Патент USA US2105560код для вставки
Jan. _18, 1938. E. STIFT BRAKE MECHANISM Filed Dec. 30, 1935 2,105,560 Patented 2,105,560 18, 1938 UNITED STATES» PATENT OFFICE ' ' i 2,105,560 ’ ` . « . ` BRAKE MECHANISM , Edward Stift, St. Louis, Mo. Application December 30, 1935. Serial No. 56,618 5 claims. (c1, 18s-79.5) This invention relates to brake mechanism for vehicles and more particularly brakes of the in-` ternal expansion type. , f ,y An object of this invention is to providev brake Gl mechanism simple in construction and efficient in operation. which will expand brake shoes positively in a radial direction to secure uniform contact with a cooperating surface, or brake drum, throughout the entire surface'of the brake 10 shoes and which will be self-adjusting to auto-k matically provide a certain minimum‘and a cer tain maximum clearance between the brake shoes and thecooperating surface. Other and specific objects will be apparent from 15 the following detail description taken in connec tion with the accompanying drawing. Fig. 1 is a front elevation of brake mecha -nism embodying my invention; ' ' Fig. 2 is a vertical section approximately on l 20 line 2_2, Fig. 1; Fig. 3 is a rear elevation; and Fig. 4 is a vertical section approximately on ' line 4_4, Fig. 2. < A cam ring I is mounted for rotation on a 25 lsupport 2 and has a plurality of cam surfaces 3 about its periphery. A plurality of brake shoes 4 are mounted about the periphery of the ring and are adapted to be pressed outwardly by the ` Inner washers Il and outer washers 'IB on the> studs I3 engage the faces of the ring I and prop erly space and hold the ring against axial dis placement. _ y Each of the brake shoes ß has a pair of in- 5 wardly extending flanges I6. Pins I'I secured in the flanges I6 carry rollers I8, which ride the periphery of the ca_m disc I and which are en gaged by a cam surface 3. In the specific em bodiment shown four brake shoes are provided, Io each having two rollers I8 and there being eight cam surfaces on the ring. „ The brake shoes are held Íagainst circumfer ential movement by lugs I9, which are secured to or integral with the support 2 and extend l5 inwardly to engage the edges oi’ the flanges I6. The flanges I6 on the respective brake shoes A provide rigidity .for the shoes which are moved outwardly as a unit'in a radial direction by the action of the cam ring I. The side edges of the 2o ñanges I6 are straight and are parallel to the radius of movement so that lugs I9 contacting those edges serve as guides for the shoes, re straining the shoes from movement in a circum ferential direction and thereby prevent chat- g; tering of the brake., ` Springs 20 connect adjacent ends of the brake shoes 4 and contract the brake shoes when the can-i` surfaces 3 upon rotation of the ring. Springs cam disc is rotated to normal position. 30 5 connected between the ring I and the support In the operation of the device the bell crank ,an 2 return the ring to and tend to hold it in av lever I0 is rotated by a rod 2|, which' may be ñxed normal position. This normal position is connected to a foot pedal or lever not shown. automatically ñxed by mechanism . comprising ' The pawl 8 being engaged in 'a notch in the undercut teeth 8 on the inner surface of the 35 ring and a spring pressed pawl 1 pivotally mounted on the support 2. The cam ring I is rotated by a ratchet mechanism comprising a Y pawl 8 and a raton-9, the pawl being carried by a bell crank lever I 0 pivotally mounted on the 40 support 2. ` - The foregoing comprises a summary of the embodiment of the invention specifically illus trated in the accompanying drawing. The es sential features of the invention are pointed out ratch 9 will rotate the cam disc I in a clock wisel direction (Figs. 1 and 4). The cam sur- :z5 faces 3, bearing against the rollers I8, press the brake shoes outwardly uniformly throughout their entire surface to contact a cooperating sur face which may be the inner circumference of a brake drum, not shown but well understood in 4o the art. If the clearance between the brake shoes in their starting position and the brake drum is excessive due to wear or ,for other reasons the ring I will be rotated by the ratchet such a dis tance that the pawl 1 will be urged by its spring 45 22 into a succeeding notch 6. Upon release of 45 in the appendedl claims but the following detail description will assist in understanding and practicing the invention. . the rod 2|, the springs 5 will rotate the cam disc The support 2, as speciñcally shown, comprises Il in a counter-clockwise direction with the a plate which is ?lxed to an axle vor'axle hous springs 20 contracting the brake shoes 4 while 50 ing. A front automobile axle is shown in the' the rollers I8 ride the cam surfaces 3. The teeth 5G drawing, the support 2 being attached thereto 6 being undercut provide a suiïlcient rotation of by screws II. 'I'hecam ring I is mounted for va cam disc I in a counter-clockwise direction so rotation on the support 2 by having its inner as to allow a ñxed minimum clearance between circumference bearing on rollers I2 which are the brake shoes and the cooperating drum. This 55 supported by studs I3 secured to the support 2.‘ clearance will be in actual practice at least .01 56 '.42'inch. 2,105,500 l It will be seen lthat the function of the pawi ‘I `and the undercut teeth l is to ilx a nor mal position for the cam discA l so as to auto-= position including undercut teeth on the ring and a spring pressed pawl carried by the support and engaging the teeth. ` _ ' 4. In brake> mechanism, the combination com matically adjust Lthe clearance between the brake » prisihg a support, a cam ring rotatively mounted shoes and its cooperating drum. It `will be understood that various changesV may on the support, a plurality of brake shoes about be made in the details oi' construction, withinl the periphery‘of said ring- and adapted to be pressed outwardly by rotation of the ring, yielding the scope of the appended claims, without de means for returning and holding the ring to and parting from the spirit of this invention. _ 10 I claim: ' ’ l. In brake mechanism, a cam ring positioned and adapted when rotated to expand brake shoes, and means for automatically iixing a normal po sition of said ring including undercut teeth on .in a normal position, yielding means for con tracting the shoes. a ratch onv the ring, a lever, a pawl'carried by the lever engaging the ratch, and means for automatically ilxing such. normal position including undercut teeth on the ring and the ring and a spring pressed pawl for'engaging a spring pressed pawl carried by the support and ' the teeth. engaging the teeth. . 2. In brake mechanism, a cam ring positioned 5. In a brake mechanism the combination com and adapted when rotated to expand brake shoes, prising a support, a plurality of rigid brake shoes. a ratch on the ring, a lever. a pawl carried by a pair of inwardly extending ñanges on each or” 20 the lever engaging the ratch, and means for psaid shoes and spaced from each other, a pair automatically ñxing a normal position of thee'ringA of rollers Journalled between the flanges on each including undercut teethon the ring and a spring shoe, a ring mounted on the support and havinga cam surface on its outer periphery arranged pressed pawi engaging the teeth. . `and adapted to contact all of said rollers and 3. In brake mechanism, the combination com 25 prising a support, a cam ring rotatively mounted thereby upon rotation to press the shoes outward on the support, a plurality ci brake shoes about ly in a radial direction by its rotation, straight the periphery _of said ring and adapted to be pressed outwardly by rotation of the ring, yielding means for returning and holding the ring to 30 and in normal position, yielding means for con tractlng the shoes, means for rotating the ring, and means for automatically ilxing such normal edges at the ends of the flanges parallel to the radius of movement of the shoes, Iand means on the support contacting said edges to restrain the shoes against circumferential movement. EDWARD s'rrs'r.