# Patent

## Title
Guard hood torsion preventer

## Abstract

The invention is based on a guard hood torsion preventer for a handheld power tool, in particular for a right-angle power sander. The invention is for preventing torsion of a guard hood on the handheld power tool, in particular in the event of damage to a tool. The guard hood torsion preventer includes at least one torsion-prevention unit which has a longitudinal axis, about which the torsion-prevention unit is rotatably supported.

## Background
CROSS-REFERENCE TO RELATE APPLICATION
This application is based on German Patent Application 10 2008 040 372.5 filed Jul. 11, 2008.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is based on a guard hood torsion preventer.
2. Description of the Prior Art
A guard hood torsion preventer for a right-angle power sander is already known that is intended for preventing torsion of a guard hood on the handheld power tool in the event of damage to a tool.
OBJECT AND SUMMARY OF THE INVENTION
The invention is based on a guard hood torsion preventer for a handheld power tool, in particular for a right-angle power sander, which is intended for preventing torsion of a guard hood on the handheld power tool, in particular in the event of damage to a tool, of a guard hood on the handheld power tool, in particular in the event of damage to a tool, having at least one torsion-prevention unit.
It is proposed that the torsion-prevention unit has a longitudinal axis, about which the torsion-prevention unit is rotatably supported. In this connection, the term “intended” should be understood in particular to mean especially equipped and/or especially designed. Moreover, the term “damage to a tool” should be understood in particular to mean a tool that bursts during operation of the handheld power tool, where individual pieces of the tool are spun outward because of a rotation of the tool. The term “preventing torsion” or “torsion prevention” should furthermore mean securing against unwanted torsion, particularly in the event of damage to a tool, of a guard hood unit out of its guard position relative to a handheld power tool, so that the guard hood always remains in a guard position that is advantageous for a user. Preferably, the guard hood together with the guard hood torsion preventer is designed so that in the event of a bursting tool, the guard hood is rotated, in response to transmission of an linear momentum from a fragment of a burst tool that has spun outward onto the guard hood, the guard hood is rotated by a maximum of 90°, and the user is shielded from the tool fragments by the guard hood, and in particular energy of the tool fragments is dissipated by the guard hood and/or by the guard hood torsion preventer while preserving a guard function for the user, and/or the tool fragments are conducted in a direction leading away from the user. The term “longitudinal axis” should also be understood in particular to mean an axis along a lengthwise direction and/or a primary direction in which the torsion-prevention unit extends. Preferably, the longitudinal axis is oriented essentially perpendicular to an axis of rotation of a tool. Advantageously, the torsion-prevention unit is intended in at least one position for securing, and in particular preventing rotation of, the guard hood. By means of the design according to the invention, advantageous protection of a user in a mode of operation of the handheld power tool, in particular the right-angle power sander, against tool fragments flying around and in particular being spun outward by a force of rotation, is achieved in the event of a bursting tool, and in particular the guard hood can advantageously be kept in a guarding position.
It is furthermore proposed that the guard hood torsion preventer has at least one bearing point, by means of which the torsion-prevention unit is braced on the handheld power tool. Preferably, the bearing point is secured or braced directly on a housing and/or a receiving unit for receiving a tool, such as a receiving flange. By means of this design, an advantageous, and in particular secure, fastening of the torsion-prevention unit can be attained via the bearing point, which is intended for secure bracing of the guard hood along with the torsion-prevention unit in the presence of strong forces and/or torques acting on the torsion-prevention unit, as in the case for example of a bursting tool.
In an embodiment of the invention, it is proposed that the torsion-prevention unit has at least one shaft, as a result of which a space-saving torsion-preventing motion can be attained, such as a rotation of the shaft, in particular about the longitudinal axis, in the torsion-prevention unit. The shaft is preferably formed by a force-locking shaft or a form-locking shaft.
It is furthermore proposed that the torsion-prevention unit is intended, by means of a rotation about its longitudinal axis, for varying the guard hood in its position. The term “varying a position” should be understood to mean in particular that for positioning when mounting of the guard hood, a plurality of different guarding positions are available, and the guard hood can be changed from one guarding position to a further guarding position upon a rotation of the torsion-prevention unit about its longitudinal axis. A change from one guarding position to a further guarding position can especially advantageously be effected in a continuously variable manner. An advantageous adaptation of the guard hood, and in particular of a guarding position of the guard hood, to a work situation, particularly by a user, can be achieved and hence a high degree of protection, in particular individual protection, for the user can be attained.
If the torsion-prevention unit has at least one actuation element that is intended for rotating the torsion-prevention unit about its longitudinal axis, then advantageously a position can be adapted to a work situation by means of a change of position of the guard hood performed by a user, and thus a high degree of user comfort and convenience can be attained. The actuation element is preferably designed for operation by a user of the handheld power tool. An especially space-saving embodiment of the actuation element can be attained if the actuation element is formed by a set screw. In principle, in an alternative embodiment of the invention, the actuation element can also be formed by a switch element that can be operated by a user, by which element a motor for rotating the torsion-prevention unit can be controlled, and/or can be formed by a further actuation element that appears useful to one skilled in the art, such as a crank, rotary knob, and so forth.
It is furthermore proposed that the torsion-prevention unit is formed at least partly by a form-locking unit, as a result of which structurally simple torsion prevention, particularly of the guard hood in a guarding position, can be attained during operation of the right-angle power sander.
Especially advantageous torsion prevention of the guard hood when mounted in a guarding position on the power tool can be attained if the torsion-prevention unit is formed at least partly by a set of teeth. The term “set of teeth” should be understood in particular to mean a component and/or element that because of its shape is intended for transmitting a force and/or torque and in the process engages a further, complementary component and/or element.
In a further embodiment of the invention, it is proposed that the torsion-prevention unit is formed at least partly by a rolling-contact worm gear. In this connection, the term “rolling-contact worm gear” should in particular be understood to mean a gear which has at least one worm shaft and/or threaded shaft for transmitting and/or converting a force and/or a torque, and axes of rotation of transmission elements of the rolling-contact worm gear, which transmit a force and/or a torque to one another, are disposed such that they are rotated, in particular skewed, by approximately 90° relative to one another. Structurally simple securing of the guard hood in a guarding position can be attained because it is advantageously possible to use self-locking of the rolling-contact worm gear in at least one direction of rotation for securing the guard hood against torsion. Additional securing elements for securing the guarding position of the guard hood, such as a detent element or other securing elements that appear appropriate to one skilled in the art, are conceivable at any time in an alternative embodiment. Especially advantageously, the torsion-prevention unit has at least one threaded shaft.
It is furthermore proposed that the torsion-prevention unit is formed at least partly by a force-locking unit, as a result of which a torsion-prevention unit can be attained that is economical in terms of material and in particular is inexpensive.
In an advantageous refinement of the invention, it is proposed that at least one further torsion-prevention unit and a guard hood, the torsion-prevention unit having at least two torsion-prevention elements, which are disposed in succession in a circumferential direction on the guard hood. In this connection, the term “disposed” should be understood in particular to mean that the torsion-prevention elements are secured directly on the guard hood and/or a force of gravity of the torsion-prevention elements is braced via the guard hood. Furthermore, the torsion-prevention elements may also be embodied in one piece with the guard hood, the term “in one piece” being understood to mean in particular one-piece and/or made in one casting and/or embodied as a single component. Moreover, the term “circumferential direction” should be understood in particular to mean a direction which extends around the guard hood in a longitudinal direction of a neck of the guard hood and/or in a mounted state of the guard hood extends about an axis of rotation of a tool. The torsion-prevention elements may be formed by form-locking elements and/or force-locking elements. By the embodiment according to the invention, structurally simple securing of the guard hood in a guarding position can advantageously be attained. Moreover, a flow of force and/or torque transmitted to the guard hood can advantageously be dissipated by way of a plurality of torsion-prevention elements, so that even if strong torques and/or linear momentums are operative on the guard hood, especially in the case of a tool that bursts during operation of the right-angle power sander, securing of the guard hood in a guarding position can be provided.
Especially advantageously, at least one of the torsion-prevention elements is formed at least partly by a set of teeth, so that especially secure prevention of torsion of the guard hood in operation of the handheld power tool can be attained. Advantageously, the torsion-prevention elements or the set of teeth forms a contrary contour to a set of teeth that is braced and/or supported on a housing and/or a receiving unit of the right-angle power sander. In principle, the form-locking element, in an alternative embodiment of the invention, can also be formed by a recess and/or further form-locking elements, which appear useful to one skilled in the art, and/or the torsion-prevention unit can be formed by a force-locking unit.
Furthermore, it is proposed that the torsion-prevention unit is disposed at least partly on a side of the guard hood facing away from a receiving region of the guard hood for a tool and/or on a side of the guard hood facing away from a receiving region of the guard hood for fastening. In this connection, the term “receiving region of the guard hood for a tool” should be understood in particular to mean a region of the guard hood that is intended for receiving a tool, where the guard hood, in particular a disklike guard hood body, shields the user from the tool receiving region. Moreover, the term “receiving region of the guard hood for fastening” should be understood in particular to mean a region of the guard hood that is surrounded by a guard hood neck and/or a tightening strap and that is intended for receiving a receiving flange of the right-angle power sander. An especially space-saving disposition of the torsion-prevention unit on the guard hood can be attained here, and moreover an advantageously large securing area for the torsion-prevention unit in the event of damage to the tool.



BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be better understood and further objects and advantages thereof will become more apparent from the ensuing detailed description of preferred embodiments taken in conjunction with the drawings, in which:
FIG. 1 shows a right-angle power sander, having a guard hood torsion preventer according to the invention, in a schematic illustration;
FIG. 2 shows the guard hood torsion preventer with a form-locking unit, in a schematic illustration;
FIG. 3 shows a guard hood of the guard hood torsion preventer of FIG. 2 in a schematic illustration;
FIG. 4 shows an alternative embodiment to FIG. 3 of a guard hood in a schematic illustration;
FIG. 5 shows an alternative embodiment to FIG. 3 of a guard hood with a flat collar, in a schematic illustration;
FIG. 6 shows an alternative embodiment to FIG. 2 of the guard hood torsion preventer, with a splined shaft, in a schematic illustration; and
FIG. 7 shows a guard hood torsion preventer with a force-locking unit, in a schematic illustration.



DESCRIPTION OF THE PREFERRED EMBODIMENTS
In FIG. 1, a handheld power tool 12a, formed by a right-angle power sander 14a, is shown, along with a guard hood unit 56a and a guard hood torsion preventer 10a. The right-angle power sander 14a includes a handheld power tool housing 58a and a primary hand grip 60a that is integrated with the handheld power tool housing 58a. The handheld power tool housing 58a includes a motor housing 62a and a gearbox 64a. The right-angle power sander 14a also has a receiving unit 66a, for receiving the guard hood unit 56a or a tool 18a fowled by a cutting disk, and the receiving unit is screwed to the handheld power tool housing 58a. The guard hood unit 56a includes a guard hood 16a and a locking unit 68a. The guard hood 16a, in a mounted state, covers an angular range of approximately 180° of the tool 18a. An additional hand grip 72a is disposed on the gearbox 64a of the right-angle power sander 14a. The guard hood torsion preventer 10a is intended for torsion prevention of the guard hood 16a on the right-angle power sander 14a to counter unwanted torsion of the guard hood 16a, in particular as in the case of a tool 18a that is bursting.
In FIG. 2, the guard hood torsion preventer 10a of FIG. 1 is shown in greater detail. For the sake of simplicity, a guard hood of the guard hood unit 56a is not shown in FIG. 2. The guard hood torsion preventer 10a has two torsion-prevention units 20a, 38a. The first torsion-prevention unit 20a is braced or secured to the receiving unit 66a by means of a bearing point 24a. In principle, it is furthermore conceivable that the bearing point 24a is disposed or secured on the gearbox 64a and/or other housing components that appear appropriate to one skilled in the art. The first torsion-prevention unit 20a has a longitudinal axis 22a, about which the torsion-prevention unit 20a is rotatably secured by means of the bearing point 24a. The bearing point 24a has two bearing elements 74a, 76a, which are disposed along the longitudinal axis 22a on opposed end regions 78a, 80a of the first torsion-prevention unit 20a on the receiving unit 66a. The two bearing elements 74a, 76a are screwed to the receiving unit 66a, each via a respective screw connection 82a, and by means of the two screw connections 82a and two further screw connections 84a, the receiving unit 66a is secured to the gearbox 64a. The torsion-prevention unit 20a is disposed on a region 86a, oriented toward the gearbox 64a, of the receiving unit 66a next to a flange neck 88a for fastening the tool 18a and the guard hood unit 56a. The longitudinal axis 22a is embodied essentially transversely to an axis of rotation 90a of a drive shaft of the right-angle power sander 14a for driving the tool 18a. 
The torsion-prevention unit 20a is formed by a form-locking unit 26a, which is formed at least partly by a rolling-contact worm gear 30a. The torsion-prevention unit 20a furthermore has a shaft 92a, which is rotatably supported by its end regions 94a, 96a along the longitudinal axis 22a in the bearing elements 74a, 76a. Along the longitudinal axis 22a, in a middle region 98a, the shaft 92a has a threaded shaft 32a, embodied as a set of teeth 28a, which is intended for form locking to the second torsion-prevention unit 38a. The shaft 92a is supported by its end regions 94a, 96a in recesses of the bearing elements 74a, 76a that are formed as angular components, and the shaft 92a is supported immovably along the longitudinal axis 22a via two securing rings 100a, which are disposed fixedly on the end regions 94a, 96a of the shaft 92a. The torsion-prevention unit 20a furthermore has an actuation element 36a, which is embodied in one piece with the shaft 92a and is disposed on one of the two end regions 94a, 96a of the shaft 92a. The actuation element 36a is embodied in the form of the head of a screw, so that for adjusting or rotating the torsion-prevention unit 20a in a direction of rotation 102a about the longitudinal axis 22a, this actuation element can be rotated or adjusted by a user using a screwdriver.
The guard hood torsion preventer 10a furthermore has the guard hood 16a, on which the second torsion-prevention unit 38a is disposed, and the torsion-prevention unit 38a is embodied in one piece with the guard hood 16a (see FIGS. 2 and 3). The guard hood 16a has a guard hood neck 104a, by means of which the guard hood 16a can be secured to the flange neck 88a. For that purpose, the guard hood neck 104a surrounds a receiving region 52a of the guard hood 16a. The guard hood neck 104a has a coding element 106a, which is formed by a coding lug oriented inward from the guard hood neck 104a in a radial direction 108a of the guard hood 16a. The coding element 106a, together with a coding element, not shown in further detail, of the flange neck 88a, is intended for preventing the mounting of the guard hood unit 56a on handheld power tools 12a that are unsuitable for it.
The torsion-prevention unit 38a is disposed on the guard hood 16a on a side 54a of the guard hood neck 104a facing away from the receiving region 52a in the radial direction 108a, and the torsion-prevention unit 38a is formed by a form-locking unit 110a. The torsion-prevention unit 38a has a plurality of torsion-prevention elements 40a, 42a, disposed in succession in a circumferential direction 44a, which are formed by form-locking elements 146a, 148a and form a set of teeth 46a. The form-locking elements 146a, 148a embodied by teeth extend, together with a guard hood body 112a of the guard hood 16a, over an angular range of approximately 180° of the tool 18a in the circumferential direction 44a, so that mounting the guard hood 16a in an unprotected position that is dangerous to a user is advantageously prevented. Fundamentally, however, it is also conceivable for the form-locking elements 146a, 148a to cover an angular range in the circumferential direction 44a of nearly 360° on the guard hood neck 104a. The teeth extend in the radial direction 108a outward from the guard hood neck 104a. It is also conceivable for the form-locking elements 146a, 148a to be formed by recesses, indentations, and/or other form-locking elements 146a, 148a, disposed in the guard hood neck 104a, the form-locking elements being of a kind that would be appropriate to one skilled in the art.
Moreover, between the flange neck 88a and the guard hood 16a or the guard hood neck 104a, a compensation element 118a (FIG. 2) is also disposed in the radial direction 108a. The compensation element 118a is formed from a rubberlike material and embodied cylindrically. The compensation element 118a is intended to counteract or prevent play between the flange neck 88a and the guard hood neck 104a. 
In an already-mounted state of the guard hood unit 56a on the right-angle power sander 14a (FIGS. 1 and 2), the two torsion-prevention units 20a, 38a are in engagement with one another. In this situation, the form-locking elements 146a, 148a of the guard hood 16a, which are formed by teeth, mesh with a threaded profile of the threaded shaft 32a. Rotation of the actuation element 36a along with the threaded shaft 32a in a direction of rotation 102a about the longitudinal axis 22a exerts a force 116a, because of the set of teeth 28a, embodied as a thread, of the threaded shaft 32a, along the longitudinal axis 22a, on the form-locking elements 146a, 148a, meshing between the thread, of the guard hood 16a, and this force is transmitted via a threaded flank 114a to the form-locking elements 146a, 148a and thus to the guard hood 16a. As a result of this force, a rotation of the guard hood 16a in the circumferential direction 44a from a first guarding position to a second guarding position is effected. A change from one guarding position to a further guarding position of the guard hood can be accomplished in continuously variable fashion here by means of the rolling-contact worm gear 30a. Because of self-locking of the rolling-contact worm gear 30a, a rotation of the guard hood 16a with transmission of linear momentum and/or force from the guard hood 16a to the threaded shaft 32a is prevented. For that purpose, a pitch of the threaded flank 114a of the threaded shaft 32a is embodied such that even at extremely strong linear momentums and/or torques, acting on the guard hood 16a or on the guard hood torsion preventer 10a, as in the case in particular of fragments of a bursting tool 18a that strike the guard hood 16a, a rotation of the guard hood 16a out of the guarding position is prevented.
Alternatively or in addition, in a further embodiment, an adjustment of a guarding position of the guard hood 16a can moreover be effected by way of a switching unit which is operable or adjustable by the user and by which a motor for rotating the torsion-prevention unit 20a can be controlled. The switch unit may have one control element for coarse positioning and one control element for fine positioning of the guarding position of the guard hood 16a. 
In FIGS. 4 through 7, alternative exemplary embodiments are shown. Components, characteristics and functions that remain essentially the same are identified by the same reference numerals throughout. However, to distinguish the various exemplary embodiments, the letters a through e are added to the reference numerals in the exemplary embodiments. The ensuing description is limited essentially to the differences from the exemplary embodiment in FIGS. 1 through 3, and the description of the exemplary embodiment of FIGS. 1 through 3 can be referred to for components, characteristics and functions that remain the same.
In FIG. 4, an alternative embodiment to FIG. 3 of a torsion-prevention unit 38b of the guard hood torsion preventer 10b is shown. The torsion-prevention unit 38b is disposed on a guard hood 16b and embodied in one piece with it. Moreover, the torsion-prevention unit 38b is formed by a form-locking unit 110b and has a plurality of torsion-prevention elements 40b, 42b, which are formed by form-locking elements 146b, 148b. The form-locking elements 146b, 148b are disposed along a semi-circular path 120b on a guard hood body 112b, on a side 50b of the guard hood body 112b facing away from a receiving region 48b for a tool. The form-locking elements 146b, 148b are embodied as a set of teeth 46b, which extend away from the guard hood body 112b in the direction of the side 50b facing away from the receiving region 48b. A form-locking connection to a further torsion-prevention unit of a guard hood torsion preventer 10b is effected analogously to the exemplary embodiment in FIG. 2. Analogously to the exemplary embodiment in FIGS. 1 through 3, here as well the form-locking elements 146b, 148b, in an alternative embodiment, may be formed by recesses and/or indentations that can be engaged by a set of teeth of a threaded shaft.
In FIG. 5, a guard hood unit 56c that is an alternative to FIGS. 3 and 4 is shown, with a guard hood 16c. Instead of a guard hood neck, the guard hood 16c has a guard hood collar 122c, which extends essentially parallel to an extension face 124c of a guard hood body 112c of the guard hood 16c. The guard hood collar 122c is intended for securing the guard hood 16c to a receiving unit of a right-angle power sander, and for that purpose, by means of a disk not shown in detail that can be screwed to the receiving unit, it can be clamped between the disk and the receiving unit. For torsion prevention, the guard hood collar 122c has a torsion-prevention unit 38c of a guard hood torsion preventer 10c. The torsion-prevention unit 38c has a plurality of torsion-prevention elements 40c, 42c, which are formed by form-locking elements 146c, 148c, and the form-locking elements 146c, 148c are disposed in a radial direction 108c outside a clamping region 150c for securing the receiving unit to the guard hood collar 122c. The form-locking elements 146c, 148c are disposed in a circumferential direction 44c on the guard hood collar 122c on a side 50c facing away from a receiving region 48c for a tool, and they extend away from the guard hood collar 122c in the direction of the side 50c facing away from the receiving region 48c. The form-locking elements 146c, 148c are formed by a set of teeth 46c, analogously to FIGS. 3 and 4. Analogously to the exemplary embodiment in FIGS. 1 through 3, here as well the form-locking elements 146c, 148c, in an alternative embodiment, may be formed by recesses and/or indentations that can be engaged by a set of teeth of a threaded shaft.
In FIG. 6, an embodiment of a torsion-prevention unit 20d, as an alternative to FIG. 2, of a guard hood torsion preventer 10d is shown. The torsion-prevention unit 20d is braced via a bearing point 24d on a receiving unit 66d for receiving a tool and a guard hood unit 56d of a right-angle power sander 14d. The torsion-prevention unit 20d has a longitudinal axis 22d, about which the torsion-prevention unit 20d is rotatably supported. The torsion-prevention unit 20d, in a middle region 98d along the longitudinal axis 22d, has a splined shaft 126d, which has a set of teeth 28d formed by splines 128d. The set of teeth 28d has three splines 128d, extending in the circumferential direction or the direction of rotation 102d around the splined shaft 126d, and the splines are embodied asymmetrically in the direction of rotation 102d of the splined shaft 126d, and a portion 130d of the set of teeth 28d or splines 128d in the direction of rotation 102d is disposed with a maximum spline height in a radial direction of the splined shaft 126d, while another portion 132d of the set of teeth 28d or of the splines 128d is disposed with a /minimum spline height. By a rotation of the torsion-prevention unit 20d or of the splined shaft 126d, the splines 128d engage a set of teeth 46d of a torsion-prevention unit 38d on a guard hood 16d, the torsion-prevention unit 38d and the guard hood 16d being embodied analogously to the exemplary embodiment in FIG. 3. Alternatively, it is also conceivable for the torsion-prevention unit 38d to have torsion-prevention elements 40d, 42d, formed by recesses, with the splines 128d of the splined shaft 126d, for torsion prevention or form-locking connection mesh with the torsion-prevention unit 38d in indentations intended for the purpose of the torsion-prevention unit 38d, which indentations are disposed on a radially outward-oriented surface of the flange neck 88d. 
By means of the splined shaft 126d, the guard hood 16d is securely held, as a result of the two meshing torsion-prevention units 20d, 38d of the guard hood torsion preventer 10d, in a guarding position by a spline clamping action between the splined shaft 126d and the guard hood 16d. By rotation of the splined shaft 126d by 180° in the direction of rotation 102d about its longitudinal axis 22d, a form-locking connection or spline clamping action between the two torsion-prevention units 20d, 38d is undone, and the guard hood 16d can be changed in its position or lifted from the flange neck 88d by a user of the right-angle power sander 14d. It is moreover conceivable for the splined shaft 126d to be prestressed or preclamped in a wedging position by means of a spring element and/or a detent element and/or other components that appear appropriate to one skilled in the art.
In FIG. 7, an embodiment of a guard hood torsion preventer 10e is shown that is an alternative to FIG. 2. The guard hood torsion preventer 10e has two torsion-prevention units 20e, 38e, which are each formed by a respective force-locking unit 34e, 134e. The first torsion-prevention unit 20e is braced via a bearing point 24e on a receiving unit 66e of a right-angle power sander 14e, and the torsion-prevention unit 20e is supported rotatably about its longitudinal axis 22e in the bearing point 24e. The torsion-prevention unit 20e has a shaft 92e, formed by a force-locking shaft 136e, which in its middle region along the longitudinal axis 22e has a force-locking element 138e, and for attaining a force lock with a guard hood 16e, the force-locking element 138e is disposed asymmetrically about the longitudinal axis 22e, and an axis of rotation 144e extends eccentrically through the force-locking element 138e. For assuring a force lock, the force-locking shaft 136e can be fixed in its position by a user, via fixation elements not shown in further detail. The second torsion-prevention unit 38e is embodied in one piece with a guard hood neck 104e of the guard hood 16e. The torsion-prevention unit 38e has torsion-prevention elements 40e, 42e, disposed in succession in the circumferential direction 44e and formed by force-locking elements 140e, which are formed by ramps that rise counter to a direction of rotation 142e of a tool. In a mounted position or guarding position of the guard hood 16e on the right-angle power sander 14e, a static friction is operative between the two torsion-prevention units 20e, 38e, or between the force-locking shaft 136e and the ramps of the guard hood 16e, and this friction counteracts rotation of the guard hood 16e out of the guarding position. Moreover, by means of the ramps, a static friction force between the ramps and the force-locking shaft 136e upon a rotation of the guard hood 16e in the direction of rotation 142e is additionally increased, so that even at strong rotary linear momentums and/or torques, as in the case for instance of tool fragments, spun outward and striking the guard hood 16e, from a tool that has burst in operation of the right-angle power sander 14e, rotation of the guard hood 16e out of its guarding position is advantageously prevented.
The foregoing relates to preferred exemplary embodiments of the invention, it being understood that other variants and embodiments thereof are possible within the spirit and scope of the invention, the latter being defined by the appended claims.

## Claims

1. A guard hood torsion preventer for a handheld power tool, comprising:
a guard hood mounted on the handheld power tool in a manner so as to partially cover a tool of the handheld power tool, the guard hood defining a first longitudinal axis; and
at least one torsion-prevention unit defining a second longitudinal axis about which the torsion-prevention unit is rotatably supported,
wherein the at least one torsion-prevention unit is configured to rotate about the second longitudinal axis and is formed at least partly by a form-locking unit, and
wherein rotation of the at least one torsion-prevention unit about the second longitudinal axis causes a portion of the at least one torsion-prevention unit configured to urge against an adjacent portion of the guard hood to rotate the guard hood about the first longitudinal axis, the portion of the at least one torsion-prevention unit configured to remain in continuous engagement with the adjacent portion of the guard hood from any starting position and for any positive or negative rotation of the at least one torsion-prevention unit about the second longitudinal axis, the interaction of the portion of the at least one torsion-prevention unit and the adjacent portion of the guard hood resisting rotation of the guard hood when the guard hood is acted upon by an external force.

2. The guard hood torsion preventer as defined by claim 1, further having at least one bearing point, through which the torsion-prevention unit is braced on the handheld power tool.

3. The guard hood torsion preventer as defined by claim 1, wherein the portion of the at least one torsion-prevention unit is embodied as a shaft.

4. The guard hood torsion preventer as defined by claim 2, wherein the portion of the at least one torsion-prevention unit is embodied as a shaft.

5. The guard hood torsion preventer as defined by claim 1, wherein the torsion-prevention unit has at least one actuation element, which rotates the torsion-prevention unit about the second longitudinal axis.

6. The guard hood torsion preventer as defined by claim 2, wherein the torsion-prevention unit has at least one actuation element, which rotates the torsion-prevention unit about the second longitudinal axis.

7. The guard hood torsion preventer as defined by claim 3, wherein the torsion-prevention unit has at least one actuation element, which rotates the torsion-prevention unit about the second longitudinal axis.

8. The guard hood torsion preventer as defined by claim 1, wherein the torsion-prevention unit is formed at least partly by a form-locking unit.

9. The guard hood torsion preventer as defined by claim 8, wherein the portion of the at least one torsion-prevention unit is embodied as a threaded portion of a shaft.

10. The guard hood torsion preventer as defined by claim 1, wherein the adjacent portion of the guard hood has at least two torsion-prevention elements disposed in succession in a circumferential direction on the guard hood.

11. The guard hood torsion preventer as defined by claim 10, wherein the at least two torsion-prevention elements includes at least two teeth.

12. The guard hood torsion preventer as defined by claim 10, wherein the adjacent portion is disposed at least partly on a side of the guard hood facing away from a receiving region of the guard hood for the tool.

13. The guard hood torsion preventer as defined by claim 11, wherein the adjacent portion is disposed at least partly on a side of the guard hood facing away from a receiving region of the guard hood for the tool.

14. A guard hood torsion preventer for a handheld power tool, comprising:
a guard hood mounted on the handheld power tool in a manner so as to partially cover a tool of the handheld power tool, the guard hood defining a first longitudinal axis; and
at least one torsion-prevention unit defining a second longitudinal axis about which the torsion-prevention unit is rotatably supported,
wherein the at least one torsion-prevention unit is configured to rotate about the second longitudinal axis,
wherein the torsion-prevention unit is formed at least partly by a form-locking unit embodied as a rolling-contact worm gear, and
wherein the guard hood has a corresponding locking portion configured for continuous engagement with the worm gear, the interaction of the portion of the guard hood and the worm gear resisting rotation of the guard hood when the guard hood is acted upon by an external force.

15. A guard hood torsion preventer for a handheld power tool, comprising:
a guard hood mounted on the handheld power tool in a manner so as to partially cover a tool of the handheld power tool, the guard hood defining a first longitudinal axis; and
at least one torsion-prevention unit defining a second longitudinal axis about which the torsion-prevention unit is rotatably supported,
wherein the at least one torsion-prevention unit is configured to rotate about the second longitudinal axis,
wherein rotation of the at least one torsion-prevention unit about the second longitudinal axis causes rotation of the guard hood about the first longitudinal axis,
wherein the at least one torsion-prevention unit includes a shaft that defines the second longitudinal axis,
wherein the shaft includes a threaded portion and rotation of the torsion-prevention unit causes rotation of the threaded portion, and
wherein the guard hood includes a plurality of teeth that meshingly engage the threaded portion, the interaction of the threaded portion and the plurality of teeth resisting rotation of the guard hood when the guard hood is acted upon by an external force.

16. The guard hood torsion preventer as defined by claim 15, wherein rotation of the threaded portion causes rotation of the plurality of teeth.