Abstract: A construction for a fluid bearing in a rotary spindle apparatus includes a spindle having first and second ends, and at least one thrust plate coupled to a shaft which is surrounded by a hub having an enclosing sleeve. The sleeve surrounding the thrust plate and shaft defines several gap regions where bearing fluid resides. A first radial gap region is defined between the shaft and sleeve and a second radial gap region is defined between the outer diameter of the thrust plate and the sleeve. A first axial gap region is defined by an upper surface of the thrust plate and the sleeve, and a second axial gap region exists between the lower surface of the thrust plate and the sleeve. A bearing fluid is disposed within these gap regions and forms capillary seals at first and second ends of the spindle. The thrust plate includes holes or pressure compensation ports which connect the first and second axial gap regions.

Abstract: An electric motor construction includes a rotor housing and sleeve which surrounds a shaft/thrust plate. The thrust plate is enclosed in a dead end cavity and is surrounded by a fluid which forms a fluid bearing. The shaft has asymmetrical grooves which create a net pressure gradient from a capillary seal formed near the bottom of the shaft toward the dead end cavity. This helps maintain the capillary seal and reduce the risk of cavitation.

Abstract: To reduce a load applied to the thrust bearing, to prevent the thrust bearing from seizing and to improve the service life of the thrust bearing, the thrust bearing is provided between a drive shaft and a block to seal a high-pressure side space from a low-pressure side space. By providing an oil supply through hole, one end of which opens into high-pressure side space and the other end of which opens into a space formed by inserting the shaft into the insertion hole, high-pressure lubricating oil can be supplied to the space. The constric within the shaft with the effect of the constriction clearance is formed between the aforementioned oscillating shaft and the insertion hole, and a pressure differential between the two ends of the drive shaft is eliminated.

Abstract: A self-replenishing hydrodynamic bearing unit comprises a shaft and housing defining an opening for receiving the shaft for relative unidirectional rotation. A plurality of reservoirs contain a lubricating fluid. A hydrodynamic bearing region lies between the plurality of reservoirs for providing a rotational journal for relative rotation between the shaft and the housing. At least one of the shaft and the housing defines a continuous pattern of herringbone or Vee-shaped pumping grooves or passages which communicate between the plurality of reservoirs for pumping the lubricating fluid during relative rotation. The groove pumping creates a pressurized hydrodynamic bearing lubricant film at the bearing region with each groove generating localized unidirectional directional flow of lubricating liquid between the reservoirs along a predetermined axial direction of rotation, wherein some passages create axial flow in a forward direction and the others create axial flow in a reverse direction.

Abstract: A roller supporting structure has a shaft having first grooves for generating a dynamic pressure, and first and second retaining plates placed opposite both ends of a roller when the roller is mounted around the shaft. The first and second retaining plates have second grooves for generating a dynamic pressure on their roller-facing end faces. When the roller is placed in an axially central portion of the shaft, that is, in the middle between the retaining plates, there is left a predetermined gap between the roller-side end face of each retaining plate and each end face of the roller. The gap is large enough so that the second grooves of the first and second retaining plates do not generate dynamic pressure between these retaining plates and the roller. The second grooves of one of the first and second retaining plates generate dynamic pressure when the roller is displaced from the axially central portion toward the one retaining plate.

Abstract: A rotary-anode X-ray tube includes a sleeve bearing having bearing faces which are rotatable relative to one another in a direction of rotation and at least one of which is provided with a pattern of grooves. The service life of such a sleeve bearing can be prolonged by providing the grooves with a recess at their rearmost end, viewed in the direction of rotation.

Abstract: A motor having a dynamic-pressure type bearing device includes a cylindrical sleeve fixedly secured to a base, a shaft rotatably inserted into a hollow of the cylindrical sleeve, a hub fixedly secured to an end portion of the shaft, a ring-like rotor magnet fixedly secured to the hub, and an armature fixedly secured onto the base to be in opposed relation to the rotor magnet so as to constitute a motor driving device. Further, the motor has a disc-like plate coaxially and fixedly secured to an end portion of the shaft to have a diameter of the disc-like plate greater than a diameter of the shaft and a plate disposed in opposed relation to a surface of the disc-like plate.

Abstract: In a dynamic pressure bearing apparatus for use in a rotary polygonal mirror type light deflector in a laser beam printer, a rotary head in a video tape recorder and the like, the apparatus includes a rotary shaft having a shaft end surface, a sleeve for rotatably supporting the rotary shaft through fluid, and a generator for generating dynamic pressure in a thrust direction. The sleeve has an end portion with a thrust receiver surface opposed to the shaft end surface. The dynamic pressure generator is formed on the thrust receiver surface. One of either the shaft end surface and the thrust receiver surface is convexly shaped for tolerating a non-flat surface of the shaft end surface and the thrust receiver surface.

Abstract: A radially disposed thrust bearing surface formed in a rotary cone is provided with at least a pair of grooves and a ramp surface on the trailing edge of the grooves. The groove provides a lubricant reservoir and the ramp serves to generate hydrodynamic pressures during rotation of the rotary cone on the thrust surface of a journal bearing thereby distributing a film of lubricant on the opposing thrust bearing surfaces.

Abstract: Cylindrical bearing pads are insertable into bearing pad recesses formed in a receiving surface of a bearing pad retainer in a load-carrying structure. The bearing pads have an insertion end which is fixed into the bearing pad recess by brazing or by interference fitting and a bearing end which projects from the receiving surface and terminates in a bearing face. The bearing face has a periphery which encircles the bearing face and an indentation having a perimeter formed centrally in the bearing face. An annular flattened area encircles the indentation forming an effective bearing contact area between an outer border of the flattened area and the perimeter of the indentation. When the indentation is filled with drilling fluid, lubrication is provided to an opposed bearing face of an opposing bearing pad.

Abstract: A device is disclosed which includes a frame (1), a turntable (3), and an electromagnetic drive unit comprising a stator section (5) and a rotor section (7). The turntable, which is rotatable about a shaft (19), and a frame portion (4) have facing annular bearing surfaces (21A and 21B respectively) to form a dynamic axial bearing. The bearing surfaces are coaxial with the shaft and radially spaced from this shaft. One of the bearing surfaces has at least one pattern of grooves which causes a pressure to be built up in a medium present between the bearing surfaces during rotation of the rotor section relative to the stator section.

Abstract: A split crankshaft bearing assembly includes two flanged half bearings adapted to collectively encircle a crankshaft. The flanges are formed with oil supply grooves that subdivide the flange surface into thrust bearing pads. Each pad includes a positively sloped ramp surface leading to a raised land surface. The rotating crankshaft drags a film of oil onto the land surface where it provides hydrodynamic thrust support for the shaft. To facilitate close tolerance control on the thrust bearing pad contour, the manufacturing process is carried out so that the oil supply grooves are formed and the thrust face presized prior to formation of the pad final contour. The pad contour is formed by a coining operation.

Abstract: A radially disposed thrust bearing surface formed in a rotary cone is provided with at least a pair of grooves and a ramp surface on the trailing edge of the grooves. The groove provides a lubricant reservoir and the ramp serves to generate hydrodynamic pressures during rotation of the rotary cone on the thrust surface of a journal bearing thereby distributing a film of lubricant on the opposing thrust bearing surfaces.

Abstract: An optical scanner has grease bearings between the rotor and the housing. The grease bearings are grooved which tends to pump the grease back into the bearing cups when the optical scanner is operating. The thixotropic property of the grease prevents its escape from the bearing cups when the optical scanner is not operating. The grease bearings can be frusto-conical or spherical in shape with complementary shaped bearing cups. The bearing cups, rather than the bearings, may be grooved. The bearing cups may also be stepped to provide a pumping region and a reservoir region for the grease. Pressure means within the scanner housing may force the bearing cups onto the grease bearing.

Abstract: A thrust bearing of a scroll compressor to be used as a fluid compressor for a refrigeration or air conditioning unit, is designed to resist the moment exerted on the orbiting scroll member, and tending to tilt the orbiting scroll member, so as to prevent the clearance between a thrust surface and a surface of the orbiting scroll member slidingly supported thereon from being reduced or the surfaces from making local contact. The thrust bearing uses wedge shaped grooves having tip end portions in which fluid is compressed by the orbiting motion of the scroll member to generate dynamic pressure at one side of the compressor. This dynamic pressure maintains the clearance between the thrust surface and the surface of the orbiting scroll member thereby stabilizing the movement of the orbiting scroll member.

Abstract: A seal face of a ring used in a non-contacting, gap-type seal having an annular groove area with microdams, each having a preferable width of about 0.025 inches, between a plurality of groove surface areas. The microdams provide a boundary to the groove surface areas whereby the recess of each groove surface area bounded by the microdams acts as a unitary pressure zone and the pressure in the separate zones decreases in a series of steps as measured from one circumference of the ring to the other circumference.

Abstract: In a system that includes a linearly movable carriage or the like, a mechanism to convert rotary motion of a leadscrew to linear motion of a nut and, hence, linear movement of the carriage to which the nut is mechanically secured. The leadscrew has a special threadform and the nut has a special threadform that matches the threadform of the leadscrew with a pressurized fluid interface therebetween, there being both axial clearance and radial clearance sufficient to accommodate angular and lateral misalignment between the leadscrew and the carriage. Shallow independent grooves along each side of the nut's helical threadform act to equalize fluid pressure across each respective side of the threadform and orifices or other fluid flow control devices connect to the grooves or passages to permit introduction of high pressure air or other fluid thereto. Exhausts are provided from the region by radial clearance between the leadscrew threadform and the nut threadform.

Abstract: A thrust bearing having a spiral element and a flat element is provided wherein bothy elements are arranged so as to be rotatable relative to each other and the spiral element is made of ceramic having a pattern of spiral grooves on the surface thereof opposing the flat element. The spiral grooves are formed by a shot-blasting process applied through a resin mask having a spiral pattern, the depth of the grooves being kept within the range between 3 .mu.m and 50 .mu.m.

Abstract: An optical deflector of an air bearing type has a fixed shaft; a rotary shaft having a hollow portion fitted onto the fixed shaft; a support device disposed between an end portion of the fixed shaft and an end portion of the hollow portion opposite thereto and supporting the rotary shaft in an axial direction thereof; a radial air bearing formed between an inner circumferential face of the hollow portion and an outer circumferential face of the fixed shaft; a polygon mirror fixed to the rotary shaft; a driving device for rotating the rotary shaft; a device for deflecting light irradiated onto the polygon mirror by rotating the rotary shaft through the driving device; a device for forming a flange for fixing the polygon mirror thereto integrally with the rotary shaft; and a device for setting an upper end portion of the support device on a fixed shaft side thereof to be lower than an upper end face of the polygon mirror.

Abstract: An axial hydrodynamic bearing having two parts which are rotatable relative to each other about an axis of rotation comprises a first surface and a second surface facing the first surface. The first surface is formed with one or more patterns of bearing grooves which in the case of a rotation of the surfaces relative to each other act to build up pressure in a lubricant which is present between the surfaces during operation. A reservoir for the lubricant is present between the first surface and the second surface, one of the surfaces being formed with a pattern of feed grooves at the location of the reservior, which pattern is situated in an annular area which is concentric with the axis of rotation, to pump lubricant towards the pattern of bearing grooves operation.

Abstract: A scroll-type machine which incorporates a self-pressurizing hydrodynamic thrust bearing to maintain a constant interface of oil between the axial thrust surfaces.

Abstract: A rotatable element is arranged on a supporting member. The element is freely rotatable and displaceable radially by being held in position by two portions attracting each other, said portions being made of magnetic material, and that a plane slot separates the supporting member and the element. The driving of the element can be effected thereby that the element forms or incorporates a rotor in an electromotor, the stator of which is arranged in an area of the supporting member.

Abstract: A rotary device is disclosed for use as a precision element such as an optical scanner. The device comprises a rotor which includes a driven element such as a polygon having a plurality of mirror surfaces thereon, an arrangement for supporting the rotor for rotational movement, and a drive motor for the rotor. The rotor supporting arrangement includes a thrust bearing. In order to provide a rotary device having a low profile and a minimum of parts, a planar motor is used as the drive motor, and the permanent magnet of the motor is incorporated in the rotor. The thrust bearing includes an arrangement for directing an axial force against a radial surface of the rotor when the motor is actuated.

Abstract: A hydrodynamic bearing device which includes a shaft, a ring-shaped member and a thrust bearing member, with a lubricating material being held in a space defined in the thrust bearing member and the inner peripheral face of the ring-shaped member. The ring-shaped member is formed, in its inner peripheral face, with a taper for feeding the lubricating material into the thrust bearing member based on centrifugal force, by which the lubricating material is prevented from flowing out.

Abstract: An aerostatic bearing with an adjustable stabilizing structure suitable to be applied to a linear sliding rail of a precision test instrument or a precision tool machine, etc., comprises a bearing body with a round or other shaped planes. The plane is furnished with a pocket, a plurality of radial grooves, and a ring-shaped grooves, being in communication with one another. The outer edge of the bearing body is provides with an air intake extended, through an intake passsage, to an area nearing a pocket. The intake passage is in communication with the pocket through a first orifice. A spacing member with a second orifice is movably mounted in the intake passage so as to form a cavity between the two orifices.

Abstract: In a two-cycle internal combustion engine (2), the sidefaces (60, 62) of the connecting rod (48) have a polymeric material coating thereon, such as polytetrafluoroethylene, PTFE, providing a bearing between the sidefaces (60, 62) and the crankfaces (38, 40) of the crankarm discs (34, 36) of the crankshaft (24), to prevent galling and eliminate the need to silver plate the sidefaces (60, 62).

Abstract: In a system that includes a linearly movable carriage or the like, a mechanism to convert rotary motion of a leadscrew to linear motion of a nut and, hence, linear movement of the carriage to which the nut is mechanically secured. The leadscrew has a special threadform and the nut has a special threadform that matches the threadform of the leadscrew with a pressurized fluid interface therebetween, there being both axial clearance and radial clearance sufficient to accommodate angular and lateral misalignment between the leadscrew and the carriage. Shallow independent grooves or passages are distributed along the length nut's helical threadform to equalize air pressure therealong and orifices are provided to the grooves or passages to permit introduction of high pressure air or other fluid thereto. Exhausts are provided from the region of clearance between the leadscrew threadform and the nut threadform. Both threadforms are ideally in the form of square threads.

Abstract: A pump including an impeller having a magnet or a second conductor therein, the impeller being adapted to be directly rotated by virtue of magnetic fields of stator coils. The impeller is rotated within a casing in close proximity thereto via ceramic bearing members, one bearing member having spiral grooves on its slide surface. The ceramic bearing members constitute a dynamic pressure bearing means.

Abstract: In a two cycle internal combustion engine (2), the sidefaces (60, 62) of the connecting rod (40) have grooves (64) formed therein dragging lubricant from the fuel-air-lubricant mixture in the crankcase (8) along the crankfaces (38, 40) of the crankarm discs (34, 36) of the crankshaft (24), providing a hydrodynamic bearing with a layer of lubricant separating the sidefaces of the connecting rod from the crankfaces of the crankarm discs such that the sidefaces of the connecting rod ride on a layer of lubricant, and eliminating the need to silver plate the sidefaces of the connecting rod.

Abstract: A scroll compressor comprises an orbiting scroll and a stationary scroll, both being mutually combined to form a compression chamber therebetween. The scroll compressor is provided with a lubricating oil feeding system to lubricate each bearing constituting a contact-sliding and contact-rotating part. A special arrangement of oil grooves is made in a thrust bearing supporting the orbiting scroll in such a manner that pressure loss in the oil grooves of the thrust bearing is greater than a pressure raised by the third oil pump means so that there causes no negative pressure at the inlet port of a radial oil feeding conduit and the outlet of the vertical oil feeding passage in the main shaft.

Abstract: A blower serves for circulating larger gas volumes, in particular for high-power laser systems operating according to the gas-transportation principle. The blower comprises a radial compressor, having a compressor element extending into a connection duct to blow a gas from a first to a second gas duct. The radial compressor is driven by a vertical shaft which is provided with an axial and radial gas bearing within a gas-tight housing. A gas duct system is provided for supplying lubricating gas to both the axial and the radial gas bearings. The gas duct system is fed by both one of the axial gas bearings and by an external pressure-gas pump. Throttles and adjustable valves are provided at predetermined locations of the gas duct system to establish a predetermined profile of gas pressure in the duct system.

Abstract: A blower is used for circulating larger gas volumes, in particular for high power laser systems which operate according to the gas-transportation principle. The blower comprises a radial feeder being arranged in a connection between two gas ducts. The radial feeder is driven by a vertical shaft, rotating at high rotary speed. In order to permit extremely large gas volumes, typically in the range of several ten thousand cubic meters per hour, to be circulated, the shaft is seated in a pressure-tight housing. Two axially acting seals are arranged on the shaft at a certain distance from the radial feeder. The seals define a pump chamber connected with one of the gas ducts, a lock chamber and a drive chamber. The seal between the lock chamber and the drive chamber comprise an axial upper sliding ring resting elastically on a lower thrust ring.

Abstract: A gas bearing designed for instantaneous 5-10 micro inch separation at startup due to regulated entry and activation of rarefield molecular gas particles. This bearing has two opposing bearing faces with carefully matched geometries. One surface having grooves with lands formed between the grooves that are designed for hydrodynamic operation. The other surface being smooth such as an optically flat plane. The lift-off occurs at startup through the friction-energized gas molecules increasing their volume, and forcing the slowly rotating bearing faces apart.

Abstract: A hydrodynamic thrust bearing adapted for positioning between a fixed base and a moving member spaced from said fixed base, the moving member having a rigid flat face confronting the fixed base, wherein the hydrodynamic thrust bearing includes a thin metal disk having undulations extending radially outward from the center of the disk in a symmetrical manner throughout one entire surface of the metal disk, and a planar face on the other side, the disk is positioned between the fixed base and the rigid flat face of the moving member whereby the undulations of the disk are in contact with the rigid flat face and the planar face is in contact with the fixed base, lubricant is supplied between the disk undulation and the confronting rigid flat face of the moving member whereby thrust movement relative to the disk will produce a very thin film of lubricant between the undulations of the disk and the cooperating rigid flat face of the fixed base.

Abstract: Statically pressurized gas bearings employ improved bearing pockets, each including one or more slots arranged in a double cross, star or other configuration, and supplemental gas exhaust slots, as well as stepped annular land flow restrictors, to optimize bearing stability and operational bandwidth.

Abstract: A thrust bearing adapted to be rotated reversibly in the normal and opposite directions comprises two flat disc elements disposed in face-to-face contact, one of the elements being provided with spiral grooves on its opposite side surfaces, one of which is reverse to the other with respect to the spiral directions, both elements having a dent formed centrally on their opposing surfaces, respectively, to form a small space in combination in which a core member of sphere is installed with a small clearance between the surfaces of the small space and the core member.

Abstract: A hydrostatic bearing is provided between two relatively movable members. Opposing sensing and bearing pads extend into either member and face the other member. These pads communicate with one another. An inlet orifice is defined between the members and extends from a fluid source to the sensing pad. An outlet orifice is defined between the members and extends from the bearing pad to the fluid return. The areas of the inlet and outlet orifices vary reciprocally in the sense that as one area increases, the other area decreases. The bearing exhibits reduced flow characteristics when one member moves axially and/or radially relative to the other member.

Abstract: A thrust bearing for an automobile turbocharger and which sustains a thrust load of the rotor shaft of the turbocharger. The thrust bearing has a first groove for holding lubricating oil supplied to the bearing. A first oil passage extends from the groove toward the axis of the rotor shaft. A second oil passage communicates with the first passage and has oil holes formed therein that extend to tapering lands formed on surfaces on which the rotor shaft bears. The second passage is so disposed that oil is spouted on both sides of the bearing. The lower end portion of the bearing is cut out portion to facilitate removal of oil. The cut out portion constitutes a planar portion of a closed loop on a surface of the bearing. A second groove is formed in the thrust bearing to hold oil discharged from the oil holes to some extent.

Abstract: A novel thrust bearing is provided in which a spiral element having a disc shape is loosely interposed between a pair of flat elements one of which is rotatable and the other of which is stationary, the spiral element having a spiral groove pattern on each of the opposite surfaces of the disc with the patterns on the respective surfaces reverse in relation to each other in their spiral direction.

Abstract: A bidirectional thrust bearing assembly is used between a downhole fluid motor and a rock bit for drilling oil wells. The bearing assembly has a stationary housing with radial journal bearing sleeves and a rotatable drive shaft also having radial bearing sleeves. A pair of oppositely facing thrust bearing rings are mounted in the housing. A second pair of thrust bearing rings are mounted on the shaft so as to have faces opposing the bearing faces on the first pair of rings. Belleville springs resiliently bias a pair of the thrust bearing rings apart and carry the thrust load between such rings. Each ring has a plurality of inserts of hard material, preferably polycrystalline diamond, at the bearing surface. Means are provided for circulating drilling fluid from the motor through the thrust bearing faces for forming hydrodynamic fluid bearing films in the bearing interfaces.

Abstract: An air bearing body has an air supply aperture opening in the center of a planar bearing surface. Shallow air circulation ducts extend spirally outwardly in the bearing surface from the air supply aperture balancing pressure in the air gap between the bearing surface and a mating bearing surface and preventing tilting forces on the bearing body. An annular air removal duct can surround the bearing surface and can be connected to a section line to contribute to the constancy of the height of the air gap between the bearing surface and a mating bearing surface.

Abstract: A wheel plate of a coupler for coupling a tractor and a trailer. The wheel plate has a lubricating arrangement for lubricating the sliding surfaces in the coupling. The lubricating arrangement includes a main groove formed in a central portion of the sliding surface of the wheel plate and surrounding the pivot shaft of the coupler, and a plurality of convolution grooves formed in the sliding surface of the wheel plate along convolution curves starting from and surrounding the main groove. The convolution grooves are communicated at their both ends with the main groove.

Abstract: A hydrokinetic spindle including a housing having a bearing in which the journal portion of a shaft is mounted. The shaft has a helical groove having a progressively decreasing cross-section formed on the journal surface thereof and extending from one end of the journal portion to the other which picks up a predetermined amount of fluid lubricant from fluid pickup posts leading from at least one fluid reservoir formed in the housing and directs the lubricant to and upon the shaft under pressure thereby maintaining a film of fluid lubricant under pressure between the shaft and the bearing of the housing. The housing and shaft are sealed in an artificial atmosphere.

Abstract: A fixed pad thrust bearing for a turbomachine comprises a ring of sector-shaped pads separated by grooves and facing a thrust collar integral with the rotor of the turbomachine within a thrust bearing cage integral with the rotor. The ring bears on a deformable ring. Each pad is fed with oil via a space formed in the wall of the cage and facing an orifice in a bore in the pad. A front surface of each pad facing the collar is inclined relative to the rear surface of the ring. Each pad is further formed with a groove communicating with the aforementioned bore but not reaching as far as the inner and outer edges of the pad, being disposed adjacent the leading edge of the pad. The oil is recovered centrifugally from the outer edge of the collar. In this way, virtually all the power consumed by the oil goes towards providing the hydrodynamic supporting force, minimizing the shearing losses between the fixed and moving parts within the thrust bearing cage.

Abstract: A highly reliable device for stopping the operation of a flywheel apparatus for storing electrical energy in the event of interruption of power supply includes a thrust plate 11 connected to the rotatory part of the apparatus, and having a lower surface defining a thrust bearing surface. A pressure receiving surface 26 facing the lower surface of the thrust plate, and defining a thrust bearing surface is provided with a plurality of radially extending grooves 27 each having at least one sidewall which defines an upwardly inclined land 28 as viewed in the direction of rotation of the rotatory part. Provided below the pressure receiving surface 26 is a cooling fluid passage 33 connected to an electromagnetic valve 35 adapted to open upon interruption of power supply to allow a cooling fluid to flow into the passage 33. The device further includes means for maintaining a hydraulic fluid between the thrust bearing surfaces during interruption of power supply.

Abstract: The invention relates to a hydrodynamic fluid bearing of rotation symmetric shape constituted of a bearing member and a counter-bearing member the faces of each being in opposition to the other one at a narrow space. One of the members is provided with fluid pockets of levelling off depth in reverse direction to the direction of rotation of the bearing member. Thus it is feasible to cope with considerable bearing loads over a wide range of rotational speeds.

Abstract: A hydrodynamic gas-lubricated bearing comprises a rotor with a smooth bearing surface, and a fixed bearing plate with a grooved surface. The grooves are of spiral configuration being separated by lands, the top surface of each of which has a convex profile. The central portion of the surface is raised above the edges so that wedge-shape regions are formed between the surface of the rotor on both sides of the central portion. The surface of the fixed bearing plate may be formed with an overall convex surface. The grooved surface of the fixed bearing plate is made by forming a pattern of grooves in a smooth blank and subsequently rounding off the top surface of the lands by rotating the bearing plate under pressure against a soft abrasive cloth.