Abstract: A nut assembly comprises two end-to-end nuts threaded onto a screw and coupled by splines which prevent relative rotation between the nuts while permitting relative axial movement. A sleeve surrounds the nuts and is threaded onto one of the nuts. The other nut is formed with ratchet teeth adapted to fit into angularly spaced notches in the sleeve. When the sleeve is rotated relative to the nuts, it forces the nuts away from one another to take up backlash between the nuts and the screw. During such rotation, the teeth ratchet into and out of successive notches and ultimately prevent relative rotation between the sleeve and the nuts during normal service use.

Abstract: A driving mechanism having a spindle which is provided with a first helical threaded portion having a lefthand direction of rotation and with a second helical threaded portion having a righthand direction of rotation. A pair of spindle guides each engage a respective spindle threaded portion for rotating the spindle and translating the spindle in an axial direction. Each spindle guide has three pairs of runner rollers on a sleeve for centering and supporting the spindle within the sleeves. The three pairs of runner rollers on each sleeve kinematically constrain the six degrees of freedom of the spindle without overconstraint to reduce friction and binding of the spindle in the spindle guides.

Abstract: A fluid-powered helical actuator including a cylindrical body; a rotatable output member supported for rotation relative to the body and connectable to an external device; first and second independently rotatable sleeves reciprocally mounted within the body; a piston reciprocally mounted within the body for application of fluid pressure to one or the other opposing sides thereof to produce axial movement, the piston operatively engages at least one or the other of the sleeves to axially move the sleeves in response to axial movement of the piston; and torque-transmitting elements for transmitting torque between the first sleeve and the body, between the first sleeve and the output member, between the second sleeve and the output member, and between the second sleeve and the body.

Abstract: A fluid-powered device having a body with interior helical grooves, an output shaft with exterior helical grooves, a plurality of rollers having circumferential grooves, and an axially reciprocating piston sleeve mounted within the body and retaining the rollers in axially offset and nested relation to each other and in fixed axial and circumferential position relative to the piston sleeve during powered operation of the device. The rollers are retained by the sleeve portion of the piston sleeve in circumferentially distributed arrangement between the grooved body and shaft surface portion in seated engagement with the grooved body and in seated engagement with the grooved output shaft for transmitting force between the body, output shaft and piston sleeve.

Abstract: This invention provides a ball screw apparatus complying with high-cleanliness specifications insofar as the apparatus has an axial through hole open at one end of the shaft and a large number of smaller holes on the periphery of the shaft which communicate with the hole, and an air sucking mechanism having a port communicating with the axial hole on the shaft so as to apply a negative pressure to the axial hole thereof. The shaft of this ball screw apparatus acts as a sucking duct so as to allow the use of ordinary grease lubrication even within a clean-room without the necessity of changing lubrication conditions depending on the type of greases.

Abstract: A fluid-powered actuator having a body with interior helical grooves, an output shaft with exterior helical grooves, a first set of rollers in rolling engagement with only the body grooves and axially skewed at an angle corresponding to the lead angle of the body grooves, a second set of rollers in rolling engagement with only the output shaft grooves and axially skewed at a skew angle corresponding to the lead angle of the output shaft grooves, and an axially reciprocating piston sleeve mounted within the body and retaining the rollers in fixed axial and circumferential position relative to the piston sleeve during powered operation of the device. In several embodiments, the first and second sets of rollers are axially spaced apart.

Abstract: A linear actuator includes a single drive gear that engages two driven gears of the same pitch diameter, which in turn drive a spindle and a sleeve, respectively. The sleeve is internally threaded to receive the spindle, which is externally threaded. The sleeve and spindle are driven rotationally at slightly different rates due to different numbers of teeth on the two driven gears, producing linear motion of the spindle relative to the sleeve. The drive gear can be rotated in increments corresponding to integral numbers of teeth and the rest positions of the gears can be full engagement positions to minimize play in the gears.

Abstract: In a rotational working cylinder comprising a shaft arranged concentrically within the working cylinder and driven out of the working cylinder with at least one end of it, a piston being divided into two piston portions perpendicularly to the shaft and the piston portions being held in tensed position in respect to each other, forced trajectories between the working cylinder and the piston portions as well as between the piston portions and the shaft, respectively, at least one of the forced trajectories is formed as a longitudinal spiral path, and the piston portions are locked in relation to each other for maintaining the tensed position of the piston portions in all operational positions and loads of the working cylinder.

Abstract: A screw-nut type driving mechanism having a rotatable screw shaft, a nut engaged with the screw shaft and a driven member secured to the nut. The nut has an axially tapered outer surface which is formed with external threads. The driven member has an internally threaded, axially tapered hole with which the nut is threadably engaged. A retaining plate is provided to hold the nut on the driven member to prevent rotation of the nut.

Abstract: A fluid-powered linear actuator having a body, and an output shaft with a piston portion disposed within the body. The shaft is axially movable in a first direction in response to fluid pressure on the shaft piston portion. A piston sleeve is mounted within the body and has a piston head to define with the shaft piston portion a fluid-tight chamber. A second fluid-tight chamber is provided on the opposite side of the piston head. Exterior sleeve splines transmit torque between the sleeve and the body in response to axial movement of the piston sleeve, and interior sleeve splines transmit axial force between the sleeve and the shaft in response to axial and rotational movement of the piston sleeve.

Abstract: A fluid-powered device having a body with interior helical grooves, an output shaft with exterior helical grooves, a plurality of rollers having circumferential grooves, and an axially receiprocating piston sleeve mounted within the body and retaining the rollers in fixed axial and circumferential position relative to the piston sleeve during powered operation of the device. The rollers are retained by the sleeve portion of the piston sleeve in circumferentially distributed arrangement between the grooved body and shaft surface portion with at least a first plurality of the rollers in seated engagement with the grooved body and at least a second plurality of the rollers in seated engagement with the grooved output shaft for transmitting force between the body, output shaft and piston sleeve.

Abstract: A feeding apparatus which employs a ball screw includes a movable table movably supported on a fixed bed. A ball screw shaft is supported at one of its ends by the fixed bed in such a manner that the ball screw shaft is movable in the direction of rotation thereof and immovable in the axial direction thereof. A ball nut is fitted on the ball screw shaft through steel balls and is supported by the movable table in such a manner that the ball nut is movable in the direction of rotation thereof and immovable in the axial direction thereof. A first drive source is mounted on the fixed bed to rotate the ball screw shaft, and a second drive source is mounted on the movable table and operatively connected to the ball nut through a hollow transmission shaft. The ball screw shaft has the other end thereof concentrically received in the hollow inside of the transmission shaft in such a manner that the ball screw shaft is rotatable and movable relative to the transmission shaft in the axial direction thereof.

Abstract: A fluid-powered helical actuator including a body, a rotatable shaft member, first and second independently rotatable sleeves reciprocally mounted within the body, a piston reciprocally mounted in the body to produce axially movement in response to the application of fluid pressure, and torque-transmitting ball races and balls for transmitting torque between the sleeves and the body, and the sleeves and the shaft. An adjustment collar is provided for applying an adjustable and oppositely directed axial force on the first and second sleeves for selective relative axially movement thereof to axially preload the first and second sleeves for simultaneously eliminating backlash in all the ball races. In one embodiment, the collar is replaced with a cam ring. An alternative embodiment utilizes a non-cylindrical body a dimension in a first lateral direction greater than a dimension in a transverse second lateral direction.

Abstract: A fluid-powered helical actuator including a cylindrical body; a rotatable output member supported for rotation relative to the body and connectable to an external device; first and second independently rotatable sleeves reciprocally mounted within the body; a piston reciprocally mounted within the body for application of fluid pressure to one or the other opposing sides thereof to produce axial movement, the piston operatively engages at least one or the other of the sleeves to axially move the sleeves in response to axial movement of the piston; and torque-transmitting elements for transmitting torque between the first sleeve and the body, between the first sleeve and the output member, between the second sleeve and the output member, and between the second sleeve and the body.

Abstract: A spindle or leadscrew and an associated nut, forming part of a driving assembly of the circulating-ball type, have helical threads of symmetrical profiles in the shape of pointed arches whose flanks engage the recirculating balls along respective helical contact lines. With the spindle virtually non-deformable in the axial direction, the pitch of its thread exceeds that of the nut thread (in the absence of stress upon the latter) by a small differential--specifically 0.02%--lying well within the limits of elastic axial deformability of the nut. Upon rotation of the spindle relative to the nut for the transmission of an axial force, this differential results in an approximately uniform stress distribution among the sets of balls lying in confronting turns of the spindle and nut threads.

Abstract: Disclosed is a back-lash eliminating mechanism in a screw-type driving device, in which a nut member is made flexible so that a screw member and the nut member can be disposed close to each other to thereby eliminate back-lash at the thread-engagement portion between the screw member and the nut member.

Abstract: A ball nut and screw assembly preadjusted and preloaded by injecting a liquefied pressurized thermoset resin through a mold and into the area between adjacent ball nuts and allowing the thermoset resin to cure and harden while pressurized. After hardening, the mold is removed and the external preload supplied to the resin is maintained by a hardened preload ring formed by the epoxy ring.

Abstract: The shaft and bush device includes a shaft, a bush having a slit in its axial direction and a pressing member which forces the bush inwardly to contact with the shaft so that the bush and shaft are pressed to each other without any clearance. The shaft and the bush may be a screw shaft and a nut engaging the screw shaft or a pin and a nut engaging the pin.A tilting steering apparatus has this shaft and bush device. Namely the device is used as a pivot pin connecting an upper bracket rotatably holding an upper steering shaft and main bracket fixed to a body of an automobile. The device is also used for an expansion-shrinking device which swings the upper bracket against the main bracket. The expansion-shrinking device has a screw shaft and nut which form the shaft and bush device.

Abstract: A sealed, precision screw feed device for equipment of the type having a stationary base and a reciprocating carriage member. The device has an elongate tubular housing carrying a shaft with a precision thread, one end of the shaft projecting from one end of the housing and being adapted for connection to a suitable drive motor carried on the base. A nut is disposed completely within the housing, carried by the shaft and connected with a hollow thrust rod that projects from the opposite end of the housing. The housing contains a quantity of lubricant; shaft seals at its opposite ends prevent the lubricant from leaking out past the threaded shaft and thrust rod. The exposed end of the thrust rod has a universal joint which is connected to the carriage member. Also, the bore of the thrust rod is sealed off, to prevent lubricant from escaping through this avenue. The disclosed arrangements provide precision movement of the carriage member, even over extended periods of use.

Abstract: A zero backlash device. The device includes a spring loaded bracket for providing a lateral force to the driving nut on a threaded rod. This lateral force is directed perpendicularly to the axis of the threaded shaft thus insuring continued intimate contact between the threads on the driving nut and the threads on the shaft.

Abstract: A lead screw positioner (10) is described, which has extremely low noise, including a nut (12) lying about a lead screw (14) and means for flowing gas under pressure between the nut and screw to keep them slightly spaced. The nut forms a plenum chamber (34) which receives pressured air, and has several holes (32) leading from the chamber to the clearance space (20) between the nut and screw to apply pressured air thereto. The nut and screw are devoid of direct sealing contact, so the pressured gas flows from the holes and axially along the screw to the end of the nut, where the gas flows into the environment.

Abstract: A hydrostatic pressure XY table comprising first and second sliding tables mounted on a bed. The two sliding tables are driven perpendicularly to each other by separate motors through a first lead screw supported on the bed and a second lead screw supported on the first sliding table. The bed has a first trapezoidal groove and the first sliding table has a second trapezoidal groove running perpendicular to the first trapezoidal groove. The first sliding table is engaged with the first trapezoidal groove and the second sliding table is engaged with the second trapezoidal groove. Four hydrostatic pressure guides are provided in the bed, to engage with engaging surfaces of the first sliding table. Four hydrostatic pressure guides are also provided in the first sliding table to engage with engaging surfaces of the second sliding table. A plurality of fluid pressure lines are provided for supplying hydrostatic pressure to the engaging surfaces of the first and second sliding tables.

Abstract: An improved nut-and-screw type device for converting rotary input to linear output. The device includes an involute-helicoidal screw, a nut assembly including a plurality of annular ring and groove rollers conjugate to said screw; a freely rotating ring having internal grooves conjugate to said roller; and bearing means engaging said rotating ring and the outer housing of said nut assembly thereby providing rolling line contact for transmission of the major forces.

Abstract: A needle valve having improved accuracy and wear characteristics is disclosed in which the valve stem is subjected to a constant force to prevent backlash throughout its entire movement with respect to the valve seat. In addition, the needle contained within the valve stem has a tapered end which moves within the cylindrical bore in a valve seat to control fluid passing through the valve and such needle is affixed to the valve stem only at its other end remote from its tapered end. The needle thus floats for a substantial portion of its length and its tapered end is relatively flexible and free of movement. The needle is, however, angled with respect to its valve seat such that the needle physically makes contact with the internal surface of the valve seat and maintains that contact throughout its lateral movement within the valve seat.

Abstract: A ball nut is sleeved upon a worm via one or more, preferably two, groups of antifriction balls capable of rolling along internal and external screw threads on the ball nut and the worm. Two crosscuts are formed across the internal thread on the ball nut in axially spaced, diametrically opposite positions thereon, each for intercommunicating two neighboring turns of the helical groove therein. Each crosscut is concaved to provide a bypass for one group of balls around the thread on the worm. Thus each group of balls recirculate along one turn of the helical groove in the ball nut, making it possible for the worm to travel axially in response to the rotation of the ball nut. The converter further includes an antifriction bearing having an outer ring surrounding the ball nut via rolling elements confined therebetween, with the ball nut serving as the inner ring of the bearing. There are also disclosed herein feed mechanisms incorporating one and two such rotary-to-linear converters respectively.

Abstract: An assembly of a worm and a ball nut, with a multiplicity of antifriction balls rollably engaged therebetween and retained in preassigned relative positions by a tubular cage, to cause relative longitudinal displacement of either of the worm and the ball nut in response to the rotation of the other. At least one turn of the internal thread at the midportion of the ball nut differs in width from the other turns for preloading the balls on its opposite sides in the opposite axial directions of the worm with a view to minimal backlash between worm and ball nut. Also disclosed is a two-speed feed mechanism incorporating a wormshaft having first and second threaded portions with different leads on which are mounted first and second ball nuts, respectively, via caged, preloaded antifriction balls. The first ball nut is rotatably mounted to a stationary part via a bearing whereas the second ball nut is fastened to an object such as a worktable.

Abstract: An improved ball nut having adjustable preloading comprises a pair of ball nut halves both in threaded engagement with a ball screw. Only one of the nut halves is secured to a movable machine member, the other nut half being movable to the relative fixed nut half. Separating the two nut halves is a pair of concentric sleeves, which are each fabricated from a piezomagnetic material such as nickel or nickel alloy. The sleeves are each keyed to the nut halves to prevent one nut half from rotating independently of the other. Between the sleeves is a magnetic coil which, when energized, causes the sleeves to expand. By varying the coil excitation, the sleeve length, and hence, the force exerted on the ball nut halves by the sleeves can be varied accordingly to vary ball nut preloading.

Abstract: A speedometer drive worm gear has at one axial end thereof an inward flange of the thickness considerably smaller than the overall thickness of the worm gear. The speedometer drive worm gear is mounted on a differential case and held axially in place by abuttingly engaging the opposed side surfaces of the inward flange with a shoulder formed in the differential case and the inner race of a differential case bearing by way of a stopper.

Abstract: Disclosed is a carrier moving mechanism for preventing occurrence of the backlash between a screw shaft and a carrier transmitted by this screw shaft. This carrier moving mechanism comprises a screw shaft and a carrier having secured thereon first and second nuts having teeth to be engaged with the lead of this screw shaft, in which the teeth of the first nut are brought into contact with one side face of the lead of the screw shaft and the teeth of the second nut are brought into contact with the other side face of the lead of the screw shaft and the carrier is moved through these first and second nuts by rotation of the screw shaft.

Abstract: An anti-backlash nut construction wherein a base portion that is adapted to be carried by a machine part, has a bore through which a lead screw can pass. The nut has a threaded portion which is connected to said base portion and which has a bore matching with the bore of the base portion, said threaded portion having a slot or slots by which it is divided into elements formed with thread formations engageable with the external threads of the screw extending through said bores. The base portion has cut-out walls forming pairs of slot ends which are located adjacent the ends of the slots of the threaded portion, so as to facilitate limited movement of the said divided elements toward and away from each other, whereby the thread formations can engage the screw with no clearance and looseness. The pairs of slot ends, together with the ends of the slots that are disposed in the threaded portion form triangles, with the slot ends being separated from each other by solid walls of the base portion.

Abstract: Disclosed is drive apparatus especially useful for controllably displacing the carrier of a printer, the drive apparatus including a lead screw having laterally spaced apart and floating threaded followers thereon. Intermediate the threaded followers are a first pair of preloaded springs which press the followers against the opposite flanks of the threads on the lead screw to thereby inhibit backlash intermediate the followers. A second pair of springs are mounted intermediate a bracket, which is fastened to the carrier, and at least one of the followers for effecting coupling between the carrier and the follower while controlling backlash therebetween. A pair of arms extend from the followers and are coupled to a restraining shaft in such a manner as to inhibit rotational movement of the arms (and thus the followers) while permitting motion of the followers in any perpendicular direction to the lead screw to accommodate runout or eccentricity.

Abstract: An anti-backlash nut assembly is disclosed of the type which undergoes translational movement longitudinally along a screw in response to relative rotational movement between the nut and screw. The assembly includes a nut which is split into first and second portions, both of which have an internal thread complementary to the external thread of the screw. The two portions of the nut are retained in the radial direction by a coaxial cylinder. A spacer means is mounted on the retainer means intermediate opposing surfaces of the nut portions and biased against at least one of said surfaces such that any gap which may occur between the thread of the screw and the thread of the nut will be closed by movement of the spacer.

Abstract: A stator and a rotor of a step motor are disposed in an axially staggered relationship with each other so that the rotary shaft of the rotor can be freely displaced in the axial direction with respect to the stator. Around the outer periphery of the rotary shaft are formed screw threads so as to be threadedly engaged with a nut provided on a casing in which the stator of the step motor is fixedly mounted. Thereby the rotational displacement of the rotor can be converted into an axial displacement thereof, and thus a minute amount of desired controlled displacement can be realized with the influence of a backlash between the screw threads on the rotary shaft and the nut eliminated by an electromagnetic characteristic of the step motor.

Abstract: A zero clearance, backlash free, adjusting mechanism wherein a multithreaded helical member is constrained against movement within a movable support by means of oppositely disposed concentric threaded members separated by a concentric torsion spring. Opposite ends of the torsion spring are captivated by respective opposite concentric members. One of said members being fixidly, slidably mounted within said movable support. Rotation of the helical member forces the two concentric members apart along the helix forcing the members into a zero clearance position effective to prevent any wobble or yawing movement of the helix and thus eliminating any backlash along the helical member. A U-shaped clip surrounds the movable support so as to retain the assembly effective to prevent accidental dislodgement or movement of the concentric members.

Abstract: A self-centering, self-aligning, anti-friction power transmission mechanism comprising a rotor cooperable with a screw to convert rotary movement to linear movement and vice versa. The rotor has one or more convolutions of rollers having their axes arranged in a helical path of the same pitch as the screw thread with their inner ends positioned to have non-scuffing, non-slipping rolling line contact with the screw thread, a result obtained by off-setting each roller axis downwardly along the helix from the line of contact by a distance such that the line of contact and the rotor axis lie in a common plane parallel to the roller axis. The screw thread is preferably of the Acme type with a sidewall taper initially slightly less than the taper of the roller ends in contact therewith whereby, in use under load, the rollers cause cold flow and work hardening of the thread sidewall thereby substantially increasing the length of the line of contact between the rollers and the screw thread.

Abstract: An anti-backlash nut having one or more longitudinal flexural members with one end fixed and one end free-floating is disclosed which undergoes translational movement along a shaft. This anti-backlash nut is improved by providing ramps at the free-floating ends of the flexural members and means to apply axial forces on the ramps to thereby create radial force vectors which maintain the ramps in contact with the shaft even after the nut has become worn.

Abstract: Means for adjusting automatically for backlash caused by wear between the teeth of a steering nut gear rack on a steering shaft worm and the teeth of a steering mechanism gear sector which engages the rack teeth. The invention utilizes a resiliently biased, e.g., spring pressed pin carried either by the steering nut member or the gear sector member and pressing against a tooth of the other to maintain a constant torque bias of the steering nut maintaining it to a rotated position on the steering shaft. Thus, the teeth of the two members will always effect engagement with no backlash when such members are positioned with respect to each other for straight-ahead steering. When steering is initiated the response is immediate and there is no play due to looseness between steering nut rack and gear sector teeth.

Abstract: An anti-backlash nut is disclosed of the type which undergoes translational movement along a screw in response to relative rotational movement between the nut and screw. This anti-backlash nut has oppositely-directed longitudinal flexure members radially biased towards the screw to provide equal drag torque and minimum relative deflection for travel of the nut in either direction.

Abstract: A ball screw and nut mechanism in which a preloaded train of balls travels through a closed circuit having an active portion and an inactive or return portion. The active portion is formed by convolutions of opposed helical grooves in the screw and the nut and a return tube on the nut defines the inactive portion. Inclined surfaces are formed on the lands between adjacent convolutions of the groove on the screw and partially unload the balls as the latter enter and leave the active portion of the circuit to prevent the balls from keystoning.

Abstract: Mechanism which compensates for backlash error in a lead screw position indicator by decoupling the indicator shaft from the lead screw when reversing rotation. The position indicator then displays correct information regardless of the direction of rotation of the lead screw.

Abstract: An anti-backlash nut assembly is disclosed of the type which undergoes translational movement along a screw in response to relative rotational movement between the nut and screw. The assembly includes a nut which is axially-split into first and second portions, both of which have an internal thread complementary to the external thread of the screw. The two portions of the axially-split nut are retained in the radial direction by a spacer, and a spring is used to apply biasing in the longitudinal direction to minimize backlash.

Abstract: A rotary actuator incorporating an enclosure with a rectilineal slideway along which a slide member is movable has means at one end of the slide member for moving the member along the slideway and further means at the other end of the slide member for restraining the slide member from rotary movement; the slide member carries a screw threaded nut assembly which engages a worm screw forming a part of an output shaft which is rotated when the slide member slides.

Abstract: A governor mechanism for a fuel injection pump is of the type having interacting fly-weights and a main governor spring for regulating engine speed, and means are included for selectively changing the spring rate of the main governor spring to change the regulation of the governor.

Abstract: An anti-backlash, automatically reversing nut construction for use with a diamond thread screw, comprising a nut proper and a separate follower movable with respect to the nut proper, both said parts having through bores for receiving the screw. The follower part carries a non-shiftable thread-engaging ball extending into the bore thereof, and also a laterally-movable thread engaging ball likewise extending into the bore. The movable ball is capable of being shifted translationally on the follower in directions substantially parallel to the screw axis whereby it can transfer from engagement in one groove to engagement in another groove of the screw to thereby effect a change in the axial direction of travel of the nut assemblage. The nut proper also carries a non-shiftable thread-engaging ball and a laterally-movable thread-engaging ball, the latter being capable of shifting translationally on the nut proper, also in directions substantially parallel to the screw axis.

Abstract: A zero-backlash anti-friction nut construction for engagement with the threads of a screw. The device comprises a pair of nut sections having aligned through bores to receive the screw, pairs of rollers respectively carried by the sections and having generally conical tip portions engageable with the walls of the screw grooves, and bearings mounting each roller for rotation about its respective axis during such engagement. The rollers have Belleville springs urging them radially inward, and in addition, a coil spring carried by one of the sections biases the two toward one another against the action of the Belleville springs, so as to minimize looseness with the screw. The arrangement is such that the coil spring loads the nut sections sufficiently to effect slight retraction of each roller against the action of its Belleville springs. Improved performance and lowbacklash tracking of the nut sections along the screw thereby result.

Abstract: An anti-backlash, self-aligning nut construction comprising specially constructed tubular nut bodies coacting with concentric spring sleeves of unique configuration to effect precise, self-aligning, anti-backlash assemblages. The nut bodies in general each have a pair of spring-biased elements provided with internal thread formations adapted for engagement with the external threads of a screw. In one embodiment of the invention a self-aligning spring sleeve is provided having solely three pairs of oppositely-disposed transverse slots to obtain the desired aligning feature. The nut body has a base portion which is separated from the spring-biased elements by means of two transverse slots which, together with an adjacent pair of slots in the spring sleeve, form in effect a universal joint. One of the remaining slot pairs in the sleeve is oriented circumferentially with respect to the first pair by an angle of 90.degree., with the third pair of slots being circumferentially aligned with the first pair.

Abstract: An improved precision lead screw and nut assembly, including an improved nut, includes a nondeformable screw member having a helical thread on the exterior thereof, the thread being formed by a rib having a crest, adjacent side walls, the rib defining a helical groove having a root which is located between the side wall of adjacent crests. The screw cooperates with a housing, the nut being positioned within the housing and cooperating with the screw such that relative rotation between the nut and the screw causes translational movement between the two. The nut includes a helical thread formed by a rib and adjacent side walls, the rib defining a helical groove having a root located between the side walls of the adjacent crests of the nut. The nut is preferably formed of a thermoplastic base material such as an acetal resin containing finely divided particles of a fluorocarbon resin such as polytetrafluoroethylene uniformly distributed throughout the base material.

Abstract: A method of effecting time-linear travel of a lead screw-driven, carriage-mounted print head during the print cycle encompassed within a predetermined period of each motor-initiated advancement thereof. This is accomplished by incorporating a predetermined maximum possible amount of built-in backlash between the threaded coupling member and the lead screw, and by utilizing a predetermined time delay before printing commences so as to compensate for the backlash. The latter is employed to minimize friction and wear due selectively to any tolerance variations in the lead screw-drive nut threads, bow in the lead screw, or misalignment thereof relative to the carriage guide rods. As a result, wear of the moving parts that produce the friction is minimized.

Abstract: An anti-backlash nut assembly is disclosed of the type which undergoes translational movement longitudinally along a screw in response to relative rotational movement between the nut and screw. The assembly includes a nut which is split into first and second portions, both of which have an internal thread complementary to the external thread of the screw. The two portions of the nut are retained in the radial direction by a coaxial cylinder. A spacer means is mounted on the retainer means intermediate opposing surfaces of the nut portions and biased against at least one of said surfaces such that any gap which may occur between the thread of the screw and the thread of the nut will be closed by movement of the spacer.

Abstract: An anti-backlash nut having one or more longitudinal flexural members with one end fixed and one end free-floating is disclosed which undergoes translational movement along a shaft. This anti-backlash nut is improved by providing ramps at the free-floating ends of the flexural members and means to apply axial forces on the ramps to thereby create radial force vectors which maintain the ramps in contact with the shaft even after the nut has become worn.