoe web free end 2b.
, 2b' are not pressed by the actuating member 11, the shoe web free ends 2b, 2b' can move freely, and the brake shoes 2, 2' are not prevented from expanding, so braking is smooth. and reliable.

Furthermore, after the wear limit value of the linings 2C and 2C' is reached, the screwing of the actuating member 11 is restricted in this way.
The stroke of the brake lever or brake pedal increases without adjusting even the wear of the linings 2C, 2C' beyond the wear limit value, thereby allowing the rider to know when it is time to replace the brake shoes 2.2'.

Furthermore, since the screwing of the actuating member 11 is restricted in this way, the adjustment gear 14 that rotates the actuating member 11 can
The adjustment gear 14 and the stopper lever 21 that are meshed with the adjustment gear 14 are not pushed out by the operating member 11. The adjustment lever 22 etc. will not be damaged or damaged.

As described above, according to the present invention, the head of the actuating member that pushes the cam collar to adjust the braking gap is brought into contact with the front end surface of the cam part that expands the brake shoes when the adjustment is completed,
Since the movement is restricted, the head of the actuating member presses the free end of the shoe web, and there is no problem of preventing the brake shoe from expanding, and smooth and reliable braking can be achieved even after the adjustment is completed.

After this time, the braking gap will not be adjusted.
The stroke of the brake lever or brake pedal is increased, which makes it easier for the rider to know when it is time to replace the brake shoes, and the adjustment gear that rotates the actuating member is no longer pushed out of the cam member by the actuating member. This provides effects such as being able to reliably prevent damage and breakage of the mechanism.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and Figure 1 is a front view;
Fig. 2 is a rear view, Fig. 3 is a llll-■I■ sectional view of Fig. 2, Fig. 4 is a plan view, Fig. 5 is a cam member, a cam collar,
It is an exploded perspective view of a washer, an operating member, an adjustment gear, a stopper lever, and an adjustment lever. 2.2' is a brake shoe, 2b and 2b' are shoe web free ends, 5 is a cam member, 5a is a cam portion, and 5e. 5e' is an opposing surface, 5f is a front end surface, 9 and 9' are cam collar grooves, 11 is an operating member, 11'C is a head, 12 and 12' are cam collars, 13 is a washer, and 14 is an adjustment gear.

Claims (1)

[Scope of utility model registration request] A cam collar, which the free end of the shoe web comes into contact with, is slidably fitted in the cam shaft direction to the cam portion of the cam member that expands the brake shoes when the brake arm rotates, and the actuating member screwed onto the cam member is fitted. In a mechanical drum brake in which the cam collar is moved in the cam shaft direction and in the shoe expansion direction by screwing to expand the brake shoes and adjust the braking gap, a shoe web free end is attached to the cam portion of the cam member. The opposing surface of the shoe web is formed to be longer than the wall thickness of the free end of the shoe web, and the head of the actuating member is brought into contact with the front end surface of the cam part to restrict movement of the actuating member and set a limit value for braking gap adjustment. An automatic braking gap adjustment device for a mechanical drum brake, characterized in that: