Patent Publication Number: US-2021170501-A1

Title: A drill for drilling railway sleepers

Description:
The present invention relates to a drill for drilling railway sleepers. 
     As is known, railway tracks made of steel are supported and maintained at a constant distance, the so-called gauge, by means of sleepers, made of reinforced concrete or wood. 
     The connection of the tracks to the sleepers, in particular made of wood, usually occurs indirectly, by connecting the track to a plate by means of anchoring bolts and connecting the plate to the sleeper by means of fastening pins. 
     To make the holes for anchoring the fastening pins in the sleepers, it is necessary to use special hole-drilling machines which are designed for this specific purpose, operating along the tracks of a railway line. 
     Generally, the weight and size of these machines are considerable and such that they present difficulty for transport. 
     In particular, machines are commonly known which, by virtue of their size, are provided with a trolley for moving on the tracks, like machines which need special supports to be able to be activated and/or stored. 
     These hole-drilling machines of the known type commonly use helicoidal tips provided with a front self-threading element, by virtue of which the tip penetrates the material (wood) in a quick, but usually poorly controllable manner, with the risk of the helicoidal tip blocking in an intermediate step of the drilling, due to the possible presence of knots in the wood. 
     If the drilling operations are carried out on live sections, i.e. affected by railway traffic, should the tip of the drilling machine be planted in the sleeper in an intermediate step of the drilling, it is indispensable to be able to evacuate the work area quickly if a train were to approach. In this regard, it must be noted that the operation of removing the tip from the hole in the sleeper is lengthy and not immediate. 
     Thus, the need is felt to be able to detach the tip from the hole-drilling machine in the event of an emergency (sudden arrival of a train) to avoid having to abandon the drill with the risk of destroying the same and potentially damaging the train. 
     A further need of hole-drilling machines for railway sleepers consists of reducing the risk of the helicoidal tip accidentally being able to come into contact with a part of the operator&#39;s body, with the consequent hazard of accidents at work. 
     A drill for drilling railway sleepers of the prior art which satisfies at least some of the needs presented, at least in part, is described in EP0863257A, which can be considered the closest state of the art for the present invention. 
     A further requirement which is not met by drills for railway sleepers of the prior art concerns the reduction of noise, vibrations and pollution of the working environment to which the user is exposed, which is caused, at least in part, by the combustion engines which actuate the drill. 
     A further difficulty of working along railway lines far from inhabited areas is the absence of a power network as a source of energy for various site functions, for example, for lighting. 
     An even further requirement which is not met by drills for railway sleepers of the prior art concerns improving visibility in the area of making the holes in the sleepers, both at night and inside unlit tunnels, both due to the shadows caused by the dimensions of the drill and by the posture of the user, who is partially above and partially at the side with respect to the work area. 
     An even further requirement which is not met by drills for railway sleepers of the prior art concerns improving their ergonomics and the posture of the user, who, besides having to contrast the moment which resists the rotation of the helicoidal tip of the drill, must balance the weight of the drill in the vertical drilling position and, at the same time, have his/her field of vision facing the work area with his/her hands in a condition to operate and switch off the drill, all of this with continuous repetition of the same working posture. 
     An even further requirement which is not met by drills for railway sleepers of the prior art concerns their use both as a tool supported and actuated by hand, and as a tool supported by a tool holder rail cart, supported on the track, without complex operations of adaption and assembly. 
     An even further requirement which is not met by drills for railway sleepers of the prior art concerns the reduction of downtimes caused by inspections of operating states, the need for unplanned maintenance, configuration and reconfiguration of the operation of the drill, depletion or faults of the drilling energy source, operating faults or errors and their identification and diagnosis. 
     An even further requirement which is not met by drills for railway sleepers of the prior art concerns the possibility of verifying the correct execution of the drilling, directly in situ, with the planned execution parameters, for example, the number of turns of the tip. 
     An even further requirement which is not met by drills for drilling railway sleepers of the prior art is that of providing users with information for intuitive operation and which is such that it avoids incorrect use. 
     An even further requirement which is not met by drills for drilling railway sleepers of the prior art is that of having a drill which is intrinsically safe, i.e. with an operating strategy which is such that it reduces the risk of unplanned use and the risk of lesions to the user. 
     An even further requirement which is not met by drills for drilling railway sleepers of the prior art is that of making holes in weather conditions or environmental conditions where water, sand, particles of soil or snow fall, or are carried, to the drill area, where they are sucked in by the drill&#39;s cooling system, or penetrate connections and electric circuits with the risk of damaging the drill and harming the operator. The most typical prohibitive weather conditions or environmental conditions include rain, storms, wind in the presence of dust, sand and water. 
     Thus, it is an object of the present invention to produce a drill for drilling sleepers, particularly for use in the railway sector, having such features as to overcome at least some of the described drawbacks, with reference to the prior art. 
     These and other objects are achieved by means of a drill for drilling railway sleepers according to claim  1 . The dependent claims concern preferred, advantageous embodiments. 
    
    
     
       A description of preferred, non-limiting embodiments will be provided below, with reference to the drawings, wherein: 
         FIGS. 1, 2, 3  are perspective views of a drill according to one embodiment, 
         FIG. 4  is a longitudinal sectional view of the drill in  FIG. 1 , 
         FIG. 5  is an enlargement of detail V in  FIG. 4 , 
         FIG. 6  shows an enlarged detail of a damping system of the drill according to one embodiment, 
         FIG. 7  is an enlargement of a display area of the drill according to one embodiment, 
         FIG. 8  is an enlargement of an area for gripping and manually controlling the drill according to one embodiment, 
         FIG. 9  is a view from above, in particular, of a handle device and an electric motor with a battery, of the drill according to one embodiment, 
         FIG. 10  is a perspective view of an electric motor of the drill according to one embodiment, 
         FIG. 11  is a perspective view of the drill with an activated lighting system, according to one embodiment, 
         FIG. 12  is a view from above of the drill showing the light cone made by a lighting device placed on the left side of the drill, 
         FIG. 13  is a view from above of the drill showing the light cone made by a lighting device placed on the right side of the drill, 
         FIG. 14  is a perspective view of the drill coupled to a tool holder rail cart, 
         FIGS. 15A, 15B  show a perspective and sectional view of details of a locking device in a release configuration, 
         FIGS. 16A, 16B  show a perspective and sectional view of details of the locking device in  FIG. 15  in a locking configuration. 
     
    
    
     With reference to the figures, a drill  1  for drilling railway sleepers (not shown), comprises a support structure  2 , preferably a main plate, a motor unit  3 , supported by the support structure  2 , a grip or a handle  4  connected to the support structure  2 , and one or more control members  5  arranged on the handle  4  to control the motor  3 . 
     A protective casing  11  is connected to the support structure  2 , at its lower end, opposite the motor  3 , which protective casing completely surrounds both a spindle  7  and a helicoidal tip  8  (sketched in  FIGS. 4, 5 ) connected thereto. The helicoidal tip  8  is preferably of the type equipped with a front self-threading element. 
     The spindle  7  is operable by the motor  3  by means of the drive shaft  9  and, optionally, a reducer  10 , for example, a cogwheel or a belt and adapted to transmit the rotation of the drive shaft  9 , with the desired gear ratio, to the spindle  7 . 
     The protective casing  11  comprises a fixed casing portion  12  and a movable casing portion  13 . The movable casing portion  13  is designed to rest in the drilling area against the sleeper. To this end, the movable casing portion  13  has a tapered shape at its end section  14  and can end in a cylindrical portion  15  adapted to engage, for example, a round hole of a connection plate, not shown. 
     The movable casing portion  13  is sliding with respect to the fixed casing portion  12  in an axial direction, with respect to the rotation axis  16  of the spindle  7  and the tip  8 , (which constitutes a tool axis), between an axially protracted position and an axially retracted position. 
     According to an embodiment, the movable casing portion  13  is permanently elastically stressed towards the protracted position, for example, by means of one or more helicoidal springs  17 ,  18  interposed between the fixed casing portion  12  and the movable casing portion  13 . 
     According to an embodiment, the movable casing portion  13  can be slidingly connected to two guide columns  19 ,  20  arranged on two diametrically opposite sides with respect to the axis  16  of the spindle  7  and extended in an axial direction, so as to guide the axial movement of the movable casing portion  13 . The guide columns  19 ,  20  are connected at the top to the support structure  2 , and the springs  17 ,  18  are inserted on the guide columns  19 ,  20 . 
     According to one embodiment, the end section  14  of the movable portion  13  is replaceable and connectable to an upper section of the movable portion  13 , preferably by means of a left-hand thread, so as to avoid unscrewing the end section  14  from the upper section on account of the friction between the tip  8 , swarf, and the end section  14 . 
     According to one embodiment, the movable casing portion  13  is constrained to the guide columns  19 , 20  by means of the insertion of two tubular seats  76  on corresponding free ends of the guide columns  19 , 20 , provided with a quick locking and release device without the aid of equipment and devoid of threads. The quick locking and release device comprises a locking key  77  arranged at the free end of each of the guide columns  19 ,  20  and can be positioned, for example, by means of rotation, preferably by snap rotation, between a release position ( FIG. 15 ), wherein the tubular seat  76  can be unthreaded from the free end of the guide column  19 , 20 , and a locking position ( FIG. 16 ), wherein the unthreading of the tubular seat  76  from the free end of the guide column  19 , 20  is prevented. 
     To this end, the tubular seat  76  can form one or more grooves  78  which allow the insertion and unthreading of the movable casing portion  13  when the locking key  77  is positioned in alignment with said one or more grooves  78 , in the release position ( FIG. 15 ). Similarly, the tubular seat  76  is shaped to interfere with the locking key  77  when the latter stops in the locking position, in order to prevent the insertion and unthreading of the movable casing portion  13  on/from the guide columns  19 , 20 . 
     The quick locking and release of the movable casing portion  13  to/from the guide columns  19 ,  20  facilitates and accelerates the assembly and disassembly of the movable portion  13  and, by virtue of the absence of threaded connections or locking nuts, prevents an undesired loosening, for example, of the locking nut caused by the vibrations of the drill  1 . 
     An annular clamp  21  axially sliding and lockable in position is provided on the fixed casing portion  12 , which annular clamp  21  allows the drilling depth to be determined in advance by means of a graduated scale  22  arranged on the outer surface of the fixed casing portion  12 . 
     The locking of the annular clamp  21  takes place by means of an eccentric cam which is operable by means of a locking/release lever  23 . 
     The drill  1  further comprises means for the quick release of the drilling tip  8 . 
     According to one embodiment, the quick release means comprise a rod  24  arranged coaxially to the spindle  7 , inside the fixed casing portion  12 , and coupled to a small rod  25  arranged transversally to a bushing  26  and integral therewith. A lever  27  is adapted to be engaged with the rod  24  to cause the lifting thereof so as to be able to release the tip  8  quickly. 
     In detail, the lever  27  engages with a fork end  28  thereof with the rod  24 , which is provided with an enlarged head  29  arranged at its upper end. 
     The engagement of the lever  27  with the rod  24  and the successive upward lifting thereof cause the bushing  26  to move upwards in opposition to the force of a spring  30  which is abutted between a projection of the bushing  26  and a projection of the spindle  7  which holds the tip  8 . 
     In one embodiment, a key  31  engages the tip  8  (in a slot defined in the shank of the tip) and is forced on engagement by a spring  32 . The lifting of the bushing  26  allows the tip  8  to free itself from engagement with the key  31  allowing the drill  1  to separate from the tip  8 . 
     According to one aspect of the invention, the motor unit  3  comprises an electric motor which can be powered by means of a rechargeable and replaceable battery  6 , advantageously a lithium-ion battery. 
     This enables a reduction in noise, vibrations and pollution in the working environment, to which the user is exposed, as well as a reduction in the weight of the drill  1  and a reduction in the risk of burns typical of combustion engines. 
     According to one embodiment, the electric motor  3  is positioned in an at least substantially centered manner with respect to a work plane  46 , between two grip portions  36 ,  37  of the handle  4  and containing the rotation axis  16  of the spindle  7 . 
     According to a further embodiment, the axis  33  of the drive shaft  9  of the electric motor  3  coincides with the spindle axis  16  or it is spaced apart from the spindle axis  16  towards the user side  41  (the side where the user is when he/she grips the drill  1  correctly). 
     Advantageously, a housing  34  of the electric motor  3  forms a battery seat  35  for a reversible coupling of the battery  6  by means of pushing or translational insertion, preferably in a direction of insertion facing the user side  41 . This facilitates both the insertion and the removal of the battery  6 . 
     Advantageously, the barycenter of the battery  6  attached to the battery seat  35  is further from the user side  41  with respect to the barycenter of the electric motor  3  which is closer to the user side  41  ( FIG. 4 ). This results in a better balancing of the masses of the drill  1  with respect to the support point thereof on the sleeper and with respect to the spindle axis  16  on which the drilling torsion acts. 
     With even further advantage, the battery seat  35  is formed in an upper surface of the motor housing  34  so that the battery  6  is positioned above the motor  3  and facing upwards. In this way, the battery  6  shields a part of the acoustic waves generated by the electric motor  3  and by the reduction gear in the direction of the user&#39;s head when it is in the work position. 
     According to a further aspect of the invention, the handle  4  comprises two opposite gripping portions  36 ,  37  for the user&#39;s two hands, which are situated on two diametrically opposite sides with respect to the spindle axis  16 , above, and external to the vertical dimensions of the electric motor  3 , and both of the gripping portions  36 ,  37  are extended on one same gripping plane  38 , inclined by less than 15° with respect to a plane perpendicular to the spindle axis  16 . The two gripping portions  36 ,  37  define an angle of less than 15° therebetween, or they are parallel to each other and both of the gripping portions  36 ,  37  are extended in a direction away from the spindle axis  16  towards one side of the drill  1  opposite the user side  4  (the side where the user is positioned with respect to the drill  1  when he/she grips the handle  4  correctly in the work position). 
     Each of the two gripping portions  36 , 37  is formed by a portion of free end of a gripping bar  39  extended and folded in a three-dimensional manner and fixed to the support structure  2  on the user side  41  of the drill  1 . 
     According to an embodiment, the gripping bar  39  is folded in the shape of a trapezium, without the larger base, wherein a first part of the trapezium containing the smaller base lies on a protection plane  40  ( FIGS. 1,9 ) which is substantially parallel to the spindle axis  16 , placed on the user side  41  of the drill  1  and wherein said free end portions forming the gripping portions  36 , 37  are folded outside the protection plane  40  and extend in the aforesaid gripping plane  38 . 
     The part of the gripping bar  39  extended in the protection plane  40  can serve to support the drill  1  and thus protect the motor  3  from damage and direct contact with the ground. 
     To this end, the drill  1  can further comprise a protection plate  42  welded to two lateral portions of the gripping bar  39  in the protection plane  40  at the position of the electric motor  3 . 
     According to a further embodiment, the handle  4 , in particular the gripping bar  39 , is connected to the support structure  2  by means of the interposition of one or more damping elements  70  ( FIG. 6 ). Advantageously, the support structure  2  forms three connection holes  71  and the handle  4  is connected to the support structure  2  by means of three pins  72  inserted into the connection holes  71  by means of the interposition of said annular damping elements  70 . 
     This decreases the transmission of vibrations from the drill  1  to the operator&#39;s hands, reducing fatigue and the risk of work-related pathologies. 
     Thus configured, the handle  4  improves the ergonomics of the drill  1  and the user&#39;s posture, besides contributing to more easily contrasting the moment which resists the rotation of the tip  8  and balancing the weight of the drill  1  in the vertical drilling position. 
     According to a further aspect of the invention, the drill  1  comprises a lighting system  43  with two light sources  44 ,  45  which are spaced apart from each other and arranged on two opposite sides with respect to a hypothetical vertical work plane  46  containing the spindle axis  16 . The two light sources  44 ,  45 , preferably two LEDs, or two LED groups, generate two lit fields (cones) which overlap, at least in a drilling region  47  of the drill  1 , wherein such overlapping of the two lit cones extends, preferably axially, along the whole travel of the movable casing portion  13  between its protracted position and its retracted position. 
     The presence and the particular configuration of the lighting system  43  improve the visibility of the drilling region  47  and reduce the formation of shadows in such region. 
     In an embodiment, the light sources  44 ,  45  are arranged at the aforesaid gripping portions  36 ,  37 , preferably at the free ends of the gripping portions  36 ,  37  or on the side thereof facing away from the user in the position of use. 
     This allows an unobstructed development of the two respective light cones, starting from the top and from the side opposite the user side, developing downwards, with a slight distancing towards the user side and towards the spindle axis  16 , thus avoiding the formation of shadows, providing the user with improved visibility conditions. 
     In fact, one of the advantageous aspects of the lighting system  43  is that the optical axes of the two light cones of the light sources  44 ,  45  are mutually converging in an axial direction towards the tip  8  of the drill  1  and they converge together from the side opposite the user side  41  towards the spindle axis  16 . 
     The drill  1  lighting system  43  improves visibility in the area where the holes are made in the sleepers, both at night and inside unlit tunnels, and to prevent the operator&#39;s eyes from fatigue while making the holes. 
     According to a further aspect of the invention, the drill  1  for drilling sleepers comprises a quick coupling interface  48  for a coupling of the drill  1 , without the aid of equipment, to a tool holder rail cart  49  ( FIG. 14 ). 
     According to an embodiment, the quick coupling interface  48  forms a coupling by means of engagement or translational insertion along a coupling direction parallel to the spindle axis  16 . In the position of use of the drill  1 , this forms a coupling in a vertical direction, which is thus assisted and maintained also by virtue of the force of gravity. 
     According to an embodiment, the quick coupling interface  48  comprises a coupling pin positioned on the side opposite the user side  41 , and having a first upper end connected to the support structure  2  and a second lower end protruding freely in an axial direction, adapted to be inserted into a corresponding vertical tubular seat  50  of the tool holder rail cart  49 . 
     This allows a quick and easy switching of the drill  1  for a hand supported use and for a use supported by a tool holder rail cart  49 . 
     Advantageously, the coupling pin  48  is substantially positioned at the same height as the barycenter of the drill  1  along the spindle axis  16 , but transversely spaced apart from the spindle axis  16 . This allows a particularly stable, balanced positioning during the use of the drill  1  with the tool holder rail cart  49 , but also the use of the coupling pin  48  as a handle for the manual transportation of the drill  1 , with an optimal balancing of the weight thereof. In this regard, the coupling pin  48  is advantageously sized with the same size order as the gripping portions  36 ,  37 . 
     The drill  1  comprises an electronic control unit  51  in connection with the rechargeable battery  6 , the electric motor  3 , the lighting system  43 , and with the activation/manual control members  5  of the electric motor  3  and, if provided, with further signaling, monitoring or control means, which will be described later on. 
     In an embodiment, the manual control members  5  comprise a three-stable-position switch  52  and an operating button  53 , the three-position switch  52  can be positioned in a first stable “drilling” position, in a second stable “off” position and in a third stable “reverse rotation” position for selecting the actuation mode of the motor  3  (with forward rotation to make a hole, with backward rotation in the reverse direction to remove the tip  8  from the hole made and to switch off the drill  1 ). 
     The operating button  53  can be operated manually to operate the motor  3  according to the mode selected by means of the three-position switch  52 . The control unit  51  is configured so that: 
     in the absence of actuation of the operating button  53  the motor  3  is not operated, 
     with the operating button  53  maintained actuated and with a successive switching of the three-position switch  52  from the stable “off” position to the stable “drilling” position or to the stable “reverse rotation” position, the motor  3  is not operated. 
     According to a further embodiment, the control unit  51  is configured so that: 
     with the drill  1  initially off, the switching of the three-position switch  52  into the first stable “drilling” position or into the third stable “reverse rotation” position turns the control unit on  51  in standby mode, ready for operation, 
     with the control unit  51  on and in standby mode, the control unit  51  automatically switches off if the operating button  53  is not actuated for a predetermined maximum standby period, which can be fixed or adjustable, for example, in the range from 60 seconds to 600 seconds, 
     with the drill  1  off, on conclusion of the maximum standby period, the drill  1  can be turned on again in standby mode by means of a switching of the three-position switch  52  first into the second stable “off” position and then into one of the stable “drilling” and “reverse rotation” positions. 
     This enables the drill  1  to be operated with maximum safety. 
     Advantageously, the operating button  53  is positioned at the handle  4 , immediately close to one of the gripping portions  36 ,  37  which are held by the user&#39;s hands. Instead, the three-stable-position switch  52  is advantageously positioned in an unreachable position by the user&#39;s hand on seizing the gripping portion  36 ,  37 , preferably at the motor housing  34  ( FIG. 10 ). 
     According to a further embodiment, the drill  1  comprises a mechanical locking member  75 , positioned at at least one of the two gripping portions  36 , 37  and configured to allow the actuation of the operating button  53  only when the user grips the gripping portion  36 , 37 , and thus the drill  1 , correctly, with his/her hand. 
     The control unit  51  can further be configured to activate the lighting system  43  automatically as a function of the activation of the drill  1  by means of the three-position switch  52  and, possibly, to deactivate the lighting system  43  automatically on switching off the drill  1 , for example, on conclusion of the maximum standby period or after positioning the three-position switch  52  in the second stable “off” position. 
     Alternatively or additionally, the lighting system  43  can comprise a lighting switch  54  for the voluntary switching on and off of the lighting system  43 . 
     Advantageously, the lighting system  43  is switched on automatically during operation of the motor  3  in “drilling” mode and in “reverse rotation” mode and it remains on after the motor  3  has been switched off for a predetermined post-drilling inspection period, for example, 10 seconds. 
     According to a further aspect of the invention, the drill  1  can comprise a light indicator  55  of the set rotation direction of the motor  3 . According to an embodiment, the light indicator  55  comprises a first light indicator  56 , for example, LED, arranged on a first side of the drill  1 , the lighting up of which indicates a rotation setting of the motor  3  in the drilling direction, and a second light indicator  57 , for example, LED, arranged on a second side of the drill  1 , opposite the first side, the lighting up of which indicates a rotation setting in the reverse direction for removing the tip  8 . 
     Advantageously, in the position of use of the drill  1  and in the user work position, the first light indicator  56  and the second light indicator  57  are both opposite the user, one on his/her right and the other on his/her left, by analogy with car light direction indicators. This provides an immediate and highly intuitive indication of the set rotation direction, both before actuation of the motor  3  by means of the operating button  53  and during actuation of the motor  3 . 
     According to one preferred embodiment, the light indicators  56 ,  57  are controlled by the control unit  51  to light up, according to the rotation mode selection of the motor  3 , green in color and in the absence of operating faults, and red and optionally flashing, in the case of operating fault. 
     The rotation direction indicator  55 , which also serves the function of signaling faults by virtue of the analogy thereof with car light indicators, contributes to increasing the user&#39;s ability to concentrate and reducing reaction times in the case of a fault. 
     According to a further embodiment, the electronic control unit  51  also comprises a memory  58  positioned inside the drill  1  configured to memorize, in such memory  58 , drill operating parameters, for example, the number of hours of operation, in particular, the number of hours of operation in “drilling” mode and in “reverse rotation” mode. 
     According to a further embodiment, the drill  1  also comprises a display  59  controlled by the control unit  51  so as to display drill  1  operating parameters. 
     The display  59  is arranged on an outer surface of the housing  34  of the motor  3 , preferably on a lateral side facing away from the user&#39;s view in a work position, so as not to distract the user&#39;s attention during the drilling of the sleeper. The parameters displayed by means of the display  59  comprise, for example, one or more from:
         a battery charge state,   hours of operation,   remaining hours of operation until maintenance is required,   rotation direction of the motor,   rotational speed (number of turns) and the spindle  7 ,   name or series number of the drill,   drill control firmware version,   possible operating faults or errors, for example   over-torque warning requested from the motor,   battery undervoltage warning,   battery overheating warning,   an incorrect motor power supply warning (which may arise, for example, in the case of inserting the battery with the three-position switch  52  not in the “off” position, or in the case of inserting an unsuitable battery).       

     The control unit  51  further comprises a connection interface  73 , for example, a miniUSB port, for a connection thereof to an external electronic device, for example, a computer, for updating the drill  1  control firmware. 
     According to a further embodiment, the control unit  51  comprises a transmission and wireless reception interface  74  for a transmission of data, in particular, operating parameters, with an external electronic device to the drill  1 . 
     With a further advantage, the control unit  51  can comprise one or more from:
         a GSM communication module for a data connection to the GSM mobile phone network,   a localization device of the position thereof,   a satellite localization device of the position thereof (GPS).       

     The drill  1  control and display system is intrinsically safe and contributes to a reduction in downtimes caused by inspections of operating states, the need for unplanned maintenance, configuration and reconfiguration of the operation of the drill  1 , depletion or faults of the battery  6 , operating faults or errors and the identification and diagnosis thereof. 
     The control and display system further improves the correct making of the drilling directly in situ with the planned execution parameters, for example, planned number of turns. 
     According to a further embodiment, the drill  1  comprises a sheath ( 60 ) made of flexible elastomeric material, which is liquid-proof and of a generally tubular shape, with a front opening ( 61 ) and a rear opening ( 62 ), opposite the front opening ( 61 ), in the direction of the spindle axis ( 16 ), so as to be insertable over the electric motor ( 3 ) and over at least a part of the battery ( 6 ) to protect them. 
     The sheath ( 60 ) forms a ventilation channel ( 63 ) with at least a first inlet opening ( 64 ) obtained in an outer surface of the sheath ( 60 ) and facing horizontally or downwards, and with an inner ventilation portion ( 67 ) which is concave and open towards the interior of the sheath ( 60 ) so as to communicate cooling air from the inlet opening ( 64 ) to a cooling system of the motor ( 3 ). 
     According to one embodiment, the ventilation channel ( 63 ) comprises one or more intake filters ( 45 ). 
     According to a further embodiment, the sheath  60  forms a discharge channel ( 65 ) with at least one outlet opening ( 66 ), obtained in an outer surface of the sheath ( 60 ) and facing in a horizontal direction or downwards, with an inner discharge portion ( 68 ) which is concave and open towards the interior of the sheath ( 60 ) so as to be able to receive air expelled by the motor  3  cooling system and discharge it through the outlet opening ( 66 ). 
     The inner discharge portion ( 68 ) can comprise two opposite lateral cavities, formed in two side walls of the sheath ( 60 ) and in communication with the at least one outlet opening ( 66 ). The discharge channel ( 65 ) can also comprise one or more filters. 
     The ventilation ( 63 ) and discharge ( 65 ) channels are mutually spaced apart so as to prevent, or hinder the intake of air from the discharge channel ( 65 ) into the ventilation channel ( 63 ). 
     Advantageously, the sheath  60  forms a battery opening ( 69 ) positioned at the battery ( 6 ) of the drill ( 1 ) to allow the coupling and uncoupling and the removal of the battery ( 6 ) from the drill ( 1 ) through the battery opening ( 69 ), without needing to remove the sheath ( 60 ) from the drill ( 1 ). 
     The sheath  60  also enables holes to be made in sleepers in environmental conditions or weather conditions where water, sand, particles of soil or snow are present.