JPS5813239A - Automatic adjuster of brake gap of mechanical drum brake - Google Patents

Abstract

PURPOSE:To contrive space saving, to improve a return of a brake shoe and to prevent adhesion and a deffective return of a cam from occurring, by overlapping a cam collar at the initial stage of incorporation and reducing a cam width of a cam of a cam component as narrow as possible. CONSTITUTION:When braking is disengaged, brake shoes 2 and 2' are returned by a shoe return spring 4, through which each of a cam component 5, cam collars 12 and 12', a adjust gear 14 and a feed claw 22 are rotated clockwise in a body for restoration to an original position respectively. When the braking is disengaged at the time of the restoration, the cam component 5 is rotated easily for the rostoration to an original position through bounce of the return spring 4, return peculiarity of the brake shoes 2 and 2' is favorable, and adhesion and deffective return are not generated as a cam width of a cam part 5a is narrow and the valve of b/a based on a relation to a contact point M among the center O of a cam shaft, the cam collars 12 and 12' and shoe webs 2b and 2b' is small.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention includes a cam member tube interposed between the free ends of a pair of playing shears whose proximal ends are pivotally supported on a pack plate, and a cam member tube passing through the back plate T. This causes the brake 9z-f to expand and control the brake by pressing it against the inner peripheral surface of the drum.
The braking gap between the lining and the inner circumferential surface of the brake drum, which is caused by wear of the lining due to nine repeated braking, is caused by the cam collar engaged with the force member. This invention relates to an automatic braking gap adjustment device for mechanical drum brakes.

A feature of the present invention is that in this type of automatic braking gap adjustment device for a mechanical drum brake, the free end of the shoe web has an opposing surface facing the cam portion of the cam member that spreads the brake shoes by rotation of the brake arm. A cam collar groove having a tapered groove bottom a is formed in the shoe pushing portion of the opposing surface, and is sandwiched between the operating member insertion hole, and the adjusting mechanism moves the operating member T into the cam collar groove. The purpose of this is to push the fitted cam collar, center it in the direction of the shear expansion, and expand the brake shoes to automatically adjust the braking gap.
By reducing the width of the cam part of the cam member, it can be applied to small-sized mechanical drum brakes, and the return characteristics of the brake shoe when braking is released are improved, and the rotational force of the cam member is reduced during braking. The transmission is transmitted from the cam collar fitted to the shoe pushing part on the opposing surface of the part to the shoe web, and the cam member can respond reliably without any loss of rotation, and the brake operation wire may stretch due to repeated braking. To provide a mechanical drum brake and a 1° braking gap automatic adjustment device capable of adjusting the amount of elongation.

1.

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

Pack play) Inside of 1 is a pair of 9 brakes'/-
-2e, 2' base end 21L #2&'
The brake shoe 2-2' is pivotally mounted on the T-77 carbine 3, and the brake shoe 2-2' is always urged in the direction of proximity by a spring 4 supported on the anchor pin 3 at the intermediate portion 41L''. The cam member 5 is composed of a large-diameter hook-in part 5a, a mounting shaft part 5b, and a serration shaft part 5c.

5 is the shake nib free end 2b of the brake shoe 2.2/
, Zb1 through the pack frame (IK) through the washer 6, and the cam portion 5a1 and both shoe web free end portions 2
A mounting shaft portion 5b is rotatably provided on the pack plate 1 opposite to b. sd is filled with grease so that the cam member 5 can rotate smoothly. The brake arm 7 is fixed to a serration @Is c of the cam member 5 which is centrally protruded outside the pack plate l, and is rotated by a brake operation wire 8 to rotate the cam member 5.

Cam portion 5aKt of cam member 5! , free end part z
A pair of opposing surfaces 5e#56 where the sides facing b and zb' are cut out, and the ends 2bezb' are opposite to each other.
/ is formed, thereby making the cam portion 5a narrow. Then, cam collar grooves 9, 9I are formed in the shoe pushing portion of this opposing surface 56*51S' at right angles to the opposing surface 561°56' at vertically symmetrical positions by inserting the operating member insertion hole 10 between them. ing. This cam collar groove 9, 9'
The bottom of the groove is tapered and becomes deeper from the rear end of the cam portion 5& to the tip, and at the tip, the actuating member insertion hole 10t is sandwiched and partially overlapped.

Actuation member 11Fi shaft portion 111! Insert into the right-hand threaded llb'i actuating member insertion hole 10 formed at the end of L, and insert the female threaded llb'i
The IIi portion 110 is in contact with a pair of cam collars 12t12' fitted in the cam collar grooves 9-9' via washers 131. This actuating member 11 engages from the opposite side with the flat plate portion 14bt at the tip of the shaft portion 142L of the adjusting gear 14 inserted through the cam member 5 - the slotted groove lid of the actuating member 11, and rotates the adjusting gear 14'. It rotates and spirals as a unit.

Cam collar 12s12' is plate-like 11111:1! It is formed into a right-angled triangular shape with a slope of 12 ael.
Za' is the bottom tapered surface 9a, 9 of the cam collar groove 9.9'.
a', and the vertical surfaces 12b, 12b' abut the shoe web free ends 2b, zb', rotate together with the cam member 5, and are pushed by the screwing of the actuating member 11 and move in the cam axis direction. As a result, the opposing surfaces 5e, 5 of the cam portion 5b
The brake shoe protrudes from e' and expands by 2°2/l.

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 a cam member 5
The camshaft 5f is a seal member 16t! - through this bulkhead 1
It stands out from 5. One end of the dust cover 17 is fitted into the accelerator shaft boss 19 via a seal member 18t, and the other end is fixed to the partition wall 15 at two locations with screws 20, so as to cover the top of the partition wall 15.

The adjustment lever 21 has a large diameter hole 21L bored at one end.
It contains a small diameter hole 21b drilled at the other end and an elastic claw part 210, and the large diameter hole 211Lt-camshaft 5fK is inserted into the large diameter hole 211Lt.
The other end is clamped between the partition wall 15 and the dust cover 17, and is fixed by inserting the screw 20t into the small diameter hole 21b so as to be aligned with each other. The tip of the elastic claw portion 2Ic is connected to the adjustment gear 1.
4 teeth 140tC7' are engaged to restrict rotation of the adjustment gear 14 when the rake arm 7' is pulled in the operating direction of direction A in FIG.

The feed pawl 22 has a mating hole 22at in its center, and a camshaft pressure contact piece 22b is formed on the inner circumferential surface of the mating hole 22L by being bent in a direction opposite to the mating direction. The feed pawl 22 is fitted into a chamfered portion 5g formed in the axial direction of the camshaft 5f by press-fitting the camshaft press contact piece 22btt. It meshes with the teeth 140 and rotates together with the cam member 5 as the arm 7 rotates in the operating direction during play, and when the lining 20*20' wears out a predetermined amount, the adjustment gear 1
When the lever 7 returns during play, the adjustment gear 14t rotates and feeds the first gear, and the elastic claw 21o of the adjustment lever 21 is engaged with the adjustment gear 14.
The adjusting action is completed by meshing with the next tooth 140.

Next, the operation of this embodiment will be explained.

To assemble the brake shoes 2, 2I, as shown in FIG.
6.56' and Kamkara"-12*12
12b # 12b'Km and assemble it in contact with the vertical surface of '. At this early stage of assembly, the cam collar 12t12' is shallowly fitted into the cam collar grooves 9 and 9I, and -a overlaps, so the cam's radius is small and the shake nib free end 2b12b' is close to each other. There is.

When braking is performed by operating the brake lever or the pedal during play, the brake arm 7 is rotated by the brake operation wire 8 in the inward direction in FIGS. 1 and 2, and as the brake arm 7 is rotated, the cam The member 5 rotates counterclockwise as shown in FIGS. 1 and 6, and the cam portion 5a moves the free end portion 2bszb' of the shake nib ξ
Then, the brake brake = 2*2' is applied against the shoe return spring 4 (4-open lining 2
c t20Ivi - Performs braking by pressing against the inner peripheral surface of the brake drum (not shown).

At this time, as the brake arm 7 rotates, the cam portion 5, cam collar 12s12', adjustment gear 14, and actuating member 11 rotate integrally, and the rotation angle is the same as that of the feed pawl 222.
Elastic claw portion 220 and elastic claw portion 2 of the adjustment lever 21
10 is the sliding range of the slope t of each of the teeth 140 of the adjustment gear 14. When the brake is released, the brake shoe 2゜2' is returned by the shoe return spring 4, and thereby the □cam member 5. Cam collar 12.12'.

The adjustment gear 14 and the adjustment claw 22 rotate clockwise as one body and return to their original positions. During this return, as shown in FIG.
- is small based on the relationship with the contact point M of the toshoe webs 2b and 2bI, so when the brake is released, the cam member 5 easily rotates due to the urging force of the return spring 4 and returns to its original position, and during play. Shoe 2, 2
The return characteristics of ' are good, and there is no sticking or return failure.

When the lining 20s20' is worn out by this braking action and a braking gap larger than the set value is created between the inner peripheral surface of the brake drum and the surfaces of the linings 2a and 2ap, the cam member 5 and the cam collar 12, 12' rotate together during braking. , the amount of rotation of the actuating member 11 and the adjustment gear 14 increases, but since the rotation is regulated by the elastic claw portion 210 of the adjustment gear 14Fi adjustment lever 21, only the cam member 5 and the cam collar 12*12' are rotated. Rotates as much as the braking gap increases. As a result, adjust gear 1
4 and the actuating member 11 rotate together, and the elastic claw portion 220 of the feed pawl 22 passes over one tooth of the adjustment gear 14 and meshes with the next tooth 140, and the actuating member 1
1 is screwed into the cam member 5 and moved to the left in FIG.
Nyo 9 back plate 1 is pushed. This is cam color 12s12'+ than K! Cam collar groove 9,9/? While sliding in the axial direction, the opposing surface 5et5e' of the cam portion 5a
The free end portion 2b of the shoe web protrudes in the shoe expansion direction.
, 2b'l to adjust the braking gap.

Then, when the braking operation is released, the brake arm 7, cam member 5, cam collar 12t12', adjustment gear 1
4 and the actuating member ll 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 feed claw 22,
As a result, the elastic claw portion 210 of the adjustment lever 21 passes over one tooth of the adjustment gear 14 and meshes with the next tooth 140, completing the adjustment and returning to the original initial position.
In this way, as the lining 20*2C' wears out, the adjustment gear 14 rotates, and the elastic claw part 210 of the adjustment lever 21 successively engages with the teeth 140 of the adjustment gear 14, and the cam collar 12*12' is rotated as shown in FIG. As shown in the figure, the brake gap is automatically adjusted by extending 1/C% in the shoe expansion direction so that the braking gap is always constant.

And, during the play, the shoe 2.2' sieve: 1'
1. ．． :1 The free end 2b-2 is expanded by the cam collar 12#12' provided on the shoe pushing part of the cam part 5a, and the cam part 5
Since the brake shoe 2.2' is adjusted apart from the opposing surface 56156' of the lining 20
1 20' expands as a fulcrum, and the outer circumferential side of the shoe web road end portion 2k) s2b' may be separated from the opposing surface 56e56' of the cam portion 5a from the inner circumferential side. is in contact with the outer circumferential side of the shoe web road edge portion 2b on the leading side, and the cam collar 12' is in contact with the outer circumferential side of the shoe web road edge portion 2b on the trailing side.
The friend that is in contact with the inner circumferential side of b', the cam member 5 during braking
The amount of 0 rotation is accurately transmitted from the cam collar 12t12/ to the leading and trailing side brake shoes 2, 2', and the brake shoes 2.2' are expanded::
:・ No loss occurs. □Furthermore, even if the brake operating wire 8 is stretched due to repeated braking, the shears 2 and 21 are always urged toward each other by the return spring 4 during play, as shown in FIG. A pressing force is applied from both sides of the cam portion 5aK of the cam member 5, and the cam m5a is held in a reversed state at one time in one direction depending on the amount of elongation of the operating wire 8 during play. According to this K, □ lining 2'c,
Although the braking gap between 20' and the inner circumferential surface of the play drum becomes larger, during braking, the amount of rotation of the cam member 50 increases as the brake arm 7 rotates, which causes the relative adjustment of the adjustment gear 14 described above. The amount of rotation increases, and the adjustment lever 21 includes an extension pipe of the brake operation wire 8, and meshes with the teeth 140 of the adjustment gear 14 to adjust the braking amount we to a constant value.

As described above, according to the present invention, the cam collar tube overlaps at the initial stage of assembly, and the cam width of the cam part of the cam member is made as small as possible, making it particularly suitable for small mechanical drum brakes, and also making it easier to release the brake shoe. The return characteristics are good, and the cam part does not stick or return defects occur, and smooth to reliable control movement can be obtained. In addition, since the cam collar tube combined with the shoe pushing part on the opposing surface of the cam part is brought into contact with the edge of the shinny web, the rotational force of the cam member during braking is transmitted from the cam collar to the edge of the shoe web without loss. During play, the shoe expands in response to the rotation of the arm during play, providing quick and reliable braking. Furthermore, even if the brake operating wire that activates the brake arm is stretched due to repeated braking, the amount of rotation of the cam member is increased by t%, so the extension of the brake operating wire can also be adjusted. This has the effect that the braking gap is always constant.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention; FIG. 1 is a front view, FIG. 2 is a rear view, FIG. 3 is a cross-sectional view taken along line II in FIG. 2, FIG. The figure is an exploded perspective view of the cam member, cam collar, actuating member, washer, adjustment gear, adjustment lever, and feed pawl. Figure 6 is a sectional view of the main parts before braking gap adjustment. Figure 7 is the main part after braking gap adjustment. cross-sectional view of the section,
FIG. 8 is a cross-sectional view of the main part in a state where the operating wire is stretched during n play and the cam member is reversed and contains water. l is back plate, 2.2't! Brake shoe, 5
is the cam member 1.7 is the brake arm; 9. 9'ij
Cam collar groove, 10f1 operating member insertion hole, ilt! The operating members are 12*12' a cam collar, 14 an adjustment gear, 21 an adjustment lever, and a 22Fi feed pawl. Voice figure 1, jar figure 2 J[-! Figure 3 Figure 6 Lua factor, Figure 8 Figure 1. Procedural amendment 1. Indication of the incident 1982 Patent Application No. 110356 Address Nitsu Shinkogi Yotsu Name Nissin Kogyo Co., Ltd. As attached (1) "Adjust lever 21J tr stopper lever 21" on page 8, line 15 of the specification lff positive! . (2) “Forwarding” claw 2 in page 9, line 1O and line 13 of the same book.
2J l r Adjust lever 22” and correct it
1+・1 “Adjust lever 21” on page 10, line 7 of the same book.
” is corrected as “stopper lever 21” 0 (4) “Pry open” in line 11 of page 11 of the same book is corrected as “open” ◎ (5) Line 4 and 11 of page 11 of the same book "Feeding claw 2
2" was corrected to "adjust lever 22." Insert "11 operating member 11, ." next to "cam collar 12*12'," in the 10th line. (6) Insert the "adjust lever 22" next to the "actuating member 11J" in the 10th line of page 1 of the same book, and insert the "adjust lever 21J t'r stopper 2#1" in the 12th line.
Insert K "and adjustment lever 22°" after 2'J. (71 Ibid., No. 14 Purchase, 2nd line, "Feed pawl 22" is corrected as "Adjust lever 22." Masaharu corrects "adjust lever 21" in lines 2 and 3 and lines 7 and 8 to "stopper lever 21." (9) "Adjust lever 21" in line 12 of page 17 of the same book.
"" to "adjust lever 22 and stopper lever 2.
1FiJ @ 顛 Ibid., page 9. line. Correct “adjustment 2.2 and feed pawl” to “stopper lever and adjustment lever” 〇 bar, 22t! Send j) Correct the pawl J to "21 is the stopper lever, 22 is the adjustment lever."that's all

Claims (1)

[Claims] L A cam member is interposed between the free ends of a pair of playxignes whose base ends are pivotally supported on the pack plate, and the cam member is rotated by the brake arm, and the cam member is rotated by the brake arm, thereby opening the brake shoe TM. Mechanical drum play S? In the actuating member, a pair of opposing surfaces are formed in the cam portion of the cam member, and the shoe pushing portion of the opposing surfaces is provided with a cam collar groove having a tapered groove bottom. The cam collar is formed by inserting the insertion hole, and is slidably fitted into the cam collar groove of the knee so as to protrude in the expansion direction of the cam collar that abuts the road end of the knee web, and is further engaged with the end surface of the cam collar. The actuating member for pushing the cam collar is screwed into the actuating member insertion hole of the cam member, and the adjusting mechanism screws this actuating member so that it protrudes in the direction in which the cam collar 1 is expanded. Braking gap automatic adjustment device for mechanical drum brakes.