Abstract: A telescopic boom including an elongated hollow outer boom, an elongated inner boom telescopically received within the outer boom, and guidance structure for guiding the inner boom for telescopic movement is provided. The guidance structure includes a plurality of guide rails attached to the interior corners of the outer boom, a first roller assembly attached to one end of the inner boom, and a second roller assembly attached to one end of the outer boom. The first roller assembly includes a plurality of wheels mounted on axles for engaging the guide rails. Each of the wheels includes an arcuate rail-engaging portion which presents a radius of curvature equal to the radius of curvature of the guide rails. The second roller assembly includes a pair of roller bars positioned on opposed sides of one end of the outer boom for guiding the inner boom during telescopic movement. Each of the roller bars extends transverse to the longitudinal axis of the outer boom and is rotatably mounted on an elongated shaft.

Abstract: A driving machine includes an articulated boom to which a scoop, bulldozer plate, loader or a similar tool is attachable. The articulated boom has a first arm which is articulated to slew around a joint in another arm of the boom in order to carry out the folding motion of the boom. In addition, the first arm is movable inside the other arm to carry out a telescopic motion.

Abstract: A telescoping four-sided drilling derrick and method of erection that is to be positioned on a drill floor over a well bore and is capable of withstanding severely adverse weather, environmental or geologic conditions. The derrick is in several sections and includes a bottom section, a top section and at least one intermediate section all for superpositioning over the bottom section to form a vertical four-sided tower. Each of the sections is composed of vertical members positioned in each of the four corners of each section to thereby form a total of four faces around the perimeter of each section. A window is one face sufficiently large to receive consecutively therebelow at least one section. In turn each of the intermediate sections is inserted within the bottom section for subsequent serial telescopic raising of the intermediate sections.

Abstract: An arrangement for accommodating telescoping masts on mobile carriers comprises devices for selectively swivelling the mast into a transport position or an operating position for support with respect to the ground surface for the raising of the mast into its operating position. The mast swivel bearing is provided on the carrier so that it can be adjusted or adapted for the respective adaptation of the center of gravity of the mast with respect to the mobile carrier, with respect to the transport position with vehicle wheels resting on the ground, and relative to the starting operating position of the mast with carrier supports resting on the ground surface.

Abstract: The present invention provides a frame constructing method for constructing frames for reducing the cost for assembling frames, for making it possible to execute the construction works under any weather conditions, further for shortening the term of works, and for enabling to improve safety in the executions, to automate the executions and to save labor.

Abstract: A lightweight extendable and retractable telescopic pole is disclosed comprising a plurality of non-metallic telescoping cylinders with sliding and sealing surfaces between the cylinders, a first plug member on the upper end of the smallest cylinder, and a second plug member on the lower end of the largest cylinder, whereby fluid pressure admitted to the largest cylinder will cause the telescoping cylinders to slide relative to one another causing the pole to extend. An elastomeric member connects the first plug member with one of the intermediate cylinders to urge the cylinders back into a collapsed position when the fluid pressure in the cylinders is vented. Annular elastomer members are provided which seal one cylinder to another when the pole is fully extended and further serve to provide a cushion to prevent damage to the cylinders when the pole is urged back into its retractable position by the elastomeric members and the venting of the pressure.

Abstract: The present invention provides a frame constructing method and an erection workbench for constructing frames for reducing the cost for assembling frames, for making it possible to execute the construction works under any weather conditions, further for shortening the term of works, and for enabling to improve safety in the executions, to automate the executions and to save labor.

Abstract: An improved mast assembly for an aerial work apparatus having improved stability and safety. A telescoping vertical main mast is connected to a telescoping vertical auxiliary mast.

Abstract: The invention provides a moving mechanism which can be made so small and lightweight as to be portable when being contracted, which can be formed into a longer higher column than conventional potable column, and which can thus realize a large moving amount without increasing the weight thereof. The movement mechanism has a slender moving member, a driving portion for moving the moving member, a plurality of centering members each having a through hole for the moving member at the center thereof, connected to each other and are moved in linkage with the movement of the moving member so that the distance between the respective centering members can be changed, and a movement passage for supporting and guiding the movement of the centering members.

Abstract: An excavator comprising a movable body, a boom mounted on the movable body, first hydraulic cylinders, an outer arm pivotally mounted on the boom, a second hydraulic cylinder mounted on a rear surface of the boom, an inner arm inserted into the outer arm and movable telescopically relative to the outer arm, a bucket connected to one end of the inner arm, a bucket connected to the tip end of the inner arm, a bucket cylinder provided between the bucket and a guide mechanism, the guide mechanism being slidably mounted on guide plates fixed to the outer arm, a third hydraulic cylinder connected to a base end of the outer arm and having a rod connected to a central portion of the inner arm for moving the inner arm relative to the outer arm, and an interlocking device connected between the guide mechanism and the front portion of the inner arm. A hook mechanism can be mounted at a front portion of the inner arm.

Abstract: A linear spacing device has first and second elongated components, which may be telescoping hollow tubes, each having linear surfaces engaging each other in sliding relationship. Each component has spaced holes disposed at regular linear intervals along its length. The intervals between the holes through the second component are different than the intervals between the holes through said first component. A pin or similar means is insertable through selected aligned holes through the first and second components to secure them in a selected orientation. Thus the overall length of the spacer can be adjusted in small increments substantially less than the diameter of the holes. The device further includes an extendable linear actuator engageable with a surface of each of the components to extend the overall length of the spacer. The actuator is removable from the device after the components are secured together.

Abstract: A vehicular self-propelled aerial work platform wherein a lower telescopic boom assembly is connected to a riser frame assembly having an upper telescopic boom assembly also connected thereto. A work platform is connected to the outer end of the upper telescopic boom assembly. Both the lower telescopic boom assembly and the upper telescopic boom assembly can be elevated and extended to increase the reach of the aerial work platform. The lower telescopic boom assembly comprises tubular telescoping boom sections connected at opposite ends between a support on a turntable and the riser frame assembly, with a telescopic cylinder extending interior of the boom sections and connected at opposite ends between the same members providing a telescoping parallelogram boom mechanism, with hydraulic controls with interlocks for operating the boom in a predetermined sequence.

Abstract: A mast, column or post is assembled from successive segments which are arrayed along turns of a helix and are connected together successively and to the turns above and below such segments to enable a large diameter mast to be erected and, upon removal of the segments, to be lowered.

Abstract: A stowable and self-deployable array antenna includes flat, rectangular antenna panels hinged side-by-side so that when deployed they are coplanar, and they fold like an accordion for stowing. The deployed array antenna is stiffened by lateral stiffening panels hingedly attached to every other hinge between antenna panels, and to the unhinged ends of the antenna panels. Foldable longitudinal stiffening panels hinged between adjacent lateral stiffening panels. Each hinged connection includes a pair of thin spring elements, corresponding to a portion of a cylinder. The two spring elements of each hinge are spaced apart with their concave sides facing, and with the axes of the defining cylinder parallel. The hinge pivots, when the spring elements buckle, about a line orthogonal to a line extending between the cylinder axes. The hinges are used as the structural elements of self-deployable masts. The mast may have a polygonal cross-section.

Abstract: An extendable pole or mast is constructed from a plurality of nested pole sections with each pole section is made from an initially flat sheet which is roll formed into a rectangular, preferably square, cross section element. A seam is formed by over lapping the edges of the sheet, with the bulk of the seam being placed inwardly of the element. Each of the inner sections includes its own seam and an offset of sufficient size and depth to receive the seam and offset of an outer sections. The sheet material permits tabs to be cut or stamped into outer walls of the outer sections in order to support an adjacent inner pole section. Tabs are formed in each of the outer pole sections. These tabs are biased to extend inwardly, against the adjacent inner pole section. Tabs may be formed below the first tab to provide a choice in the amount of extension of the pole.

Abstract: An extendible and retractable mast is shown which features a tubular body having telescopic sections carried therein. A travelling carriage is driven by means of a winch over associated sheaves to sequentially engage the trailing ends of the telescopic sections for moving the sections between a collapsed position and any desired degree of elevation projecting from the upper end of the tubular body. A series of locking cams allow each telescopic section to be locked into position at a desired degree of elevation. A power assist is provided for assisting the retraction of the telescopic sections.

Abstract: A mast which is retractable to a lesser height and volume, and deployable to a greater height, and which when deployed can survive a very high temperature event. All structural elements which are required for structural integrity while the mast is deployed are rigid members made of high temperature resistant material. Where the ends of structural diagonals must move toward one another during retraction, that diagonal is provided as a rigid body of two relatively sliding parts which can be latched in an extended condition when the mast is deployed. A lanyard is provided for unlatching and retraction purposes, which may be sacrificed to a high temperature event.

Abstract: A telescoping mast assembly includes a plurality of interconnected mast sections nested within each other for movement between a fully retracted height and a fully extended height. A novel, rigid drive assembly, disposed within the interconnected mast sections, telescopes the mast sections to any position between the fully retracted and the fully extended heights. The rigid drive assembly is constructed of two interconnected, flexible chain elements which accurately position the interconnected mast sections.

Abstract: An apparatus comprising a telescoping tower which has a first tubular tower member and a second tubular tower member which are relatively telescoped between an extended position and a retracted position. A first aperture is formed in the first tubular tower member. A second aperture is formed in the second tubular tower member, the second aperture being aligned with the first aperture when the tower is in the retracted position. A lock is inserted into the first and second apertures when the tower is in the retracted position, the lock limits relative displacement of the first and the second tubular tower members. The lock consists of a rod which is affixed to a vehicle. The tower is pivotally attached to the vehicle. When the tower is pivoted into a stored position, the lock will be inserted into the aligned apertures.

Abstract: A portable display structure comprising a number of upright columns joined by a number of horizontally extending beams, the columns and/or beams being formed in a similar manner of a central structural member made of a number of units and each unit comprising a plurality of rod elements connected at their ends to associated hubs.

Abstract: A device raises and aligns a tiltable telescopic mast which is mounted on a transport vehicle and which can be raised by one or more lifting cylinders from a horizontal or almost horizontal transport position in a vertical plane parallel to the longitudinal axis of the transport vehicle up to a vertical position of the mast in this plane. Vertically adjustable support booms brace the telescopic mast on the ground in a vertical plane transverse to the longitudinal axis of the transport vehicle. The device includes a supporting frame for the telescopic mast and which is connected to the vehicle frame so as to be vertically adjustable three lifting elements, and four support booms that are mounted on the supporting frame and each of which can be lowered and swung out by actuating only one pull device.

Abstract: A portable light tower apparatus includes a portable chassis having a first tubular member mounted in the chassis. A second tubular member is at least partially contained within the first tubular member so that a space is formed between the first and second tubular members. A tensioner, attached to the first tubular member, applies tension to an associated cable. A pulley is also attached to the first tubular member. A first portion of the cable is connected at one end to the second tubular member, and extends to the pulley. A second portion of the cable extends from the pulley to the tensioner. The first and second cable portions are contained within the first tubular member.

Abstract: A lightweight extended aluminum or similar telescopic equilateral triangular tubular mast or tower assembly with coaxially disposed inner triangular sections and cable elevating and lowering drive apparatus for controlling low-resistance telescopic movement with alternate outside-to-inside canted pulley wheels mounted near the top of each section passing the cable downwardly and inwardly of the section to a flat pulley wheel mounted near the bottom of the next inner section.

Abstract: An excavator comprising a movable body, a boom mounted on the movable body, first hydraulic cylinders, an outer arm pivotally mounted on the boom, a second hydraulic cylinder mounted on a rear surface of the boom, an inner arm inserted into the outer arm and movable telescopically relative to the outer arm, a bucket connected to one end of the inner arm, a bucket connected to the tip end of the inner arm, a bucket cylinder provided between the bucket and a guide mechanism, the guide mechanism being slidably mounted on guide plates fixed to the outer arm, a third hydraulic cylinder connected to a base end of the outer arm and having a rod connected to a central portion of the inner arm for moving the inner arm relative to the outer arm, and a synchronizing device for moving the base end of the outer arm for a length corresponding to the distance the inner arm moves relative to the outer arm. A hook mechanism can be mounted at a front portion of the inner arm.

Abstract: A telescopic beam has a cross-section comprising an array of members (11-17) whose cross-section are of essentially spiral or modified spiral form such that members have lengths of identical (or broadly identical) cross-section (in profile and dimension) and constant (or broadly constant) cross-section along their axis. In the array the members are rotationally offset relative to one another about an axis (A) of the beam parallel to their own axis. In addition the members in the array engage one another such that relative linear movement between two adjacent members is constrained to be possible only in the direction of their axis. The array is assembled to produce the telescopic beam. The maximum number of members in any beam is dependent on the magnitude of the rotational offset incorporated in the particular section used.

Abstract: An extension and retraction system for a four section telescopic boom having simultaneous and equal extension and retraction of the telescopic sections, wherein a pair of hydraulic cylinders are mounted exteriorly of the boom for extending and retracting the inner mid section relative to the base section; a pair of extension chains or cables are connected between the base section and the outer mid section, and between the fly section and the inner mid section; and a pair of retraction cables are connected between the base section and the outer mid section, and between the fly section and the inner mid section. The extension and retraction chains and cables are positioned within the boom sections to thereby be protected from damage.

Abstract: An extendable boom fork lift vehicle is described wherein the boom and its actuator are positioned over the rear axle of the vehicle such that the weight of the frame between the front and rear axles and behind the rear axle may be reduced. A modified boom and jib are also described wherein the jib may be selectively fixed relative one telescoping member of the boom. A light-duty carriage is provided to operably engage and articulate a secondary heavy-duty carriage.

Abstract: A telescoping pole system is described which is useful for supporting an antenna, for example, in an elevated position. The pole system can also be used to support a prism. The pole system is collapsible and portable. The uppermost pole section can be aligned with the lowermost pole section.

Abstract: A staging and seating understructure which provides a base frame for a multiplicity of support panels. The base frame consists of a series of vertical cross frames, usually having different levels, each cross frame being connected to another cross frame by collapsible gates at each end which fold inwardly to allow movement of the cross frames close toward each other wherein the entire base frame assembly may be stored compactly.

Abstract: An axially extensible and retractable structure including a plurality of cylindrical, threadedly engaged elements rotatable relative to one another for movement between axially extended and retracted positions together with a plurality of non-rotatable, telescoping segments. Preferably, none of the threads is exposed on the outside of the structure as the elements are moved between their extended and retracted positions. The structure is described in several embodiments, some with the telescoping segments positioned within the threaded elements, and some with the threaded elements within the segments which, in one embodiment, is adapted to support another element such as a boat sail, along its axial length. Also disclosed is a preferred method for fabricating the threaded elements utilizing relatively strong, light-weight materials such as carbon fiber impregnated with a curable epoxy resin.

Abstract: A lift truck upright having a fixed upright section, one or more telescopic upright sections supported outwardly and rearwardly of the fixed section and a load carrier mounted from the outer telescopic section. The side upright rail assemblies are mounted at predetermined forwardly diverging angles relative to the central plane of the lift truck and may be mounted from the truck either over the drive wheels, in front of and in alignment with the drive wheels, or inwardly of the drive wheels, in both two-stage and triple-stage upright constructions. Primary lift cylinders are nested behind respective upright rail sections and, in the triple-stage version, full free-lift cylinders are mounted either in front of the upright rail assemblies or behind said rail assemblies in nested relation with the rail assemblies.

Abstract: A deployable truss structure desirable for space applications is disclosed. The structure is triangular in cross section, with each longitudinal face of the structure being comprised of parallel longeron members interconnected by parallel batten members, the battens located at the mid-section of each face being non-rigid members, the structure including hinged diagonal members.

Abstract: A double telescoping horizontal arm, adapted for use in a robotic palletizer, including an outer member, an intermediate member and an inner member in telescoping relationship to one another. An idler wheel, mounted to the intermediate member, simultaneously engages both the outer member and the inner member so as to rotate in response to movement of the inner member relative to the intermediate member. Rotation of the idler wheel, in turn, drives the intermediate member in the same direction as the inner member thereby resulting in a double telescoping action.

Abstract: A telescopic drilling derrick apparatus that is light for easy transportation and utilizes structure to enable the mast to be raised from a collapsed horizontal position to a vertical position while still in an unextended position and thereafter telescopically raising the mast to full vertical height.

Abstract: A telescopic mast system has a base tube, a plurality of axially movable coaxial inner tubes nestable successively within each other and within the base tube, and a winch supported at the lower end of the base tube with a pair of preferably wire ropes driven thereby for extending and retracting the inner tubes. The base and inner tubes have collars at their respective ends, the collars of adjacent tubes engaging each other to limit extension thereof and to provide additional structural support during application of bending loads on the mast system. The ropes are connected to pulleys mounted near or within tube collars so that the ropes and pulleys are totally enclosed within the mast system. As the winch is rotated in one direction, the ropes axially move the inner tubes from a nested or stowed position within the base tube to a fully vertically extended operational position.

Abstract: A control system for a surveillance vehicle (V) is disclosed. The vehicle includes a rapid deployment and retraction mechanism (A') and a jack system (B') for continuously maintaining a detection device (28) a top a mast (12) within a prescribed vertical condition when extended. The control system includes a jack leveling logic circuit (C), a jack pressure control circuit (D), a ram control circuit (E), and a mast control circuit (F). Ram control circuit (E) controls a ram (52, 54, 56) which deploys and retracts mast (12). Jack pressure control circuit (D) senses the pressure on jacks (142a, 142b, 142d) at the four corners of the vehicle. Jack leveling logic circuit (C) receives pressure signals representing the pressure on the jacks and controls extension and retraction of the jacks in pairs at diagonal corners to maintain the vehicle within prescribed leveling conditions and to prevent the over extension or over adjustment under certain unleveling conditions.

Abstract: A telescopic, length extensible device, having a plurality of telescoping hollow elements, including an innermost one, at least one further, and an outermost one, further indluded a drive connected for obtaining telescopic extension and retaction is improved by a device for ensuring a predetermined sequence in the extension and retraction of the element comprising a first pin mounted for radial displacement, on one of any two mutually adjacent ones of the elements, the first pin having slot means, and being provided for selective insertion into and retraction from a third one of the elements; a couter latch element for latching insertion under spring bias and connected to another one of the two elements, such that when latching obtains, the first pin is retracted from the third element; a second spring-biased pin has a nose for lateral engagement with notches in the first pin and a control lever, operates in response to positions of the third element for locking and unlocking the second pin so that the second

Abstract: An extensible mast is shown which is erected from a portable base having a plurality of tape reels mounted thereon. The tape reels are angularly oriented on the base with respect to a common, vertical axis, and each of the tape reels is adapted to receive a resilient metal tape having longitudinal edges for winding and unwinding the tape. A plurality of guide rollers on the base receive the respective longitudinal edges of the metal tapes and orient the tapes whereby the tapes are fed upwardly in plane parallel to the vertical axis and at an angle to each other to form a rigid structure. A geared winding mechanism is located above the guide rollers and includes a plurality of rotatable windings which rotate about the vertical axis and wrap and wrap material about the rigid structure to reinforce the structure as it is being erected.

Abstract: A mast defined by three flexible longerons with cross elements coils into a canister. Extension and retraction are controlled by three axially oriented lead screws which engage protuberances spaced along the longerons. The lead screws are mutually synchronzied by an annular planet gear, and are driven by a spiroidal gear set. At a predetermined mast extension, motor drive is switched over for rotation of the mast rather than extension-retraction. The switch over is controlled by an actuator in the form of a movable guide element dimensioned to clear normal-sized protuberances but to be seized and carried by an oversize protuberance at the desired mast extension. The actuator is coupled to a lock which unlocks the annular gear to the canister so that motor drive results in mast rotation. An auxiliary lock allows re-locking of the canister to the support structure for allowing resumption of the mast extension-retraction mode.

Abstract: A folding telescoped drill rig mast having wheel assemblies which travel along the power swivel guide rail to guide the telescoped upper mast as it retracts or extends within the lower mast. The fully extended upper mast locks into a transfer frame which moves laterally relative to the lower mast between a first position with the upper guide rail offset from the lower guide rail to a second position with the upper guide rail in longitudinal alignment with the lower guide rail. This lateral movement aligning the upper and lower masts enables pinning the upper and lower masts together to transfer the upper mast loading to the support members of the lower mast. The mast includes a base structure, a lower mast with a guide rail, and an upper mast held within the lower mast. The upper mast includes a guide rail for the power swivel.

Abstract: A rapid deployment surveillance vehicle is disclosed for detecting illegal immigration across national borders and the like. An off-the-road vehicle (V) is equipped with a rapid mast erection/retraction assembly (A) which includes a carriage mechanism (24) which carries a telescoping mast (12). A track mechanism (20) slidably carries the carriage mechanism (24) by means of a fixed support (22) and pivoting support arms (26). Ram air cylinders (52, 54, 56) move the carriage mechanism in translational and rotational movement as guided on the track mechanism in a manner that the mast (12) is moved from a stowed horizontal position to an erect vertical position. During erection of mast (12), a longitudinal roof opening (10) is opened by means of a main door (14) and displacement door (16) in an automatic manner. Once erect, a leveling system (B) checks to ensure that the vehicle is within one degree of level.

Abstract: A carrier track assembly for extensible and retractable boom machines wherein the carrier track assembly is positioned within the telescopic boom sections and has one end connected to the extension and retraction fluid cylinder in the base boom section and the opposite end connected to the inner end of the next adjacent extensible and retractable boom section, the carrier track assembly being supported by the extension and retraction fluid cylinder when the boom sections are fully extended. An elevated support member is secured to the fluid cylinder at a position between the inner end of the base boom section and the end connection of the carrier track assembly on the fluid cylinder, the carrier track assembly being reversely bent upon itself and supported by the elevated support member when the boom sections are fully retracted.

Abstract: An extendable material handling arm which is particularly suitable for use as a dipper stick of a back hoe digger. The arm has an outer member with a slot extending along its length, and an inner member provided with a digging bucket pivotally mounted adjacent one end. The inner member is encircled by the outer member for sliding therein to vary the effective length of the arm. A first support structure carried by the inner member adjacent the end remote from the bucket includes a support plate with a support surface for sliding contact with longitudinally extending portions of the outer surface of the outer member adjacent the slot.

Abstract: An improved liquid chemical applicator is provided and consists of a mechanism that can activate a plurality of spray nozzles to apply a plurality of overlapping sprays of liquid chemical at a constant height, at a constant pressure and at a proper direction onto horizontal, vertical and angular surfaces to form a uniform coating thereon.

Abstract: To guide and restrain essential hoses and cables of telescoping boom machines, a carrier track system for the hoses and cables is provided in which all parts of the flexible carrier track are supported during extension and retraction of the telescoping boom. The system includes a stiff leg attached to the forward end of the boom fly section and extending rearwardly thereof and engaging a guiding and restraining device on the forward end of a carrier track bridge attached to the forward end of the boom mid-section and extending rearwardly thereof and engaging a restraining and guiding device on the forward end of the boom base section. The rear of the bridge carries a guide roller assembly which engages the bight portion of the flexible carrier track which is connected between the stiff leg and the forward end of the boom base section. Spaced support rollers on the top of the bridge engage and support the stiff leg and the top stretch of the flexible carrier track along its entire length.

Abstract: The invention relates to multi-element masts and a method of raising a multi-element mast by adding successive elements wherein a direction of traction (15) to be exerted by at least one operator on the free portion (16) of a tieline (8) emerging from a support plate (7) that enables raising the mast elements by the ascending movement of the plate (7) is defined and on a locking device (18) is fixed with respect to a mast guide shaft (4) and allows the portion of the tieline (8) emerging from the support plate (7) to unwind when the support plate is engaged and the tieline is pulled in the defined direction of traction (15). The locking device also permits locking of the tieline (8) against translation in the direction opposite the direction of traction previously defined, substantially at the end of any traction action.

Abstract: Apparatus for spraying of liquids for herbicidal and insecticidal application and the like has a supporting frame for being carried by a vehicle. An upright support is carried by the frame including an upright post and includes a hydraulic cylinder for providing selective vertical telescoping movement of the post. A hydraulic cylinder provides rotation of the post, for rotating a boom carried by the post. A hydraulic cylinder also provides selective pivoting of the supporting boom section relative to the post for vertical movement. The boom has a supporting boom section, a mid-boom section and a reconfigurable boom end element which may be either an articulating tip boom section or a strip spray attachment of "wishbone" configuration. A hydraulic motor provides selective telescoping movement of the mid-boom section relative to the supporting boom sections. The supporting boom section, mid-boom section and boom end element all include spray nozzles.

Abstract: A roof assembly exemplarily for use in outdoor theatrical and musical productions comprises a roof trusswork elevated by means of a plurality of telescoping legs. The legs are raised in unison so that the roof trusswork maintains the same orientation throughout a raising or lowering operation. A clamping or locking mechanism is provided for rigidifying the entire structure upon the raising thereof.

Abstract: A support shoe assembly (30,32) for a boom having telescoping inner and outer boom sections includes a pair of articulated wear pads (52) which are mounted at the outer end of the inner boom section in sliding engagement with the inner boom section. The wear pads (52) include rounded upper surfaces in sliding engagement with the outside lower corners of the inner boom section, and rounded lower surfaces supported in similarly contoured blocks (54) for rocking movement about a transverse axis to avoid point loading and reduce bending effects so that lighter boom sections can be utilized without reducing reach or loading capacity. The support blocks (54) are preferably mounted for adjustable lateral positioning for wear/play takeup and maintenance of proper frictional engagement between the contoured support pads (52) and the lower corners of the inner boom section.

Abstract: A telescopic arm for use in civil engineering machines, in which guide rails extended axially are disposed while being protruded outwardly on both lateral sides of a base arm which is pivoted to the boom of a civil engineering machine main body, guide grooves each concaved inwardly in a U-cross sectional shape are formed axially on both lateral sides of the slide arm which moves along the axial direction of the base arm, slide blocks disposed on both lateral sides at the forward end of the base arm are in a slidable fitting engagement into the guide grooves of the slide arm, while slide blocks of a U-cross sectioned concaved shaped disposed on both lateral sides at the rearward end of the slide arm are in a slidable fitting engagement with the rails of the base arm.