WO2014168534A1

WO2014168534A1 - Wall saw with detachable gear wheel shaft

Info

Publication number: WO2014168534A1
Application number: PCT/SE2013/050405
Authority: WO
Inventors: Anders Johnsen
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-04-12
Filing date: 2013-04-12
Publication date: 2014-10-16
Anticipated expiration: 2015-10-12

Abstract

A wall saw comprising: - a saw arm (11) pivotally mounted to a carriage (2) and com- prising an external housing (20); - a spindle (10) rotatably mounted to the saw arm and configured for connection to a saw blade; - an electric drive motor; and - a transmission mechanism for transmitting torque from the mo- tor to the spindle, the transmission mechanism comprising a gear wheel (16) fixed to a gear wheel shaft (14), which constitutes or is non-rotatably connected to an output shaft of the motor. Said shaft (14) is accessible through an opening (80) provided in an external wall (81) of the saw arm housing. Said shaft (14) is, together with said gear wheel, removable by an axial displacement outwards through said opening and mountable to the wall saw by an axial displacement inwards through said opening.

Description

Wall saw with detachable gear wheel shaft

FI ELD OF THE I NVENTION AND PRIOR ART The present invention relates to a wall saw according to the preamble of claim 1 .

A wall saw is a sawing machine primarily used for cutting walls, ceilings or floors made of concrete or similar materials. A con- ventional wall saw comprises a carriage which is moveable along a guide rail by means of a feeding device. A saw blade is mounted to a spindle, which is rotatably mounted to a saw arm . The saw arm is in its turn pivotally mounted to the carriage. The spindle is rotated by means of a drive motor, which is mounted to the carriage and operatively connected to the spindle through a transmission mechanism accommodated in the saw arm. When the saw arm is pivoted , the saw blade is moved upwards or downwards for adjustment of the depth of the cut. The saw arm may be pivoted by means of a motor or a manually operated ac- tuating device mounted to the carriage.

Wall saws of the above-mentioned type are for instance disclosed in WO 2009/108094 A1 , US 3 722 497 A and US 2007/01 63412 A1 .

The above-mentioned transmission mechanism may comprise a set of gear wheels acting between the output shaft of the drive motor and the saw blade spindle, wherein driving torque for the rotation of the saw blade spindle is transmitted from the output shaft of the drive motor to the spind le via these gear wheels. In such a case, a first smaller gear wheel is normally non-rotation- ally connected to the output shaft of the drive motor and in engagement with a substantially larger gear wheel rotatably mounted to a housing of the saw arm, as illustrated in US 3 722 497 A. An electric drive motor of a wall saw is normally operated at a high rotational speed , which implies that said first gear wheel rotates at high speed and thereby is subjected to wear. Said first gear wheel will get worn out faster than the other gear wheels of the transmission mechanism and normally has to be replaced for a new gear wheel much earlier than the other gear wheels of the transmission mechanism.

OBJECT OF THE I NVENTION

The object of the present invention is to provide a wall saw having a new and favourable design .

SUMMARY OF THE I NVENTION

According to the invention , said object is achieved by a wall saw having the features defined in claim 1 .

The wall saw according to the invention comprises:

- a carriage, which is to be mounted to a guide rail so as to be moveable along the gu ide rail;

- a saw arm pivotally mounted to the carriage, the saw arm com- prising an external housing ;

- a rotatable spindle configured for connection to a saw blade, the spindle being rotatably mounted to the saw arm housing ;

- an electric drive motor, which is mounted to the carriage; and

- a transmission mechan ism for transmitting torque from the drive motor to the spind le, the spindle being rotatable under the effect of the drive motor via the transmission mechanism, wherein the transmission mechanism comprises:

• a first gear wheel non-rotatably fixed to a gear wheel shaft, which constitutes or is non-rotatably connected to an out- put shaft of the drive motor,

• a second gear wheel non-rotatably fixed to the spind le, and

• a number of gear wheels rotatably mounted to the saw arm housing and acting between said first and second gear wheels. According to the invention , said gear wheel shaft is detachably mounted and accessible through an opening provided in an external wall of the saw arm housing , the gear wheel shaft being , together with said first gear wheel , removable from the wall saw by an axial displacement outwards through said opening and mountable to the wall saw by an axial displacement inwards through said open ing .

In the wall saw according to the invention , the above-mentioned first gear wheel of the transmission mechan ism , which wears out faster than the other gear wheels of the transmission mechanism, is easily accessible for replacement through the opening in the external wall of the saw arm housing , without requiring any demounting of the saw arm. Thus, said gear wheel can be replaced for a new gear wheel in a rapid manner by the operator of the wall saw without requiring any transportation of the wall saw to a service workshop or the similar. Hereby, the wall saw may be in operation during a comparatively long period of time before the transmission mechanism has to be subjected to repairs of more complicated and time consuming type.

Accord ing to an embodiment of the invention , said opening is closed by a cover, which is removable from the opening . Accord ing to another embodiment of the invention , the cover constitutes an axial stop member for the gear wheel shaft. Hereby, the axial movability of the gear wheel shaft and the associated gear wheel is automatically restricted by the cover when the opening in the external wall of the saw arm housing is closed by the cover.

Accord ing to another embodiment of the invention , the gear wheel shaft is provided with a pulling tool fitting designed for detachable engagement with a pulling tool to be used for pulling the gear wheel shaft and the first gear wheel axially outwards through said open ing , this fitting being accessible from the end of the gear wheel shaft that faces the opening . Hereby, a pulling tool may easily be connected to the gear wheel shaft when the cover has been removed from the opening in the external wall of the saw arm housing . This tool may then be used for pulling the gear wheel shaft and the first gear wheel through said open ing in order to remove them from the wall saw, whereupon the tool may be connected to a new gear wheel shaft of the same design and used for mounting the new gear wheel shaft and the associated gear wheel to the wall saw. Accord ing to another embodiment of the invention , the pulling tool fitting comprises an internal thread provided in an axial hole in the gear wheel shaft, this internal thread being designed for engagement with a corresponding external thread on the pulling tool. Hereby, the pulling tool may be connected to the gear wheel shaft in a simple and reliable manner by being screwed into said axial hole.

Another embodiment of the invention is characterized in :

- that the rotor of the drive motor comprises a rotor hu b; and - that the gear wheel shaft constitutes an output shaft of the drive motor and is operatively connected to the rotor hu b through a safety clutch so as to allow torque to be transmitted from the rotor hub to the gear wheel shaft via the safety clutch , the safety clutch being configured to allow mutual rotation between the ro- tor hub and the gear wheel shaft when said torque reaches a given threshold value.

Accord ing to another embodiment of the invention , the gear wheel shaft is provided with a torque tool fitting designed for de- tachable engagement with a torque tool to be used for rotating the gear wheel shaft in order to check said threshold value, th is fitting being accessible from the end of the gear wheel shaft that faces said opening . Hereby, a torque tool may easily be connected to the gear wheel shaft when the cover has been removed from the opening in the external wall of the saw arm housing . This tool may then be used for checking the torque threshold value of the safety clutch . Accord ing to another embodiment of the invention , the pulling tool fitting and the torque tool fitting are provided in one and the same axial hole in the gear wheel shaft. Hereby, two different tool fittings are incorporated in the gear wheel shaft in a space- saving manner.

Further advantages as well as advantageous features of the wall saw according to the invention will appear from the following de- scription and the dependent claims.

BRI EF DESCRI PTION OF THE DRAWI NGS

With reference to the appended drawings, a specific description of preferred embod iments of the invention cited as examples follows below. In the drawings:

Fig 1 is a perspective view of a wall saw accord ing to an embod iment of the present invention

Fig 2 is a perspective view of the wall saw of Fig 1 , as seen from another direction and with a saw blade mounted to the wall saw, Fig 3 is a perspective view of a carriage and a saw arm included in the wall saw of Fig 1 ,

Fig 4 is a partially sectioned lateral view of the carriage and saw arm included in the wall saw of Fig 1 ,

Fig 5 shows a part from Fig 4 in a larger scale

Fig 6 shows another part from Fig 4 in a larger scale Fig 7 is a sectioned front view of the saw arm included in the wall saw of Fig 1 , is a perspective view of an actuating device included in the wall saw of Fig 1 ,

Fig 9 is a perspective view of a chassis included in the car- riage of the wall saw of Fig 1 ,

Fig 10 is a perspective view of the chassis of Fig 9, as seen from another direction , Fig 1 1 is an exploded view of a motor module and the carriage included in the wall saw of Fig 1 ,

Fig 12 is a longitudinal section through a safety clutch included in the wall saw of Fig 1 ,

Fig 13 is an exploded view of the safety clutch of Fig 12 , and

Fig 14 is an exploded view of parts included in the wall saw of Fig 1 .

DETAI LED DESCRI PTION OF EMBODI MENTS OF THE I NVENTION

A wall saw 1 according to an embod iment of the present inven- tion is illustrated in Figs 1 and 2. This wall saw 1 is primarily intended to be used for cutting walls, ceilings or floors made of concrete or similar materials. The wall saw 1 comprises a carriage 2, which is to be mounted to an elongated gu ide rail 3 so as to be moveable along the guide rail . The guide rail 3 is mounted to a floor or other supporting surface by means of support members 4, wh ich are secured to the guide rail 3.

Guide rollers 5a-5d are rotatably mounted to the carriage 2. These guide rollers 5a-5d are in engagement with guide tracks 6a, 6b on the guide rail 3 and are arranged to keep the carriage 2 in place on the guide rail 3, while allowing the carriage 2 to move along the guide rail 3 in the longitudinal direction thereof. In the illustrated embodiment, the guide rail 3 is provided with an upper guide track 6a and a lower guide track 6b, wh ich extend in parallel with each other along the guide rail. In the illustrated embod iment, two guide rollers 5a, 5b are in engagement with the upper guide track 6a from above and two other guide rollers 5c, 5d are in engagement with the lower gu ide track 6b from below.

A cog track 7 is fixed to the gu ide rail 3 and extends in the longitudinal direction thereof in parallel with the guide tracks 6a, 6b. The carriage 2 is moveable along the cog track 7 by means of a feeding device, which comprises a feed gear wheel 8 (see Fig 3) rotatably mounted to the carriage 2. The feed gear wheel 8 is in engagement with the cog track 7. The feeding device also comprises a feed motor (not shown) mounted to the carriage 2, by means of which the feed gear wheel 8 is rotatable in order to move the carriage 2 along the guide rail 3. The feed motor is preferably an electric motor, but could alternatively be a hydraulic motor. A circu lar saw blade 9 (see Fig 2) is to be attached to a rotatable spindle 10. I n Fig 1 , the wall saw is shown without any saw blade attached to the spind le 10. The saw blade 9 is detachably attachable to the spindle 10 by means of a suitable coupling . The spindle 10 is rotatably mounted to a saw arm 1 1 by means of suitable bearings 12 (see Fig 4) and is rotatable about a first axis of rotation A1 . The spind le 10 is driven in rotation by means of an electric drive motor 13, which is mounted to the carriage 2. Driving torque is transmitted from the drive motor 13 to the spindle 10 through a transmission mechanism 15 (see Figs 4 and 7) . Thus, the spindle 10 is rotatable under the effect of the drive motor 13 via the transmission mechanism 15. The transmission mechanism 15 comprises a set of gear wheels acting between the drive motor and the spind le 10. A first gear wheel 16 of the transmission mechanism 15 is non-rotatably fixed to a gear wheel shaft 14. Th is gear wheel shaft 14 is rotatable about a second axis of rotation A2, which extends in parallel with and at a distance from said first axis of rotation A1 . In the illustrated em- bodiment, the gear wheel shaft 14 constitutes an output shaft of the drive motor 13. However, the gear wheel shaft 14 may as an alternative be a separate shaft which is non-rotatably connected to an output shaft of the drive motor 13 by means of a spline coupling or the similar. Another gear wheel 1 7 of the transmission mechanism 15, here denominated second gear wheel, is non-rotatably fixed to the spindle 10. These gear wheels 16, 1 7 are operatively connected to each other via a number of intermediate gear wheels 18a, 18b, 18c rotatably mounted in an external housing 20 of the saw arm 1 1 . In the illustrated example, two of said intermed iate gear wheels 18b, 18c are non-rotatably connected to each other.

The saw arm 1 1 is pivotally mounted to the carriage 2 by means of suitable bearings 21 , 22 , 23 and is pivotable about a pivot axis A3, which is perpendicular to the longitudinal axis of the guide rail 3 and coincides with said second axis of rotation A2. The saw arm 1 1 is adjustable into different rotational positions in relation to the carriage 2 by being pivoted about the pivot axis A3. In the illustrated embodiment, a ring gear 24 (see Figs 4 and 6) is non- rotatably fixed to the saw arm housing 20 by means of fastening members 25 in the form of screws. A gear wheel 26 (see Fig 8) is rotatably mounted to the carriage 2 and in engagement with the ring gear 24. The wall saw 1 comprises an actuating device 27 (see Fig 8), by means of which said gear wheel 26 is rotatable in order to rotate the ring gear 24 and thereby pivot the saw arm 1 1 in relation to the carriage 2 about the pivot axis A3. The actuating device 27 comprises a motor 28 mounted to the carriage 2, by means of wh ich said gear wheel 26 is rotatable. Said motor 28 is preferably an electric motor, but could alternatively be a hydraulic motor. The actuating device 27 also comprises a transmission mechanism 29 for transmitting torque from the output shaft of said motor 28 to said gear wheel 26. In the illustrated example, this transmission mechanism 29 comprises a worm screw 30a non-rotatably connected to the output shaft of the motor 28 and a number of intermediate gear wheels 30b, 30c, 30d acting between the worm screw 30a and said gear wheel 26. The gear wheel 26 is non-rotatably connected to the last one 30d of said intermed iate gear wheels.

In the illustrated embodiment, the drive motor 13 and the saw arm 1 1 are carried by a chassis 31 included in the carriage 2. The chassis 31 is vertically oriented and is preferably of metallic material, such as for instance steel. The chassis 31 comprises a vertical wall 32 (see Figs 4, 9 and 10) and a flange 33 protruding in a horizontal direction from this wall 32. This vertical wall 32 and the flange 33 are preferably formed in one piece, but are alternatively formed as separate pieces which are rigid ly joined to each other by welding . The saw arm 1 1 is pivotally mounted to the chassis 31 on a first side of said wall 32 and a motor cavity 34 is provided in the chassis 31 on an opposite second side of said wall 32. In the following , said first side of the wall 32 is denominated the outer side of the wall, whereas said second side of the wall 32 is denominated the inner side of the wall. The motor cavity 34 is delimited in one axial direction by said wall 32 and in the rad ial direction by said flange 33, which forms a cylin- drical inner wall of the motor cavity 34. The stator 35 and rotor 36 of the drive motor 13 are accommodated in the motor cavity 34. Thus, the stator 35 and rotor 36 of the drive motor 13 are protected by said wall 32 and flange 33 of the chassis 31 . The gear wheel shaft 14 extends through an open ing 37 in the wall 32.

The gear wheel shaft 14 is detachably mounted and accessible through an opening 80 provided in an external wall 81 of the saw arm housing 20. The opening 80 is closed by a cover 82, which is removable from the opening 80. The gear wheel shaft 14 is, together with the above-mentioned first gear wheel 16 of the transmission mechanism 15, removable from the wall saw 1 by an axial displacement outwards through said opening 80 and mountable to the wall saw by an axial displacement inwards through said opening 80, when the cover 82 has been removed from the opening 80. In the illustrated embodiment, the cover 82 constitutes an axial stop member for the gear wheel shaft 14, as illustrated in Fig 5, wherein an end of the gear wheel shaft 14 abuts against an inner surface of the cover 82.

In the illustrated embodiment, the cover 82 is detachably mounted to the above-mentioned wall 81 of the saw arm housing 20 and is provided with an external thread 83 that is in engagement with a correspond ing internal thread 84 in the opening 80 in the wall 81 . Thus, the cover 82 may be detached from and mounted to said wall 81 by screwing .

The gear wheel shaft 14 is with advantage provided with a pu lling tool fitting 100 designed for detachable engagement with a pulling tool 101 (see Fig 14) to be used for pulling the gear wheel shaft 14 and said first gear wheel 1 6 axially outwards through the opening 80, th is fitting 100 being accessible from the end of the gear wheel shaft 14 that faces the opening 80. In the illustrated embodiment, the pulling tool fitting 100 comprises an internal thread 102 provided in an axial hole 103 in the gear wheel shaft 14, th is internal thread 102 being designed for engagement with a corresponding external thread 104 on the pulling tool 101 .

In the illustrated embod iment, a first axial bearing 21 and a second axial bearing 22 are provided between the saw arm 1 1 and the carriage 2, as illustrated in Figs 4 and 6. The first axial bearing 21 comprises a flat and ring-shaped first sliding element 38, preferably in the form of a disc of plastic material, clamped between a contact surface 39 of the saw arm 1 1 and a corresponding contact surface 40 on the outer side of the wall 32. The second axial bearing 22 comprises a flat and ring-shaped second sliding element 41 , preferably in the form of a ring of plastic material, clamped between a lateral surface 42 (se Fig 6) on the ring gear 24 and a clamping member 43 fixed to the chassis 31 . The clamping member 43 is of metallic material. The clamping member 43 is flat and ring-shaped and comprises an outer part 43a (see Figs 6 and 1 1 ), through which the clamping member is fixed to the chassis 31 , and an axially springy part 43b which extends rad ially inwards from the outer part 43a and bears against the second sliding element 41 in a pre-tensioned manner. The axially springy part 43b of the clamping member is pre-tensioned against the second sliding element 41 so as to keep the second sliding element 41 clamped between the clamping mem- ber 43 and said lateral surface 42 on the ring gear under the effect of a spring force exerted by the clamping member. The outer part 43a of the clamping member is fixed to the chassis 31 by means of fastening members 44 in the form of screws. The above-mentioned contact surface 39 of the saw arm 1 1 is pressed towards the corresponding contact surface 40 on the outer side of the wall 32 under the effect of the clamping member 43. The saw arm 1 1 is retained in engagement with the chassis 31 under the effect of the spring force exerted by the clamping member 43. Thus, the clamping member 43 keeps the saw arm 1 1 secured to the carriage 2 in a pre-tensioned manner.

In the illustrated embodiment, a radial bearing 23 (see Figs 4 and 6) is provided between an outer circular cylindrical surface 45 of the chassis 31 and an inner circular cylindrical surface 46 of the saw arm 1 1 . The radial bearing 23 comprises a sliding element 47, preferably in the form of a band of plastic material , arranged between said surfaces 45, 46.

In the illustrated embod iment, the ring gear 24 is received in an annular recess 50 (see Figs 6 and 10) in the chassis 31 and the outer part 43a of the clamping member 43 is fixed to a part 51 of the chassis which surrounds said recess 50. Furthermore, the guide rollers 5a-5d and the feed gear wheel 8 are rotatably mounted to the chassis 31 , and the feed motor and the motor 28 of the actuating device 27 are received in a cavity 52 (see Fig 9) provided in the chassis 31 .

The carriage 2 may be lifted and carried by means of handles 54 mounted to the chassis 31 .

A lid 55 is fixed to the flange 33 of the chassis at the outer free end thereof by means of fastening members 57 (see Figs 3 and 1 1 ) in the form of screws or bolts. In the illustrated embod iment, the lid 55 and the drive motor 13 form part of a motor module 60 (see Fig 1 1 ) which is detachably mounted to the chassis 31 . The motor module 60 comprises a cylindrical sleeve 61 which is rig- idly connected to the lid 55 and projects therefrom into the motor cavity 34, the stator 35 of the drive motor 13 being fixed to the sleeve 61 on the inner side thereof. An outer peripheral surface of the sleeve 61 abuts against an inner peripheral surface of the above-mentioned flange 33 of the chassis 31 . A channel 62 for cooling fluid is provided in the interface between the outer peripheral surface of the sleeve 61 and the inner peripheral surface of the flange 33, as illustrated in Fig 4.

In the illustrated embodiment, the rotor 36 of the drive motor 13 comprises a rotor hub 66 (see Figs 4 and 5) , which is rotatably mounted in the carriage 2 through at least one first bearing 72, for instance in the form of a ball bearing or a roller bearing , provided on the outer side of the rotor hub 66 at a first end thereof and at least one second bearing 74, for instance in the form of a ball bearing or a roller bearing , provided on the outer side of the rotor hub 66 at an opposite second end thereof. In the illustrated example, said at least one first bearing 72 is provided between a flange 73 on the inner side of the lid 55 and an outer peripheral surface at the first end of the rotor hub 66, and said at least one second bearing 74 is provide between a flange 75 on the inner side of the wall 32 of the chassis 31 and an outer peripheral surface at the second end of the rotor hub 66.

In the illustrated embod iment, the stator 35 of the drive motor 13 is located on the outside of the rotor 36. As an alternative, the stator 35 of the drive motor 13 may be located between an outer part of the rotor 36 and the rotor hub 66. In the latter case, the stator 35 is fixed to the lid 55 of the motor module 60. In the illustrated embod iment, the rotor hub 66 is operatively connected to the gear wheel shaft 14 through a safety clutch 67 so as to allow torque to be transmitted from the rotor hub 66 to the gear wheel shaft 14 via the safety clutch 67. The safety clutch 67 is configured to allow mutual rotation between the rotor hub 66 and the gear wheel shaft 14 when said torque reaches a given threshold value. The safety clutch 67 is accommodated in a space inside the rotor hub 66 and comprises one or more first clutch members 68 (see Figs 5, 12 and 13), each of which being non-rotatably fixed to the rotor hub 66, and one or more second clutch members 69 each of which being non-rotatably fixed to the gear wheel shaft 14. Said first and second clutch members 68, 69 are pressed towards each other under the effect of a spring member 70 so as to allow torque to be transmitted from the rotor hub 66 to the gear wheel shaft 14 via these clutch members 68, 69. The spring member 70 is also accommodated in the space inside the rotor hub 66. Said first and second clutch members 68, 69 and the spring member 70 are located between an inner peripheral surface of the rotor hu b 66 and an outer peripheral surface of a part 14a of the gear wheel shaft 14 surrounded by the rotor hub 66. The above-mention threshold value is given by the spring force of the spring member 70.

The gear wheel shaft 14 is with advantage provided with a torque tool fitting 105 designed for detachable engagement with a torque tool to be used for rotating the gear wheel shaft 14 in order to check the above-mentioned threshold value of the safety clutch 67, this fitting 105 being accessible from the end of the gear wheel shaft 14 that faces the above-mentioned opening 80 in the external wall 81 of the saw arm housing 20. When the threshold value is to be checked by means of said torque tool, the rotor 36 of the drive motor 13 is temporarily prevented from rotating by means of a suitable stop member (not shown) that is brought into engagement with the rotor. In the illustrated embodiment, the torque tool fitting 105 has the form of an Allen key fitting provided in an axial hole 103 in the gear wheel shaft 14. The torque tool fitting 105 and the above-mentioned pulling tool fitting 100 are preferably provided in one and the same axial hole 103 in the gear wheel shaft 14. In the illustrated embodiment, said first and second clutch members 68, 69 have the form of ring-shaped discs and are arranged side by side in frictional engagement with each other. The gear wheel shaft 14 extends through a central opening in each clutch member 68, 69. The clutch members 68, 69 are moveable in the axial direction of the gear wheel shaft 14 and the rotor hub 66. In the illustrated example, each first clutch member 68 is provided with teeth 76 on its outer periphery, which teeth 76 are in engagement with internal splines in the rotor hub 66 so as to force the clutch member 68 to rotate together with the rotor hub 66, while at the same time allowing the clutch member 68 to slide axially in relation to the rotor hub 66. Each second clutch member 69 is provided with teeth 77 on its inner periphery, which teeth 77 are in engagement with external splines 78 on the gear wheel shaft 14 so as to force the clutch member 69 to rotate together with the gear wheel shaft 14, while at the same time allowing the clutch member 69 to slide axially on the gear wheel shaft 14. The first and second clutch members 68, 69 are arranged alternately side by side and are pressed towards each other by the spring member 70 so as to allow torque to be transmitted from the rotor hub 66 to the gear wheel shaft 14 by the frictional engagement between the clutch members.

In the illustrated embod iment, the spring member 70 is clamped between an internal shoulder 79 (see Fig 5) on the rotor hub 66 and an axially outermost one of said clutch members 68, 69. The spring member 70 preferably comprises one or more Belleville washers 71 , the gear wheel shaft 14 extending trough a central opening in each Belleville washer. In the illustrated example, the spring member 70 comprises four Belleville washers 71 arranged side by side.

The spring force of the spring member 70 is adjustable by means of an adjustment member 86, which is provided with an external thread 87 that is in engagement with a corresponding internal thread 88 in the rotor hub 66 at the above-mentioned first end of the rotor hub, as illustrated in Fig 5. The adjustment member 86 abuts against an axially outermost one 68' of the first clutch members (see Fig 1 2). The position of the adjustment member 86 in the axial direction of the rotor hub 66, and thereby the axial pre-tensioning and spring force of the spring member 70, is ad- justable by screwing the adjustment member 86 in either direction in relation to the rotor hub 66. At least one locking screw 90 is received in an axial through hole 91 in the adjustment member 86. An inner end 90a of this locking screw 90 is engageable in a recess 93 in the last-mentioned clutch member 68' in order to lock the adjustment member 86 to this clutch member 68' and thereby prevent mutual rotation between the adjustment member 86 and the rotor hub 66. Thus, when the end 90a of the locking screw 90 is received in a recess 93 in the clutch member 68' , the adjustment member 86 will be locked in its prevailing position in relation to the rotor hub 66. The locking screw 90 is provided with an external thread 89a that is in engagement with a corresponding internal thread 89b in said through hole 91 , as illustrated in Fig 12. In the illustrated example, two such locking screws 90 are used . To make possible an accurate adjustment of the position of the adjustment member 86, the clutch member 68' is provided with several recesses 93 distributed around the centre axis of the clutch member and/or the adjustment member 86 is provided with several threaded through holes 91 distributed around the centre axis of the adjustment member.

The above-mentioned space inside the rotor hub 66 is limited in a first axial direction by the above-mentioned shoulder 79 on the rotor hub 66 and in the opposite axial direction by the adjustment member 86.

At the above-mentioned first end of the rotor hub 66, the gear wheel shaft 14 is rotatably mounted to the rotor hu b 66 through the adjustment member 86. In the illustrated example, a stub shaft 94 fixed to the gear wheel shaft 14 is slidably and rotatably received in an axial recess 95 in the centre of the adjustment member 86. The stub shaft 94 is mounted in a recess 97 at the end of the gear wheel shaft 14, for instance by press fit. In the illustrated example, the adjustment member 86 is ring-shaped and the above-mentioned recess 95 is formed as an axial through hole in the adjustment member 86. At the above-mentioned second end of the rotor hub 66, the gear wheel shaft 14 is rotatably mounted to the rotor hub 66 through a sleeve-shaped slid ing element 98 provided between the rotor hu b 66 and the gear wheel shaft 14. This slid ing element 98 is clamped between a shou lder 96 on the gear wheel shaft 14 and a Belleville washer 71 of the spring member 70, as illustrated in Fig 12.

As an alternative to a disc type safety clutch 67 of the type described above, the safety clutch 67 may be a ball type safety clutch . I n th is case, the safety clutch comprises a number of balls which are moveable by a cam and against the action of a spring member from a first position , in which the balls are capable of transmitting torque from a first clutch member non-rotatably fixed to the rotor hub 66 to a second clutch member non-rotatably fixed to the gear wheel shaft 14, to a second position , in which the balls are incapable of transmitting torque from said first clutch member to said second member.

As a further alternative, the gear wheel shaft 14 and the rotor 36 of the drive motor 13 may be non-rotationally connected to each other directly without any intermed iate safety clutch , for instance by means of a spline coupling .

The wall saw 1 also comprises an electronic unit 63, which com- prises electron ic components for controlling the power supply to the stator 35 of the drive motor 13. In the illustrated embod iment, the electronic unit 63 is fixed to the lid 55 on the side thereof facing away from the motor cavity 34. The adjustment member 86 is accessible through an opening 99 (see Fig 5) in the lid 55 when the electronic unit 63 has been detached from the lid . The drive motor 13 is preferably a switched reluctance motor, but may alternatively be a permanent magnet motor or any other suitable electric motor. The invention is of course not in any way restricted to the embodiments described above. On the contrary, many possibilities to modifications thereof will be apparent to a person with ordinary skill in the art without departing from the basic idea of the invention such as defined in the appended claims.

Claims

CLAI MS

1 . A wall saw comprising :

- a carriage (2), which is to be mounted to a guide rail (3) so as to be moveable along the guide rail;

- a saw arm ( 1 1 ) pivotally mounted to the carriage (2) , the saw arm comprising an external housing (20);

- a rotatable spindle (10) configured for connection to a saw blade (9), the spind le (10) being rotatably mounted to the saw arm housing (20);

- an electric drive motor (1 3), which is mounted to the carriage (2) ; and

- a transmission mechanism ( 15) for transmitting torque from the drive motor (13) to the spindle ( 10), the spindle being ro- tatable under the effect of the drive motor (13) via the transmission mechan ism (15), wherein the transmission mechanism (15) comprises:

• a first gear wheel (1 6) non-rotatably fixed to a gear wheel shaft (14) , which constitutes or is non-rotatably connected to an output shaft of the drive motor (1 3),

• a second gear wheel (1 7) non-rotatably fixed to the spindle (10) , and

• a number of gear wheels (18a, 18b, 18c) rotatably mounted to the saw arm housing (20) and acting between said first and second gear wheels (1 6, 1 7),

characterized in that said gear wheel shaft (14) is detachably mounted and accessible through an open ing (80) provided in an external wall (81 ) of the saw arm housing (20) , the gear wheel shaft (14) being , together with said first gear wheel (16), removable from the wall saw (1 ) by an axial displacement outwards through said opening (80) and mountable to the wall saw by an axial displacement inwards through said opening (80). 2. A wall saw according to claim 1 , characterized in that said open ing (80) is closed by a cover (82), which is removable from the open ing (80). A wall saw according to claim 2, characterized in that the cover (82) constitutes an axial stop member for the gear wheel shaft (14).

A wall saw according to claim 2 or 3, characterized in that the cover (82) is detachably mounted to said wall (81 ) and provided with an external thread (83) that is in engagement with a correspond ing internal thread (84) in said opening (80).

A wall saw according to any of claims 1 -4, characterized in that the gear wheel shaft (14) is provided with a pulling tool fitting ( 100) designed for detachable engagement with a pulling tool ( 101 ) to be used for pulling the gear wheel shaft ( 14) and said first gear wheel (1 6) axially outwards through said open ing (80), this fitting (100) being accessible from the end of the gear wheel shaft (14) that faces the opening (80).

A wall saw according to claim 5, characterized in that the pulling tool fitting (100) comprises an internal thread (102) provided in an axial hole ( 103) in the gear wheel shaft (14), this internal thread (102) being designed for engagement with a corresponding external thread (104) on the pulling tool (101 ).

A wall saw accord ing to any of claims 1 -6, characterized in :

- that the rotor (36) of the drive motor (1 3) comprises a rotor hub (66) ; and

- that the gear wheel shaft (14) constitutes an output shaft of the drive motor (1 3) and is operatively connected to the rotor hub (66) through a safety clutch (67) so as to allow torque to be transmitted from the rotor hu b (66) to the gear wheel shaft (14) via the safety clutch (67), the safety clutch being configured to allow mutual rotation between the rotor hub (66) and the gear wheel shaft (14) when said torque reaches a given threshold value.

8. A wall saw according to claim 7, characterized in that the gear wheel shaft (14) is provided with a torque tool fitting (105) designed for detachable engagement with a torque tool to be used for rotating the gear wheel shaft (14) in order to check said threshold value, this fitting (105) being accessible from the end of the gear wheel shaft (14) that faces said opening (80).

9. A wall saw according to claim 8, characterized in that the torque tool fitting (105) has the form of an Allen key fitting provided in an axial hole ( 103) in the gear wheel shaft (14).

10. A wall saw according to claim 9 in combination with claim 6, characterized in that the pulling tool fitting (100) and the torque tool fitting (105) are provided in one and the same axial hole ( 103) in the gear wheel shaft (14).

1 1 . A wall saw according to any of claims 7-10, characterized in that the safety clutch (67) is accommodated in a space inside the rotor hub (66).

12. A wall saw according to claim 1 1 , characterized in that the safety clutch (67) comprises one or more first clutch members (68), each of which being non-rotatably fixed to the rotor hub (66), and one or more second clutch members (69), each of which being non-rotatably fixed to the gear wheel shaft (14), wherein said first and second clutch members (68, 69) are pressed towards each other under the effect of a spring member (70) so as to allow torque to be transmitted from the rotor hub (66) to the gear wheel shaft (14) via these clutch members (68, 69) .

13. A wall saw according to claim 12, characterized in that said first and second clutch members (68, 69) are located between an inner peripheral surface of the rotor hub (66) and an outer peripheral surface of a part (14a) of the gear wheel shaft ( 14) surrounded by the rotor hub (66).

14. A wall saw according to claim 13, characterized in that said first and second clutch members (68, 69) have the form of ring-shaped discs and are arranged side by side in frictional engagement with each other.

15. A wall saw according to claim 13 or 14, characterized in that each one of said second clutch members (69) is provided with teeth (77) on its inner periphery, these teeth (77) being in en- gagement with external splines (78) on the gear wheel shaft (14).