100results about How to "Adjustable preload" patented technology

The invention discloses a perpendicular rope climbing patrolling robot in ultra-deep vertical shaft steel-rope guide. The perpendicular rope climbing patrolling robot comprises an explosion-proof shell, a driving mechanism, a wheel mechanism, a clamping mechanism, a carrying mechanism and an electric control device. The explosion-proof shell comprises an upper driving shell body, a lower driving shell body, a driver shell body, an electric control device shell body and a carrying mechanism shell body. The driving mechanism comprises an upper driving part, a lower driving part and a motor driver. The wheel mechanism comprises an upper driving wheel part, an upper left side driven wheel part, an upper right side driven wheel part, a lower driving wheel part, a lower left side driven wheel part and a lower right side driven wheel part. The clamping mechanism comprises a left side clamping part and a right side clamping part. The carrying mechanism comprises a movable trolley, an intrinsic safety camera and a cloud deck. The rope climbing patrolling robot can meet the explosion-proof requirement of a coal mine, can climb on the ultra-deep vertical shaft steel-rope guide and can monitor the strain of the shaft wall and the derrick structure situation.

The invention relates to a device for automatically eliminating clearances of a screw drive pair, which comprises a leading screw, a main nut, a bolt, a machine tool sliding plate, an adjusting bolt, a spring, a guide post, a nut with an inclined plane, a bolt, a locking nut, a wedge block and a ball. The device is characterized in that the main nut and the nut with the inclined plane are connected with the leading screw respectively, the main nut is connected with the machine tool sliding plate through the bolt, and the flange of the nut with the inclined plane is provided with a through hole so that the nut with the inclined plane can move axially along the guide post. The wedge block with a self-locking function is supported between the main nut and the nut with the inclined plane; andone end of the spring is pressed on the wedge block with the self-locking function, while the other end is tightly pressed by the adjusting bolt. The incline plane of the nut with the inclined plane is provided with a guide groove. The device automatically eliminates axial clearances, has no reverse idle stroke, has adjustable pretightening force, good axial rigidity, smooth transmission, low cost, compact structure and high space utilization rate, is applied to feed drive systems of a metal cutting machine tool and a numerical control machine tool, and can greatly improve the processing accuracy.

A drilling head (1) with an axial oscillation generator, includes a mounting (2) for coupling the head to a motor for rotating the mounting about an axis, the mounting (2) having a longitudinal axis (5) coinciding with the axis of rotation of the motor, a tool holder (3), an elastically deformable element (6) for retaining the tool holder (3) in the mounting (2) and an element (7) for guiding the tool holder (3) in the mounting (2) along the longitudinal axis (5) of the mounting, wherein the mounting of the drilling head includes a controlled generator (8) of reciprocating movements in the direction of the aforementioned axis (5) positioned between the mounting (2) and the tool holder, the tool holder and the generator being connected by a longitudinal coupling member (9) suitable for damping the impacts withstood by the tool holder while enabling the transmission of the reciprocating movements.

The invention discloses an extremity-traction type upper limb rehabilitation robot adopting gravitational equilibrium devices and a working method thereof, belonging to the field of medical instruments. The robot comprises a movable frame, a robot base, a waist part, a big arm, a middle arm, a forearm, a wrist part, an extremity handle and has six degrees of freedom. The big arm, the middle arm and the forearm are internally equipped with the gravitational equilibrium devices which are used for equilibrating loading moment generated by self weight of a connecting rod of the robot. Middle arm and forearm joint driving motors are disposed at the waist part. Sleeve ropes are adopted to transfer driving moment. Encoders are arranged in all the motors and used for measuring postures of the robot. An extremity handle module is equipped with a six-dimensional force sensor used for measuring man-machine interaction force. Driving force required by the motors is reduced. The extremity load capability of the robot is improved. Cost of the rehabilitation robot is lowered. The self weight of the robot is decreased. The sleeve ropes smoothly drive joints so that safety of man-machine interaction is enhanced. Rehabilitation training of left and right upper limbs of a patient is achieved. Additionally, the extremity-traction type upper limb rehabilitation robot is not particularly applied torehabilitation training.

The invention discloses a ball screw linear driver for a built-in permanent magnet synchronous motor. The ball screw linear driver comprises a stator (4) as well as a rotor (5) and a rotor shaft (7) which are coaxial with the stator (4), wherein the rotor shaft (7) is a hollow cylinder; the rotor (5) is fixed on the rotor shaft (7); the rotor (5) is totally packed by the stator (4); the front end of the rotor shaft (7) is connected with a lead screw nut (15); the rear end of the rotor shaft (7) is provided with a position sensor (9); a lead screw (6) is arranged in the inner cavity of the rotor shaft (7) and is matched with the lead screw nut (15); and two ends of the rotor (5) are provided with gimbal rings (11). The ball screw linear driver for the built-in permanent magnet synchronous motor has the advantages of small size, high operating precision, high reliability and simple structure.

A fixed torque preload piece is positioned between two nuts of a ball screw, the preload piece is formed with through hole located in an axial direction of the two nuts for receiving at least two steel balls. Two terminal openings of each of the through holes are defined in the surfaces of the preload piece facing the two opposite nuts. Three radial threaded holes are formed in the outer periphery of the preload piece, and the threaded holes are vertical to and in communication with the through holes. An adjusting member, an elastic member and an adjusting screw are received sequentially in the respective threaded holes. The steel balls in the through holes are pushed against the two nuts by the arc-shaped abutting surface of the adjusting member, the pushing of the steel balls can produce an adjustable preload, and can absorb the sudden increase of the pressure effectively, thus obtaining the objective of the present invention of outputting torque stably.

The invention discloses a convenient-to-disassemble / assemble / repair cable winding device. The cable winding device comprises a base, a winding drum, a guide movable pulley, an elastic support component, a locking sleeve and a guide fixed pulley, wherein a fixed sleeve is fixedly mounted on a bracket located at the front end of the base, a guide slider is arranged in the fixed sleeve in a sliding manner, a clamping spring is arranged in the fixed sleeve, a support presser rod is also arranged on the fixed sleeve in a sliding manner and penetrates through the fixed sleeve, one end of the supportpresser rod is in rotating connection with the guide slider, a connecting sleeve is fixedly mounted at the other end of the support presser rod, and the connecting sleeve and the support rod are in detachable connection through a connecting bolt. The structure is simple and reasonable, the winding effect is great, the quality is high, and the use is flexible and convenient due to the adjustable pretension force of the elastic support component. The two ends of the winding drum are both fixedly mounted by adopting a detachable connecting mode, so that the disassembly, assembly and change of the winding drum are facilitated, and the cable winding operation is facilitated. The cable winding device is suitable for popularization and use.

The invention discloses an automatic adjustment type steel wire rope tensioning device. The automatic adjustment type steel wire rope tensioning device comprises a base, guide wheels, tensioning wheels, a rotating shaft, a fixed shaft, a swing arm, a fixing piece and torsional springs, wherein the guide wheels are fixed on the base; the tensioning wheels are matched with the guide wheels; the rotating shaft is connected onto the base in a rotating mode, and driving gears are fixed on the rotating shaft; the fixed shaft is fixed on the base, and driven gears engaged with the driving gears are connected onto the fixed shaft in a rotating mode; the swing arm is connected onto the fixed shaft in a rotating mode, one end of the swing arm is coupled with the tensioning wheel; the fixing piece is used for realizing relative fixation of the rotating shaft and the base; the torsional springs are also arranged on the fixed shaft in a sleeving mode, one end of each of the torsional spring is fixed with the swing arm, and the other ends of the torsional springs are fixed with the driven gears. The automatic adjustment type steel wire rope tensioning device is compact in structure, high in pretensioning efficiency, adjustable in pretensioning force, good in pretensioning effect and low in manufacturing cost, meanwhile can realize automatic pretensioning, and can be applied to small and light instruments.

The invention discloses a prestretching mounting structure for a screw rod. One end of the screw rod is fixed, and the other end of the screw rod is free; bearings are separately arranged at the fixed end and the free end; the bearing at the fixed end is arranged in a bearing block fixed with a machine tool main body structure; a bearing bush is arranged outside the bearing at the free end of the screw rod; a motor base connecting flange is arranged outside the bearing bush and is fixedly connected with a motor base; a through hole is formed in the motor base connecting flange; a longitudinal sliding chute is formed in a position, corresponding to the through hole, of the bearing bush; a thread section is arranged at the outer side of the bearing bush; a thread section part is located at the lower side of the motor base connecting flange; part of the thread section part extends from the outer side of the motor base connecting flange; and a bearing bush adjusting nut is screwed in the thread section. The bearing bush adjusting nut can screw in the thread section of the bearing bush by a certain distance, so that the prestretching amount of the screw rod can be controlled, further the control over the prestretching amount of the screw rod is conveniently realized, and the simplicity in operation is realized.

The thread tensioner (9) for a sewing machine has a supporting plate (12) equipped with a first thread tensioning device (18) and a second thread tensioning device (17) on the supporting plate, and the tension load to the thread (10) is overcome. For the purpose, a release lever (31) is connected with the supporting plate (12), and works to abut on a release pin (30) of the thread tensioning devices (17, 18). The thread tensioner works in a manner that the release lever (31) abuts on the first thread tightening device (18) first and then the second thread tensioning device (17) with the progress of the pivotably moving processes by separate releasing steps by using a solenoid (36).

The invention relates to the field of underground engineering surrounding rock support and in particular relates to an underground engineering roadway yielding support system. The system comprises a yielding hydraulic prop, a yielding anchor rod, a mesh, a steel beam, a pressure sensor and a controller, wherein the mesh is spread on roadway surrounding rock, and the roadway surrounding rock is supported by using the yielding anchor rod; the steel beam is erected, and top plate support is performed through the yielding hydraulic prop; the yielding anchor rod comprises an anchoring head, one or more yielding connectors, an elastic cushion block, a W-shaped steel strip, a base plate, a yielding device and a handle nut; each yielding connector is used for connecting two left and right sections of anchor rod bodies and is a cavity; the connected two sections of anchor rod bodies are positioned at the end of the cavity, and a piston stopper is arranged at the end; a spring is arranged between the piston stopper and the end of the cavity of each connector. The constant yielding support can be realized according to actual geological surrounding rock stress conditions, the conditions of the support system are regulated, a good yielding-supporting support system is formed, and the optimized constant yielding support is achieved.

A novel cable rope climbing device comprises a rack (1) and a climbing unit (K) composed of an upper idler wheel (2), an upper hinge I (3), an upper connecting rod I (4), a brake (5), an upper hinge II (6), an upper supporting seat (7), an upper hinge III (8), an upper connecting rod II (9), an upper hinge IV (10), a pre-tightening piece (11), a lead screw (12), a pre-tightening motor (13), a lower hinge I (14), a lower connecting rod I (15), a drive motor (16), a synchronous pulley I (17), a lower supporting seat (18), a lower hinge II (19), a synchronous belt (20), a lower hinge III (21), a lower connecting rod II (22), a synchronous pulley II (23), a lower hinge IV (24) and a lower idler wheel (25). The novel cable rope climbing device can serve as a movement carrier for equipment for cable rope detection, maintenance and the like, and the problems that manual operation is high in labor intensity and low in safety, and an existing cable rope climbing device is poor in adaptability are solved.

The invention discloses a magnetic attraction type locking and positioning device. The magnetic attraction type locking and positioning device comprises a base, a cover plate, an electromagnetic suction cup, an electromagnetic suction cup supporting base, spring guiding rods and supporting type compression springs. The electromagnetic suction cup is arranged on the electromagnetic suction cup supporting base, and the electromagnetic suction cup supporting base bearing the electromagnetic suction cup is arranged in the base. The spring guiding rods sleeved with the supporting type compression springs are arranged between the electromagnetic suction cup supporting base and the base, and the cover plate is arranged on the base. The device can adjust the pre-tightening force, low-voltage direct current power supply is utilized, and the beneficial effects of stability, strong attraction force and small residual magnetism after the power failure are achieved; and functions are safer and morereliable, the structure is simple and economical, and mounting, dismounting, maintaining and component replacement are convenient.

The invention relates to the field of underground construction surrounding rock support and particularly to a supporting pressure adjustment roadway surrounding rock support method. The supporting pressure adjustment roadway surrounding rock support method utilizes an underground construction roadway yield support system. The underground construction roadway yield support system comprises yield hydraulic pillars, yield anchor bolts, meshes, a steel beam, a pressure sensor and a controller. The meshes are laid on roadway surrounding rock, and the roadway surrounding rock is supported through the yield bolts; the steel beam is erected and performs roof support through the yield hydraulic pillars; every yield anchor bolt comprises an anchoring head, one or more yield connectors, an elastic cushion block, a W-shaped steel strip, a base plate, a yield device and a handle nut, wherein the yield connector is used for connecting a left anchor bolt body and a right anchor bolt body and is a cavity, the two anchor bolt bodies are arranged inside the end portions of the cavity and provided with piston stoppers, and springs are arranged between the piston stoppers and the end portions of the connector cavity. Therefore, the supporting pressure adjustment roadway surrounding rock support method can achieve constant yield support according to actual geological surrounding rock stress situations, adjust the status of a support system to form a good yield-support support system and accordingly obtain optimized constant yield support.

A power steering apparatus includes: a worm driven by a motor for assistance; a worm wheel engaged with the worm and transmitting an assist force to a steering shaft; a housing which houses the worm and the worm wheel; a plug having a male screw on an outer peripheral surface of the plug, the male screw being screwed with a female screw formed at the housing; an elastic member, one end of which in a biasing direction of the elastic member is supported by the worm and other end of which in the biasing direction is supported by the plug, giving a preload between the worm and the worm wheel; and a plug fixing member for fixing the plug, a position of which is adjusted to a screwing position at which the preload is a predetermined value, so that the plug is unrotatable with respect to the housing.

The invention provides a check valve with spring pre-tightening force adjustable. The check valve comprises a valve body, a valve seat, a valve plate, a valve rod and a spring. The valve seat is clamped on an opening of the valve body; one side of the valve plate is connected with the valve seat; the valve rod penetrates through the valve seat, and the valve plate is fixed through a nut; the spring penetrates through the valve rod, one end of the spring is fixed on the valve seat, and one end of the spring is connected with an adjusting shim placed on an adjustment nut; and the adjusting nut is connected with outer threads corresponding to the valve rod through inner threads. The check valve with the spring pre-tightening force adjustable has the advantages that because the pre pre-tightening force of the spring of the check valve is adjustable, the adjusting nut rotates to drive the adjusting shim to move left and right along the valve rod, and therefore compression amount of the spring is changed, the pre-tightening force of the spring is adjusted, and accordingly pressure loss of the check valve is changed to satisfy requirements of different users.

The invention discloses a pilot type pipe burst shutoff valve and a method for controlling the same. The pilot type pipe burst shutoff valve is characterized in that a main valve is connected with a pilot valve by a connecting pipeline; the pilot valve comprises a pilot valve body, a pilot valve end cover is mounted at the bottom of the pilot valve body, a closed chamber is formed by the pilot valve body and the pilot valve end cover, a pilot valve spring and a pilot valve element are mounted inside the closed chamber, an adjusting bolt is mounted on the top of the pilot valve body, and the bottom surface of the adjusting bolt is matched with the top of the pilot valve spring in a contact manner; a first pilot valve opening is formed in a side surface of the bottom of the pilot valve bodyby means of machining and is communicated with an opening in a water outlet side of the main valve; a pilot valve bottom opening is formed in the center of the pilot valve end cover by means of machining and is communicated with a main valve opening of the main valve; a second pilot valve opening and a third pilot valve opening which are communicated with the atmosphere are further formed in a side wall of the pilot valve body. The pilot type pipe burst shutoff valve and the method have the advantages that the pilot type pipe burst shutoff valve can adapt to normal change of internal pressuresof pipelines, and action pressures of the pilot type pipe burst shutoff valve can be freely adjusted.

The invention discloses a robot buffering foot with adjustable pretightening force. The robot buffering foot comprises a foot bottom supporting rod, a foot basic joint, a pretightening adjustment adapter sleeve, a pretightening adjustment buffer sleeve, and an adapter sleeve anti-loosening spring, wherein the foot bottom supporting rod performs a supporting and connecting function; the foot basicjoint is cooperated with the foot bottom supporting rod through a foot end buffer spring; meanwhile, the top of the foot basic joint is connected with a power source; the pretightening adjustment adapter sleeve is arranged on the lower part of the food basic joint in a sleeving manner and is cooperated with the foot basic joint through a thread; the pretightening adjustment buffer sleeve is arranged on the foot bottom supporting rod in a sleeving manner; the adapter sleeve anti-loosening spring is positioned in the pretightening adjustment adapter sleeve for carrying out loosening prevention;after the lower part of the foot bottom supporting rod penetrates through the adapter sleeve anti-loosening spring and the pretightening adjustment adapter sleeve, the foot bottom supporting rod is connected with a foot bottom ball through a foot bottom ball connecting sleeve; and the outer circumference of the upper part of the foot bottom supporting rod is provided with one circle of first groove in which a plurality of supporting rod lubrication balls are arranged. The robot buffering foot has the characteristics of reliable structure, good buffering and vibration resistance ability, adjustable pretightening force and convenience in maintenance, adjustment and replacement.

The invention provides a composite one-way valve. The composite one-way valve comprises a one-way valve body and a valve core arranged in the one-way valve body. The one-way valve body comprises a fluid inlet pipe, a barrel and a fluid outlet pipe, both the fluid inlet pipe and the fluid outlet pipe are embedded in the barrel, one end of the valve core is arranged on the fluid outlet pipe, and the other end of the valve core is abutted against and seals the fluid inlet pipe. The valve core is arranged in the barrel of the one-way valve body, one end of the valve core is arranged on the fluid outlet pipe of the one-way valve body, and the other end of the valve core is abutted against and seals the fluid inlet pipe of the one-way valve body, so that functions of the one-way valve are realized. Fluid enters the barrel from the fluid inlet pipe and flows out of the barrel from the fluid outlet pipe after being subjected to noise reduction in the barrel, so that the composite one-way valve has the functions of conducting in one way and eliminating noise, and in the engineering application with the functions of one-way conduction and silencing, mounting procedures can be reduced, and engineering mounting efficiency is improved.

The invention discloses a horizontal CNC gear hobbing machine which comprises a lathe bed, a spindle box, a workpiece holder, a tailstock, a hob rest, a hob, a workbench, a cross beam and an oblique support. The spindle box is mounted on the lathe bed, the spindle box comprises a workpiece spindle, and the workpiece holder is mounted on the workpiece spindle. The hob rest is mounted on the workbench, the workbench is mounted on the lathe bed, and the hob is mounted on the hob rest. One end of the cross beam is mounted on the top of the spindle box, the other end of the cross beam is mounted on the oblique support, and the oblique support is mounted on the lathe bed. The tailstock is inversely hung on a trapezoidal guide rail of the cross beam. According to the technical scheme, the tailstock breaks the routine to be mounted on the cross beam and is in a suspension mode, the tailstock and the hob rest are arranged up and down, and a condition is created for guaranteeing wide-range adjustment of the hob rest which is horizontally arranged below; besides, the horizontal mode of a main machine body of the gear hobbing machine is arrayed into a gantry mode, due to the up-down arrangement of the hob rest and the tailstock, the occupied space of a machine tool is saved, and thus the machine tool structure can be simplified easily.

A bearing preload adjuster for a bicycle crank set and bottom bracket comprises an adjustment ring for coupling with a bicycle crank arm, a movable plunger comprising an external thread for rotatably coupling with the adjustment ring. The adjustment ring is rotated in order to cause the plunger to extend along an axis of the bottom bracket and apply pressure to a bottom bracket bearing inner race. The adjustment ring is rotated until the clearance in the bearing assemblies and the play in the bottom bracket assembly has been eliminated. This allows the crank assembly to rotate freely, while preventing the crank assembly from sliding side to side inside the bearing bores and along the axis of the crank spindle.

The invention relates to a bogie structure for a magnetic levitation engineering vehicle, which can effectively reduce the axle load and the track surface bearing, improve the running stability and comfort of a bogie, and meanwhile, effectively reduce abrasion to the side face of an F rail and damage to a rail face by walking wheels. The bogie structure is of a #-shaped structure when overlooked and is composed of a cross beam and side frames. The lower portion of the cross beam is used for installing walking wheel sets, the wheel sets are arranged in a mode in which the wheels rotate and theaxles are fixed, and the wheels are in bolted connection with hubs. Traction and side blocking devices are installed on the upper portion and the middle area of the cross beam, driving and braking devices are installed on the outer sides of the wheels of the wheel sets, hydraulic motors or driving motors are in bolted connection with wheel frameworks to drive the wheels to rotate, and the hydraulic motors or the driving motors can be provided with braking devices to provide traveling and parking braking for the bogie. Four groups of guide wheel devices are configured for each bogie and are arranged at the positions of the side frames around the structure, and four groups of stabilizing wheel devices are configured for each bogie and are arranged at the bottoms of the side frames around thestructure.

The invention discloses a self-induced vibration device for a small subsoiler, and belongs to the field of agricultural machinery. The device is mainly characterized by being composed of a lever, a pivot pin, a lead screw, a horizontal spring, a sliding block, a pre-tightening bolt, a top block, a vertical spring, a locking nut, a limiting bolt and the like. The self-induced vibration device in the horizontal direction and the vertical direction generates vibration due to the fact that resistance generated in the working process of a sub-soiling shovel changes constantly, the sub-soiling shovel is driven to vibrate. The penetrating angle of the sub-soiling shovel and the pretightening force of the vertical spring and the horizontal spring are adjustable. A sliding groove formed in the leftside of the lever can discharge sundries in time. When a locating pin is in an insertion state, the self-induced vibration device is in a non-vibrating working mode; when the locating pin is in a pulling-out state, the self-induced vibration device is in a vibrating working mode. According to the self-induced vibration device, the sub-soiling operation power consumption can be lowered to the maximum extent, the device has the advantages of being flexible in mechanism motion, simple in structure and convenient to install, and sub-soiling operation of the small subsoiler can be better adapted.

The invention discloses a steel wire rope pre-tightening device for flexible attachment of a tower crane. The steel wire rope pre-tightening device comprises a first connecting plate, a second connecting plate, screws, a connector and a plurality of pulleys. The first connecting plate is in threaded connection to one end of each screw. The second connecting plate is in threaded connection to the other end of each screw. The positions, on the outer side of the first connecting plate and the outer side of the second connecting plate, of each screw are each provided with a nut. The connector comprises an upper connecting plate, a lower connecting plate and two rib plates, wherein the upper connecting plate and the lower connecting plate are parallel, and the two rib plates are fixed between the upper connecting plate and the lower connecting plate. The two rib plates are rotationally connected to the outer side of the first connecting plate. Second mounting plates perpendicular to the second connecting plate are fixed to the outer side wall of the second connecting plate. The pulleys are arranged on the second mounting plates. According to the steel wire rope pre-tightening device for flexible attachment of the tower crane, flexible attachment of the tower crane can be achieved, and for buildings and variable-section buildings with attachment points far away from a tower body, the field construction requirement is met, and safety operation, smooth mounting and smooth demounting of the tower crane are achieved.

The invention discloses an improved hydraulic motor, a front end tapered roller bearing, a rear end tapered roller bearing and a driving shaft are installed by interference fit, an intermediate pressure ring is installed on the front end tapered roller bearing by interference fit, an oil groove radial channel arranged on the driving shaft is extended to the driving shaft front end to prompt the driving shaft to generate centrifugal force to improve the hydraulic energy to transform into mechanical energy efficiency; the intermediate pressure ring and an outer ring of the rear end tapered roller bearing are in interference fit with an inner hole of a motor casing; a bearing pressure cover is mounted in the motor casing, a plunger ring shrinks and sheathes a plunger, the plunger and a ball head end of a center connecting rod are respectively installed in the driving shaft, a cylindrical spring is installed in the center connecting rod for prevention of locking of the center connecting rod, the cylindrical spring and the axially uniformly distributed plunger are filled into a cylinder body, an oil distributing plate and the cylinder body spherical surface are fit, a spring seat is arranged in the end part of the center connecting rod; a rear end cover is installed in the motor casing end part, a positioning pin is inserted into the oil distributing plate, and a flush valve is tightly installed on the rear end cover end part in order to realize the automatic control of cooling.

The invention relates to a bearing assembly (1) for radially and axially mounting a shaft part (2) relative to a housing (3). Said bearing assembly comprises two radial antifriction bearings (4, 5) which are disposed on the shaft part (2) at an axial distance from each other as well as two axial antifriction bearings (6, 7) that are arranged on the shaft part (2) at an axial distance from each other. In order improve mounting especially of a bevel pinion, the inventive bearing assembly further comprises an outer bearing ring (9) which is inserted into a housing (3) bore (8), is embodied as a monolithic component, and encompasses the tracks (10, 11, 12, 13) for the two radial antifriction bearings (4, 5) and the two axial antifriction bearings (6, 7).