Spot-type disc brake

Abstract

There is disclosed a spot-type disc brake having a non-rotating brake carrier to receive the brake torque with brake shoes disposed on both sides of the brake disc. A yoke or frame embraces the disc and is movably guided in the brake carrier and held without clearance by resilient means. The frame transmits the operating force of an actuating device to the brake shoe disposed on the side of the disc remote from the actuating device. The frame is rigidly supported at and movable with respect to three guide points on the brake carrier. A biased spring is disposed between the brake carrier and frame. The spring tensions forces the frame at against its guide points and the spring force acts on the frame at a point distant from the three guide points.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of application Serial No. 209,233, filed November 19, 1980, now abandoned, which is a continuation of application Serial No. 021,053, filed March 16, 1979, now abandoned, which is a continuation of application Serial No. 842,008, filed October 13, 1977, now abandoned, which is a reissue application of Serial No. 479,934, filed June 17, 1974, now Patent No. 3,913,709. tension hold frame 3 relative to against brake carrier 1. Spring 17 has two arms 18 projecting into holes 19 in the plate of brake carrier 1 and are jammed in the brake shoe backing plate by deflections 20 at the ends of arms 18. Spring 17 is bent at arms 18 projecting out of holes 19, and--supported at the brake shoe backing plate--is guided underneath the housing of actuating device 6, and is designed with a loop 21 projecting to the outside, the end of which rests against the bottom surface 22 of the housing of actuating device 6 under tension. This contact surface 22 is designed in a way that it has a slant which inclines from the region close to brake disc 5 to the region distant from brake disc 5. This results in a horizontal force component of spring 17 which assists in bringing about a reset to the necessary brake lifting clearance after a braking process. The vertical component of spring 17, acting on the housing of actuating device 6, which is rigidly connected with frame 3, tensions frame 3 in such a way that frame 3 is forced radially to the inside and is supported by slot 15 of brake shoe 10 by means of frame pin 16 and is forced radially to the outside against the guide points GPI and GPII defined by bolts 4. Owing to the fact that these guide points GPI and GPII are arranged as far as possible on the outer edge of frame 3, big and favorable levers are provided with the help of which--even with greater forces from the outside--only low spring forces are necessary in order to avoid a lifting of frame 3 from the guide points GPI and GPII (bolts 4) at the brake carrier. Slot 15 and pin 16 provide a third guide point GPIII.

If nevertheless, these forces from the outside overcome the spring force of spring 17, frame 3 will move away from the rotation contour of the wheel dish in the direction of the wheel axis, because the center of gravity of the frame with the members carried by the frame is between the point of application of force of spring 17 and the axis passing through bolts 4. This permits an arrangement of the brake close to this rotation contour of the wheel dish, and, thus, the brake can take advantage of a larger brake disc diameter.

Moreover, owing to the tensioning forcing of brake shoe 10 in the direction of the wheel axis, and as a result of the friction between brake shoe 10 and the support surface at arm 7 or 8, with the support surface absorbing the brake forces, brake shoe 10 is impeded from rotating round one of holding pins 12 so that a sudden bouncing of brake shoe 10 at one of its holders is avoided.

The embodiment illustrated in FIG. 5 shows a spot-type disc brake having a brake carrier 1 to which the actuating device 6 is fastened. Frame 3 is supported at one side by a pin 28 projecting into a slot 26 in the brake piston 27 on the back side of actuating device 6.

In the middle region of the brake, frame 3--such as in the preceding embodiment--is upwardly supported by two bolts 4 fastened to the brake carrier 1. The holding pins 23 which are to suspend the brake shoes 9 and 10 are designed with loops 24 at their ends and engage slots of a holder 25 disposed on frame 3. Holding pins 23 and loops 24 are made out of a resilient material and are mounted under prestress directed radially to the outside.

Owing to this resilient design of holding pins 23, the middle region of frame 3 is pressed against bolts 4, and the other end of frame 3 is supported with its pin 28 in slot 26.

Owing to the fact that holding pins 23 with their loops 24 tension force the frame 3 relative to against bolts 4 in the direction of the rotation contour of the wheel dish and that frame 3 is supported at the third immovable guide point with its pin 28 in slot 26 in brake piston 27, frame 3 cannot move further in the direction of the rotation contour of the wheel dish.

The only possibility--which, however, is unlikely on grounds of the leverages--that frame 3 can be lifted from its guide points is when the spring forces of the holding pins 23 are overcome. If such a lifting movement occurs, frame 3, however, will move away from the wheel dish. Thus, it is possible to arrange the brake very close to the rotation contour of the wheel dish and to take advantage of a favorable, largest possible brake disc diameter in this arrangement. With regard to this embodiment the support of brake shoe 10 has no influence on the direction of the prestress in the spring, since the brake forces are absorbed close to their line of application.

While we have described above the principles of our invention in connection with specific apparatus it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of our invention as set forth in the objects thereof and in the accompanying claims.

Claims

1. A spot-type disc brake comprising:

a brake disc;

a brake actuating means;

a pair of brake shoes each having a backing plate and a brake pad, one of said brake shoes being disposed on one side of said disc actuated by said actuating means and the other of said brake shoes being disposed on the other side of said disc;

a non-rotating brake carrier carrying said brake shoes and receiving braking torque, said carrier being immovable relative to said disc;

a frame embracing said disc and movably guided with respect to said carrier in a direction toward and away from said disc, said frame transmitting the actuating force of said actuating means to said other of said brake shoes;

said brake actuating means including a housing rigidly connected to said frame and having a force receiving contact surface below said frame which is inclined upward toward said frame in a direction away from said disc;

at least three guide points to rigidly support and movably guide said frame, at least two of said guide points being rigidly connected to said carrier; and

a biased spring having two arms each engaging a different one of two circular holes formed in and extending through said carrier parallel to, spaced from and below said frame and a loop interconnecting said two arms under tension resting against said contact surface to apply a horizontal and vertical component of force to a point on said contact surface to hold said frame without clearance against said guide points, said point on said contact surface being spaced from said guide points;

each of said arms including deflection on the ends thereof fastened in an associated one of said holes of said carrier and fastened in said backing plate of said one of said brake shoes.

2. A brake according to claim 1, wherein

said point on said contact surface is disposed outside an imaginary triangle formed by imaginary lines interconnecting said guide points.

3. A brake according to claim 1, wherein

said two of said guide points include two bolts immovably secured to said carrier.

4. A brake according to claim 3, wherein

said two bolts are disposed on an axis parallel to said disc.

5. A brake according to claim 4, wherein

the third of said guide points includes

a recess in a backing plate of said other of said brake shoes, and

a pin formed in said frame engaging said recess.

6. In a spot-type disc brake having

a brake disc;

a brake actuating means;

a pair of brake shoes, one of said brake shoes being disposed on one side of said disc and actuated by said actuating means, and the other of said brake shoes being disposed on the other side of said disc;

a non-rotating brake carrier receiving braking torque, said carrier being immovable relative to said disc;

a frame or yoke element embracing said disc and movably guided with respect to said carrier in a direction toward and away from said disc, said element transmitting the actuating force of said actuating means to said other of said brake shoes; and

said brake actuating means including a housing and being in force transmitting contact with said element;

the improvement comprising only three guide points to rigidly support and movably guide said element, two of said guide points being rigidly connected to said carrier and disposed above said element to rigidly support and movably guide said element, said two of said three guide points exerting a downward force on said element and a third of said three guide points being disposed in one of said actuating means and a backing plate of said other of said brake shoes, said third of said three guide points exerting an upward force on said element; and

a single biasing spring having at least one end connected to said carrier at a point radially spaced from said two of said three guide points and said element and another portion thereof acting on one of said actuating means and said element to apply an upward component of force to hold said element without clearance against all of said three guide points;

said spring acting on said one of said actuating means and said element at a point spaced axially from all of said three guide points, said point being outside an imaginary triangle formed by imaginary lines interconnecting all of said three guide points;

said actuating means being secured to said element;

said third of said three guide points including

a recess in a backing plate of said other of said brake shoes, and

a pin formed in said element engaging said recess; and

said spring is fastened to said carrier and acts on said actuating means, said spring projecting away from said carrier and disposed under said element and said actuating means;

said spring being a wire spring having two arms fastened in holes of said carrier and a loop acting upwardly on said actuating means;

said actuating means including

a contact surface for said loop of said spring which is inclined upward toward said element in a direction away from said disc.

7. A brake according to claim 6, wherein

said two of said guide points include

two bolts immovably secured to said carrier. 8. A brake according to claim 7, wherein

said two bolts are disposed on an axis parallel to said disc.

9. A brake according to claim 1, wherein

each of said arms includes

deflections on the end thereof fastened in an associated one of said holes of said said carrier.