Abstract:
A brake system comprising a structural unit adapted to be connected to a structure and defining a channel for the axial movement of a hoisting rope therein. A brake unit has a brake pad and an arm secured to one another for concurrent movement and movably mounted to the structural unit by at least one joint. The arm is in operative contact with a user end of the hoisting rope to be displaced with the brake pad between a hoisting position by a tautening of the hoisting rope, in which hoisting position the brake pad is distanced from the hoisting rope in the structural unit to allow movement of the hoisting rope in both pulling and releasing directions of the axial movement, and a braking position by a release of tension in the hoisting rope, in which the brake pad is displaced into contact with the hoisting rope.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority on U.S. patent application Ser. No. 61/548,279, filed on Oct. 18, 2012, incorporated herein by reference. 
     FIELD OF THE APPLICATION 
     The present application relates to hoisting systems by which users manually hoist loads by way of a cable, rope, etc, in addition to mechanical units such as sets of pulleys or devices such as capstans, and more particularly to a brake system for braking movement of the hoisting cable or rope. 
     BACKGROUND OF THE ART 
     It is commonly known to provide pulley arrangements and/or devices such as capstans to help users in manually hoisting heavy loads. The pulleys and devices such as the capstans reduce the load at the user end, whereby the user can manually hoist the load with the weight of the load being substantially reduced at the user end. 
     Brake systems or lock systems have been created in the event that the user wants to release the hoisting rope (or cable, etc) while the load is lifted in the air. The existing brake systems are applied when the tension in the hoisting rope is released, for instance by the user letting go of the hoisting rope. 
     In order to lower the load, such existing brake systems typically require additional manipulations by the user, for instance, by way of a secondary rope that must be manipulated by the user to release the brake while hoisting the load with the other hand. However, this type of system is accident-prone in that the user may perform inadequate maneuvers in emergency situations, and drop the load. Moreover, with such systems, the user must typically have one hand on the hoisting rope, and another on the secondary rope, and this is not ideal for releasing gradually the hoisting rope when lowering a load. 
     SUMMARY OF THE APPLICATION 
     It is therefore an aim of the present disclosure to provide a brake system for hoisting rope that addresses issues associated with the prior art. 
     Therefore, in accordance with the present application, there is provided a brake system for hoisting rope, comprising: a structural unit adapted to be connected to a structure and defining a channel for the axial movement of a hoisting rope therein; and a brake unit having a brake pad and an arm secured to one another for concurrent movement and movably mounted to the structural unit by at least one joint, the arm being in operative contact with a user end of the hoisting rope to be displaced with the brake pad between a hoisting position by a tautening of the hoisting rope, in which hoisting position the brake pad is distanced from the hoisting rope in the structural unit to allow movement of the hoisting rope in both pulling and releasing directions of the axial movement, and a braking position by a release of tension in the hoisting rope, in which the brake pad is displaced into contact with the hoisting rope by the arm reacting to the release in tension in the hoisting rope at the user end, whereby the hoisting rope is held captive between the brake pad and a surface of the channel in the braking position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a brake system for hoisting rope in accordance with an embodiment of the present disclosure; 
         FIG. 2  is a side elevation view of the brake system of  FIG. 1 , with a gate unit being opened; 
         FIG. 3  is an elevational view of the brake unit of  FIG. 1 , with the gate unit in the process of being closed; 
         FIG. 4  is an elevational view of the brake unit of  FIG. 1 , with the gate unit in a closed position; 
         FIG. 5  is a perspective view of the brake system of  FIG. 1  with a hoisting rope, with the brake unit in a hoisting position; 
         FIG. 6  is a perspective view of the brake system of  FIG. 1  with a hoisting rope, with the brake unit in a braking position; and 
         FIG. 7  is a schematic view illustrating an interaction between a cam of the brake system and the hoisting rope. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings, and more particularly to  FIG. 1 , a brake system for a hoisting rope, cable, etc is generally illustrated at  10 . For simplicity purposes, reference is made to hoisting rope, although the brake system may be used with any appropriate hoisting means, such as cable, chain, cord, etc. The use of hoisting rope is intended to cover all possible hoisting means of such type. In  FIGS. 5 and 6 , the brake system  10  is illustrated in an operative arrangement with a hoisting rope A. 
     As shown in  FIG. 1 , the brake system  10  has a structural unit  12 , a gate unit  13  and a brake unit  14 . 
     The structural unit  12  is the part of the brake system  10  that is anchored to a structure and that supports the movable components of the brake system  10 , namely the gate unit  13  and the brake unit  14 . The structural unit  12  is also the interface of the brake system  10  with the hoisting rope A ( FIGS. 5 and 6 ), and hence supports a part of a load during braking. 
     The gate unit  13  may be provided in the brake system  10 . The gate unit  13  is devised to hold captive the hoisting rope A within the structural unit  12 . 
     The brake unit  14  brakes the movement of the hoisting rope A along its longitudinal axis when sliding or translating along the structural unit  12 . The brake unit  14  is displaceable as a function of movements performed by a user person hoisting a load, by pulling or releasing the hoisting rope A, as described in further detail hereinafter. 
     Still referring to  FIG. 1 , the structural unit  12  has a connector portion  20  by which it is anchored to a structure. The structure may be any of a vehicle, a post, a frame, parts of a building, or any other appropriate stable structure capable of supporting the brake system  10 , considering that loads of a hoisting maneuver will be sustained at least partially by the brake system  10 . In  FIG. 1 , the connector portion  20  is illustrated as being a C-channel with bores  21 . However, any other type of structural configuration is considered for the connector portion  20 , as long as it can sustain the loads to which the brake system  10  will be subjected. 
     The structural unit  12  further features a rope interface  22  integral with the connector portion  20  in  FIG. 1 . The rope interface  22  defines a channel  23  in which the hoisting rope A will slide along its longitudinal axis, and thus approximately along axis X. Therefore, the rope interface  22  typically has an arcuate section to allow this translational movement of the hoisting rope A relative to the channel  23 . The rope interface  22  has a J shape, thereby defining a clearance  24 . The clearance  24  is sized so as to allow the hoisting rope A to be laterally inserted into the channel  23  of the rope interface  22 . In an alternative embodiment, the rope interface  22  may be closed off with the hoisting rope A being inserted by a free end into the channel  23 . It may be desired to close off the clearance  24 , whereby an aperture  25  is defined in the rope interface  22  to receive a part of the gate unit  13 , as will be described hereinafter. 
     A brake support  26  is positioned atop the rope interface  22  and is integral therewith. The brake support  26  is shaped as a housing to accommodate a portion of the brake unit  14  and allow a pivoting movement thereof relative to the structural unit  12 . Moreover, pivot  27  and stop  28  are positioned on a lateral wall of the brake support  26 . The pivot  27  and the stop  28  are used to interface the gate unit  13  to the structural unit  12 . The gate unit  13  has a slot  30  defined in its body, with the slot  30  having an obround shape or other appropriate elongated shape. Therefore, the body of the gate unit  13  is operatively connected to the structural unit  12  by the pivot  27  threaded through the slot  30 . An appropriate enlarged head and, possibly, washer are provided at the free end of the pivot  27  to hold the gate unit  13  captive thereon. Accordingly, the gate unit  13  may pivot and translate relative to the structural unit  12  by way of the interaction between the pivot  27  and the slot  30 . Hence, the joint formed by the pivot  27  and the slot  30  is a two degree of freedom (DOF) joint, although a single DOF joint could be used provided sufficient space is provided between the gate unit  30  and the boundaries of the clearance  24  to allow the lateral access of the hoisting rope A in the channel  23 . 
     The gate unit  13  further comprises a tongue  31 . The tongue  31  is sized so as to be accommodated in the aperture  25 , as shown in  FIG. 4 . This complementary engagement, along with the weight of the gate unit  13 , will generally ensure that the gate unit  13  remains in the closed position of  FIG. 4  during the use of the brake system  10  for hoisting a load, thereby keeping the hoisting rope A captive therein. A handle  32  projects laterally from the gate unit  13 . The handle  32  is used manually by a user of the brake system  10  to open or close the gate. Abutment  33  and depression  34  are also defined in the body of the gate unit  13  to control and limit its movement relative to the structural unit  12 . 
     Referring sequentially to  FIGS. 2 ,  3  and  4 , the movement of the gate unit  13  relative to the structural unit  12  is described. In  FIG. 2 , the gate unit  13  is in an opened position relative to the structural unit  12 . Therefore, the clearance  24  is opened, whereby hoisting rope A may be fitted into the rope interface  22 . In the opened position of  FIG. 2 , the stop  28  is received in the depression  34  of the gate unit  13 . Alternatively, a free end of the rope A may be threaded through the rope interface  22  in an embodiment of the brake system  22  without a lateral entry, such as the clearance  24 , for the rope A. 
     In  FIG. 3 , the gate unit  13  is in the process of being displaced to its closed position. The body of the gate unit  13  has, therefore, pivoted relative to pivot  27 , and the stop  28  abuts the abutment  33 , resulting in the tongue  31  being in register with the aperture  25 . It is also observed that the collaboration between the stop  28  and an edge of the body of the gate unit  13  will limit the gate unit  13  to translating downwardly or pivoting back to the opened position of  FIG. 2 . 
     In  FIG. 4 , the tongue  31  is accommodated in the aperture  25 , in the closed position of the gate unit  13  relative to the structural unit  12 . It is when the gate unit  13  is in the closed position of  FIG. 4  that the hoisting rope A may be used to hoist a load, as the hoisting rope A is laterally captive in the structural unit  12 . 
     It is pointed out that the gate unit  13  will tend to stay in the closed position of  FIG. 4  by the effect of gravity (and/or spring). Therefore, according to an embodiment, the gate unit  13  must be handled to reach and stay in the opened position, otherwise the gate unit  13  will bias back to the closed position of  FIG. 4  by the effect of gravity. 
     Referring now concurrently to  FIGS. 1 ,  5  and  6 , the brake unit  14  is described. The brake unit  14  has a brake pad  40 . The brake pad  40  is shown as being a cam having a semicircular component with a braking surface  41  on a radial surface thereof. Other shapes and configurations are also possible for the brake pad  40 . The radial surface is typically arcuate in section in view of an operative engagement of the braking surface  41  with the hoisting rope A. Moreover, the braking surface  41  may have friction means, such as teeth, a rugged surface treatment, etc. The brake unit  14  further comprises a release arm  42 . The release arm  42  is integral with the brake pad  40 , and moves relative to the brake support  26  of the structural unit  12 , for instance in rotation and/or in translation by an appropriate joint(s). In an embodiment, the brake pad  40  and the arm  42  are monolithic. In the illustrated embodiment, the brake pad  40  is the cam that has the pivot axis located such that the cam  40  is eccentrically positioned relative to the rotational axis of the arm  42 . Still in the illustrated embodiment, the center of the cam  40  is offset relative to the pivot axis of the release arm  42 . Therefore, as shown in the combination of  FIGS. 5 and 6 , a movement (i.e., pivoting) of the brake unit  14  will cause the cam  40  to be lowered onto the hoisting rope A, at which point the braking surface  41  will come into contact with the hoisting rope A. 
     The release arm  42  has an elongated portion  43 , with two prongs  44  at a free end of the elongated portion  43 , in an inverted U-shape. Other configurations are possible as alternatives to the fork shape of the release arm  42 , such as a closed loop instead of the prongs, or a simple transverse abutment, but the two-prong configuration illustrated in  FIGS. 1 ,  5  and  6  is well suited for keeping the hoisting rope A captive between the prongs when a load is being hoisted, and to disengage the rope A from the release arm  42  when the rope A is not being handled. The brake unit  14  biases downwardly by the effect of gravity and, therefore, abuts the hoisting rope A when the latter is taut, as seen in  FIGS. 5 and 6 . 
     Referring to  FIG. 7 , it is observed that the pivot axis B of the release arm  42  is horizontally offset from an edge C of the rope interface  22  (i.e., not aligned on a horizontal axis). The hoisting rope A generally pivots about the edge C when a tension in the rope A is varied. This offset, combined to the eccentric position of the cam  40  relative to the pivot axis B (in the embodiment with the cam  40 ), causes a clearance between the braking surface  41  and the rope A even when the rope A is not fully taut. 
     Now that the various components of the brake system  10  have been described, a method of using the brake system  10  for hoisting loads is described. Referring to  FIGS. 5 and 6 , there is illustrated the end of the hoisting rope A being manually handled (user end), and the other end of the hoisting rope A being connected to the load (load end). The end of the hoisting rope A being connected to the load typically goes through various mechanical devices to help the user in hoisting a load. For instance, the brake system  10  is well suited to be used with a capstan. Alternatively, the hosting rope A passes through a set of pulleys that will lessen the weight of the load as felt on the user end of the hoisting rope A. 
     With the hoisting rope A being within the channel  23 , the hoisting rope A passes through the prongs  44  of the brake unit  14 . In  FIG. 5 , the brake system  10  is in a hoisting position in that the hoisting rope A is relatively taut straight as the user is hoisting a load by a pulling or retaining action on the free end of the rope A. Therefore, the hoisting rope A is generally horizontal, whereby the brake unit  14  is raised to the hoisting position, resulting in the cam  40  not engaging contact with the hoisting rope A. This allows the sliding or translational movement of the hoisting rope A in the channel  23  without any braking impact from the brake system  10 . Moreover, the hoisting rope A does not rub against the cam  40  when the brake system  10  is in the hoisting position, by the space between the braking surface  41  and the channel  2  being sufficiently large (greater than a dimension of the rope A), to prevent any rub, although rub could also be accepted. Accordingly, the surface of the hoisting rope A will not be grated by the braking surface  41 , avoiding premature wear of the hoisting rope A. 
     In  FIG. 6 , the brake unit  14  is shown in the braking position. In this position, the user has released the hoisting rope A, whereby the hoisting rope A is relatively loose on the user end. Therefore, by the effect of gravity, the release arm  42  of the brake unit  14  will pivot downwardly, resulting in the cam  40  coming into contact with the hoisting rope A. The friction between the braking surface  41  of the cam  40  and the hoisting rope A is sufficient so as to block movement of the rope A at the brake system  10 , and thus support the load. 
     If the user decides to pull the hoisting rope A once more, the brake unit  14  will simply pivot to the hoisting position of  FIG. 5  by the hoisting rope A reaching the tautened state, thereby releasing the brake system  10  and allowing movement of the hoisting rope A. The clearance between the braking surface  41  and the hoisting rope A may be large enough that the brake system  10  remains in the hoisting position of  FIG. 5 , despite the hoisting rope A being semi-taut (not fully taut as in  FIG. 5 , not loose as in  FIG. 6 ). This feature is quite practical as a variation of tension in the hoisting rope A will impact the speed at which the load is lowered. 
     It is therefore observed that the brake system  10  does not require any other manipulation in lowering a load other than the releasing action of the user on the hoisting rope A. The brake system  10  therefore adapts to the logic of movements of the hoisting rope A, thereby simplifying the manipulations required to brake movement of the hoisting rope A relative to the load. Moreover, if the hoisting rope A is released at the user end by inadvertence, the brake system  10  will naturally be released as soon as the hoisting rope A loses its tension on the user end. 
     It is pointed out that the gate unit  13  is shown as being away from the closed position in  FIGS. 5 and 6 , for instance as being manipulated by a user keeping the gate unit  13 . However, for safety purposes, the gate unit  13  should be closed when a load is hoisted via the brake system  10 .