Abstract:
A shoe brake has a brake element for generating a braking force has at least one brake element that is adjustably settable relative to the brake shoe. The brake element may include an arcuate or segment-shaped base plate that fits in a corresponding arcuate or segment-shaped recess in the brake shoe and is adjustably mounted to the brake shoe by a pair of side panels.

Description:
[0001]     The invention relates to a shoe brake for a lift drive with at least two brake shoes, which generate a braking force at a brake drum and are releasable. The present application is a Continuation of PCT/CH2006/000134, filed 3 Mar. 2005. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     An internal shoe brake with two brake shoes has become known from the specification of JP 57107443. Two brake elements are provided per brake shoe, wherein a cut-out into which the brake element is insertable is provided at the brake shoe for each brake element. The brake element consists of a base plate carrying a brake lining, wherein the brake element fits into the shape on the arc of the brake shoe. The brake element inserted into the cut-out in the brake shoe is fixed in place at the brake shoe by means of clips.  
         [0003]     The complicated production of the groove-shaped cut-outs is disadvantageous. Moreover, the brake elements can stick in the cut-outs due to contamination and abrasion dust.  
         [0004]     The present invention is intended to avoid such disadvantage and to create a shoe brake which functions in an optimum manner under difficult operating conditions with brake elements arranged at brake shoes.  
       BRIEF SUMMARY OF THE INVENTION  
       [0005]     The present invention is a shoe brake having brake shoes with brake elements carrying brake linings that are measurably mounted to the shoe. The positioning of the brake elements with respect to the shoe to which it is mounted is settable, thus allowing the orientation of the brake linings to be adjusted.  
         [0006]     The advantages achieved by the invention are substantially to be seen in that an optimum setting of the brake linings on the brake drum can be achieved by the brake elements according to the invention. With an optimum setting of the brake linings, small brake moment adjustments can be made in the final checking at the factory. In addition, tolerances of all brake parts can be accounted for, wherein also wider tolerances can be accommodated. Wider tolerances in turn mean cheaper production of the brake parts. In addition, it is advantageous that the brake elements are easily releasable from the brake shoes, because they cannot be fixed by either abrasion dust or by contamination. The shape of the brake element and the cut-out at the brake shoe guarantees even after long operating times a precise placing of the brake elements on the brake shoes. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     The present invention is explained in more detail in the following detailed description of a preferred, but nonetheless illustrative embodiment thereof, in association with the accompanying figures, in which:  
         [0008]      FIG. 1  is a perspective illustration, partially in section, of an internal shoe brake in accordance with the invention;  
         [0009]      FIG. 1   a  is an elevation view of a shoe brake of the invention with two brake shoes;  
         [0010]      FIG. 2  is a schematic illustration of a portion of a brake shoe according to the invention with brake element;  
         [0011]      FIG. 3  is a view of the brake shoe of  FIG. 2 , further showing a side panel for fastening of the brake element;  
         [0012]      FIG. 4  is a perspective view of a brake shoe for an internal shoe brake; and  
         [0013]      FIG. 5  is a perspective view of a brake shoe for an external shoe brake. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0014]      FIG. 1  is a perspective illustration of an internal shoe brake consisting of a housing plate  2 , a housing ring  3 , a brake drum  4  and two brake halves  5 . 1 ,  5 . 2  of identical construction. The brake drum  4  can be, for example, part of a drive pulley. The lefthand brake half  5 . 1  comprises an upper brake shoe  6  and a lower brake shoe  7 . The upper brake shoe  6  is mounted at an upper brake bearing  6 . 1  and has at the opposed free end an actuating roller  6 . 2 , and is pressed against the brake drum  4  by means of a compression spring  6 . 3  supported by the housing ring  3 . The upper brake shoe  6  is illustrated in section, for which reason its brake lining is not apparent in  FIG. 1 . The section also runs through the roller axis at which the actuating roller  6 . 2  is arranged. The lower brake shoe  7  is constructed in mirror image to the upper brake shoe  6 . Parts of the lower brake shoe are provided with the following reference numerals: shoe bearing  7 . 1 , actuating roller  7 . 2 , compression spring  7 . 3  and brake lining  7 . 4 . The free ends of the brake shoes  6 ,  7  are adjacent to each other.  
         [0015]     An actuator in the form of a brake magnet is provided for release of the brake shoe pair  6 ,  7 . The actuator  8 , which is arranged at an actuator plinth  8 . 1  connected with the housing plate  2 , acts by means of a pushrod  9  on an actuating fork  10  by which the actuating rollers  6 . 2 ,  7 . 2  are acted on to roll against the spring force of the compression springs  6 . 3 ,  7 . 3 . A brake lever  11  serves for manual release of the brake shoe  6 ,  7 .  
         [0016]     The right hand brake half  5 . 2  is constructed in mirror image to the lefthand brake half  5 . 1 . Parts of the righthand brake half  5 . 2  are provided with the following reference numerals: upper brake shoe  12  with shoe bearing  12 . 1 , compression spring  12 . 3 , and brake lining  12 . 4 ; lower brake shoe  13  with shoe bearing  13 . 1 , compression spring  13 . 3 , and brake lining  13 . 4 , actuator  14  with actuator plinth  14 . 1 , pushrod  15 , actuating fork  16  and brake lever  17 .  
         [0017]     In left hand rotation of the brake drum  4  the brake shoes  6 ,  13  are trailing and the brake shoes  7 ,  12  leading. In a righthand rotation of the brake drum  4  the brake shoes  6 ,  13  are leading and the brake shoes  7 ,  12  trailing. The braking action is amplified in the leading brake shoes and is weakened in the trailing brake shoes.  
         [0018]      FIG. 1   a  shows a shoe brake with only two brake shoes. The reference numerals of the lower brake shoes of  FIG. 1  have been used for analogous parts, with actuator roller  13 . 2 . The brake drum at which the brake linings engage is not illustrated.  
         [0019]      FIGS. 2 and 3  show a brake shoe according to the invention with a brake element. The lower brake shoe  7  of the lefthand brake half  5 . 1  of  FIG. 1  is illustrated in  FIG. 2  and  FIG. 3 . The remaining brake shoes  6 ,  12 ,  13  are of the same construction, as is a brake shoe of a shoe brake with only two brake shoes, as illustrated in  FIG. 1   a . The brake shoe can also be constructed with more than one brake element. Such a brake element, placeable on the brake shoe  7 , is denoted by  20 . The brake element  20  consists of an segment-shaped base plate  20 . 1  which fits in a corresponding arcuate or segment-shaped recess  7 . 5  of the brake shoe  7 . The base plate  20 . 1  carries the brake lining  7 . 4 , which is, for example, glued and pinned to the base plate. A threaded hole  7 . 6  is provided in the brake shoe  7 , and threaded holes  20 . 2  are provided in the base plate  20 . 1 . The same threaded holes are provided on the other side (not visible) of the brake shoe  7  and the brake element  20 .  
         [0020]      FIG. 3  also shows a side panel  21  which releasably connects the brake element  20  with the brake shoe  7 . The side panel  21  is connected to the base plate  20 . 1  by means of crews  20 . 3 , wherein the screws  20 . 3  fit in the threaded holes  20 . 2 . The side panel  21  has an elongated slot  21 . 1 , wherein a screw  7 . 7  extends through the longitudinal slot  21 . 1  and fits in the threaded hole  7 . 6 . The longitudinal slot  21 . 1  allows setting of the brake element  20  relative to the brake shoe  7 . The base plate  20 . 1  is displaceable in the segment-shaped recess  7 . 5 , wherein the brake lining  7 . 4  can be adjusted on the brake drum  4 . A similar side panel is provided on the other side, of the brake shoe  7  of the brake element  20 .  
         [0021]      FIG. 4  shows, by way of example, a lower brake shoe  13  of the righthand brake half  5 . 2  with the brake element  20  according to the invention. In this construction a projection  13 . 10  is provided at the brake shoe  13  for reception of the compression spring  13 . 3 . The construction of the brake element  20  with the components brake lining  13 . 4 , recess  13 . 5 , screw  13 . 7 , base plate  20 . 1 , screws  20 . 3 , side panel  21 , etc., corresponds with the brake element illustrated in  FIG. 2  and  FIG. 3 .  
         [0022]     The brake element  20  can also be used for external shoe brakes.  FIG. 5  shows a brake shoe  22  for an external shoe brake, in which the brake drum is braked by means of the brake element  20 , which is illustrated in the preceding figures, at the outer side.