1. Field of the Invention
This invention relates to a brake-actuating mechanism for use on a drum brake device, designed to mechanically move a pair of brake shoes away from each other in response to operation of a brake lever. More particularly, it relates to a brake cable connecting apparatus designed to prevent the inadvertent disconnection of a brake cable from the brake lever, even during the transportation of the drum brake device with the brake cable already connected to the brake lever of the brake-actuating mechanism.
2. Description of Related Art
Previously, one known type of a prior art brake cable connecting apparatus in a brake-actuating mechanism as described above is illustrated in FIG. 15, disclosed in the U.S. Pat. No. 5,311,793.
In FIG. 15, a pair of brake shoes is identified by reference numerals 1 and 2, respectively. A strut, a brake lever and a brake cable are identified by reference numerals 3, 4 and 5, respectively. The strut 3 and the brake lever 4 comprise an actuating mechanism 6.
One brake shoe 1 is functionally engaged with one end of the strut 3. The brake lever 4 is pivotally supported on the strut 3 in a state in which a proximal end of the brake lever 4 is pivoted about the other end of the strut 3 by means of a pivot pin 7. The other brake shoe 2 is functionally engaged with the proximal end of the brake lever 4. Notched grooves 4a are formed on a free end of the brake lever 4, with which a cable end 5a of the brake cable 5 is engaged in a cable operating direction.
If a cable operating force as shown in xe2x80x9cWxe2x80x9d is applied to the brake lever 4 via the brake cable 5, the brake lever 4 rotates around the pivot pin 7 in a correspond direction so as to push the brake shoe 2.
On the other hand, a rotation of the brake lever 4 around the pivot pin 7 as described above furnishes the strut 3 with a counteracting force via the pivot pin 7 so as to push the strut 3 leftward FIG. 15 together with the brake shoe 1.
Due to the movement of both brake shoes away from each other, the brake shoes 1, 2 are pushed against an inner circumferential surface of a brake drum not shown in FIG. 15, thereby providing a predetermined braking action.
However, the drum brake device is often transported in a condition that the cable end 5a is engaged with the brake lever 4. In such a case, the brake cable 5 can easily be disconnected from the brake-actuating mechanism 6, causing a notable decrease in work efficiency for connecting the brake cable and increasing a chance of misassembling of the brake cable.
The following structure is added to the brake-actuating mechanism 6 in order to prevent the inadvertent disconnection of the brake cable 5.
A distance between a free end surface of the brake lever 4 and an inner end wall 3a of the strut 3 is sized to reserve a sufficient clearance for the cable end 5a to pass through, into which a V-shaped plate spring 8 is inserted so as to normally plug the clearance. However, a tapered space 9 is formed between the V-shaped plate spring 8 and the free end surface of the brake lever 4 so as to guide an insertion of the cable end 5a. 
For connecting the brake cable 5 to the brake lever 4, the cable end 5a is temporary inserted in the tapered space 9 from the outside of the drum brake device as shown in a two-dot chain line in FIG. 15, and then the brake cable 5 with the cable end 5a is pushed into the tapered space 9 in the direction of an arrow xcex1.
During this process, the cable end 5a approaches against the tapered space 9 with resilient deformation, in the direction of an arrow xcex2, of the V-shaped plate spring 8. When the cable end 5a moves beyond the free end surface of the brake lever 4, the cable end 5a is snapped in and engaged with the notched grooves 4a of the brake lever 4 because of a resilient force, in an opposite direction of the arrow xcex2, of the V-shaped plate spring 8. Then, the V-shaped plate spring 8 returns to the initial position by the resilient force; therefore the clearance for the cable end 5a to pass through is plugged, thereby eliminating a chance of the disengagement of the cable end 5a from the brake lever 4.
Previously, another type of a conventional brake cable connecting apparatus in a brake-actuating mechanism is illustrated in FIGS. 16(a) and 16(b), disclosed in the Japanese Provisional Patent Publication Number 2000-103855. Same reference numerals in FIG. 15 are used for members and portions with same functions in FIGS. 16(a) and 16(b).
When the cable end 5a of the brake cable 5 engages with the notched grooves 4a on the free end of the brake lever 4, the cable end 5a is temporary positioned above the notched grooves 4a according to a process as shown in FIG. 16(a). Then, the brake cable 5 is operated as shown in arrows in FIG. 16(b) to snap the cable end 5a in the notched grooves 4a. 
If a drum brake device is transported in the condition that the cable end 5a is being engaged with the brake lever 4, in order to prevent the inadvertent disconnection of the brake cable 5 from the brake-actuation mechanism 6, the size of mouths on the notched grooves 4a is designed to be smaller than a diameter of the cable end 5a so as to snap in the notched grooves 4a with applying a large cable operating force xe2x80x9cWxe2x80x9d to the brake cable 5 at a final process as shown in the arrows in FIG. 16(b), thereby preventing the inadvertent disconnection of the brake cable 5.
However, between the above-described conventional ways of preventing the inadvertent disengagement of the cable end from the brake lever, the former way described in FIG. 15 requires the high-costly V-shaped plate spring 8 as an additional member which relatively increases the cost of the brake-actuating mechanism 6 while the latter way described in FIGS. 16(a) and 16(b) requires a larger cable operating force in a process of snapping the cable end in the notched grooves 4a, which not only decreases work efficiency for snapping the cable end in but also creates a chance of damaging and deforming the cable end 5a and/or the mouths of the notched grooves 4a during the process.
An object of a first invention is to provide a brake cable connecting apparatus which realizes a way to prevent the inadvertent disengagement of a cable end of a brake cable from a brake lever of a brake-actuating mechanism based on a different concept as used in the conventional ways or methods. This invention, which fundamentally using existing members without an additional member, accurately prevents the inadvertent disengagement of the cable end from notched grooves of a free end of the brake lever. Further, this invention eliminates necessary large cable operation force at the time of snapping the cable end in the notched groove. Accordingly, there is no need to sacrifice the work efficiency for connecting the brake cable and create a chance of damaging or deforming the cable end and/or the mouths of the notched grooves, thereby surely preventing the inadvertent disengagement of the cable end from the notched grooves.
An object of a second invention is to provide a brake cable connecting apparatus which achieves the same level of effectiveness as in the first invention by way of using a shoe return spring of a drum brake device.
An object of a third invention is to provide a brake cable connecting apparatus which achieves the same level of effectiveness as in the first invention by way of using a lever return spring comprising a brake-actuating mechanism.
This invention is a brake cable connecting apparatus of a brake-actuating mechanism for a drum brake. The brake-actuating mechanism comprising: a strut engaging with one of a pair of brake shoes at one end thereof; and a brake lever, being pivotally attached to the other end of the strut, engaging with the other of the brake shoes at the other end thereof. A cable end of a brake cable engages with a cable end engaging portion of the brake lever in a cable operating direction. A cable end stopper, preventing an inadvertent disengagement of the cable end from the brake lever in cooperation with the free end of the brake lever, is provided on the strut. When the cable end is operated to move toward the cable end engaging portion in the cable operating direction in a clearance between the stopper and the free end of the brake lever so as to engage the cable end with the cable end engaging portion of the brake lever, the cable end can pass through a clearance between the stopper and the free end of the brake lever because of a rotation of the brake lever against the returning force of the brake lever.
This invention still is a brake cable connecting apparatus as above, wherein the returning force of the brake lever is generated by a shoe return spring.
This invention yet is a brake cable connecting apparatus as above, wherein the returning force of the brake lever is generated by lever return spring.
If a cable operating force of a brake cable is transmitted to the brake lever via a cable end, the brake lever and a strut around their pivoting section relatively rotates to move the brake shoes.
In the first invention, the cable end stopper provided on the struts prevent an inadvertent disengagement of the cable end from the brake lever in cooperation with the free end of the brake lever; therefore the brake cable does not disengage from the free end of the brake lever in the brake-actuating mechanism while transporting the drum brake device prior to its assembly on a vehicle, thereby eliminating a chance of decreasing the work efficiency for connecting the brake cable and a misassembly of the brake cable.
Accordingly, if the cable end of the brake cable is engaged with the brake lever, when the cable end is operated between the stopper and the free end of the brake lever, the cable end can pass through a clearance between the stopper and the free end of the brake lever because of a rotation of the brake lever against the returning force of the brake lever; therefore the cable end may be engaged with the free end of the brake lever.
Accordingly, generating the returning force of the brake lever by the existing members, there is no need for additional members to prevent the inadvertent disengagement of the cable end from a cable end engagement recesses on the free end of the brake lever securely.
The cable end engages with the free end of the brake lever with a force only rotating the brake lever against the returning force of the brake lever. Therefore, this invention realizes an effective way to engage the cable end with the brake lever without large cable operation force, thereby preventing a sacrifice of work efficiency for connecting the brake cable, and damages or deformations of the cable end and/or the brake lever.
Further, this invention makes it possible to confirm the snapping of the cable end by feeling the cable operating force while rotating the brake lever against the returning force of the brake lever and the impact noise of the cable end abutting against the cable end engagement recesses.
The second invention achieves the same level of effectiveness as in the first invention by way of providing the returning force of the brake lever by using a shoe return spring in a drum brake device.
The third invention achieves the same level of effectiveness as in the first invention by way of providing the returning force of the brake lever by using a lever return spring.