AN ARRANGEMENT IN EXTRACTOR CRANES

Abstract: In an extraction crane (1) having an arm (2) on which to mount an extractor and other equipment, the arm (2) is hinged by means of its inner end (9) to a support (17) with the intermediary of a mounting bracket (14), so as to be allowed to pivot essentially in the horizontal plane. A retaining device (18) acts between the arm (2) and the mounting bracket (14) to retain the arm in the set pivotal position. The retaining device (18) comprises a rod (24) which carries friction washers (23) and which may be actuated by an actuator (20) via a rotationally mounted yoke (38) in order to move the friction washers (23) from their retaining frictional engagement with a plate (34) connected to the mounting bracket (14) and thereby allow the arm (2) to be pivoted as desired. The power actuator (20) is remote-controlled by a control unit positioned on the extraction hood of the extractor.

Description: AN ARRANGEMENT IN EXTRACTOR CRANES The subject invention concerns an arrangement in extractor cranes comprising an arm arranged to mount an extractor and/or some other equipment, said arm being articulated by means of one of its arms to a support with the intermediary of a mounting bracket, so as to be allowed to pivot or swing essentially in the horizontal plane, a retaining device acting between the arm and the bracket or the support for the purpose of maintaining the arm in the set position of pivot thereof. A device of the kind referred to is generally known from SE, C, 7706374-1, corresponding to SE, B, 423 059. With the prior-art device it is necessary, when the extractor or other piece of equipment is to be mounted on or suspended from the pivotable arm, to exert a braking force on the ball-bearing mounted joint in the bracket with the aid of a braking element. This braking element is adjustable so as to allow regulation of the frictional force. However, the pressure required to prevent un¬ intentional pivotal movement of the arm is quite considerable. The disadvantages found in this prior-art device are, primarily, that the operator need to exert considerable force in order to be able to pivot the arm against the action of the frictional force, and secondly, that the frictional force will change as the braking element wears out from use, with consequential need for resetting. In order to obviate these and other disadvantages, the subject invention proposes to fit the retaining device with a retaining element which is actuated by means of a power actuator arranged, by overriding the retaining force, to allow the desired pivotal movement of the arm, and to provide for remote control of the actuator from a place spaced from said one end of the arm. The invention will be described in closer detail in the following with reference to the accompanying drawings, wherein Fig. 1 is a perspective view obliquely from below of an extractor crane, and Figs. 2 and 3 illustrate in respectively a lateral view and a longitudinal sectional view one end of an arm incorporated in the extractor crane of Fig. 1 and a retaining device cooperating therewith. The extractor crane illustrated in the drawing figures and generally designated by reference 1 is fitted with an essentially horizontally directed arm 2 of a suitable material, preferably a tubular steel section. The arm 2 may be a one-piece section, as illustrated, or consist of two or several mutually articulated sections, depending on the desired range of the extractor crane 1. The arm 2 is arranged to serve as a support or a suspension means for a fume extractor 3 of a prior-art design including a fan 4, hoses 5, tubes 6, and a hood 7 for extraction of the air-polluting substances ( elding fumes) that are generated for instance during welding operations, and/or optionally for other equipment, such as welding-wire feeders 8, cables, hand tools and the like. At one 9 of its ends the arm 2 is fitted with a vertically directed bearing tube 10, preferably secured to the arm through welding, which bearing tube 10 encloses and by means of suitable bearings 11 is mounted on a vertically directed spindle 12, thus allowing pivotal movements of the arm 2 essentially in the horizontal plane. Nuts 13 or similar means secure the spindle 12 non-rotationally between two vertically spaced and horizontally projecting lugs 15 which are secured, preferably through welding, to a mounting bracket 14. In accordance with the embodiment illustrated in the drawings, the mounting bracket 14 consists of a flat plate which by means of bolts 16 or similar fasteners extending through holes made in the plate, may be mounted on a support 17, preferably a wall, a stanchion or the like. In order to retain the arm 1 of the extractor crane together with the equipment 3, 8 mounted thereon in the desired angular position in which it is set a retaining device, generally designated by reference 18, is arranged so as to act between said one end 9 of the arm 2 and, in the embodiment illustrated, the bracket 14. Generally speaking, the retaining device 18 comprise a retaining element 19 which is arranged to be actuated b a power actuator 20 for the purpose of overriding the retaining force, thus allowing the arm 2 to be pivoted as desired. The power actuator 20 is remote-controlled from point to be described in closer detail in the following, spaced from the said one end 9 of the arm 2. More precisely, the retaining element 19 is equipped with a friction element 21 which is arranged to be dis¬ placed inside the arm 2 at the said one end 9 thereof and which is arranged to be actuated by the acctuator 20 into and out of frictional engagement with a back-up or counte element 22 connected with the bracket-14. In accordance with the embodiment illustrated, the friction element 21 consists of two circular friction washers 23 disposed at one, the lower, end of a rod 24 so as to sandwich the back-up element 22 between them. The upper friction washer 23 is situated between the lower face 25 of the arm 2 and the upper face of the back-up element 22 whereas the lower friction washer 23 is situated between the lower face of the back-up element 22 and a support washer 27 mounted in abutment against a head 26 of the rod 24. The rod 24 is made from metal and forms part of the retaining element 19. In the manner illustrated, the rod 24 extends in an essentially vertical direction and is displaceable lengthwise, through the arm 2, through holes 28 formed in the latter, the said lower end of the rod 24 which supports the friction washers 23 and the support washer 27, projecting below the lower face 25 of the arm 2. Intermediate its ends, the rod 24 supports a sprin means 33 which is inserted on the rod 24 between an abutment 29 on the arm 2, in the subject case formed by the upper face 30 of the arm 20, and a set nut 31 and its associated tightening nut 32. In accordance with the embodiment illustrated, the spring means 33 is designed a a helical compression spring but it could equally well be in the form of two or more cup springs, a rubber spring o the like. The back-up element 22 in accordance with the embodi ment illustrated is designed as a crescent-shaped plate 3 which is positioned below the arm and which is attached a its free ends to the bracket 14 by means of bolts 35 or similar fastening means so as to project essentially horizontally away from the bracket 14. The plate 34 could be given another configuration than the crescent-shape but irrespective of its configura tion it is formed with an arcuate slit 36 having a radius the centre of which essentially coincides with the pivot centre of the arm 2 about the spindle 12. The lower end o the rod 24 on which end the friction washers 23 and the support washer 27 are mounted, extends through the slit 3 with the friction washers 23 positioned one on either sid of the plate 34. As appears from the drawing figures, the spring means 33 urges the friction washers 23 into engagement with the upper and lower faces of the plate 34 in order to provide the retaining effect, whereby the retaining force, i.e. the friction force between the friction washers 23 and the plate 34, may be set by adjusting the spring force by setting the set nut 31. The upper free end 37 of the rod 24 may be actuated by the actuator 20 in order to effect disengagement of the friction washers 23 from the upper and lower faces of the plate 34 against the action of the spring means 33 in order to override the retaining force. In accordance with the illustrated and preferred embodiment of the invention, the actuator 20 is mounted at one end of a double-arm yoke 38, which is made of shee metal and which has a cross-sectional configuration essentially in the form of an inverted U comprising an upper web 39 and two downwardly directed lateral flanges 40. At the opposite end of the yoke 38, in alignment wit the previously mentioned second, upper end 37 of the rod 24, the yoke is fitted with an actuating means 41 which i mounted in the yoke web 39. The actuating means is in the form of a bolt 43 with a locking nut 42 and is screwed into the yoke web, and the the bolt head 44 may be displaced into engagement with the upper end 37 of the ro 24 for actuation thereof, as will be described in closer detail in the following. A pivot through-pin 46 intermediate the yoke ends pivotally mounts the yoke 38 via the lateral flanges of the latter, to reinforcement flanges 45 formed on the arm 2 of the extractor crane 1 to allow pivotal mouvement of the yoke about an essentially horizontal axis. For this purpose, the actuator 20 is fitted with an actuating element 47 on its side facing the arm 2, which actuating element is arranged to move lengthwise or out¬ wards and inwards and which upon remote control of the actuator 20 moves outwards and into engagement with the upper face 30 of the arm 2 in order to turn the yoke 38 counter-clockwise A about the pivot 46, thus displacing, via the actuating means 41, the rod 24 of the retaining element 19 downwards against the action of the spring means 33 with consequential disengagement of the friction washers 23 from the plate 34. The remote control of the actuator 20 already referred to is effected by means of an appropriate control unit 48 which in accordance with the embodiment illus¬ trated is positioned at the free end of the extractor crane 1, so as to be easily accessible to the crane operator. In this case, the control unit 48 preferably i positioned on or adjacent the extraction hood 7 of the extractor 3. However, the control unit 48 may be position ed elsewhere, remote from the retaining device 18 and may for instance be carried by the operator and be connected to the retaining device in a wireless mode or by means of cables. The actuator 20 proper may be designed in a variety of different ways. In accordance with one embodiment it consists of a pneumatic cylinder and in accordance with another of a hydraulic cylinder, the cylinder piston rod preferably forming the actuating element 47. According to a third alternative, it consists of an electro-magnet wit a displaceable armature, the latter in this case preferably forming the actuating element 47. Further alternative embodiments of the actuator 20 obviously are possible, the essential feature being the ability of the actuator to pivot the yoke in the manner described above. Independently of the design and nature of the actuator 20 the control unit 48 may consist of a pneumatic or hydraulic valve, a switch or a similar means connected to the actuator 20 via supply lines 49 for pressurized air, hydraulic fluid, electricity etcetera. To allow the operator to remote control the actuator 20 from the control unit 48 the latter includes a manually operable control element 50 of a suitable type, such as a control lever, a push button or the like. In order to supply the actuator 20 and the control unit with the required energy (pressurized air, hydraulic fluid, electricity and so on) the actuator 20 is connected in any suitable manner to an external source of energy, not shown. The invention must not be regarded as limited to the embodiment described herein and illustrated on the accompanying drawings but may be modified in many ways within the scope of the appended claims. For instance, in accordance with an alternative embodiment, the yoke 38 may be dispensed with and the actuator 20 be arranged to act directly, by means of its actuating element 47, on the rod 24 of the retaining device 18 or even form the rod, in which case the actuato is rigidly mounted on the arm 2. In accordance with further embodiments, the retainin device 18 and the actuator 20 may constitute a unit in th form of e.g. a horizontally directed piston- and cylinder unit the cylinder of which is hinged to the bracket 14 an the piston rod of which to the arm 2 or vice versa, in order to pivot and retain, respectively, the arm in the set position of pivotement, or a rotational motor the output shaft of which is connected to or forms part of th bearing tube 10 to turn and retain the latter, respect¬ ively, and thus to effect pivotal movement and retainment of the arm in the set pivotal position.

Claims: CLAIMS 1. An arrangement in extractor cranes (1) comprising an arm (2) arranged to mount an extractor (3) and/or some other equipment (8), said arm (2) being articulated by means of one (9) of its ends to a support (17) with the intermediary of a mounting bracket (14), so as to be allowed to pivot essentially in the horizontal plane, a retaining device (18) acting between the arm (2) and the bracket (14) or the support (17) to retain the arm (2) in the set position of pivot thereof and comprising a retaining element (19) which is arranged to be actuated b means of an actuator (20) which, by overriding the retaining force, allows the arm (2) to be pivoted as desired and which is remote-controlled from a point spaced from said one end (9) of the arm (2), c h a r a c t e r ¬ i z e d in that the retaining element (19) incorporates a friction element (21) which is arranged for displacement inside said arm (2) at said one end (9) or the arm and which is likewise arranged to be displaced into and out of the retaining frictional engagement with a counter element (22) connected to the bracket (14) or the support (17). 2. An arrangement as claimed in claim 1, c h a r a c t e r i z e d in that the friction element (21) is in the form of at least one friction washer (23) and is positioned at one end of a rod (24), the latter forming part of the retaining element (19) and extending essentially vertically and arranged to be displaced in its lengthwise direction through the arm (2), said one end, which supports the friction washer/washers 23, projecting downwards from said arm (2). 3. An arrangement as claimed in claim 2, c h a r a c t e r i z e d in that intermediate its ends said rod (24) supports a spring means (33) which is held between an abutment means (29) on the arm (2) and an adjustment means (31) on the rod (24). 4. An arrangement as claimed in any one of the preceding claims, c h a r a c t e r i z e d in that the counter-element (2) is in the form of a plate (34) positioned below the arm (2) and having an arcuate, essentially horizontally directed slit (36) the radius of which has its centre positioned essentially in the pivot centre of the arm (2), said one end of the rod (24) extending through the slit (36) with the friction washer/washers (23) positioned on the lower face of the plate (34) or sandwiching the plate (34) between them. 5. An arrangement as claimed in any one of the preceding claims, c h a r a c t e r i z e d in that the spring element (33) urges the friction washer/washers (23) into engagement with the upper/lower face of the plate (22) for retaining purposes, and in that the rod (24) is arranged to be actuated at its opposite end (37) by the actuator (20) in order to disengage, against the action of the spring means (33), the friction washer/washers (23) from their engagement with the plate in order to override the retaining force. 6. An arrangement as claimed in any one of the preceding claims, c h a r a c t e r i z e d in that the actuator (20) is arranged at one end of a yoke (38) the opposite end of which is formed with an actuating means (41) in alignment with said other end (37) of the rod (24), said yoke being pivotally mounted to the arm (2) intermediate its ends so as to be able to pivot about an essentially horizontal axis, said actuator (20) being formed with an actuating element (47) which is movable lengthwise and which upon remote control of the actuator (20) may be moved into abutment against the upper face (30) of the arm (2) in order to pivot the yoke (38) and to thus displace the rod (24) downwards via the actuating means (41) against the action of the spring means (33) with consequential disengagement of the friction washer/ washers (23) from their engagement with the plate (22), 7. An arrangement as claimed in any one of the preceding claims, c h a r a c t e r i z e d in that the remote control of the actuator (20) is effected by means of a control unit (48) positioned at the opposite free en of the arm (2) of the extractor crane (1) so as to be easily accessible to the crane operator, preferably on or adjacent an extraction hood (7), in the cases when the extractor crane (1) is fitted with an extractor (3) provided with such an extraction hood (7). 8. An arrangement as claimed in any one of the preceding claims, c h a r a c t e r i z e d in that the actuator (20) consists of a pneumatic or hydraulic cylinder the piston rod of which forms said actuaτing element (47), or of an electro-magnet the movable armatur of which forms said actuating element (47), and in that the control unit (48) consists of a pneumatic or hydraulic valve or of a switch with a manually operable control element (50), preferably a control lever or a push button, the control unit (48) being connected to the actuator (20) via supply lines (49). 9. An arrangement as claimed in any one of the preceding claims, c h a r a c t e r i z e d in that the actuator (20) is connected to an external source of energy.

Inventors: HOLMGREN AMBJOERN, HOLMGREN, AMBJOERN
Applicants: PLYMOTH CELSIUS VENT AB
Application year: 1992
Main classification: B08B15
IPC codes: B08B15