Abstract: A rotary cutter for a mower is described including at least one cord of a predetermined length extending from the cutting head driven for rotation, and at least one fastening element for fixing one end of the cord to the cutting head main body. The fastening element includes a pair of ratchets. Each ratchet pivots for turning on the main body and is constantly applied with a rotational force in a predetermined direction by a spring. The cord is clamped and fastened by the ratchets. An inner end portion of the cord inserted from the sidewall of the main body is fastened by the fastening element, and the cord is removed and replaced with a new cord when the cord is worn out. The fastening element including a pair of ratchets with each ratchet of the pair including at least two or more sheets of laminated ratchets.

Abstract: An apparatus and method is provided for removing a retained member from a rotary head assembly configured for attachment to a rotary power source.

Abstract: The mowing head (1) comprises: a body (3), which can be engaged to a motor shaft and defines a peripheral edge (3C); at least one member for anchorage (9) of a cutting line (F), with an elastically loaded eccentric oscillating element, which co-operates with a surface of contrast fixed to the body for anchoring said cutting line. The oscillating element (11) projects from the peripheral edge of the body of the mowing head with a knurled edge (11Z), which forms a gripping surface for causing oscillation of the oscillating element and release of the cutting line.

Abstract: A powered rotary knife includes a handle, a blade housing, an annular blade, and a blade bushing for rotatably mounting the blade within the housing. The blade housing includes an inner groove that is operable to receive the blade bushing therein. The blade housing and blade bushing are split in order to expand and receive the blade. The blade includes an outer groove that is also operable to receive the blade bushing. Thus, the blade bushing is spaced between the blade housing and blade and rotatably secures the blade within the blade housing.

Abstract: An invention is provided for a hinged trimmer head for use in flexible line rotary trimmer systems. The invention includes a hinged housing and cover capable of being opened to allow access to the interior of the trimmer head without risk of losing the housing parts. In addition, an open faced channel is provided is a spool that allows easy loading of cutting line. Further, a bumper button is disposed in an annular opening of the cover, providing an automated line feed mechanism and an easy cutting line spool winding mechanism.

Abstract: The invention relates to a cutting head for a brush cutter, edge trimmer or similar, the head being of the type including at least a passageway for a cutting string and a locking element of the cutting string. The cutting head is characterized in that the locking elements include at least one ratchet wheel, including a toothed wheel mounted in rotation around an axis in such a manner that said teeth project in the passageway. The ratchet can be arranged in such a way that the toothed wheel can turn in a given direction to allow the introduction of the cutting string in the passageway and cannot turn in the opposite direction, thereby locking the cutting string in the passageway.

Abstract: The present invention generally pertains to a saw device. More particularly, the present invention relates to a handheld centerless saw. The saw comprises a frame and a pair of driving rollers mounted to the frame for rotation. The saw also comprises an annular blade mounted between the drive rollers and functionally engaged thereby, where the blade defines frontward and backward hemispheres. At least two guide wheels are mounted to the frame, or to a cover mounted to the frame, the guide wheels being positioned in the backward hemisphere of the blade. The guide wheels are operatively engaging the inner circular edge of the blade. A drive assembly mounted to the frame is operable for urging the countersense rotation of drive rollers, thereby causing rotation of the blade.

Abstract: An improved head for a vegetation trimmer has a drop-down line reservoir that remains in cooperation with the head housing when the reservoir is in a load position. The reservoir fits inside the head housing and is biased against the housing for secure use. The reservoir is rotated to unlock it from the housing, whereby it drops down to allow access to the line in the reservoir. A user can add, remove, and manipulate line as desired without the inconvenience of detachable pieces. The reservoir can be pushed back into the housing and locked into place for use. The reservoir can also be placed in an advance position and rotated to advance more line through line openings in the housing as needed.

Abstract: A generally cylindrical cutting head for a weed cutting machine has blades that are exposed and lifted off of the head when an upper portion is rotated, with respect to a lower portion and/or a cap, without tools and without disassembly of the structure. A lock ensures that the upper portion does not open until desired, by a rigid plate or aim extending, in the locked position, through portions of both the upper portion and the lower portion, or through portions of both the upper portion and a cap portion. The lock plate/arm may extend into the cutting head from the top, bottom, or side. When pushed inward, the lock plate or arm moves to no longer reside in both upper and lower portions, or both upper and cap portions, to free the upper portion to rotate relative to the lower portion and cap.

Abstract: A trimmer head assembly and the method of configuring the trimmer head assembly. The trimmer head assembly has a housing that attaches to a string trimmer machine. A spool is provided inside the housing. The spool rotates about an axis of rotation. The spool can move longitudinally along the axis of rotation between a first position and a second position. A ratcheting mechanism is provided between the trimmer head housing and the spool. When the spool is in its first position, the ratcheting mechanism enables the spool to continuously rotate about the axis of rotation in the direction opposite that in which the trimmer head assembly spins. The ratchet mechanism also prevents the spool from rotating within the housing in the same direction in which the trimmer head is spinning.

Abstract: An aerodynamic trimmer head for use in flexible line rotary trimmers having an aerodynamic, generally ellipsoidal profile and a plurality of aerodynamic elements defined by the upper and lower head surfaces for directing air, during rotation of the head, off of and over the upper and lower head surfaces and preferably away from the line extending from the housing, thereby reducing the drag on the head and the line projecting from the housing. The aerodynamic elements on the upper head surface preferably are defined by a plurality of equidistantly spaced inclined troughs extending downwardly and forwardly along curvilinear paths on the upper head surface and the aerodynamic elements on the lower head surface preferably are defined by a plurality of dimples formed in an annular surface extending about the lowermost end of the spool and a plurality of rearwardly inclined troughs formed about and above the dimples.

Abstract: An aerodynamic trimmer head for use in flexible line rotary trimmers having a plurality of aerodynamic elements defined by the upper and lower head surfaces that during rotation of the head, draw air downwardly about the trimmer drive mechanism onto the upper head surface and move the air outwardly from the head into the plane of the extended cutting line and at forward inclination in the direction of rotation. The downwardly moving air cools the trimmer drive mechanism and the outwardly and forwardly moving air reduces the drag on the head and the extended cutting line. The aerodynamic elements preferably include a plurality of troughs extending downwardly and forwardly along the upper head surface, a perimeter surface for deflecting air moved by the troughs into a generally horizontally extended zone of moving air about the extended cutting line and a plurality of dimples formed in a lower surface of the head.

Abstract: A trimmer head which receives fixed-length trimmer line segments has a housing with a side wall forming an open end with opposed holes formed therein. The trimmer head receives an insert that is rotated by the main housing. The insert has an arcuate channel from the first hole to the second hole adjacent the opposed side of the insert body when the insert body is in a load/unload position. The insert body is rotatable and movable axially with respect to the housing to an operational position where the line segment is forced to take an indirect path between the first and second holes securing the line segment in place during use of the trimmer head.

Abstract: A power operated rotary knife having a large diameter, annular rotary knife blade and interfitting blade housing wherein the rotary knife blade includes notched bearing race providing for an enhanced or enlarged area of bearing contact between the blade bearing race and the corresponding blade housing bearing structure. The enhanced area of bearing contact is offset radially inwardly of and axially from a radial outer surface of a drive gear region of the blade thereby reducing wear on the radial outer surface of the blade drive gear region.

Abstract: The mower head (1) includes a body (3) with at least one exit hole (9A) for one end of a cutting cord (F) and includes, adjacent to the exit hole of the cutting cord and on at least one side of said hole, a radial projection (11) to protect the cutting cord.

Abstract: A trimmer head wherein the driveline of the power tool is connected to a core member. A spool is mounted to the core member and directly driven by the core member. A housing is mounted for axially sliding on the core member and a spring urges axial movement of the housing relative to the core member. Interlocking structure on the spool and housing produces interlocking for common rotation of the spool and housing responsive to urging by the spring. Release of the interlocking structure is affected by opposing said spring urging. Desirable additional features include selective alternate positioning of the spring for automatic and manual only release of said interlocking and a line loading assist provided by a tubular post through the spool alignable with housing eyelets for threading line through the eyelets and spool and winding thereof onto the spool by manual turning of the spool relative to the housing.

Abstract: The grass-cutting head (101) has a body (103) forming a housing for at least one spool of cutting line (F1; F2), provided with at least one outlet hole (111) of an end of the cutting line wound on said spool positioned inside the head. For each outlet hole, a guide channel for the cutting line is also provided, extending from the inside of the housing towards the hole and having an inclined trend, gradually moving away from said axis of rotation.

Abstract: A guard including three sub-systems: a main guard body, a solid shield, and an attachment mechanism. The main guard body includes a base, a peripheral exterior ring, and a plurality of supports for holding the peripheral exterior ring in spaced relationship with the base. Together, the base, the peripheral exterior ring, and the plurality of supports define at least one aperture. The solid shield is attachable to the main guard body. The attachment mechanism is used to attach the main guard body to an extension member of a filament-type trimmer. When positioned, a rotatable non-rigid filament of the filament-type trimmer is peripherally surrounded by the main guard body when the rotatable non-rigid filament is rotating.

Abstract: An improved spool construction for carrying a length of cutting line in a trimmer head housing on a flexible line rotary trimmer wherein the spool comprises separately molded upper and lower sections of single piece construction that are pressed together in a snap fitment to define a cylindrical body portion, at least one flange projecting radially therefrom and a line receptor channel having a smooth interior surface that traverses the spool and communicates opposed open outer channel ends in the flange that are radially alignable with opposed line openings in a housing skirt, with an open channel portion in a lower spool surface to provide access to the channel intermediary of the open channel ends with the spool operatively connected to the housing for line loading and replacement without having to interrupt the operative connection between the spool and the housing.

Abstract: A novel abrasive cutting string for use in a string trimmer provides for a thermoplastic string with abrasives in the surface, but not in the central core of the string, the string being wound on a spool for rotation and incremental extension of at least one extremity in combination with the operation of the string trimmer.

Abstract: A brushcutter blade with an undulated peripheral cutting edge, wherein the edge alternates partly circular cutting sections, with partly arcuate, radially recessed cutting sections. Recessed cutting sections provide accelerated radial cutting and also additional axial shredding. Auxiliary axial segments are formed or deflected out of the blade body around a base line or juncture with the blade, at angles acute to the plane of the blade, and the openings through the blade created thereby, are radially outward of the juncture. The segments are configured to provide an inclined leading edge for each segment, that cuts a laterally extended path with the movement of the blade, and enhances both radial and axial shredding. A contrasting vivid color band on distal cutting sections optically merges into a distinctively visible cutting edge for obstacle avoidance and safety enhancement.

Abstract: A cutting head attached to a powered rotary weed cutting machine has a generally cylindrical structure containing a plurality of cutting blades. The cylindrical structure has upper and lower portions which may be rotated with respect to one another to expose each entire cutting blade for replacement when required. A lock may be included to ensure that the upper portion does not open until desired by including a rigid plate or arm that, in a first position, extends through portions of both the upper portion and the lower portion to lock them together.

Abstract: A trimmer head for a rotary line trimmer including a housing operatively connected to the trimmer and a spool for carrying cutting line thereon. The spool is operatively connected to the housing for rotation therewith and defines a pair of opposed line receptor channels having opposed open ends, traversing opposed portions of the spool and defining opposed outlet openings above a lowermost end of the spool. The channels can be aligned with the eyelets in the housing skirt such that lengths of cutting line can be inserted therethrough and wrapped about the spool upon relative rotation of the spool and housing without having to interrupt the operative connection therebetween. The channel outlet openings provide access to the inner ends of the line so that the line also can be pulled from the head without having to interrupt the operative connection therebetween.

Abstract: A vegetation trimmer with a spool and hub assembly has a cutting filament wound around the spool. The free end of the filament extends through an aperture in the hub into the cutting plane. The spool and hub are rotated at a high rate to allow the filament to cut vegetation. The spool includes a plurality of arms which engage with arms on the hub. When the spool is acted upon, the arms on the spool disengage with the arms on the hub to permit relative rotation of the spool to the hub to feed additional filament into the cutting plane. An indexing feature is used to regulate the amount of additional cutting filament that is allowed to be fed into the cutting plane.

Abstract: A rotary cutter for a mowing machine includes a cord for mowing grass by rotating, a reel which contains the cord and intermittently rotates to pay out the cord, a case which contains the reel, and a cover which covers the case, wherein the reel includes an upper cam and a lower cam, a stopper is incorporated in the case at a center of a bottom thereof, one end of the stopper is engaged with the upper cam thereby to stop the rotation of the reel, the other end of the stopper is engaged with the lower cam, one end of the cord is engaged with the stopper from outside thereof and guided out of the rotary cutter through a cord guide, and the other end of the cord is guided out of the rotary cutter without touching the stopper.

Abstract: A tile rebate cutting apparatus has a guide member, which may be formed by a spirit level, forming a linear guide for a rebate cutting tool, the rebate cutting tool incorporating at least one cutting device, the rebate cutting tool being adapted to engage with said guide member to move along a predetermined line determined by the position of the guide member to enable a cut for a rebate to be made in a ceiling tile.

Abstract: A cutter head of an implement, comprising a cutting blade rotatably drivable about an axis of rotation. The cutting blade is provided with at least two blade wings that extend along a longitudinal axis in a radial direction relative to the axis of rotation. The cutting blade is clamped between two contact or pressure pieces, at least one of which is provided with at least one radially extending dampening projection that rests against at least one of the blade wings.

Abstract: A trimmer head for use in a flexible line rotary trimmer including a housing adapted to be operatively connected to the trimmer to effect rotation of the head and a spool operatively connected to the housing for rotation therewith. The spool defines at least one inwardly extending line receptor channel, preferably formed by a plurality of inwardly tapered walls so as to be polygonal in cross-section. So configured, the channel walls will securely grip the cutting line upon the line being inserted in the channel and wound about the spool. To provide uniform winding of the line, a plurality of cam, cam abutment and sliding surfaces are operatively connected to the housing and spool such that when the spool is manually rotated relative to the housing in the drive direction, the spool is caused to reciprocate axially within the housing evenly distributing the line about the body of the spool.

Abstract: A trimmer head configured for operating in a fixed line configuration and a bump-feed configuration. The trimmer head includes a base including a cup having a top wall and a substantially cylindrical side wall defining an aperture. The base also includes a collar extending axially from the top wall of the cup for coupling the trimmer head with the output shaft. A fixed line head is at least partially received within the cup when the trimmer head is in the fixed line configuration and a bump-feed spool is at least partially received within the cup of the base when the trimmer head is in the bump-feed configuration.

Abstract: The present invention provides a trimmer line for a grass trimmer. The trimmer line is comprised of a cutting string having a cutting end and an engagement end. An engagement device is affixed to the engagement end of the cutting string and has an expanded position and an install position. When the engagement device is in its expanded position, it has a greater outer diameter than in its install position.

Abstract: A cutting head for a rotary trimmer is provided. The cutting head of the present disclosure provides a control mechanism for loading a spool member of the cutting head quickly and efficiently without having to disassemble the cutting head. In one embodiment, a control mechanism is provided in the cutting head interacting between a follower member and a spool member so as to provide for one way rotational loading of flails, e.g., cutting line, into the cutting head; in other words, to load the flails, the spool member is rotated continuously 360° in one direction only, e.g., clockwise. In another embodiment, a cutting head allows the flails to be loaded by a ratcheting-type operation, i.e., a back and forth rotational movement, which is less fatiguing and even more efficient in its loading operation.

Abstract: A blade assembly for use with a food processor includes a hub configured to be coupled to a drive shaft of the food processor, a first blade rotatably coupled to the hub and configured to rotate with respect to the hub at least up to a predetermined angle with respect to a second blade, which is fixedly coupled to the hub. The first blade is rotatable between a first position in which it is in phase with the second blade for receiving a blade guard protecting both blades, and a second position, in which the first blade is out of phase with the second blade for optimally processing a food item in the food processor, the blade assembly also including a biasing member for returning the first blade to the first position after use.

Abstract: In a rotating grass trimmer, a top loading line blade and corresponding head securely hold the cutting lines with multiple orientations of the line blade. An alternative embodiment provides a simplified loading scheme where a cutting line is loaded into the trimmer head from its outside, through a line outlet to a fixed receiver without the need for a moving or mechanical line gripping or biting type mechanism. With this construction, a worn line can be replaced by pulling it back out or by reversing it back through the same outlet from which it was initially inserted. The design eliminates practically all of the costs associated with the current state of the art rapid loading mechanisms as there is no physical compression, gripping or biting into the line by any mechanical or moving mechanism. Additionally, the line is insertable in multiple orientations.

Abstract: A knife which has a body with a blade head at one end and roller at the other end. The blade head also has a planar first guide cheek and planar second guide cheek. positioned at an angle, alpha relative to the blade which is received between the first and second guide cheeks. The knife also has a device for urging the blade between a retracted position and an extended position. The roller is made of a right wheel half and a left wheel half such that the roller made of two halves in intimate contact with each other.

Abstract: A trimmer head wherein the driveline of the power tool is connected to a core member. A spool is mounted to the core member and directly driven by the core member. A housing is mounted for axially sliding on the core member and a spring urges axial movement of the housing relative to the core member. Interlocking structure on the spool and housing produces interlocking for common rotation of the spool and housing responsive to urging by the spring. Release of the interlocking structure is affected by opposing said spring urging. Desirable additional features include selective alternate positioning of the spring for automatic and manual only release of said interlocking and a line loading assist provided by a tubular post through the spool alignable with housing eyelets for threading line through the eyelets and spool and winding thereof onto the spool by manual turning of the spool relative to the housing.

Abstract: A chain-type flexible cutting edge, particularly for bush-cutter is described, comprising at least one linear connecting and cutting link (3) and at least one toothed connecting and cutting link (5) mutually connected in an articulated manner in order to have a smooth cutting-start edge (TL) and a toothed cutting-start edge (TD).

Abstract: A head for string trimmer machines uses fixed length segments of line including at least two line segments. The head includes a generally cylindrically shaped main housing member with at least two sets of first and second line entry holes on the housing member intermediate the first and second ends. At least two sets of first and second line exit openings also are found on the main housing member intermediate the first and second ends and spaced apart a greater distance than the distance between the first and second line entry holes. Arcuate guide channels are located between the respective entry holes and exit openings where the corresponding entry openings and exit openings of corresponding sets are located at different distances measured axially on the main housing member from the first end thereof.

Abstract: The mowing head (1) includes: a body (3), which can be engaged to a motor shaft and defines a peripheral edge (3C); at least one member for anchorage (9) of a cutting line (F), with an elastically loaded eccentric oscillating element, which co-operates with a surface of contrast fixed to the body for anchoring the cutting line. The oscillating element (11) projects from the peripheral edge of the body of the mowing head with a knurled edge (11Z), which forms a gripping surface for causing oscillation of the oscillating element and release of the cutting line.

Abstract: A cutter wheel is disclosed, which comprises a cutter wheel body, a cutting unit, and a solder layer. The cutter wheel body consists of the first substrate and the second substrate, wherein each substrate has an inner surface and an outer surface. The inner surface of the first substrate is treated with surface modification. The cutting unit can be formed on a rough surface. The solder layer is formed between the cutting unit and the second substrate. The present invention also provides a method for manufacturing the cutter wheel as mentioned above.

Abstract: The invention relates to a cutting head for a brush cutter, edge trimmer or similar, the head being of the type including at least a passageway for a cutting string and a locking element of the cutting string. The cutting head is characterized in that the locking elements include at least one ratchet wheel, including a toothed wheel mounted in rotation around an axis in such a manner that said teeth project in the passageway. The ratchet can be arranged in such a way that the toothed wheel can turn in a given direction to allow the introduction of the cutting string in the passageway and cannot turn in the opposite direction, thereby locking the cutting string in the passageway.

Abstract: An improved rotary cutting blade assembly which is characterized by reduced friction and enhanced cutting efficiency is disclosed. The improved rotary cutting blade includes a rotary cutting blade having a blade hub, a plurality of blade arms extending outwardly from the blade hub and a plurality of blade winglets carried by the plurality of blade arms, respectively.

Abstract: A lawn trimmer of the present disclosure has a trimmer head with a first opening for receiving string and a second opening for extending the string through so that the string can be used to cut weeds. In addition, the lawn trimmer has a first spool of string mounted to the lawn trimmer, and the string is wound around the spool and has a free end that is inserted into the first opening and out of the second opening. The spool rotates such that when the string breaks during use a user can manually forward the string through the second opening for continued use of the string.

Abstract: A trimmer head wherein the driveline of the power tool is connected to a core member. A spool is mounted to the core member and directly driven by the core member. A housing is mounted for axially sliding on the core member and a spring urges axial movement of the housing relative to the core member. Interlocking structure on the spool and housing produces interlocking for common rotation of the spool and housing responsive to urging by the spring. Release of the interlocking structure is affected by opposing said spring urging. Desirable additional features include selective alternate positioning of the spring for automatic and manual only release of said interlocking and a line loading assist provided by a tubular post through the spool alignable with housing eyelets for threading line through the eyelets and spool and winding thereof onto the spool by manual turning of the spool relative to the housing.

Abstract: The invention relates to a cutting wire (2) which is designed to trim or cut vegetation and which can be used on rotating head devices, such as brush cutters and edge trimmers. The external surface of the cutting wire is provided with tooth-type (5) or similar formations along the length of said wire (2). In the case of a wire having one or more longitudinal cutting edges (4), said tooth-type formations (5) are disposed on the cutting edge(s) along the length of each edge (4). In this way, the sharpness of the wire (2) is improved.

Abstract: A trimmer head assembly and the method of configuring the trimmer head assembly. The trimmer head assembly has a housing that attaches to a string trimmer machine. A spool is provided inside the housing. The spool rotates about an axis of rotation. The spool can move longitudinally along the axis of rotation between a first position and a second position. A ratcheting mechanism is provided between the trimmer head housing and the spool. When the spool is in its first position, the ratcheting mechanism enables the spool to continuously rotate about the axis of rotation in the direction opposite that in which the trimmer head assembly spins. The ratchet mechanism also prevents the spool from rotating within the housing in the same direction in which the trimmer head is spinning.

Abstract: A trimmer line, hook disk system in the form of a line trimmer head (e.g. FIGS. 11 & 11A) as a replacement for attaching to a powered, rotational device to provide a line filament grass cutting action, which trimmer head includes a circular, protective base or bottom (D2), a circular, main trimmer head substrate (D3), the two forming a disk shape, and a series of peripherally spaced line holders; with these three basic elements attached together with appropriate fasteners for ultimate attachment to a powered device. Eleven exemplary line holders are shown in FIGS. 1-10B, respectively, with some allowing oscillating (O) motion in their attachment to the trimmer head substrate (D3) and/or fixed (F) in their attachment. A “broom” embodiment is shown in FIG. 18. When in use, flexible line made, for example, of nylon, is inserted in and held by the line holders preferably using hook or hook-like line attachments.

Abstract: A vibration-absorbing coupler (30A) which is capable of suppressing the torsional vibration of the transmission shaft (7) and also capable of enhancing the durability thereof is disclosed. This vibration-absorbing coupler (30A) is featured in that the rotation of an output shaft (31) of an internal combustion engine (6) is enabled to transmit to a transmission shaft (7) through a torsion coil spring (40A) and torsional vibration of the transmission shaft (7) is enabled to be absorbed by the torsion coil spring (40A). The vibration-absorbing coupler (30A) further includes a regulator (50, 37A) for regulating the rotation of the torsion coil spring (40A) so as not to allow it to twist more than a predetermined angle.

Abstract: A cutting head for a brush cutter, edge trimmer or similar, the head comprises a passageway (112) for a cutter string (300) and at least one curved surface (120) for supporting the string, the surface extending between an exit region (115) for said string from said passageway and a peripheral region of the head. According to the invention, the passageway extends (A) in a manner that is offset from an axis of rotation (C) of the head so as to present an inside edge constituted by its edge closest to said axis of rotation, said inner edge corresponding to a trailing edge of the string while the head is rotating, and the curved portion extends from said inner edge. This serves to reduce the radius of curvature of the curved portion without needing to increase the diameter of the head.

Abstract: A trimmer head for use in a flexible line rotary trimmer including a housing adapted to be operatively connected to the trimmer to effect rotation of the head and a spool operatively connected to the housing for rotation therewith. The spool defines at least one inwardly extending line receptor channel, preferably formed by a plurality of inwardly tapered walls so as to be polygonal in cross-section. So configured, the channel walls will securely grip the cutting line upon the line being inserted in the channel and wound about the spool. To provide uniform winding of the line, a plurality of cam, cam abutment and sliding surfaces are operatively connected to the housing and spool such that when the spool is manually rotated relative to the housing in the drive direction, the spool is caused to reciprocate axially within the housing evenly distributing the line about the body of the spool.

Abstract: A trimmer comprises a cutting head (1) housing a cutter (5), and an elongate shaft (2) for supporting the cutting head. The cutting head (1) is connected to the shaft (2) by connection means (3) permitting the cutting head (1) to be positioned with the cutter (5) either substantially horizontal or substantially vertical. The connection means (3) is such that, when the cutter (5) is substantially vertical, the longitudinal axis of the shaft (2) is parallel to the plane of rotation of the cutter.