Abstract: A motion transmitting remote control assembly (10) of the type for transmitting motion in a curved path includes a terminal member (20) for operatively interconnecting an extending length of a core element and a control member (22). The control member (22) has a body portion (32) and a ball pin (36) extending therefrom. The terminal member (20) includes a passageway (38) defining an opening having a central longitudinal axis and a plurality of flexible fingers (40) defining a portion of the passageway (38). The flexible fingers (40) have an engaged condition for engaging and retaining the ball pin (36) disposed within the passageway (38) and a disengaged condition for releasing the ball pin (36). The assembly (10) is characterized by including a cap member (42) for radially outwardly spreading the fingers (40) to the disengaged condition during insertion and removal of the ball pin (38).

Abstract: In heating and cooling assemblages, that use a thermoelectric module of the Peltier type held tightly between heating and cooling members, an improvement, for avoiding fracture of the frangible components of the Peltier type thermoelectric module, is provided by using a clamping means, that acts against the members clamped against the thermoelectric module, that employs spring means that exert the assembly pressure against the thermoelectric module's substrates. The spring means desirably apply force in line with the central portion of the module's substrates, where the hottest portion of the module's substrate is located. The spring means employ one or more elongated leaf springs whose center is offset from the ends of the springs that are engaged by selectively actuatable clamping means. In one specific form a cooling box for use in the field is equipped with assemblages, as disclosed, provided at the corners of the box.

Abstract: A heat shield for high thermal loading and particularly pulse heat loading n fusion reactors e.g. as first wall, plasma physics installations, particle accelerators, etc. contains a cooled support plate carrying a large number of shielding or limiter members on its side facing a heat source, e.g. a hot plasma. The shielding or limiter members are detachably connected to the support plate by a good thermally conducting seat, e.g. a bevel, ball or flat seat. By suitably shaping and arranging the limiter members, it is possible to substantially cover the surfaces of practically any desired shape such as, e.g., the inner wall of a toroidal vacuum vessel. As a result of their limited size, the limiter members can be adapted in a optimum manner to locally differing requirements. The size and shape of the support member can be adapted to widely differing boundary conditions.

Abstract: A kit for use in refurbishing a worn joint in a member, such as a tie or drag link, is provided. The kit contains a bushing, a spring, a housing and a plug for use with the old stud to provide a reliable, rotational, flexible and tight joint.

Abstract: In order to prevent expensive subsequent damage because of a shaft fracture in machines which are coupled together, one of the two shaft ends is provided outside of one coupling flange with a predetermined breaking point. At one coupling flange a safety element is mounted which extends past the axial length of the predetermined breaking point. The safety element can be constructed as a pin rotatably mounted inside the shaft end or as a safety ring mounted around the shaft end to hold a fractured shaft in the predetermined position until standstill without it being possible for the shaft to be deflected.

Abstract: A connecting assembly comprising a support including spaced-apart sides, and a bore extending between the sides, a first member slideable in the bore, and including a first portion located on one side of the support, and a second member including an opening therein. The connecting assembly also includes a connecting device adjacent to one side of the support for connecting the second member to the first portion of the first member and comprising a first piece fixedly connected to the first portion, and a second piece located between the first piece and the one side of the support. The second piece also includes a bore which receives the first member for movement thereof relative to the second piece between a connect position with the first piece adjacent the second piece and a disconnect position with the first piece spaced from the second piece.

Abstract: A novel one piece plastic couple is disclosed. The couple comprises a first member whose inner surface is conformed to the shape of the member to be coupled and has a first latch means on its distal end, a second member hingedly connected to the first member as its distal end and to a base member at its proximal end, a third member affixed to the base member at its proximal end and disposed in the same direction as the first member and spaced a predetermined distance from the first member with a second latch means on its distal end which is designed to properly engage the first latch means when the first member is pivotally moved toward the third member to a final latched position.

Abstract: Apparatus for and method of forming any selected one of a plurality of different articles of furniture, such as seating, storage, and sleeping units comprising a plurality of panels each having inner and outer faces terminating in a perimetrical edge, and mechanism for detachably coupling any selected number of panels together in angular relation such that the perimetrical edge of each panel is positioned inwardly of the outer face of an adjacent angularly related panel and the outer face of each panel is positioned outwardly of the perimetrical edge of the adjacent angularly related panel to provide outwardly opening openings adjacent the adjacent perimetrical edges of adjacent panels. One aspect of the invention includes a corner coupling bracket for coupling adjacent angularly related panels to form outwardly opening openings at the adjacent ends of adjacent panels.

Abstract: A quick connect coupling for connecting a threaded push-rod to a clevis of a brake actuating lever, the coupling comprises the combination of a collar having an internal bore threaded for engagement with the push rod, a head at one end of the collar and a recess forming a shoulder spaced from the head, latching means carried by the clevis and biased into a first position extending internally of a bore provided to the clevis and latch displacing means carried by the collar adjacent to the shoulder. During assembly the latch displacing means serves to displace the latching means upon axial insertion of the collar into the bore and the latching means returns to its first position and engages the shoulder provided to the collar to prevent withdrawal of the collar from the clevis bore.

Abstract: A drive shaft assembly for providing a drive connection between the power take-off shaft of a tractor and an agricultural implement is formed in two drive shaft parts with one of the parts which is attached to the tractor joint being formed with a coupling sleeve and with the other drive shaft part which is attached to the implement to be driven being formed with a coupling hub engageable and disengageable in the coupling sleeve. The other drive shaft part is also formed with a length adjusting device comprising a pair of spring-loaded telescoping tubes arranged between the coupling hub and the end of the other drive shaft part which is attached to the implement to be driven and, as a result, the disconnecting point of the drive shaft assembly is thus located between the joint which is associated with the tractor and the length adjusting device of the other drive shaft part thereby to facilitate engagement and disengagement of the drive shaft assembly.

Abstract: A railway truck pedestal has a pedestal tie bar irremovably secured to one of the pedestal legs but arranged for easy movement between open and closed positions. The tie bar is of generally I-shape in plan and it is slidably mounted in channel-shaped saddles secured by their flanges to the bottom of the pedestal feet to provide generally aligned openings extending lengthwise of the pedestal.

Abstract: A split, circular flanged bushing for securing driving or driven elements such as sheaves, pulleys, and the like to a rotatable shaft, having an integrally formed key in the center opening of the bushing for insertion in a corresponding keyway in the shaft. The bushing is formed in a sintering operation and increased density is imparted to fillets or junctions between the flange and the outer wall of the body, thereby providing increased resistance to stress fatigue in these critical areas. Fillets between the key and the inner wall of the body are provided to distribute the stress concentration inherent in these areas.

Abstract: An article of furniture comprising a door and/or a drawer which are openable and closeable by a handle, the handle comprising a hollow elongate body made of a flexible material, a pair of end collar members which are a sliding fit one over each end portion of the body, and a pair of screw members for screwing one into each end portion of the body to secure the body to the door or the drawer with the end collar members abutting the door or the drawer, the end collar members being slideable along the entire length of the body so that the body can be cut to any desired length to fit any existing handle holes in the door or the drawer and to have any desired curvature permitted by the flexible material, the end collar members being a sufficiently tight sliding fit that they act to try and prevent outward expansion of the end portions of the body as the screw members are screwed into position in the end portions of the body so that the end portions become firmly sandwiched between the collar members and the screw

Abstract: A helicopter rotor includes attachment means for attaching a rotor hub to a tubular rotor drive shaft in a manner establishing a primary thrust load path and further attachment means adapted to provide a normally passive secondary thrust load path and operative automatically to retain the rotor hub in the event of a failure in the primary thrust load path. In the described embodiments the further attachment means comprise a multi-part collet consisting of a plurality of identical collet parts located internally of the drive shaft. Each collet part has an external frusto-conical surface one end for location adjacent a mating surface formed internally of the drive shaft, and a radially extending flange portion at its other end for attachment to an end surface of the drive shaft.

Abstract: In a steel truss an upper longitudinal beam and a lower longitudinal beam are interconnected at their respective ends by vertical posts, and between their ends by a plurality of mutually intersecting, obliquely extending struts and ties only. Each end post is composed of two parts of substantially equal lengths, which are interconnectable end to end, and each strut and tie is composed of two parts, which are interconnectable at the intersection between them, whereby the truss may be factory-made in sections of moderate size for convenient transportation to the building site, where the assembly of the same requires only a minimum of work.

Abstract: An upholstery fixing device consists of a bracket having a holdfast suspended therefrom with bendable or flexible straps. In use the bracket is riveted to the back of a trim board, and the holdfast is pushed into an associated aperture of an inside panel of a car door. Then, the bendable straps can be yieldingly bent to automatically reduce any misalignment between a fixed bracket (and hence its holdfast) and an associated aperture of the inside panel of the car door, thus facilitating the fixing of the upholstery to the inside panel of the car door in exact registration.

Abstract: A connecting fixture is provided for detachably connecting two platelike furniture parts, which abut preferably at right angles to each other. The connecting fixture comprises two fixture elements, which are adapted to be secured to one of the furniture parts to be connected and one of which comprises a detent lever, which is mounted to be pivotally movable against the force of a spring and at its forward end carries a hook-shaped detent projection, which when the detent lever has been pushed into an opening of the other fixture element snaps with its rear side face behind a step or bar of the other fixture element, which step or bar has a supporting edge. The radial distance from said side face to the pivotal axis of the detent lever continuously decreases toward the root of said side face and the side face when snapped in lies on the supporting edge above the root of the side face.

Abstract: A two-part fastener for fastening two objects together comprising a first fastener part mounted on one of the objects and a second fastener part mounted on the other object. The first fastener part has a plurality of openings therein and the second fastener part has a contractible and expansible locking member which is inserted through one of the openings for fastening the two fastener parts together. The locking member is independently movable with respect to the object upon which the second fastener part is mounted. This enables the locking member to freely move to a position in which it is aligned with an opening in the first fastener part for insertion therethrough.

Abstract: A wedging device comprises at least two bodies which are movable in relation to each other, namely a first body having two diverging surfaces and a second body which is displaceable relative to the first body along one of its diverging surfaces. A heat-shrinkable casing, made for example from a tape, sheet or film of polymeric material, is arranged around the movable bodies of the device. When the device is heated, the casing shrinks, causing relative displacement between the first and second bodies and a consequent change in the outer dimensions of the device.

Abstract: Device for mutual assembly of two parts which have to be occasionally disassembled, said two parts being produced from a synthetic material by moulding. There is provided on the outer wall of said parts at least one assembling group comprising a male portion on one of the parts and a female portion on the other part, the female portion defining a member for freeing the male portion and each of the two parts being formed with protrusions or noses for the subsequent engagement of resilient clips should there be a deterioration, even partial, of the assembling group during disassembly.

Abstract: A self-aligning mounting arrangement for aligning a fastener to secure a first workpiece to a second workpiece. The arrangement includes a plurality of bores each of substantially identical cross-sectional area in one of the workpieces. These bores are arranged in a matrix grid pattern having a predetermined grid dimension. The cross-sectional area of each bore is a predetermined fractional part of the average cross-sectional area of the fastener used to secure the two workpieces. The predetermined grid dimension is a predetermined proportion of a cross-sectional dimension of the fastener.

Abstract: An armature of an electromagnetic clutch is connected to a mounting plate which is coupled to the toothed driven hub of the clutch through the intermediary of an elastomeric spider. If the spider is melted by heat, the mounting plate wedges against the tips of the teeth of the hub and is prevented from flying axially off of the forward end of the hub.

Abstract: A fail-safe zero-load hinge or pivot-joint having a first load primary support path comprising a sleeve and nut combination and a secondary or redundant load support path comprising a shaft, sized to be inserted axially through the sleeve with diametrical clearance, for threaded engagement with a nut providing axial clearance from said primary members. The secondary shaft and nut combination holds the joint intact after the primary load members have failed permitting the joint assembly to perform its normal designed function of load carrying with the continued full range of movement without the risk of restricted operation seizure or jamming.A locking cap is provided for simple, safe holding of the nuts of primary and secondary member from disengagement, or even partial back off.A dye indicator may be used to indicate failure of the primary load carrying members.

Abstract: A self-adjusting assembling arrangement, where a shaft can be properly and quickly fitted within a cylindrical body member, which becomes resiliently supported on the shaft. The body member may form part of a rotatory piston member eccentrically mounted within a cylindrical casing, or of a wheel.

Abstract: A latch mechanism for the head restraint of a vehicle seat comprises latches 22 pivotally connected to the bases of projections 5 and 6 of a frame forming a part of the restraint. These projections 5 and 6 fit into complementary tubes 7 and 8 in the top of the corresponding seat. Respective balls 26 normally maintain the latches 22 in an inoperative position so that the projections 5 and 6 can be withdrawn from the tubes. In the event of a collision tending to force the restraint upwards away from the seat the balls are thrown upwards releasing the latches and allowing them to swing outwards so that they hook the bottoms of the tubes 7 and 8 as the restraint moves upwards to prevent further upward movement. Each latch may be double hooked if desired.

Abstract: For lubricating-oil filters for combustion engines, wherein the space available for the installation and removal of the filter cartridge is very confined, there are provided, instead of one filter cartridge, at least two filter cartridges which are axially arranged in series one behind the other.In order to allow these filter cartridges to be installed or removed without difficulties, there is proposed for the connection of these filter cartridges an articulated connecting means which ensures that the filter cartridges can be tilted relative to each other. A clip hinge or a wire or plastics-material strip, provided with clasps or detents, can be used as the connecting means.

Abstract: A threaded fastener having a self tool movable from an operable position to an out-of-the-way position which includes a threaded shaft, a laterally expanded head having a cavity beneath it surrounding the shaft, holes in either side of the expanded head, a D-ring having its opposite ends in the holes through the sides of the head, and an elastomeric ring such as an O-ring surrounding the threaded shaft and extending partly into the cavity so that when the threaded fastener is screwed into a threaded opening to receive it the O-ring is forced into the cavity when the fastener is tightened providing enough friction to hold the D-ring in its out-of-the-way position. If the object being held with the threaded fastener has a circular cavity having a diameter greater than the diameter of the D-ring, the D-ring, in its out-of-the-way position, will also lie in that recess where it will not interfere with the use of the object being held with the threaded fastener.

Abstract: A passive vehicle safety belt system having a belt transfer member that is moved between restraining and releasing configurations along a guide rail by a drive device that includes a racked wire comprising a connector for joining the casing for the drive wire to the guide rail having two parts defining an elongated retaining portion that are joined to clamp the casing within a longitudinally disposed socket. A plurality of closely spaced, annular grooves help in holding the casing in the socket. The halves clamp the sleeve in the bore. A clasp portion is joined to the retaining portion and is disposed in the guide rail. Resilient ears are received in holes in the guide rail to lock the retaining portion to the guide rail.

Abstract: The invention overcomes the drawbacks of a conventional device employing a screw and a nut, in particular as concerns the mounting of the derailleur. This is achieved by providing on a support plate of the derailleur an elastically yieldable fastener which is permanently fixed on the support plate and adapted to cooperate with the frame lug so as to ensure that the support plate remains in position relative to the frame lug. The support plate further comprises means for centering the support plate relative to the frame lug.

Abstract: An elongated sleeve is provided and has a centrally apertured end wall secured over one end through which the shank portion of a headed and threaded fastener may be slidingly received. The other end of the sleeve is beveled sharply and includes a radial bore spaced slightly inwardly of the tip end thereof. The sleeve is snugly slidably receivable in the outer counterbore of a fastener receiving bore formed through one end of a vehicle door arm rest and is seated against the shoulder at the inner end of the counterbore. A first threaded fastener passes through the end wall of the sleeve and is threaded into the anchoring support for the arm rest and a second threaded fastener passes through the radial bore and is threaded into the body of the arm rest.

Abstract: A torque transmitting coupling including a housing, an internally splined opening in the housing being adapted to receive an externally splined shaft. Locking structure is provided for selectively locking the shaft into the opening in the housing, such locking structure being biased to a locked position and selectively movable to an unlocked position. The locking structure includes means for automatically locking the shaft into the housing upon insertion of the shaft into the housing and further includes a structure for allowing unlocking of the shaft from the housing.

Abstract: A feature of this invention is the provision of a quick disconnect and connect mechanism for the transmission of torsional power between two concentric shafts including a collar, spring means which biases said collar to a first disposition whereat it holds at least one element in a position interlocking said two shafts, and cam means for converting torsional movement of said collar to axial movement of said collar against the bias of said spring means to translate said collar to a second disposition whereat said element is free to unlock said two shafts.

Abstract: A coupling device adapted for use with floor maintenance machines of the type such as floor brushing, buffing, polishing, scrubbing or the like which enables automatic coupling of the maintenance element (i.e. brush, buffing disc or the like) without direct manual implementation thereof. The device includes an annular plate member having a circular opening adapted to receive a circular mounting flange carried by the machine drive shaft with the drive shaft having radially projecting lugs which are adapted to pass through radially extending arcuate recesses formed in the plate member so as to lockably engage behind the plate member. On one side of the plate member a first series of inner peripheral cam-like ramps communicate with one end the arcuate recesses and on the opposite side of the plate member a second series of inner peripheral cam-like ramps communicate with the opposite ends of the arcuate recesses.

Abstract: Residual favorable stresses are induced in a zone of stress concentration in a coupling and connection joint mechanism of a drill collar or drilling tool, for example. The residual favorable stress is created by tensily stressing the material within elastic limits, relieving the stress in the zone by heating the material therein into a nonstressed plastic or liquid state, and releasing the tensile stress maintained in an area adjacent the zone. The residual force of elasticity in the area adjacent the zone applies the favorable residual stress in the zone. Preferably, the favorable residual stress is a compressive stress to resist fatigue failures from tension-induced cracks. The extent and depth of penetration of the favorable residual stress in the zone is controlled and is substantially greater than that available from mechanical cold-working surface-hardening techniques.

Abstract: A replacement stud for an original stud damaged in existing equipment consists of an oversized section having a threaded diameter larger than the original stud and a nominal section having a threaded diameter identical to that of the original stud. The nominal section is topped by a frangible, necked-down diameter capped by a suitable drive head for use with conventional hand or power drive tools. When the original stud has been damaged so as to preclude removal of a segment of it from the original stud hole, the stud hole is counterdrilled, enlarging its diameter and eliminating the broken segment. The larger threaded diameter of the snap-stud invention is set by the original stud's threaded diameter and the drill size predetermined for counterdrilling the original stud hole.

Abstract: A structural joint for a space frame having connecting members or nodes and tubular structural member is provided in which the shank of a connecting bolt, whose head is located within the hollow end portion of the tube, extends through an aperture in the tube end for engagement with a threaded opening in the node. The tube shank has a longitudinally extending keyway formed therein in which a key is slidably received. A nut or sleeve having an unthreaded inner bore receives the bolt shank and has an internal keyway which receives a portion of the key to rotatably lock the nut and bolt together so that the nut may be rotated to rotate the bolt and engage its shank in the threaded opening of the connecting member.

Abstract: The coupling for connecting a winding rod for a roll of web material to a driver shaft, includes a tenon-like end portion of the rod and a matching socket formed at the end of the driver shaft; exchangeable wearing plates are inserted in between the flat coupling surfaces of the end portion and the socket or the socket snugly accommodates a one-piece wearing insert defining a recess for engaging the end portion of the rod.

Abstract: An apparatus including a first part, a second part, a plurality of spaced apertures in the first part and a plurality of holding devices for holding the first part against the second part. The plurality of apertures are each selectively sized so a first of the apertures forms a close clearance fit with one of the holding devices on at least one diameter of the first aperture. A second of the apertures forms an equally close clearance fit, on one of its diameters, with a second of the holding devices, but forms a looser clearance fit with the second holding device on a second diameter thereof, which generally parallels a line between the first and second apertures. The remainder of the plurality of apertures each form a substantially looser fit with an associated holding device than is formed by either of said close clearance fits.

Abstract: A method of repairing a box beam is disclosed in which a cracked or broken portion of a box beam may be repaired and the strength returned to normal by forming a pair of plates that fit snugly about at least one half of the box beam, the plates being welded to the box beam and to each other, each edge of the plates being either welded to its juxtaposed plate or to the box beam to provide full strength to the structure.

Abstract: A four part guard assembly for the rotating drive connection between a drive motor and a pump. The guard assembly being rigidly and removably secured to the frame of the pump and extending to a point short of the drive motor and encompassing the drive connection therebetween. The sleeve is of two part construction removably secured together to permit removal of one part for gaining access to the drive connection for field servicing maintaining the remaining components in assembled condition.

Abstract: A repair part for a small ball joint is provided in the form of a sleeve open at least at one end and having a flattened section extending from that one end toward its middle. A slot extends lengthwise of the flattened section and is open at the one end of said sleeve to embrace the shank of the ball part of the joint. A retainer member extends inwardly from the wall of the sleeve at a location generally opposite the end of said slot, for engaging the socket part of the joint and holding the sleeve around the assembled joint.

Abstract: A serviceable welded MacPherson type strut in which the upper end of the support tube can be circumferentially cut to facilitate removal of the shock absorber components mounted therein so that an empty support tube is provided. Subsequent to such removal, a shock absorber service cartridge is inserted into the support tube and is retained therein by a service nut which is threadedly connected to the internal wall of the support tube.

Abstract: A handle stem fixing device for a bicycle is described in which a rotary control is provided at the head of a bolt, the head being larger in diameter than the bolt stud or alternatively having a flange, and a socket is provided at a hollow handle stem, into which the head is lodged and a retainer is provided, whereby the retainer substantially blocks the bolt's axial movement and the bolt is screwed to which is forced to be axially movable.

Abstract: A wheel assembly adaptable for use with a motor vehicle, a light aircraft, and the like, or in a pulley system or gear train. The wheel assembly comprises an axle or spindle-retained hub member, and a removable wheel member that is releasably connected by unique snap/lock pins. The hub member is made of a more dense material than the material of which the wheel member is made. In the adaption for use with a motor vehicle, light aircraft, and the like, the wheel member (with a tire mounted on it) is significantly lighter than the conventional rim-mounted tire, because of the absence of the hub portion; and, therefore, the wheel member can be easily changed or removed by even the weak, the aged, and the handicapped. Additionally, because the customary bolt/nut or lug/lug nut fastening combinations are not used, the wheel member is easy to change or remove, and, as importantly, the need for a "lug wrench" is eliminated.

Abstract: Holding members for engaging the corners of base plates of nail plates while wooden beams are force down on the upwardly projecting nails to form a truss are made of resilient plastics material of about the same thickness as the base plate and provided with a self-adhesive surface for fixing them relatively to a preparation table. Each holding member is formed at one side so as to lie against the edge of the base plate at at least two points respectively on both sides of the the associated corner. A comparatively thin supporting layer of harder material may be secured on the upper face or between or on both faces of the resilient material.

Abstract: A snap-on handle structure for attachment to an operating shaft having detent notches and cam members including a handle with an internal recess, and a generally U-shaped spring member in the handle recess with a pair of spaced-apart arms with free ends extending toward an open end of the recess. Each of the arms has a generally V-shaped hook portion intermediate the central base of the spring member and the free ends of said legs with a pair of inclined legs to coact with the cam members on placement of the handle on the operating shaft and coaction with the detent notches for retention of the handle on the shaft.

Abstract: A pivotal joint in which a first member having a wheel-shaped end is pivotally connected to a second member having a forked end enveloping the wheel-shaped end and including a primary pivot bolt arrangement extending through the first and second members at the center of the wheel-shaped end to pivotally join the parts, as the primary pivotal connection therebetween and wherein the forked end of the second member presents a circumferential array of three friction surfaces which will cooperate with the periphery of the wheel-shaped end of the first member to pivotally join the two parts as the secondary pivotal connection therebetween if the primary pivot connection fails.

Abstract: A dead end connector for a transmission cable. The connector includes an elongated body and a cable-receiving longitudinal channel formed in the body. A pressure pad is provided with an elongated base portion which is adapted to be aligned with the longitudinal channel of the body. A cross piece is on the side of the base portion opposite to the side adjacent the channel of the body when aligned therewith and the cross piece extends across and outwardly from both sides of the aligned body and pad at an oblique angle with respect thereto. Coupling structure is provided for retaining the pressure pad in overlying aligned position with respect to the channel to hold a portion of a transmission cable therein with the cross piece enabling the provision of a holding pressure along at least a substantial portion of the engagement surface of the pressure pad with the transmission cable.

Abstract: Nuclear reactor coolant pump having a tooling boom mounted on the periphery of the motor stand of the pump for transferring pump components through openings in the motor stand during performance of maintenance on the pump. The tooling boom comprises an articulated arm mounted on the periphery of the motor stand with a gripping mechanism attached to the arm at the end opposite the arm's attachment to the motor stand. The gripping mechanism is capable of having pump components firmly attached thereto so that when the articulated arm is swung in the horizontal plane, the pump components may be transferred between the inside and outside of the motor stand.

Abstract: A tenon and mortise are formed with a taper-dovetail shape. As the tenon is inserted into the mortise, because of the friction force between the contacting surfaces and the squeezing force of the taper, the tenon is fixed sturdily in the mortise and the tenon can be easily assembled or dismantled by a particular shaping of its outer surface.