JPH0320128A - Automatic adjustor mechanism of drum brake - Google Patents

Abstract

PURPOSE:To easily demount a brake drum by forming a side groove parallelly to a main groove on a head of an adjusting bolt member and continuously thereto, which side groove is deeper than the main groove and engageable with an end of a second brake shoe, and thereby providing a spacer demountably. CONSTITUTION:In the case that a brake drum 1 is hard to demount at the time of maintenance or inspection of a brake device because of over-adjusting of an automatic adjustor mechanism or stepped abrasion of the brake drum 1, a spacer 9 which is installed on a side groove 8d formed on a head of an adjusting bolt member 8 is demounted. The length of the automatic adjustor mechanism is shortened with just one operation, that is, by dropping an end of a second brake shoe 2 into the side groove 8d. As a result, the clearance between the second brake shoe 2 and the brake drum 1 is enlarged in accordance with the difference between the depth of a main groove 8c and that of the side groove 8d, and the brake drum 1 is easily demounted.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an improvement in an auto-adjuster mechanism for a drum brake, and in particular, when the auto-adjuster mechanism is over-adjusted or when the brake drum is removed. To provide an auto-adjuster mechanism for a drum brake, in which the auto-adjuster mechanism can be easily reduced with one touch to easily remove a brake drum when it is difficult to remove the brake drum due to stepped wear.

[Conventional technology]

As a conventional drum brake auto-adjuster mechanism, for example, the one described in Japanese Utility Model Application Publication No. 1988-102041 is known. As shown in FIGS. 4 and 5, this conventional mechanism has a first brake shoe (this is not shown, but a fourth
It is placed on the left side of the drawing in the figure. ) and the second brake shoe 2 are arranged. The left end of the strut 3 is in contact with one end of the first brake shoe, and the strut 3 extends toward the end of the second brake shoe 2. An insertion hole 3a is formed at the right end of the strut 3. In this insertion hole 3a,
The bolt part 4a of the adjustment bolt member 4, which has a bolt part 4a and a head 4b, is fitted so as to be slidable in the axial direction, and a second groove part 4c is formed in the head part 4b of the adjustment bolt member 4. The ends of brake shoe 2 fit and come into contact. An adjustment wheel 5 is screwed onto the outer periphery of the bolt portion 4a of the adjustment bolt member 4 with its end surface facing the end surface of the strut 3, and a one-way ratchet 5a is formed on the outer periphery of the adjustment wheel 5. An adjustment lever 6 that operates in conjunction with a service brake or a parking brake is engaged with this one-way ratchet 5a. A spring (not shown) is installed between the end of the first brake shoe and the end of the second brake shoe 2 to bias the distance between the two. This conventional drum brake auto-adjuster mechanism is
When the clearance between the brake shoes and the brake drum l becomes excessive due to wear of the linings of the first and second brake shoes 2, the adjustment wheel 5 is rotated by the adjustment lever 6 when the service brake or parking brake is activated. Then, the adjustment bolt member 4 is slid in the direction of extension from the strut 3 to enlarge the distance between the ends of the first and second brake shoes 2, and the clearance is automatically adjusted to a predetermined value. [Problem to be Solved by the Invention] However, in such a conventional drum brake auto-adjuster mechanism, when the brake drum 1 is removed for maintenance or inspection of the brake device, the connection between the brake drum l and the brake shoes is When the clearance is over-adjusted or the brake drum 1 has stepped wear, it is not easy to remove the brake drum 1 due to insufficient clearance, and therefore the back plate (not shown) must be removed. The brake drum 1 must be removed by rotating the adjustment wheel 5 while pushing the adjustment lever 6 out of the small adjustment hole to reduce the length between the left end of the strut 3 and the right end of the adjustment bolt member 4, which reduces work efficiency. The problem was that it was extremely bad.

This invention was made by focusing on these conventional problems, and even if the auto-adjuster mechanism is over-adjusted or the brake drum is worn in stages, it can easily adjust the brake drum. The purpose is to provide a removable drum brake auto-adjuster mechanism. [Means for Solving the Problems] Therefore, the drum brake auto-adjuster mechanism according to the present invention includes a strut whose one end abuts the end of the first brake shoe and has an insertion hole at the other end, and the strut. An adjustment bolt member having a bolt portion that fits slidably in the axial direction into the insertion hole of the second brake shoe, and a head formed with a main groove portion that fits into the end of the second brake shoe, and a bolt of the adjustment bolt member. an adjustment wheel that is threadedly engaged with the strut and has a one-way ratchet on the outer periphery; an adjustment lever that rotates the adjustment wheel in one direction in conjunction with the service brake or parking brake and extends the adjustment bolt member from the strut; and a spring that biases in a direction to reduce the distance between the ends of the second brake shoe. The present invention is characterized in that a side groove is formed which is deeper than the main groove and into which the end of the second brake shoe can fit, and a spacer is removably attached to the side groove. [Operation] When maintaining or inspecting the brake system, if the auto-adjuster mechanism is over-adjusted or the brake drum is worn in stages, and the brake drum cannot be easily removed, remove the head of the adjustment bolt member. The length of an auto adjuster mechanism can be reduced with one touch by removing a spacer attached to a side groove shaped like this and dropping the end of a brake shoe into the side groove. As a result, the brake drum is removed with the clearance between the brake shoes and the brake drum expanded to correspond to the difference in depth between the bottom of the main groove and the bottom of the side groove. [Example] An example of the present invention will be described below with reference to the drawings. First, I will explain the structure.

In Figures 1 and 2, parts that are the same as those in the conventional mechanism described above are given the same reference numbers. A first brake shoe (not shown, but placed on the left side of the drawing in FIG. 1) and a second brake shoe 2 are arranged opposite to the inner peripheral surface of the brake drum 1. A strut 3 is attached to one end of the first brake shoe.
The left end of the brake shoe 2 abuts the strut 3, and the strut 3 extends toward the end of the second brake shoe 2. An insertion hole 3a is formed at the right end of the strut 3. A bolt portion 8a of an adjustment bolt member 8 having a bolt portion 8a and a head 8b is fitted into the insertion hole 3a so as to be slidable in the axial direction thereof.
The end of the second brake shoe 2 fits into and comes into contact with the main groove 8c formed in the head 8b of the adjustment bolt member 8. A side groove part 8d is formed in the head part 8b, parallel to and continuous with the soil groove part 8c, which is deeper than the main groove part 8C and into which the end of the second brake shoe 2 can fit. Then, the spacer 9 is attached to the side groove 8d with the end of the second brake shoe 2 fitted into the upper groove 8c. This spacer 9 has protrusions 9a and 9b, and has a head 8b.
This prevents it from coming off.

An adjustment wheel 5 is screwed onto the outer periphery of the bolt portion 8a of the adjustment bolt member 8.
A one-way ratchet 5a is formed on the outer periphery of.

An adjustment lever 6 that operates in conjunction with a service brake or a parking brake is engaged with this one-way ratchet 5a.

Further, between the end of the first brake shoe and the end of the second brake shoe 2, a force is applied in a direction to reduce the gap between the two, thereby maintaining the clearance between the brake shoe and the brake drum 1. A spring (not shown) is attached.

Next, the operation of the above embodiment will be explained.

When the clearance between the brake shoes and the brake drum 1 becomes excessive due to wear of the linings of the first and second brake shoes 2, the adjustment wheel 5 is moved by the adjustment lever 6 when the service brake or parking brake is activated. Rotate and slide the adjustment bolt member 8 in the direction of extension from the strut 3 to enlarge the distance between the ends of the first and second brake shoes 2 and automatically adjust the clearance to a predetermined value. do.

When removing the brake drum 1 for maintenance or inspection of the brake system, if the clearance between the brake drum 1 and the brake shoes is overadjusted, or if the brake drum 1 has stepped wear, the adjustment bolt member should be removed. The spacer 9 attached to the side groove 8d formed on the head 8b of 8 is attached to the side groove 8d.
Remove from. For this removal, use a tool such as a screwdriver to connect the protrusion 9b of the spacer 9 to the adjustment bolt member 8.
and the head 8b of the tool and twist the tool. As a result, the projection 9a of the spacer 9 can be removed by riding over the head 8b while elastically deforming the tow 8b in a direction in which the groove width of the side groove 8d of the head 8b is expanded. Therefore, as shown in FIG. 3, a second
When the end of the brake shoe 2 is dropped into the upper groove part 8c
The distance between the left end of the strut 3 and the right end of the adjustment bolt member 4 can be reduced with one touch by the difference in the depth of the side groove portion 8d. Therefore, the spacing between the two brake shoes is reduced by the spring (not shown), and the clearance between the two brake shoes and the brake drum is increased, so that the brake drum l can be easily removed.

Note that the protruding portion 9a of the spacer 9 may be plastically deformed and come out from the side structure portion 8d during the removal. When reinstalling the brake drum 1, insert a second groove into the main groove 8C formed in the head 8b of the adjustment bolt member 8.
The ends of the brake shoes 2 are fitted together, and the spacers 9 are installed in the side grooves 8d in advance. [Effects of the Invention] As explained above, according to the drum brake auto-adjuster mechanism according to the present invention, the main groove formed in the head of the adjustment bolt member is parallel and continuous, and the depth is greater than the upper groove. Since the side groove is deep and into which the end of the second brake shoe can fit, and the spacer is removably attached to the side groove, even if the auto-adjuster mechanism is over-adjusted or Even if the brake drum has stepped wear, the effect is that the brake drum can be easily removed by simply removing this spacer.

[Brief explanation of drawings]

Fig. 1 is a cutaway front view of essential parts showing an embodiment of an auto-adjusting star mechanism for a drum brake according to the present invention, Fig. 2 is a sectional view taken along line 1 and 2 in Fig. 1, and Fig. 3 is an embodiment of the above-mentioned embodiment. Fig. 4 is a cutaway front view of main parts similar to Fig. 1 showing an example of the auto-adjuster mechanism of a conventional drum brake; −
It is a sectional view taken along the V line. 1... Brake drum, 2... Second brake shoe, 3... Strut, 5... Adjustment wheel,
6... Adjustment lever, 8... Adjustment bolt member, 8a... Bolt part, 8b... Head, 8C...
・Main groove part, 8d... Side groove part, 9... Spacer. Figure 1

Claims (1)

[Claims] An auto-adjuster mechanism disposed between opposing ends of one side of first and second brake shoes disposed to face the inner circumferential surface of a brake drum, the end of the first brake shoe a strut having one end in contact with the strut and having an insertion hole in the other end; a bolt part that fits into the insertion hole of the strut so as to be slidable in the axial direction; and a bolt part that fits into the end of the second brake shoe. an adjustment bolt member having a head portion with a main groove formed therein; an adjustment wheel screwed into the bolt portion of the adjustment bolt member and having a one-way ratchet on its outer periphery; A drum that rotates a wheel in one direction and includes an adjustment lever that extends the adjustment bolt member from the strut, and a spring that biases in a direction to reduce the distance between the ends of the first and second brake shoes. In the brake auto-adjuster mechanism, the main groove is formed in the head of the adjustment bolt member in parallel with and continuous with the main groove, the depth is deeper than the main groove, and the end of the second brake shoe is fitted into the main groove. 1. An auto-adjuster mechanism for a drum brake, characterized in that a side groove portion that can be adjusted is formed, and a spacer is removably attached to the side groove portion.