Abstract:
An elevator installation has an elevator car that moves in a vertical direction along guide tracks and is braked or held at standstill by a braking equipment. The braking equipment includes at least two brake units, at least one of the brake units, but preferably each of the brake units, is provided with a wear-compensating device which, when the brake unit is opened or released, sets a clearance distance between a brake lining and an associated brake surface, which clearance arises on opening of the brake unit, in correspondence with a substantially constant value. Thereby, use may be made of customary and thus economic brake materials which may wear during braking.

Description:
FIELD OF THE INVENTION 
     The invention relates to an elevator installation with an elevator car and to a method of braking an elevator car. 
     BACKGROUND OF THE INVENTION 
     In an elevator installation installed in a shaft, the shaft usually consists of solid building materials, but it can also be, at least partly, open. The elevator installation substantially consists of a car for transport of persons and/or goods. The car is connected with a counterweight by way of support means. The car is moved along a substantially vertical car travel path by means of a drive, which selectably acts on the support means or directly on the car or the counterweight, and is kept at a stop or is braked from a travel state to a stopped state by means of a brake. 
     Use is usually made of a brake, which is arranged at the drive, for holding and braking in the operational state and use is made of a safety brake device, which is arranged at the car, for holding and braking in the emergency case. The operational state comprises, for example, the normal operating sequences such as waiting at a floor or at a stop, receiving or unloading goods, travel of the car to another floor, stopping of the car or activities for performance of service operations on the elevator installation. By contrast, the emergency case comprises, for example, incorrect behavior during operation such as, for example, overloading of the car, failure of components, such as severing of a support means, or defects in control or mechanics. 
     In more recent solutions for holding and braking propose use is made of braking equipment which is frequently arranged at the car and which in the case of need comes into engagement and comprehends both states, i.e. both the operational state and the emergency situation. 
     Braking equipment of that kind is known from European patent document EP 0 648 703. Braking equipment mounted at the car is controlled in the drive appropriately to need and can fulfil demands resulting from the operational state and the emergency case. This braking equipment has the characteristic that in the case of wear of a brake plate a clearance changes. This has the effect that the time to bring the braking equipment into braking action changes, usually increases, since a greater advance path has to be covered, or wear-resistant brake plates have to be used. There are, for example, ceramic brake materials, which are specifically wear-resistant. Materials of that kind are, however, very expensive. Wear results from abrasion of brake material during braking. 
     Braking equipment which can compensate for wear of brake plates is described in U.S. Patent Application Publication No. 2006/180406. The wear compensation illustrated there can set a total sum of clearances or it can set a braking force independently of the wear of brake plates. This braking equipment also obliges the total sum of clearances to be selected to be large in such a manner that the wear of individual brake plates does not have a negative effect. This equally has the effect that the time to bring the braking equipment into braking action is correspondingly increased or that appropriately wear-resistant brake plates have to be used. 
     SUMMARY OF THE INVENTION 
     Objects of the present invention include providing an elevator installation with an elevator car and a method for braking and holding an elevator car which enable operation over a longer operating period. There should be tolerance with respect to inaccuracies in the car travel path and a rapid response should be possible in the case of need. Moreover, the braking equipment shall nevertheless be economic, i.e. able to be operated, inter alia, with economic non-wear-resistant brake plates. 
     The present invention fulfils at least one of these objects. The elevator installation comprises an elevator car which moves in vertical direction along guide tracks. In the case of need the elevator car is braked or held at standstill by braking equipment. The braking equipment consists of at least two brake units. Each of the brake units comprises at least one brake lining, which in the case of need co-operates with a brake track. According to the present invention at least one of the brake units, but preferably each of the brake units, is provided with a wear-compensating device which when the braking equipment is relieved sets a clearance, which arises between the brake lining and the brake track, in correspondence with a substantially constant value. The clearance is a free distance, which results when a brake is opened, between the brake lining and associated brake surface. 
     It is thereby achieved that use can be made of customary and thus economic brake materials which wear during use. A worn brake material would necessarily lead to a larger clearance. A larger clearance would cause a greater need for time in order to bring the brake unit into braking setting. The wear-compensating device according to the present invention now produces the advantage that: operation of the braking equipment is made possible over a long operating period, since a wear-compensating device compensates for arising wear: the braking equipment is tolerant with respect to inaccuracies in a brake track, since a clearance can be predetermined in correspondence with the anticipated inaccuracies: and the braking equipment can respond rapidly in the case of need, since a greater advance travel is not required as a consequence of wear. The brake track can be a separate track provided for the purpose of braking or it can be identical with the guide track. Inaccuracies in this brake track or guide track result on the one hand from joining together individual track elements to form a track as well as deviations of the track over its entire length as a consequence of building settling, thermal expansion differences, etc. 
     In an advantageous embodiment the brake unit comprises a brake housing, a brake plate movable with respect to the brake housing and a brake plate fixed with respect to the brake housing, wherein the brake plates in the case of need are brought by means of an advance device into contact with a brake track. The advance device comprises advance checking means which recognizes and checks a total advance travel. The wear-compensating device in that connection keeps a clearance on the side of the fixed brake plate substantially constant and the advance device keeps a total clearance constant. In the case of actuation of the brake unit, advance of the movable brake plate by means of the advance device until the movable plate contacts the brake track thus takes place in a first step. Through further actuation of the advance device the brake housing together with the fixed brake plate is then urged towards an opposite side of the brake track until the fixed brake plate contacts the opposite side of the brake track. Tightening of the brake plates relative to the brake track, whereby braking takes place, is now carried out by a further advance movement. Compensation for abrasion or wear of the movable brake plate is provided directly by further advance of the movable brake by the advance device. Wear of the fixed brake plate takes place indirectly in that the advance device further advances the brake housing together with the fixed brake plate and this advance of the brake housing is determined by the wear-compensating device. The thus-achieved advanced position of the brake housing together with the fixed brake plate forms the final working position of the fixed brake lining. This final working position forms the basis for resetting the brake housing together with the fixed brake plate. The reverse sequence analogously results when the brake unit is opened. The advance device relieves the brake plates, thereafter the brake housing together with the fixed brake plate is reset, beginning from the final working position, in correspondence with the set clearance of the fixed brake plate and as soon as the fixed brake plate has attained its clearance the movable brake plate is drawn back by the residual amount of the total clearance. This embodiment enables provision of an economic brake unit, since advance regulating means alone checks the total clearance and the wear-compensating device sets the clearance of the fixed brake side, which can be realized by simple means. 
     Advantageously the total clearance corresponds with twice the amount of the clearance of the side of the fixed brake plate. This allows even division of the clearance to the side of the fixed brake plate and the movable brake plate. In the individual case it can be advantageous to distribute the clearance asymmetrically, for example in the ratio of 1 to 3. This is of advantage in the case of use of a guide system loaded at one side, for example a “car with rucksack guidance”, since a smaller clearance can be feasible on a less loaded side by comparison with a highly loaded side. 
     The brake unit is guided along the brake track. The form of guidance defines, inter alia, requisite plays in transit and thus the requisite clearance. In an advantageous embodiment the brake unit comprises a guide support which is directly guided along the brake track by means of a guide shoe substantially free of play. The wear-compensating device, preferably a mechanical wear-compensating device, is in that case arranged at a connecting point between the guide support and the brake housing. This arrangement is advantageous, since the brake unit is thereby guided very precisely along the brake track and thus the clearances, which are required for compensation for guidance inaccuracies, can be kept small. In this embodiment it is essentially only necessary to take into account track deviations which result through joining together individual track elements. In this connection, clearances respectively of 0.15 to 0.35 millimeters typically result. 
     In a first embodiment the elevator car is in that case guided along its travel path by means of own car guide shoes and a connecting point of the elevator car with the guide support transmits braking and/or holding forces in vertical direction and makes possible lateral compensation for guidance inaccuracies. This permits a comfort-specific guidance of the elevator car, but is more cost-intensive, since individual guide elements are required for the elevator car and the brake unit. In a embodiment the elevator car is guided by means of the guide support of the braking equipment or by guide shoes integrated in this guide support and a connecting point of the elevator car with the guide support transmits lateral guidance forces and braking and/or holding forces in vertical directions. Costs are reduced, since the functionality of the car guidance is integrated in the guidance of the brake unit. 
     In another embodiment the guide support is executed as part of the elevator car. The wear-compensating device is correspondingly arranged at a connecting point between the guide support or the elevator car and the brake housing. In this connection a clearance has to be formed to be of such a size that the anticipated guidance deviations can be absorbed. This alternative usually demands, by comparison with the aforesaid embodiments, a larger clearance, which obliges a correspondingly longer advance travel or advance time. These influences have to be taken into consideration in the design of the braking system. In this embodiment it is essentially necessary to take into account not only the track deviations resulting due to joining together individual track elements, but also track deviations resulting due to, for example, assembly inaccuracies, building settlement and also thermal expansions. In order that deviations of those kinds do not influence travel comfort, clearances each of 0.75 to 1.5 millimeters or more typically result with this embodiment. It is clear that the response delays, which arise due to these larger clearances, in the case of use of the brakes have to be taken into consideration in the design of the brakes. 
     The mechanical wear-compensating device comprises at least one positioning part, a restoring memory, for example in the form of a spring, and a slip connection, for example in the form of a friction connection. The positioning part is arranged to be sliding by way of a slide connection within the desired clearance between guide support and brake housing and it is further displaceable, in slipping manner, in the amount of wear anticipated in the extreme case. The positioning part is then, if no further forces act, held by the restoring memory in a rest position or standby position. This position at the same time corresponds with the unactuated or opened brake unit. The adjusting force required for displacing the slip connection is greater than the restoring force procured by the restoring memory. 
     On actuation of the fixed brake plate the positioning part is displaced in correspondence with its freely displaceable slide path, which substantially corresponds with the clearance, in the slide connection against the restoring memory. On further advance movement, which is required due to, for example, wear, the positioning part is displaced in the slip connection. On opening of the fixed brake plate the restoring memory now displaces the positioning part back in correspondence with the slide path freely displaceable in the slide connection, whereby the associated clearance is set. 
     This simple mechanical wear-compensating device is economic to produce, simple in function and correspondingly functionally reliable. 
     The wear-compensating device optionally makes possible setting of the desired clearance by means of, for example, a clearance setting screw or nut. This is advantageous, since the brake unit can be adjusted to requirements in situ. 
     Advantageously the guide support comprises a holder which accepts vertical braking forces directly at the brake lining or the fastening plate thereof, introduces the vertical braking forces into the guide support and into the car and substantially relieves the brake housing of vertical forces. This is advantageous, since accordingly the brake housing together with the movable elements such as advance device and wear-compensating device merely has to be dimensioned in correspondence with advance forces. This allows simpler and more economic production. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The above, as well as other advantages of the present invention, will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment when considered in the light of the accompanying drawings in which: 
         FIG. 1  is a schematic side elevation view of a part of an elevator installation according to the present invention; 
         FIG. 1   a  is a schematic plan view of the elevator installation shown in FIG. 
         FIG. 2  is a schematic sectional view of the brake unit with a wear-compensating device and guide support, which is integrated in the elevator car shown in  FIG. 1 ; 
         FIG. 3  is a schematic detail view of an adjustable wear-compensating device according to the present invention; 
         FIGS. 4.1  through  4 . 4   a  show functional sequences, by way of example, for the compensation of wear wherein  FIG. 4.1  shows the brake unit of  FIG. 2  in the new-state rest position (without wear),  FIG. 4.1   a  shows a detail of the wear-compensating device of  FIG. 4.1 ,  FIG. 4.2  shows the brake unit in the new-state braking position (without wear),  FIG. 4.2   a  shows a detail of the wear-compensating device of  FIG. 4.2 ,  FIG. 4.3  shows the brake unit in a used state (with wear),  FIG. 4.3   a  shows a detail of the wear-compensating device of  FIG. 4.3 ,  FIG. 4.4  shows the brake unit in a used state (with wear), and  FIG. 4.4   a  shows a detail of the wear-compensating device of  FIG. 4.4 ; 
         FIG. 5  is a schematic sectional view of a brake unit with wear-compensating device and an elevator car guide, which is integrated in brake unit, according to a second embodiment of the present invention; 
         FIG. 6  is a schematic sectional view of a brake unit with wear-compensating device and separate guide for brake unit and elevator car according to the present invention; 
         FIG. 7  is a schematic sectional view of an alternate embodiment of a brake unit with wear-compensating device according to the present invention; 
         FIG. 8  is a view if brake unit according to  FIG. 7  with an integrated holder; and 
         FIG. 9  is a schematic sectional view of another embodiment of a brake unit with wear-compensating device and support pin according to the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following detailed description and appended drawings describe and illustrate various exemplary embodiments of the invention. The description and drawings serve to enable one skilled in the art to make and use the invention, and are not intended to limit the scope of the invention in any manner. In respect of the methods disclosed, the steps presented are exemplary in nature, and thus, the order of the steps is not necessary or critical. 
     One possible overall arrangement of an elevator installation is illustrated in  FIG. 1  and  FIG. 1   a .  FIG. 1  shows the elevator installation  1  in a schematic side view and  FIG. 1   a  shows the same elevator installation  1  in a schematic plan view. The illustrated elevator installation  1  comprises an elevator car  3  which moves in a vertical direction in a shaft  2  along guide tracks  7 . The elevator car  3  is supported by support means  5  and is connected with a counterweight  4 . The counterweight  4  and the elevator car  2  are driven by a drive  6  by way of the support means  5  and move in opposite sense in the elevator shaft  2 . The elevator car  3  is provided with braking equipment  11  which brakes the elevator car or keeps it at standstill. The braking equipment  11  comprises at least two brake units  12  which each act on a respective one of the guide tracks  7 . The brake units  12  co-operate as a single braking equipment  11 , wherein the braking equipment  11  can optionally define the braking force requirement for a single individual brake unit  12 . The brake units  12  are, in the illustrated example, attached below the car body  3 . However, attachment laterally and/or above the elevator car  3  is also possible. Obviously, combinations of these attachment locations are also conceivable. This would be useful above all if, for extending the braking performance, several brake units  12  are used. The elevator car is provided with guide shoes which guide the car  2  along the guide track  7 . In the illustrated example the guide track  7  is formed by a T-shaped guide rail, which at the same time is also a brake track  8 . Other forms of elevator installations are obviously possible. An automotive elevator car, for example with a linear motor, can be used and the elevator shaft can be partly open, or separate tracks for guiding (guide track  9 ) and braking (brake track  8 ) can be used. 
       FIG. 2  shows the elevator brake unit  12  as used in correspondence with the present invention in the elevator installation  1  according to  FIG. 1 . The brake unit  12  is attached to the car  3 . The brake unit  12  comprises a brake housing  13 , a brake plate  14  movable with respect to the brake housing  13  and a brake plate  15  fixed with respect to the brake housing  13 . The brake plates  14  and  15  are, in the case of need, brought by means of an advance device  19  into contact with the brake track  8 . The brake plates  14  and  15  are connected by means of fastening plates  16  with the brake housing  13  and the advance device  19 , respectively. The brake track  8  in the illustrated example is at the same time the guide track  7 , wherein a conventional T-shaped guide rail is used. The brake unit  12  further comprises a guide support  17 . The guide support  17  serves for fastening or connecting the brake housing  13  with the car  3 . It is fixedly connected with the car  3 . A wear-compensating device  30  is, in the illustrated example, arranged between the guide supports  17  and the brake housing  13 . The guide support  17  at the same time comprises the guide shoe  9  which guides the elevator car  3  along the guide track  7 . The guide shoe  9  is resiliently mounted with respect to the car  3 . This enables insulation from guidance vibrations. A resilient intermediate element  10  allows the car  3  oscillatory deviations (distance “a”) relative to the guide track  7 . A clearance “If”, “Ib” of the brake unit is in this case set to be of such a size that even in the case of outward oscillation of the car within the scope of the guidance resilience “a” and possible guidance plays “f” as well as offsets in the meeting of guide track parts no contact of the brake plates  14 ,  15  with the guide track  7  or brake track  8  takes place. 
     The wear-compensating device  30  now keeps the fixed clearance “If”, during release of the brake  12 , substantially constant on the side of the fixed brake plate  15 . The illustrated brake unit  12  further consists of electromechanical components. It comprises advance regulating means  21  which keeps a predetermined total clearance “It” constant by actuating the advance device  19 . The total clearance “It” is formed by the sum of the fixed clearance “If” and the movable clearance “Ib”, wherein the fixed clearance “If” corresponds with the side of the fixed brake plate  15  and the movable clearance “Ib” corresponds with the side of the movable brake plate  14 . The terms “fixed” and “movable” are used in this connection merely for definition. The advance regulating means  21  moves the movable brake plate  14  directly perpendicularly to the brake or guide surface  7 ,  8 . As a rule, several wear-compensating devices  30  are arranged in parallel, preferably one above the other. 
     The brake unit  12  is an electromechanical brake unit in which the movable brake lining  14  is advanced by means of an electromechanical drive, such as, for example, a spindle drive. In the case of need the advance spindle is actuated by way of a gear stage. The brake unit  12  preferably comprises advance checking means in the advance regulating means  21 . By means of this advance checking means a brake plate wear and/or deviations from a normal behavior of the brake unit  12  can be ascertained and a signal generated on an advance checking signal line  24  so that the overall wear can be checked by this method. 
     As a rule the wear-compensating device  30  is set in such a manner that the clearance “If” of the side of the fixed brake plate  15  is equal to the clearance “Ib” of the movable brake plate  14 . It thus corresponds with half the total clearance “It”. This setting is advantageous when centrally suspended or centrally guided elevator cars  3  are concerned. However, the wear-compensating device  30  also enables asymmetric settings, whereby an uneven division of the clearances (If, Ib) can be achieved. This is useful particularly in the case of asymmetrically suspended elevator cars, where a possible wear of the guide shoes  9  makes itself noticeable on one side. 
     The guide support  17  further comprises a holder  18 . The holder  18  supports the brake plates  14 ,  15  or the fastening plates  16  and conducts braking forces directly into the guide support  17  and further into the car  3 . The brake housing  13  itself is thereby relieved of the actual braking force; merely the normal force acting in one direction and generating the braking force by way of friction has to be accepted. 
       FIG. 3  illustrates the settable wear-compensating device  30  in detail. The wear-compensating device  30  consists of a positioning part  31 , a restoring unit  32 , a first abutment  33  and a second abutment  34 . The wear-compensating device  30  produces a connection of the brake housing  13  with the guide support  17 . In this embodiment the positioning part  31  is connected by a slip connection  35  with the guide support  17 . The positioning part  31  is preferably produced from a plastic material. It can be displaced relative to the guide support  17  only by a substantial force of, for example, approximately 25 N to 50 N. The positioning part  31  itself is slidably arranged in the brake housing  13  to be easy-running. The brake housing  13  can thereby displace relative to the guide support  17  in two stages. The direction of displacement is in that case oriented in the direction of the normal force. In a first displacement stage the brake housing  13  can be displaced by a small force slidingly relative to the positioning part  31  and thus also slidingly relative to the guide support  17 . This sliding displacement is limited by the first abutment  33  and the second abutment  34 . This first displacement stage corresponds with the desired clearance “If” of the fixed brake plate side. In the example, this first displacement stage or the clearance “If” is settable by means of a clearance play setting screw  36 . The restoring unit  32 , which is arranged between the brake housing  13  and the positioning part  31 , in the form of a spring in this connection displaces the brake housing  13  up to the boundary mark of the first abutment  33 . In a second displacement stage the brake housing  13  together with the positioning part  31  can be displaced in slipping manner relative to the guide support  17 . The  FIG. 4  series—comprising  FIGS. 4.1  to  4 . 4   a -now explain by way of example the functional sequence for compensation of wear.  FIGS. 4.1 ,  4 . 2 ,  4 . 3  and  4 . 4  each show a working setting, by way of example, of the brake unit and the details according to  FIGS. 4.1   a ,  4 . 2   a ,  4 . 3   a  and  4 . 4   a  show the respectively associated setting of the wear compensation device. 
       FIG. 4.1  and  FIG. 4.1   a  show the brake unit  12  in the working setting, i.e. the brake is open. The brake linings  14 ,  15  are spaced on both sides of the brake track  8  by the clearance (If, Ib). The positioning part  31  of the wear compensating unit  30  is pressed against the first abutment  33  defined by the clearance play setting screw  36 . The possible free displacement path or slide path of the positioning part  31  is set in correspondence with the desired fixed clearance “If”. In the case of actuation of the brake unit  12  there thus takes place in a first step (S 1 ) advance of the movable brake plate  14  by means of the advance device  19  until the movable plate  14  contacts the brake track  8 , and then, by further actuation of the advance device  19 , the brake housing  13  together with the fixed brake plate  15  is urged towards the opposite side of the brake track  8  (S 2 ) until the fixed brake plate  15  contacts the opposite side of the brake track  8 . Tightening of the brake plates  14 ,  15  relative to the brake track  8  now takes place by a further advance movement, whereby braking is carried out. 
     This work setting is illustrated in  FIGS. 4.2  and  4 . 2   a . It is illustrated in the following how now compensation is provided for the clearance in the wear compensating unit  30 . The positioning part  31  stands against the second abutment  34 . Compensation for abrasion or wear of the movable brake plate  14  is now, as illustrated in  FIGS. 4.3  and  4 . 3   a , provided directly by a further advance of the movable brake plate  14  by the advance device  19 . Compensation of wear “v” of the fixed brake plate  15  is carried out indirectly in that the advance device  19  further advances the brake housing  13  together with the fixed brake plate  15  (S 3 ) or pulls this tight and this advance of the brake housing  13  produces in the wear-compensating device  30  a slipping in the slip connection  35  between the brake housing  13  and the guide support  17 , since the slide path of the positioning part  31  is already applied. The advanced position of the brake housing  13  together with the fixed brake plate  15  thus now achieved forms the final working position of the fixed brake lining  15  in this braking sequence. This final working position now necessarily forms the basis for resetting of the brake housing  13  together with the fixed brake plate  15 . 
     On opening of the brake unit  12  the reverse sequence takes place analogously, which leads to the state according to  FIGS. 4.4  and  4 . 4   a . The advance device  19  relieves the brake plates  14 ,  15 , and thereafter the brake housing  13  together with the fixed brake plate  15 , beginning from the final working position, is reset in correspondence with the set clearance “If” of the fixed brake plate  15  (S 4 ). This resetting is produced by the restoring unit  32  which, acting against the positioning part  31 , displaces the brake housing  13  in acting in correspondence with the set clearance path “If” back to the first abutment  33 . As is apparent in  FIG. 4.4   a , the positioning part  31  now slips relative to the guide support  17  by the wear amount “v”. The fixed brake plate  15  has reached its clearance “If” and the movable brake plate  14  can now be drawn back by the residual amount of the total clearance (Ib=It−If). The brake unit is ready for the next braking action and the advance travels correspond with the new state. Thus, actuating times, which were applicable to the new brake, can also be maintained for a worn brake. 
       FIG. 5  shows a schematic view of a second embodiment brake unit  12   a  with a wear-compensating device and an elevator car guide integrated in the brake unit. The guide support  17  is guided along the brake and guide track  7 ,  8  directly by the guide shoe  9 , whilst the car  3  is fastened relative to the guide support  17  by way of a resilient element  10   a , for example a rubber spring, a damper or an active vibration damping means. The function of the braking equipment  12   a  itself corresponds with the foregoing illustrations. The advantage of this solution results from the fact that the clearance “If” can be executed to be smaller, since an oscillatory path of the car does not have to be taken into consideration. Obviously the coupling of the guide support  17  is designed in such a manner that vertical braking and retaining forces can be transmitted. 
       FIG. 6  shows a schematic view of a third embodiment brake unit  12   b  with a wear-compensating device and a separate guidance for the brake unit and the elevator car. The guide support  17   b  is guided along the brake and guide track  7 ,  8  directly by the guide shoe  9  and the car  3  is guided by own guide elements (not illustrated). The function of the brake equipment  12   b  itself corresponds with the preceding illustrations. The advantage of this solution results from the fact that the clearance “If” can similarly be formed to be small, since an oscillatory path of the car  3  does not have to be taken into consideration and a design of the guide shoe  9  of the brake can be undertaken independently of the car  3 . 
       FIG. 7  shows a fourth of embodiment of a brake unit  12   c  with wear-compensating device. The guide support  17  is fastened relative to the car  3 . The brake housing  13  is connected with the guide support  17  by way of the positioning part  31   c  and a support pin  37 . The support pin  37  is analogously a part of the guide support  17 . The brake housing  13  is slidingly displaceable on the sleeve-shaped positioning part  31   c , wherein the displaceability on the positioning part  31   c  is limited by a slide limitation, which can be set by means of clearance play setting screw or clearance play setting nut  36  in correspondence with the desired clearance “If”. The restoring unit  32  urges the brake housing  13 , when the advance device  19  is relieved, into the release position with respect to the first abutment  33 . When the wear “v” occurs, the positioning part  31   c  can slip on the support pin  37 , which leads to a wear compensation, as analogously explained in the  FIG. 4  series. Two support pin arrangements of that kind are preferably arranged one above the other, whereby braking forces are also directly transmissible. The slip connection  35  in this example of embodiment is solved in particularly economic manner. O-rings  38  are inserted in the positioning part  31   c  and the positioning part  31   c  is pushed by light pressure onto the support pin  37 , which is advantageously produced from metal or steel. This slip connection  38  is preferably lubricated. The definition of the required slip force takes place in co-ordination with the definition of the restoring unit. The force required for slipping lies by more than approximately 40% above the force able to be applied by the restoring unit. Instead of the illustrated slip connection  35  on a friction basis, use could also be made of detent connections. Detent connections re-adjust in steps. 
       FIG. 8  shows the brake unit according to  FIG. 7  with an integrated holder. The guide support  17  already illustrated in  FIG. 7  is provided with the holder  18 , which directly supports the brake plates  14 ,  15  during braking and thus introduces braking and holding forces into the guide support  17 . The brake housing  13  together with the wear-compensating device  30  and the entire advance device  19  is thereby loaded merely by normal forces. 
       FIG. 9  shows another embodiment of a brake unit with a wear-compensating device and a support pin according to the present invention. The brake housing  13  is, similarly to that shown in  FIG. 7 , connected with the guide support  17  by way of the positioning part  31  and a support pin  37   d . The support pin  37   d  is analogously a part of the guide support  17 . The brake housing  13  is arranged on the sleeve-shaped positioning part  31   d  to be slidingly displaceable. The displaceability on the positioning part  31   d  is limited by a slide limitation, which can be set by means of clearance play setting screw or clearance play setting nut  36  in correspondence with the desired clearance “If”. The functionality of the slide limitation in this example is integrated in the support pin  37   d  and the functionality of the slipping is integrated between brake housing  13  and the positioning part  31   d . The restoring unit  32  urges the brake housing  13 , when the advance device  19  is relieved, towards the first abutment  33  into the clearance position. When the wear “v” occurs, the brake housing  13  can slip on the positioning part  31   d , which leads to a wear compensation as explained analogously in the  FIG. 4  series. Here, too, two support pin arrangements of that kind are preferably arranged one above the other, whereby the braking forces were transmitted directly to the guide support. 
     With knowledge of the present invention and the illustrated variants of embodiment the elevator expert can change and combine the set forms and arrangements as desired. For example, the illustrated use of O-rings, the solution of the support pin and also the arrangement of guide elements or the use of a holder can be combined with the illustrated arrangements of wear-compensating devices. Similarly, the guide shoe can be formed with use of known technologies. In particular, use can be made of a sliding guide shoe or a roller guide shoe  9   a  in  FIG. 5 . The guide shoe  9   a  can comprise a measuring system on the basis of which a travel speed of the braking equipment or of the car can be ascertained to generate a signal on a line  25 . This information can be used, for example, by a regulating unit of the braking equipment. In addition, a regulated clearance play setting with use of a servomotor is possible. In that case, for example, a clearance play “If” of the fixed brake plate side would be changed in dependence on the operational state of the elevator installation in that the clearance play setting screw  36  would be screwed in or out by means of the servomotor. 
     In accordance with the provisions of the patent statutes, the present invention has been described in what is considered to represent its preferred embodiment. However, it should be noted that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.