Abstract: Means for securing a member, such as a blade retainer, to a structure, such as a disc. An annular, preferably split, retaining ring is disposed in a recess of the disc and is shaped to receive a part of the blade retainer which is also disposed within the recess thereby securing the blade retainer to the disc.A method of securing the blade retainer to the disc is also provided and includes the steps of inserting the retaining ring into the recess and compressing the ring, inserting a part of the blade retainer into the recess and deflecting it axially, and releasing the retaining ring from compression and the blade retainer from deflection.

Abstract: A spacecraft specifically adapted for launch from the space shuttle by means of a cradle having locking and ejection mechanisms mounted therein. The cradle fastens into the payload bay of the space shuttle and returns therewith for reuse in subsequent launches. The spacecraft mounts at three points to the cradle, and the cradle mounts at three points to the shuttle such that a plane through the attachment points passes through the roll axis of the spacecraft at approximately the center of mass thereof. The cradle utilizes the truss structure of the spacecraft to produce the required stiffness by providing a structural tie between the two ends and the bottom of the cradle. At launch, the spacecraft is ejected with both linear and angular momentum, the spin providing gyroscopic stability. The locking mechanisms in the cradle can be remotely controlled to relock the spacecraft to the cradle in the event of an unsuccessful deployment attempt.

Abstract: A quick coupling bucket mounting mechanism is disclosed for coupling a material handling bucket, blade, compactor, impact hammer or other attachment to the free end of a scoop arm extending from a loader or backhoe. A quick coupler is provided which is pivotally mounted to the loader scoop arm for readily receiving various types and sizes of attachments. The quick coupler has a three-leg configuration including a pair of bucket mounting legs adaptable for engagement with a bucket mounting pin. One end of each bucket mounting leg has a hook portion which cooperatively locks around lateral projections of the bucket mounting pin. A releasable latch mechanism is pivotally mounted on the third leg of the quick coupler for engagement with a complementary latch pin on the bucket. The latch mechanism is selectively rotatable to two positions. In a first position, it is aligned with and forms an opening which permits the quick coupler to be seated on the bucket latch pin.

Abstract: A coupling for connecting one end of a strap to a musical instrument or other body consists of a post fixed to the instrument and a catch fixed to the strap and cooperable with the post. The post has an enlarged head which is movable laterally into and out of a cavity in the catch. When the post head is received in the catch cavity a spring biased plunger of the catch enters a central opening of the post to prevent the catch and post from moving laterally out of assembly, while nevertheless permitting the catch and the associated strap to pivot or swivel relative to the post. The plunger is movable by hand out of the path of the post head during connection and disconnection of the post and catch relative to one another. Further, the two coupling parts can be quickly and easily connected and disconnected relative to one another with one hand of the user and without requiring extremely precise movements.

Abstract: A coupling arrangement for detachably connecting a driven unit to a drive unit, which is connected to the housing of a power source. Mounted to the housing is a frame, having any desired shape, being open toward the center, and comprising two flat pieces which are connected to one another along their outer peripheral edges. The inwardly directed portions of the pieces are spaced from one another to form a slot. A locking slide open toward the center and having no bottom side is insertable in the slot. The sides of the slide and the inwardly directed portions of the frame have grooves which are uniformly dimensioned and symmetrically distributed essentially identically to each other. In at least one not fully inserted position of the slide, its grooves are aligned with corresponding grooves of the frame pieces. A drive gear is rotatably mounted to said housing in the vicinity of the open center of the frame and is operatively connected to the power source.

Abstract: A device for rapidly securing and releasing a helicopter is provided. The vice effects positive haul down of an aircraft from a landing attitude above a landing pad aboard ship to a predetermined landing position on the pad, among other uses, through a plurality of rotatable spring-loaded over-center dogs clamped onto the free end of a haul-down cable and a sliding, cylindrical spring-loaded latching device which maintains the dogs in clamped relationship with the haul-down cable. The haul-down cable is instantly released upon freeing of the dogs.

Abstract: A device for releasably connecting two parts together characterized by a projection on one part slideably received in a socket or recess of another part to prevent twisting and to guide the two parts as they begin at connection until stop surfaces abut to define the final connecting position and a connecting mechanism having at least one pair of connecting elements mounted on the parts with one connecting element of the pair having an engagement surface for engaging the other element of the pair and being mounted for rotation on the one part with the engagement surface moving in an arc between an unlocked position to a lock position and the mechanism includes a resilient member acting on the one element to urge the engagement surface along the arc at least during the last part of travel towards the lock position so that two parts are held in a final connecting position by the resilient element acting on the one element.

Abstract: A coupling for a flexible shaft for a pump rotor orbiting within a stator. Coupling of the shaft to a driving or driven member is made easily by screwing the end of the shaft by hand into a socket in the member, and by then locking the shaft against rotation in the socket by means of abutting complementary oblique faces at the end of the shaft and at the end of a locking element in a transverse bore intersecting the socket. The screwing in of the shaft into the socket need not be more than fingertight. This permits the use of a shaft of uniform cross section (no flats for spanners) having a smooth surface finish, thereby providing good fatigue life.

Abstract: A brake to decelerate the driving movement of an actuating rod along an axis. The actuating rod is driven relative to a frame by an actuating mechanism. The actuating rod has an external tapered surface whose lateral dimension decreases in the direction in which it is driven. The brake includes a case attachable to the frame which contains within it a peripheral cylindrical brake band and a wedge member. The wedge member has an outer wall, and a tapered inside wall with substantially the same taper angle as the actuating rod. The wedge member and the brake member are disposed inside a passage in the case, with the brake band disposed between the case wall and the wedge member. There is a spacing between the wall of the passage and the outer wall of the brake band. The tapered inside wall is axially aligned with at least a portion of the inside wall of the brake band.

Abstract: The device comprises an element for rigidly fixing the articulated coupling device to a mast and a boom end-piece which are capable of pivotal displacement in perpendicular planes and each mounted on a common nut by means of a fork. Ribs and grooves formed respectively on the fork and in the nut remain in a position of interengagement after relative rotation through an angle of approximately 180.degree. with respect to a position of introduction of the fork into the nut.The invention is primarily applicable to the boom of a sailing boat which is pivotally coupled to a mast.

Abstract: A hinge arrangement between a lifting foil and a flap. The flap comprises a plurality of sections. Each section is mounted by one coupling restraining hinge device to the foil, the hinge device has a hinge pin that extends into a socket located in an adjacent section so that both sections are supported by the hinge. In addition, each two sections are interconnected by a shear key protruding from one section into the same socket of the adjacent section.

Abstract: A hitch head or fifth wheel is provided including a pair of pivotable jaws which hold in place a kingpin of a highway trailer. A horizontally movable lock block, biased by a stiff spring to closed position, engages the jaws and holds them in closed position, maintaining the kingpin in place. The lock block is movable to an open position by a finger extending through an opening in the lock block. The finger is rigidly attached to a horizontally extending operating shaft which is rotatable by a handle to move the finger to an overcenter position holding the lock block in open position. The finger includes a transversely extending protrusion which is engaged by the jaws as the kingpin exits to pivot the finger from the overcenter position and allow the lock block to move to a position engaging the rear portion of the jaws, holding the jaws open until another kingpin enters the jaws and pivots the jaws to closed position.

Abstract: A friction clutch assembly comprising a resilient annular member adapted to be engaged by a clutch release bearing to control axial movement of a pressure plate relative to a cover is disclosed. The resilient annular member comprises tabs which extend axially through apertures in the cover to provide said annular member with a fulcrum. Each tab defines a free end which is bent before assembly and resiliently deformable in an axial direction, whereby the cover is axially prestressed by the tabs after assembly. In a preferred embodiment of the invention, the apertures comprise a first portion permitting axial introduction of the tabs and a second portion permitting rotation of the annular member in a given direction relative to the cover, bent portions of the cover preventing the annular member from rotating in the reverse direction. In another embodiment, a locking ring is inserted between the free ends of the tabs and the cover to prevent the tabs from escaping through the apertures.

Abstract: A connector system including a socket with a retaining flange to hold the socket in an opening in one of the parts to be joined. A plug with a longitudinal slot is wedged in an opening of the other part to be joined. A head on the plug coacts with a bayonnet slot opening of the socket to secure the parts together. The wedge for securing the plug can be connected to the plug initially with a break-away connection so the entire plug is a single unit. A disk retained in the socket assists holding the socket in the other part to be joined.

Abstract: A solder evacuation system for removing molten solder from multiple holes in a printed circuit board. The system comprises a hollow cup assembly adapted to contact the printed circuit board. The cup assembly includes a resilient mouth adapted to contact the circuit board and encircle the molten solder area. Conduit means are connected to the cup assembly and in communication with the interior thereof. A vacuum source is connected to the conduit means and is operative for instantaneously generating a vacuum. The vacuum source comprises a hollow cylinder having a piston therein and a port to which the conduit is connected. The piston is connected to spring means which are operative when enabled to instantaneously pull the piston down the cylinder to create the vacuum. Quick-acting latch means are provided coupled to the piston to enable the piston to be withdrawn by the spring instantaneously in response to the unlatching of the latch means.

Abstract: A U-shaped connector, having one leg fixed to an end of a horizontal beam of a storage rack and a free leg attachable to a vertical post of such a rack, carries a self-locking spring clip on the free leg. One end of the clip has a locking portion which projects toward the fixed leg through an aperture in the free leg and which overlaps a locking surface on a portion of the vertical post received between the fixed and free connector legs when the beam is attached to the post.

Abstract: Improved locking or keeper pin system for replaceably retaining digger teeth on large power excavator shovels includes a pair of wedge-shaped keeper pin members which cooperate to produce a seizing taper lock. The keeper pin members are easily installed and released from the top of the tooth. One of the keeper pin members includes a retaining spring which snaps into a recess in the tooth and base member to provide positive locking. The other keeper pin member has a hardened retaining hook which engages a lip on the base member. An access port in the top of the tooth permits a chisel to be brought into contact with the top of the retaining hook. The retaining hook is easily severed, using the lip as an anvil, to release the lock when the tooth is to be replaced.

Abstract: Apparatus for detachably coupling two objects together including a pair of coupling blocks relatively movable between remote, inoperative positions, and adjacent, coupling positions. A locking tongue projects outwardly from one of the blocks and is received in a recess provided in the other of the blocks. A locking pin, mounted on the other of the blocks, is provided for movement thereon between a position in which the blocks may be moved toward and away from each other, and another position in which a portion of the locking pin bears against the tongue to urge the blocks toward each other.

Abstract: A fastening device with positive locking means is provided comprising a generally cylindrical threaded portion and a headed portion proximate thereto. An elastically deformable annular ring portion is spaced apart from the threaded portion and includes locking means disposed thereon which are adapted to selectively prevent rotation of the fastening device in accordance with deformation of the ring.

Abstract: A vehicle gearchange lever comprising a rod with a longitudinal hollow accommodating a current conduction element electrically connected with a clutch and with a contact mounted on said rod. The gearchange lever also comprises a knob with a contact mounted therein, which knob is elastically mounted on the rod and is adapted to be moved relative to the rod for the purpose of closing the contacts in the process of gearchange. The contact mounted on the rod is constructed in the form of a cup installed on a sleeve made of an insulating material and removably mounted on the rod. The knob is hollow, has a hole for the rod to fit therethrough with a clearance, and bears on a shoulder provided on the rod. Said clearance is dimensioned so as to enable the contacts to be closed by moving the knob in the process of gearchange.

Abstract: A camera mounting device for an endoscope consists of a hollow connecting tube provided at one end with a camera mount and at the other end with a cavity for receiving an ocular portion of the endoscope having a conical rear surface, engaging elements pivoted to the other end of the connecting tube and circumferentially spaced from each other in the cavity so as to normally press the conical rear surface of the ocular portion thereby to hold the ocular portion in the cavity, and a releasing mechanism for rotating the engaging elements out of the cavity, whereby connection and disconnection of the camera mounting device to and from the ocular portion of the endoscope can be made by a single-handed operation of an operator.

Abstract: A device for mounting a windscreen wiper blade on a pivotal arm, of the type in which one of the two parts comprises a projecting pin adapted to cooperate with a bore of the other part. Said pin is provided with locking means adapted to cooperate with the end of said bore opposed to the end through which said pin is introduced.

Abstract: An improved locking tab for horizontal components of hook-in type shelving, of the kind that is integral with the horizontal components and bent into the upper part of one of the slots of the posts, this locking tab having:(1) an upper surface that is slanted backwards a certain amount so that this surface is perpendicular with the centerline of the port or slightly slanted backwards when the locking tab is bent into the locked position, thus preventing that the locking tab is bent back by shaking of the shelving.(2) a secondary tab with a shoulder surface abutting the post when the tab is bent into the locked position, and a surface away from the post such that the end of a screwdriver can be placed between the latter surface and the post and twisted to bend the locking tab back into its original position, thus making it easy to disassemble the shelving.

Abstract: A coupling which permits the rapid assembly without tools, of furniture frame members into a complete furniture frame. Each coupling of the system includes a hook member formed of a metal plate and having a pair of hooks that can hook onto corresponding rods in another frame member to connect the frame members together. The hook member lies in a slot formed in one furniture piece, while the other furniture piece has a corresponding slot for receiving the hooks and has a pair of dowel rods which receive the hooks. The rods extend through the slot, in the case of a thick furniture piece, and lie behind the slot in the case of a panel furniture piece.

Abstract: A novel fastener is provided for securing a valve actuator housing to a valve mounting flange. The fastener, according to the present invention, comprises an elongated and generally cylindrical pin member which threadably engages the valve mounting flange so that a portion of the pin member extends outwardly from the valve mounting flange. The protruding portion of the pin member is received within an appropriate bore formed in the bottom of the valve actuator housing as the valve actuator housing is positioned on the valve mounting flange. A threaded transverse bore radially intersects the housing bore and threadably receives a locking screw. Upon tightening, the locking screw abuts against a reduced diameter circumferential portion of the pin member and, thus, locks the valve actuator housing to the valve mounting flange.

Abstract: A removable wheel and handle apparatus for use with trash receptacles such as garbage cans or the like includes a handle adapted to engage the open edge of the trash receptacle, a bracket affixed to the bottom of the receptacle and a wheel assembly adapted to removably receive an extending portion of the bracket. The handle permits easy tilting of the trash receptacle on to the wheel assembly, thereby permitting the receptacle to be readily moved from one place to another. The handle and the wheel assembly may then be removed and applied to another receptacle in a like manner.

Abstract: The invention relates to a coupling device acting between to adjacent tubs of a scraping conveyor for mines in which each tub comprises two side members.The recesses for the abutment flanges, like the access openings, are laterally accessible. The retaining partition of the male connecting member is positioned behind the projecting portion of this member. The cross-section of the connecting spindle has dimensions which differ in at least two directions, which are preferably perpendicular to one another. As regards the partition, the width of the access opening of each connecting member is smaller than the maximum dimension, but greater than the minimum dimension of the spindle cross-section. The spindle locking means are arranged so as to prevent the spindle appearing in front of the opening in a position in which the small dimension of its cross-section coincides with the width of the said opening.

Abstract: A device for mounting a windscreen wiper blade on a pivotal arm, of the type in which one of the two parts comprises a projecting pin adapted to cooperate with a bore of the other part. Said pin is provided with locking means adapted to cooperate with the end of said bore opposed to the end through which said pin is introduced.

Abstract: A mounting bracket assembly for releasably attaching a hose supporting boom to an overhead swivel cartridge of a car washing apparatus comprises a hinge plate adapted to be attached at one end to the rotatable outlet of the swivel cartridge, a boom body member from which the boom arm extends which body member has a hinge plate-receiving recess, compression means maintaining the hinge plate in the hinge plate recess of the boom body member and a jack which can be moved from an inoperative position to an operative position in which it is effective to maintain the compression means in a compressed state so that the boom assembly can be quickly detached from the hinge plate and the swivel cartridge can be replaced.

Abstract: A truss for supporting cages in a poultry cage system comprises a pair of inclined upstanding legs and a series of vertically-spaced horizontal cross-members connected thereto by novel clips which are specially designed to enable the cross-members to be connected to the legs with a minimum of labor. Opposite ends of each cross-member have a pair of spaced apertures which register with a pair of similarly-spaced apertures in the truss legs. The clip has a front flange with a pair of rearwardly turned lugs which are received in the leg and arm apertures and which have hooks located below the lower edges of the apertures. The legs also have holes located below their apertures and below the lower edge of the cross-member, and the clip has a deformable angulated tab depending from the lower portion of the flange and extending into the holes in the legs.

Abstract: A coupling of the type including a housing having a rotating locking sleeve therein for selectively locking the housing to a splined shaft. The locking sleeve is biased to a locked position, but a mechanism is provided for automatically holding the locking sleeve in an unlocked position upon removal of the housing from the shaft whereby the shaft will be automatically locked to the housing upon replacement of the housing on the shaft.

Abstract: A socket lug assembly for attaching bombs and the like to bomb racks and/or other attachment points on an aircraft. A spring-loaded spindle locks multiple spheres in place securing the lug with attached store. An externally operated lever moves the spindle to the release position when activated allowing the spheres to move inward, freeing the lug to fall away from the attached assembly. The spindle is held in the release position by a spring-operated sear. When the next store is loaded, the lug urges the sear out of the spindle detent allowing the spindle spring to force the spindle to the "lock" position securing the lug with attached store to the rack.

Abstract: A pneumatic spring conductively connecting a heater on the window pane in the tail gate of a station wagon to a battery is mounted between ball-and-socket joints whose plastic socket parts are equipped with barbs permitting insertion of the ball part without tools, but preventing accidental release.

Abstract: A coupling device for coupling together heavy cargo pipes or the like which includes releasable plunger locking means to prevent rotation of a cam element in a locked condition and permit rotation in an unlocked condition. A liquid exit is also provided to prevent liquid accumulation and freezing together of relatively movable locking parts.

Abstract: An improved resilient retainer which provides a highly reliable clamping action upon grooved clevis pins and the like. The pinless retainer configuration comprises two essential sections; a clamping section which is spring loaded to be secured around the core diameter of a grooved clevis pin together with an entry section which prevents the retainer from being removed easily. The retainer requires a grooved clevis pin and the like to be inserted past a first entry section and then snapped into the clamping section. The retainer may be formed from any resilient material and operates effectively with a minimum of insertion force without sacrifice of positive clamping effectiveness. In a second form the pinless retainer includes an encompassing guard clip for the entry section with removal from a grooved pin requiring a first removal of the associated guard clip.

Abstract: A connection between a handle and a valve stem is provided by a snap latch arrangement. The usual button at the top of the handle carries a dog bar that prevents the detent from releasing when the button is in place. But when the button is removed, the handle is automatically removable by upward force. No attachment screw need be manipulated. When the handle is removed, a cartridge can be removed. The cartridge includes a frontally facing segment that fits into the cylindrical contour of the valve body cup. The segment is snapped outwardly whereupon the segment, together with associated valve parts can be lifted from the valve cup for repair or replacement.

Abstract: A releasable coupling of the type having interlocking elements wherein two structural components can be joined in interconnection to one another. The releasable coupling includes a structural member having a pair of opposed channels separated by a web. A pair of lugs is provided at one end of an end wall member for engagement with a slot in a receiving member. A recess is locked at one end of the slot for receiving the lugs when the structural member is engaged with the pair of channels.

Abstract: A quick acting coupling for coupling together heavy cargo pipes which includes releasable locking means to permit rotation of a cam element in one direction and prevent rotation in an opposite direction, and upon release of this locking means to permit rotation in the opposite direction.

Abstract: A scaffolding structure comprising upright members connected together by cross members and including additional members which serve as braces, including at least one brace secured to a member, the brace being provided with at least one transverse pin and the member being provided with an aperture for the reception of the pin, the brace having means captively associated therewith for releasably restraining the brace from movement in a direction longitudinally of the pin.

Abstract: Means are disclosed for securing together a first, U-shaped member and a second member received within the first member. In the preferred embodiment, the second member is a holder for a mineral cutter pick and the U-shaped member is formed on a drum or cutter chain of a mining machine. The means comprise registering bores in the legs of the U-shaped member and in the second member, one of the members being formed with a recess extending transversely from the bore therein. A hollow cross pin is received within the bores and a locking pin is driven through a transverse bore in the cross pin to extend into said recess. The cross pin has a length equal to or less than said bores in registration, and part of its internal surface is provided with a screw thread.

Abstract: Structure for removably locking a cover in a covering disposition. The locking device is arranged to be released notwithstanding the disposition thereof in a relatively inaccessible area of the machine on which the cover is mounted. The locking device includes a locking pin which is axially movable so as to have clearance with the cover with the pin being so moved by a tool inserted through the small access space available to the locking device. The pin is drawn back outwardly into locking arrangement with the cover by a threaded device having a shank portion passed through a hole in the cover into threaded association with the locking pin, permitting threaded operation of the device to draw the pin outwardly into the hole of the cover and thereby lock the cover against rotation about a pivot mount thereof.

Abstract: A socket for use in a ball and socket joint comprising a bearing basket having a bearing seat to accommodate the pivot ball with a resilient interlocking element to retain the pivot ball in the bearing seat and a displacement member positively locking the resilient element after the ball has been seated.

Abstract: A device for mounting a windscreen wiper blade on a pivotal arm, of the type in which one of the two parts comprises a projecting pin adapted to cooperate with a bore of the other part. Said pin is provided with locking means adapted to cooperate with the end of said bore opposed to the end through which said pin is introduced.

Abstract: A mining bit, especially an impact bit for down-the-hole operations and the like, in which the bit comprises a body adapted for being chucked in an impact motor for being impacted by the hammer of the motor and for being rotated by the motor. The working end of the bit includes a detachable cup-shaped cap in which hard wear resistant inserts are mounted.

Abstract: A framework is constructed using posts having side walls in which vertically aligned and spaced-apart slots are formed. The posts support frame members having end edges which abut the side wall. A pair of hooks on the end edge enter into a pair of slots and, when the frame members are moved relative to one another, the hooks engage the side wall and the end edge is clamped to that wall. The end edges have locking tabs which are bent into a slot to prevent disengagement of the frame members.

Abstract: A storage rack assembly comprises laterally spaced vertical units defining a storage area therebetween and each having a base provided by a W-configured truss and three co-planar posts secured to and extending upwardly from the top of the truss. Spacers maintain the posts in fixed relationship within each vertical unit. Spreaders and shelving members extending between the vertical units are secured to sleeves which in turn are detachably secured to the posts thereof in tightly fitting engagement therewith. Each sleeve comprises a pair of interfitting sections having interfitting oppositely dispoed L-shaped fingers along the vertical edges thereof. Resiliently deformable S-configured clamping members each have offset hook portions which engage recesses in the bases of each pair of interfitting fingers to prevent inadvertent disassembly of the sleeve sections.

Abstract: A connector to provide a fast-make coupling by which releasably to interconnect a control device to a push-pull control cable assembly. The control device has at least a sheath member and a plunger movable longitudinally within a passage through the sheath member. A connector housing is substantially permanently secured to the casing of the push-pull control cable assembly and releasably attached to the sheath member so as to be longitudinally aligned with the passageway therein. A shuttle plug, which is secured to the core of the push-pull control cable assembly is slidably received within the connector housing and the passageway in the sheath member to which the connector housing is releasably attached. A lug is presented from the plunger and interacts with a socket in the shuttle plug to effect an interconnection that is readily engaged and released, but only when the connector housing is not attached to the sheath member.

Abstract: Locking device locking the suspension nut of a driven shaft from rotation relative to the shaft, upon reversal in the direction of rotation of the shaft or such vibration as would loosen an ordinary nut. The locking device is particularly adapted for cantilevered shaft vertical pumps in which the shaft and pump impeller on the end of the shaft are susceptible to vibration. The locking device includes a pump coupling including a motor shaft coupling part and a pump shaft coupling part detachably secured to the motor shaft coupling part. A nut part having a cylindrical periphery is threaded on the pump shaft and recessed within the pump shaft coupling part, to suspend the shaft from the pump shaft coupling part. The full weight of the pump shaft, coupling and impeller, including the hydraulic thrust, is borne by the threaded connection between the pump shaft and the coupling nut. The coupling nut is tightened by a spanner wrench having projections fitting into drilled holes in the coupling nut.

Abstract: A chain anchor which provides for manual quick engagement of a chain with a fixed anchor member, and manual quick disengagement of the chain from said anchor member, both readily, conveniently, and without the use of tools; the structural configuration of such chain-engaging anchor member, together with an associated guard, precluding accidental escape of the chain from the anchor member yet without hindering such manual quick engagement and manual quick disengagement of the chain.

Abstract: A coupling device including a first member that is formed with a hooked-shaped element having a circular opening and an elongated slot that communicates with said opening, and a second member having a connecting portion that includes a circular bar and at least one leg interconnected thereto, said bar and leg being movable through said slot in oriented relation for location in said opening, wherein the bar is rotatably positioned in the opening in the hook-shaped member for coupling the members together for relative movement therebetween. A resilient friction element is mounted on the first member and partially extends into and obstructs the entrance portion of said slot as formed therein so as to prevent the members from being inadvertently disconnected.