Brake shoe lining bonding fixture

A brake shoe lining bonding fixture wherein a brake shoe support is encompassed by a tension band which has a shoe support with radial finger locators and buffer pads at each end of the shoe to carry the band near the ends of the pressured brake lining to prevent corner crushing of the lining. A pressure bar to urge the shoe support against the tension band is interengaged with guide slots on the shoe support and lies in contact with a heavy leaf spring to maintain pressure when mechanically applied and locked in to the shoe support mechanism.

This invention relates to a Brake Shoe Lining Bonding Fixture and more 
particularly to that type of apparatus in which a brake shoe lining is 
bonded to a brake shoe under the conditions of heat and pressure to 
eliminate the need for riveting. 
BACKGROUND OF INVENTION 
For quite some time, it has been known to bond brake shoe linings to the 
curved surface of a brake shoe which is sometimes called a brake shoe 
table. This bonding is done with a special adhesive which is applied to 
the contacting surfaces after which pressure is applied around the surface 
of the brake shoe and the entire fixture is passed through a heating oven 
which causes a setting of the bonding material. Other related patents on 
this subject are U.S. Pats. to Morgan et al, No. 3,638,560, and Morgan et 
al 3,752,062. 
The present invention relates to an improvement in what might be called the 
band type device in which reinforcing structures are provided for the 
brake shoe itself and a band is placed around the outside to clamp the 
brake shoe lining prior to heating. 
One of the problems in connection with this type of device has been the 
elimination of the crushing of the corners of the brake shoes where the 
band passes around the lining and also to eliminate undue strain on the 
band itself to prevent distortion and breaking. 
Another problem has been the method of holding the band pressure while the 
device is being passed through the heat zone. 
It is an object of the present invention to provide a base support for a 
brake shoe which provides ample structural strength to prevent distortion 
of the brake shoe while permitting the passage of heat into the bonding 
areas. 
It is a further object to provide a device in which the pressure can be 
applied and maintained during the heating cycle and yet easily released 
when the bonding is complete. 
Other objects and features of the invention relating to details of 
construction and operation will be apparent in the following description 
and claims in which the principals of the invention are set forth together 
with details of the structure which would enable a person skilled in the 
art to practice the invention all in connection with the best mode 
presently contemplated.

DETAILED DESCRIPTION 
With reference to the drawings, in FIG. 1, two brake shoe support fixtures 
10 and 12 are shown in opposed relationship at each end of the figure. 
Each unit consists of an arcuate wall 14 which extends from a horizontal 
diametrical bar 16 that terminates in curved surfaces 18. This structure 
results in openings 20 and 22 which allow the passage of air and 
circulation through the device. 
The arcuate elements 14 are slotted at 24 in an arcuate slot which extends 
around to penetrate also the solid diametrical bar 10 at the ends. Each of 
the arcuate elements 14 is provided with semicircular surface slots 26 
which facilitate the flow of air during the heating cycle in addition to 
the open slot 24. The bottom arcuate member 14, illustrated in FIG. 3, has 
spaced radial lugs 30 which project therefrom to provide a supporting 
ledge for a brake shoe which is mounted on the device. 
A solid reinforcing strut 32 extends between the diametrical bar 16 and the 
center of the semi-circular runs 14 to provide a rigid support and it will 
be seen that forward of each of the surfaces 18 is a shoulder 34 which 
provides room for the brake shoe and the brake lining to seat within the 
circumferential confines of the two surfaces 18. Above and below the 
reinforcing bar or wall 32 are surface slots 35 which serve as guides. 
Extending toward the center of the assembly, as shown in FIG. 1, directly 
above and below the reinforcing strut 32, are straight upper and lower 
bars 36 and 38, the central ends of which are rigidly attached to a 
cross-piece 40 composed of spaced wings 42 connected by a rigid central 
pillar 44 which has an inwardly projecting pressure lug 46 with an angled 
face 48. The upper and lower bars 36 and 38 are dimensioned to slide in 
the slots 32 so that the assembly, which is composed of these bars 36 and 
38 and the central member 40, will slide back and forth in relation to the 
basic brake shoe support. 
A surface recess 50 is formed in the front face of the diametrical bars 16 
and in front of this recess is mounted an extremely heavy leaf spring 
element 52 loosely retained endwise by recessed studs 54 and retained 
against dislodgement by headed bolts 56. It will be noted that the wings 
42 are angled back toward a central portion 58 which bears against the 
central area of the spring 52. 
In FIG. 4, there is illustrated a view of one of the support fixtures 10 
taken at a chordal face on line 4--4 of FIG. 1. The spaced radial, 
bottom-support lugs 30, shown in FIGS. 1 and 2, appear at the bottom of 
FIG. 4 as do also round support pads 31 shown in dotted lines in FIG. 2. A 
cored open cavity 106 (shown in dotted lines in FIG. 2) substantially 
rectangular in shape appears at each side of the face of the fixture 10 
and a rectangular window 102 appears in the cavity 106 by reason of the 
arcuate slot 24 which extends around the entire fixture except for the 
vertical pillars 104 adjacent the chordal face of the fixture. The pins 54 
shown in FIG. 1 also are shown in FIG. 4 as well as the holes for the 
headed bolts 56 shown in FIG. 2. Centrally of FIG. 4 is a radial rib 32 
shown in dotted lines and underlying the operating groove 35 for the slide 
bar 36 shown in FIGS. 1 and 2. 
As shown best in FIG. 2, central tubular risers 60 are held by bolts 62 on 
the forward end of bars 36 to form pillars for a bridging cross-piece 64 
which carries a vertically disposed rod 66 having a washer and nut 68 and 
70 respectively at the top end and carrying a coil spring 72. At the 
bottom of this rod 66 is a wedge 74 which has opposed sides angled to 
conform to the angles of the extensions 46. On each side of the wedge 74 
are guide plates 76. The bolt 62 is retained in a slot 78 in the bridge 
portion 64 to allow a limited free movement. 
In the operation of the device, a brake shoe is first assembled on the 
arcuate support 14. This brake shoe 80 has a central web which is 
illustrated at 82, this web extending into the slot 24 between the 
portions 14 of the arcuate support. A small indentation or deformation 84 
interfits in a suitable recess 86 to locate the brake shoe. The brake 
lining 90 is then placed on the brake shoe or the two may be pre-assembled 
if desired with the bonding material interposed in the area 92 between the 
lining and the brake shoe. 
A similar assembly is made at the other end although in FIG. 1 the device 
is shown without a part at the right-hand end. Then a closed band 96 is 
placed around the assembly and a suitable expanding device is applied to 
the wings 42 to tighten the entire assembly against the constraint of the 
band. The tightening device for this type of thing is illustrated in the 
two patents above referenced in the introduction. Once the prescribed 
pressure has been placed on the assembly, the wedge 74 is dropped into 
place between the projections 46 to maintain the pressure on the assembly. 
The pressurizing mechanism can then be released and the entire fixture 
handled as a unit and passed through a heating oven on a suitable 
conveyor. 
A significant part of the present invention is the curved surfaces 18 to 
serve as buffers for the band support and which are dimensioned such that 
they have an effective diameter 0.010 inch less than the brake lining 
diameter. This insures that adequate pressure is placed on the lining 
against the brake shoe but prevents a braking of the corners shown at 100 
which otherwise happens when the band is not properly supported as it 
comes off the brake lining. The apparatus described allows the application 
of extremely high pressures to the brake lining during the heating cycle 
and yet provides ample support to prevent damage to the linings under 
these great pressures which may range from 2500 to 6000 pounds per square 
inch.