52results about How to "Achieve mechanical locking" patented technology

The invention provides a self-unlocking sleeve device capable of being unfolded and folded, which belongs to the technical field of machinery and comprises a sleeve portion, a guide portion, a driving portion, a pull wire portion and a locking portion. The sleeve portion at least comprises three sleeve structures, and the pull wire portion comprises a steel wire rope and a pulley system. The driving portion is utilized to drive the pull wire portion to enable sleeves to be unfolded or folded along the guide portion. The locking portion achieves mechanical self locking when the sleeves are completely unfolded, and unlocking, folding and unfolding of the sleeves share one set of driving device. The self-unlocking sleeve device has the advantages of simplifying the driving device and the operation process, being simple in structure, small in mass, reliable in locking and capable of achieving self-unlocking.

The invention belongs to the technical field of locknuts and discloses a locknut for a rotor of a gas turbine. The locknut comprises a recessed part arranged on the outer side face of a nut body, the distance between any point on the recessed part and the center of the nut body is smaller than the radius of the outer side face of the nut body, and the recessed part penetrates the whole nut body in the radial direction. Through the arrangement of the recessed part penetrating the whole nut body in the radial direction on the outer side of the nut body, the recessed part is matched with a protruding shoulder, and the locking function is achieved. The structure of an existing wheel disc is fully used, the structure is simple, assembly and disassembly are convenient, and the anti-looseness self-locking effect is good. The invention discloses two machining methods of the locknut. Multiple recessed parts can be machined at the same time through a tool rotary disc and linear cutting, and the recessed parts are not limited to the contour shape.

A three-freedom-degree transmission mechanism comprises a helical pair, a revolute pair and a cylindrical pair. The axis of the helical pair is perpendicular to the axis of the revolute pair, and the axis of the revolute pair is parallel to the axis of the cylindrical pair. The revolute pair comprises a support (7), a movable sliding block (5), the helical pair (3), a nut (4), a left limiting block (1) and a right limiting block (6). The left limiting block (1) and the right limiting block (6) are fixedly arranged on the support (7), and the helical pair (3) is provided with the movable sliding block (5). The transmission mechanism is characterized in that the helical pair (3) mounted on the support (7) and the revolute pair can form 0-degree to 180-degree intersection angles through the movable sliding block (5). According to the transmission mechanism, under the condition of identical number of rotation of a screw rod, the speed of the straight line motion (opening and closing) of the nut (a door leaf) is improved. The mechanical locking of a vehicle door is achieved without another set of mechanical locking mechanism. The transmission mechanism is simple, the motion procedures of unlocking and locking are removed, procedure control is simplified, and two fault hazards are eliminated.

The invention discloses an adjustable computer cabinet with solar energy to provide power, which comprises a cabinet body (2) and a door cover (20), wherein the door cover (20) removably covers the opening of the cabinet body (2); the inner side, facing the cabinet body, of the door cover (20) is provided with a locking hook (60) in an integrated mode to pass through a through hole (200) in the wall part of the cabinet body and to be connected with the inner side of the wall part via a hook tail end (601) to realize to lock the door cover (20) on the cabinet body; the inner side of the door cover (20) is also provided with a driving concave part (309) for being connected with a driving block (30) so as to enable the driving block (30) to drive the driving concave part along the direction parallel to the plane of the wall part and the direction vertical with the plane of the wall part to further enable the locking hook (60) to be unlocked; and the inner side of the driving block (30) is provided with a driving connection convex part (303) for being matched with a connection concave part (402) in an inner thread sliding block (40) in screw driving by a screw rod (50).

The invention provides a lock cylinder and an unlocking key. The lock cylinder comprises a lock case, a lock core, a locking part, locking blades, a driving assembly and a driving control blade; the lock core is rotatably arranged in the lock case; the locking part is movably arranged between the lock core and the lock shell and has a locking position and an unlocking position; the locking bladesare movably connected with the lock core and can stop or avoid movement of the locking part so as to lock or unlock the locking part; at least one part of the driving assembly is movably arranged relative to the locking part and can stop or avoid movement of the locking part so as to lock or unlock the locking part; and the driving control blade is movably connected with the lock core and has a stopping position and an avoiding position, when the driving control blade is located at the stopping position, the driving control blade stops movement of the driving assembly, and when the driving control blade is located at the avoiding position, the driving control blade avoids movement of the driving assembly. According to the lock cylinder and the unlocking key, the problem that in the prior art, the safety of a lock cylinder is low is solved.

The invention provides a self-locking rotary knob gearshift device comprising a rotary knob, a gearshift control assembly and a self-locking control assembly. The gearshift control assembly and the self-locking control assembly share the same shift column support; the rotary knob is fixedly connected with the shift column support; a gearshift control panel of the gearshift control assembly detects a photoelectric signal of a photoelectric sensor and matches a corresponding shift; when the gearshift control assembly is switched to a preset shift, a self-locking slide block of the self-locking control assembly is inserted into a self-locking spacing ring; and the rotary knob is mechanically locked in the preset shift.

The invention discloses a bridge pushing and sliding device, which comprises upper and lower support plates respectively provided with grooves, spherical crown liners installed in the grooves of the upper support plates, spherical crown liners The upper plane of the spherical crown liner is in contact with the bottom of the groove of the upper support plate, and the lower spherical surface of the spherical crown liner fits with the radial end surface of the stud. The stud is connected to the lock nut and its upper flange is in contact with the upper support plate. The side wall of the lower support plate is in contact with the side wall; the piston rod is installed in the groove of the lower support plate, the piston rod is provided with a sealing ring that forms a seal with the side wall of the lower support plate, and the side wall of the lower support plate is installed with a screw thread with the piston rod The connecting limit ring, the bottom of the lower support plate is provided with a hydraulic hole connected to the hydraulic system and communicated with the annular flow channel at the bottom of the piston rod, and the lower support plate is embedded in the slideway. Its advantages are: it can meet the two requirements of force measurement and height adjustment at the same time, and it can monitor the force situation of the vertical support points in real time, so as to grasp the dynamic changes of the vertical force of each support point of the bridge.

A mobile computer cabinet guided by a guide rod is disclosed. The mobile computer cabinet comprises a cabinet body (2) and a door cover (20) that removably covers the opening of the cabinet body (2); a shifting mechanism is arranged at the bottom of the cabinet body (2); the shifting mechanism comprises a supporting frame (6) and a moving wheel (7) fixedly arranged on the supporting frame (6); the supporting frame (6) is fixedly connected with the cabinet body (2); a locking hook body (60) is integrally arranged on the inner side, facing to the cabinet body, of the door cover (20), wherein the locking hook body is used for penetrating through a through hole (200) in the wall part of the cabinet body to lock the door cover (20) on the cabinet body through joint between a hook part tail end (601) and the inner side of the wall part; a driving concave part (309) is further formed in the inner side of the door cover (20); the driving concave part is jointed with a driving block (30), so that the driving block (30) drives the door cover in a direction parallel to the plane of the wall part and in a direction perpendicular to the plane of the wall part so as to enable the locking hook body (60) to be unlocked.

The invention discloses an intelligent antitheft lock and an antitheft method. The intelligent antitheft lock is characterized by comprising a lock shell, a lock cylinder, an electromagnetic lock pin, a controller and a triggering module, the lock cylinder is mounted in the lock shell in an inserted manner, the electromagnetic lock pin controls action of the lock cylinder, the controller controls working state of the electromagnetic lock pin, the triggering module communicates with the controller, the electromagnetic lock pin is fixedly mounted on the lock shell, and at least one locking groove is formed in positions, directly facing a pin head of the electromagnetic lock pin, of the outer wall of the lock cylinder. By adopting the above technical scheme, a mechanical lock and electric control technology are combined into a whole, in other words, the electromagnetic lock pin is added on the basis of a conventional mechanical lock, in this way, mechanical locking is realized while electric control locking is performed on mechanical locking parts, so that a function of double locking is realized. Consequently, when opening the intelligent antitheft lock, a thief has to release control, on the mechanical lock, of the electromagnetic lock pin to realize opening of the mechanical lock.

The invention relates to a mast arrangement for a construction machine with a mast having a mast guide, along which a mast carriage is supported in a movable manner which is connected to a hydraulic source and has a first hydraulic coupling part for hydraulically connecting a tool unit to a hydraulic source on the mast carriage. According to the invention provision is made for the tool unit to have a tool guiding means, with which the tool unit can be fixed and positioned on the mast guide. On a frame of the tool unit a second hydraulic coupling part is arranged which corresponds to the first hydraulic coupling part of the mast carriage. Upon movement of mast carriage and tool unit towards each other along the mast guide the first hydraulic coupling part of the mast carriage can be linked up hydraulically to the second hydraulic coupling part on the tool unit. A locking means is provided which is spaced from the hydraulic coupling parts and has at least one hydraulically operable latch bolt, with which the frame of the tool unit can be connected mechanically to the mast carriage. The invention furthermore relates to a corresponding method for connecting the tool unit to the mast carriage.

The invention provides an attitude adjusting method and hydraulic system for antenna testing. The system involves a platform hydraulic subsystem, a rotary platform, an erecting hydraulic subsystem, alevel gauge, a controller and a rangefinder; the rotary platform is installed on the platform hydraulic subsystem, the erecting hydraulic subsystem is installed on the rotary platform and used for erecting or lowering a tested antenna, and the rotary platform is used for driving the erecting hydraulic subsystem and the tested antenna to rotate in the horizontal direction; the level gauge is used for monitoring the platform hydraulic subsystem; the controller receives a monitoring result of the level gauge for monitoring and can control the platform hydraulic subsystem and the erecting hydraulic subsystem; and the rangefinder is used for measuring the distance between the tested antenna and an external test reference surface, and sending the measured distance to the controller, and the controller controls the platform hydraulic subsystem to adjust the distance between the tested antenna and the external test reference surface according to an external target requirement and the measureddistance. The system has the advantages of being high in adjusting precision and high in adjusting speed.

A shock-absorption type computer cabinet convenient to maintain comprises a cabinet body (2) and a door cover (20) removably covering an opening of the cabinet body (2); a locking hook (60) used for penetrating through a through hole (20) in the wall of the cabinet body is integrally arranged on the inner side, facing the cabinet body, of the door cover (20), and the inner side, facing the cabinet body, of the door cover (20) is connected with the inner side of the wall through the hook tail end (601), and accordingly, the door cover (20) is locked on the cabinet body; a concave drive part (309) is further arranged on the inner side of the door cover (20) and is used for being connected with a drive block (30), and the drive block (30) can drive the concave drive part (309) in the direction parallel with the wall surface and in the direction vertical to the wall surface, so that the locking body (60) can be unlocked; a drive connection bulge (303) is arranged on the inner side of the drive block (30) and used for being matched with a concave connection part (402) in an internal threaded sliding block (40) driven by a screw rod (50) through threads.

The invention relates to a locking device for a downhole sliding sleeve of an intelligent well and an operation method thereof. The locking device is characterized by comprising a thickened oil pipe, wherein the periphery of the thickened oil pipe is sleeved with a locking hydraulic cylinder, and the locking hydraulic cylinder comprises a hydraulic cylinder cover and a cylinder sleeve that are connected through a bolt; the other end of the hydraulic cylinder cover is connected with a lower cover plate and an upper cover plate and positioned by a clamping ring arranged between the upper cover plate and the thickened oil pipe; a sliding sleeve is arranged between the locking hydraulic cylinder and the thickened oil pipe, a piston is arranged between the sliding sleeve and the cylinder sleeve, a piston annular space is kept between the piston and the sliding sleeve, and a returning spring is arranged between the piston and the cylinder sleeve; the hydraulic cylinder cover is provided with an oil inlet communicated in the cylinder sleeve, and the cylinder sleeve is provided with an oil outlet communicated with the outside; the contact part of the thickened oil pipe and the sliding sleeve is provided with a plurality of positioning grooves at intervals and a positioning steel ball; and the sliding sleeve is provided with a key slot, and the key slot is oppositely provided with a feather key. In the invention, the sliding sleeve can be locked through regulation under driving of hydraulic power so as to adjust the size of a downhole production runner. Therefore, the locking device is widely applied in a production control process of an oil and gas well.

The invention discloses a computer cabinet capable of giving an alarm when contacted and performing displacement, which comprises a cabinet body (2) and a door cover (20), wherein the door cover (20) removably covers the opening of the cabinet body (2); the bottom part of the cabinet body (2) is provided with a displacement mechanism; the displacement mechanism comprises a supporting frame (6) and moving wheels (7) fixedly arranged on the supporting frame (6); the supporting frame (6) is fixedly connected with the cabinet body (2); the inner side, facing the cabinet body, of the door cover (20) is provided with a locking hook (60) in an integrated mode to pass through a through hole (200) in the wall part of the cabinet body and to be connected with the inner side of the wall part via a hook tail end (601) to realize to lock the door cover (20) on the cabinet body; the inner side of the door cover (20) is also provided with a driving concave part (309) for being connected with a driving block (30) so as to enable the driving block (30) to drive the driving concave part along the direction parallel to the plane of the wall part and the direction vertical with the plane of the wall part to further enable the locking hook (60) to be unlocked.

The invention discloses a mechanical locking device for hydraulic supporting legs. The mechanical locking device comprises a hydraulic cylinder body, a sliding spiral transmission mechanism arranged in the hydraulic cylinder body, a rotating supporting mechanism arranged in the hydraulic cylinder body and connected with the sliding spiral transmission mechanism, and a manual driving mechanism or an automatic driving mechanism which provides power for the rotating supporting mechanism. Under the effect of the manual driving mechanism or the automatic driving mechanism, the rotating supporting mechanism drives the sliding spiral transmission mechanism to move to the predetermined position so as to achieve locking or unlocking of the hydraulic supporting legs.

A computer cabinet control system comprises a DSP controller, a motor driving circuit and a computer cabinet. The computer cabinet comprises a cabinet body (2) and a door cover (20) covering an opening of the cabinet body (2) in a removable manner. The inner side, facing towards the cabinet body, of the door cover (2) is integrally provided with a locking hook (60) which is used for penetrating a through hole (200) in the wall part of the cabinet body and being connected with the inner side of the wall part through a hook part tail end (601) so that the door cover (20) can be locked to the cabinet body; a driving concave part (309) is further arranged on the inner side of the door cover (20) and used for being connected with a driving block (30) so that the driving concave part (309) can be driven by the driving block (30) in the direction parallel with the plane of the wall part and the direction perpendicular to the plane of the wall part and the locking hook (60) can be unlocked accordingly; and a driving connection protrusion (303) is arranged on the inner side of the driving block (30) and used for being matched with a connecting concave part (402) in an internal thread slider (40) driven by a screw (50) through threads.

A computer cabinet with a guide rail groove comprises a cabinet body (2) and a door cover (20), wherein the door cover (20) detachably covers an opening of the cabinet body (2), a locking hook body (60) is integratedly arranged on the inner side, facing the cabinet body, of the door cover (20), is used for passing through a through hole (200) formed in the wall part of the cabinet body and is in overlap joint with the inner side of the wall part by a hook part tail end (601) so that the door cover (20) is locked on the cabinet body, a driving concave part (309) is further arranged at the inner side of the door cover (20) and used for being in overlap joint with a driving block (30) so that the driving block (30) drives along a direction parallel to a wall part plane and a direction perpendicular to the wall part plane to further make the locking hook body (60) unlocked, a driving connection bulge (303) is arranged at the inner side of the driving block (30) and used for matching with a connection concave part (402) in an internal threaded sliding block (40) which is driven by a screw rod (50) in a threaded way.

The invention discloses a computer cabinet. The computer cabinet comprises a cabinet body (2) and a door cover (20) which covers an opening of the cabinet body (2) in a removable way, wherein a locking hook body (60) is integrally arranged on an inner side, which faces the cabinet body, of the door cover (20), and used for passing through a through hole (200) in a wall part of the cabinet body and being jointed with an inner side of the wall part through a hook tail end (601) in order to lock the door cover (20) on the cabinet body; a driving recess (309) is further arranged on the inner side of the door cover (20), and used for being jointed with a driving block (30) in order to be driven by the driving block (30) to move along a direction being parallel to a plane of the wall part and a direction being vertical to the plane of the wall part, thereby unlocking the locking hook body (60); and a driving joint bump (303) is arranged on an inner side of the driving block (30), and used for being matched with a joint recess (402) in an inner threaded slide block (40) which is driven by a screw (50) in a threaded way.

The invention discloses a heat dissipation type computer cabinet. The heat dissipation type computer cabinet comprises a cabinet body (2) and a door cover (20) which covers the opening of the cabinet body (2) in a removable manner; a locking hook body (60) is integrally arranged at the inner side, facing the cabinet body, of the door cover (20) and is used for penetrating through a through hole (200) in the wall part of the cabinet body and being hinged with the inner side of the wall part through a hook tail end (601) so as to lock the door cover (20) on the cabinet body; a driving recess (309) is arranged on the inner side of the door cover (20) and is used for being jointed with a driving block (30) and driven by the driving block (30) along a direction parallel to the plane of the wall part and a direction vertical to the plane of the wall part so as to unlock the locking hook (60); and a driving jointing bulge (303) is arranged on the inner side of the driving block (30) and is used for being matched with a jointing recess (402) in an internal thread sliding block (40) which is thread driven by a screw rod (50).

The invention provides a vertical roller cardan shaft safety device and a using method, after a cardan shaft is supported by a bracket, safe locking protection of the cardan shaft bracket is achieved through an interlocking mode of components such as an electric cylinder, a proximity switch and an electric mortise lock, potential safety hazards caused by oil leakage and pressure loss of a hydraulic cylinder are avoided, the safety of operators in operation is ensured, due to the introduction of an electric control mode, the process of manually climbing to install a safety clamping plate is omitted, and the danger of high-place operation is reduced.

The invention discloses a noise reduction computer cabinet with a cushion. The noise reduction computer cabinet comprises a cabinet body (2) and a door cover (20) which covers an opening of the cabinet body (2) in a removable way, wherein a locking hook body (60) is integrally arranged on an inner side, which faces the cabinet body, of the door cover (20), and used for passing through a through hole (200) in a wall part of the cabinet body and being jointed with an inner side of the wall part through a hook tail end (601) in order to lock the door cover (20) on the cabinet body; a driving recess (309) is further arranged on the inner side of the door cover (20), and used for being jointed with a driving block (30) in order to be driven by the driving block (30) to move along a direction being parallel to a plane of the wall part and a direction being vertical to the plane of the wall part, thereby unlocking the locking hook body (60); and a driving joint bump (303) is arranged on an inner side of the driving block (30), and used for being matched with a joint recess (402) in an inner threaded slide block (40) which is driven by a screw (50) in a threaded way.

The invention provides a computer cabinet with a guide rail groove and a buffer cushion. The computer cabinet comprises a cabinet body (2) and a door cover (20), wherein the door cover (20) removably covers an opening of the cabinet body (2); the inner side, toward the cabinet body, of the door cover (20) is integrally provided with a lock hook body (60), which is used for passing through a through hole (200) in a wall part of the cabinet body and is engaged with the inner side of the wall part through a hook tail end (601), so that the door cover (20) is locked on the cabinet body; the inner side of the door cover (20) is also provided with a drive recess (309) which is used for being engaged with a drive block (30) to be driven by the drive block (30) along the direction parallel to the plane of the wall part and the direction vertical to the plane of the wall part, so that the lock hook body (60) is unlocked; and the inner side of the drive block (30) is provided with a drive joint bulge (303), which is used for being matched with a joint recess (402) in an inner thread slide block (40) driven by a thread.

The invention relates to a quickly-cooled computer cabinet. The quickly-cooled computer cabinet comprises a cabinet body (2) and a door cover (20) which covers the opening of the cabinet body (2) in a removable manner; the inner side of the door cover (20), which faces the cabinet body, is integrally provided with a locking hook body (60) which passes through a through hole (200) in the wall portion of the cabinet body and is connected with the inner side of the wall portion through a hook portion tail end (601) so that the door cover (20) can be locked on the cabinet body; the inner side of the door cover (20) is also provided with a driving recessed portion (309) which is connected with a driving block (30), so that the driving recessed portion (309) can be driven by the driving block (30) in a direction vertical to the plane of the wall portion along a direction parallel to the plane of the wall portion, and therefore, the locking hook body (60) can be unlocked; and the inner side of the driving block (30) is provided with a driving joint protrusion (303) which is matched with a joint recessed portion (402) in an inner threaded slide block (40) which is driven by a screw rod (50) by means of screw threads.

A solar powered computer cabinet comprises a cabinet body (2) and a door cover (20), wherein the door cover (20) detachably covers an opening of the cabinet body (2), a locking hook body (60) is integratedly arranged on the inner side, facing the cabinet body, of the door cover (20), is used for passing through a through hole (200) formed in the wall part of the cabinet body and is in overlap joint with the inner side of the wall part by a hook part tail end (601) so that the door cover (20) is locked on the cabinet body, a driving concave part (309) is further arranged at the inner side of the door cover (20) and used for being in overlap joint with a driving block (30) so that the driving block (30) drives along a direction parallel to a wall part plane and a direction perpendicular to the wall part plane to further make the locking hook body (60) unlocked, a driving connection bulge (303) is arranged at the inner side of the driving block (30) and used for matching with a connection concave part (402) in an internal threaded sliding block (40) which is driven by a screw rod (50) in a threaded way.

The invention relates to a noise-reduction type computer cabinet. The noise-reduction type computer cabinet comprises a cabinet body (2) and a door cover (20) which covers the opening of the cabinet body (2) in a removable manner; the inner side of the door cover (20), which faces the cabinet body, is integrally provided with a locking hook body (60) which passes through a through hole (200) in the wall portion of the cabinet body and is connected with the inner side of the wall portion through a hook portion tail end (601) so that the door cover (20) can be locked on the cabinet body; the inner side of the door cover (20) is also provided with a driving recessed portion (309) which is connected with a driving block (30), so that the driving recessed portion (309) can be driven by the driving block (30) in a direction vertical to the plane of the wall portion along a direction parallel to the plane of the wall portion, and therefore, the locking hook body (60) can be unlocked; and the inner side of the driving block (30) is provided with a driving joint protrusion (303) which is matched with a joint recessed portion (402) in an inner threaded slide block (40) which is driven by a screw rod (50) by means of screw threads.

The invention discloses a computer cabinet with solar energy for power generation, power supply and lighting, which comprises a cabinet body (2) and a door cover (20), wherein the door cover (20) removably covers the opening of the cabinet body (2); the inner side, facing the cabinet body, of the door cover (20) is provided with a locking hook (60) in an integrated mode to pass through a through hole (200) in the wall part of the cabinet body and to be connected with the inner side of the wall part via a hook tail end (601) to realize to lock the door cover (20) on the cabinet body; the inner side of the door cover (20) is also provided with a driving concave part (309) for being connected with a driving block (30) so as to enable the driving block (30) to drive the driving concave part along the direction parallel to the plane of the wall part and the direction vertical with the plane of the wall part to further enable the locking hook (60) to be unlocked; and the inner side of the driving block (30) is provided with a driving connection convex part (303) for being matched with a connection concave part (402) in an inner thread sliding block (40) in screw driving by a screw rod (50).

The invention provides a displaceable computer cabinet. The computer cabinet comprises a cabinet body (2) and a door cover (20) covering an opening of the cabinet body (2) in a removable mode. A shifting mechanism is arranged at the bottom of the cabinet body (2) and comprises a supporting rack (6) and moving wheels (7) fixedly arranged on the supporting rack (6). The supporting rack (6) is fixedly connected with the cabinet body (2). The portion, facing the cabinet body, of the inner side of the door cover (20) is integrally provided with a locking hook body (60) which is used for penetrating through a through hole (200) in the wall part of the cabinet body and jointed with the inner side of the wall part through a hook part tail end (601) so that the door cover (20) can be locked to the cabinet body. The inner side of the door cover (20) is further provided with a drive dent part (309) which is used for being jointed with a drive block (30) and driven by the drive block (30) in the direction parallel to the plane of the wall part and the direction perpendicular to the plane of the wall part, so that the locking hook body (60) is unlocked.

The invention discloses an adjustable computer cabinet, which comprises a cabinet body (2) and a door cover (20), wherein the door cover (20) removably covers the opening of the cabinet body (2); the inner side, facing the cabinet body, of the door cover (20) is provided with a locking hook (60) in an integrated mode to pass through a through hole (200) in the wall part of the cabinet body and to be connected with the inner side of the wall part via a hook tail end (601) to realize to lock the door cover (20) on the cabinet body; the inner side of the door cover (20) is also provided with a driving concave part (309) for being connected with a driving block (30) so as to enable the driving block (30) to drive the driving concave part along the direction parallel to the plane of the wall part and the direction vertical with the plane of the wall part to further enable the locking hook (60) to be unlocked; and the inner side of the driving block (30) is provided with a driving connection convex part (303) for being matched with a connection concave part (402) in an inner thread sliding block (40) in screw driving by a screw rod (50).