Abstract: A device or oven and a method for soldering components (34, 36) onto boards (18), with the device having at least a preheating zone (10) and a soldering zone (12), and a transport device (16), by means of which the boards (18) can be moved from one zone (10) to the next. Infrared radiators (22) extending in the transport direction (20) are disposed in the preheating zone (10) and infrared radiators (24) extending transversely to the transport direction (20) are disposed in the soldering zone (12), with the radiators radiating essentially diagonally, i.e., obliquely, the board surface. As a result, it is achieved that less radiation is absorbed on the surface of the board, or the top surfaces of the components (34, 36), than on the side walls of the corresponding components (34, 38). Moreover, according to a further feature of the invention soldering ovens are adjusted using sensors (54, 56) disposed on measuring boards (18') and in the oven (10, 12).

Abstract: Wiring of terminals of electrical apparatus or apparatus systems (4, 5, 7) is done automatically in the course of the direct wiring. A preassembled electrical apparatus or apparatus system is made available with terminals (9, 10, 11) fixedly located in it, whereupon by means of an automatically guided line-laying tool (59), an endlessly supplied line (68) is moved into the contacting zones of the specially formed terminals, fixed there, and either clipped or through-wired.

Abstract: A method for manufacturing a timepiece wheel having a bearing portion integrally formed with a pinion and gear wheel. A strip of material is compressed to simultaneously form a thin gear, a pinion and bearing surfaces. The formed gear is then sheared from the remainder of the strip formed of a metal.

Abstract: A new improved cleaning apparatus is provided for all powered-shaver to replace their hand-used brushes for the cutting blade compartment and the cover cleaning. It works quickly, thoroughly and securely, as well as contributes to good health maintenance.

Abstract: A hand operated tubing cutter adapted to apply a selectable force to tubing to be cut, with the cutter having an elongate, substantially "C" shaped body member and defining a recess for receiving a piece of tubing to be cut. A spaced pair of rollers is operatively mounted in the central recess, directly against which rollers a piece of tubing to be cut is to be placed. An elongate cavity is disposed in the body member in substantial alignment with the pair of rollers, and an elongate ram member is slidably disposed in a non-rotatable manner in the elongate cavity, one end of which ram member supports a cutter wheel. The cutter wheel is rotatably supported in an opposed relationship to the rollers, and a rotatable adjustment device is located on the body member at a location comparatively remote form the rollers. A compression spring is disposed in the body member and operably interconnected with the ram member.

Abstract: A folding knife has a generally elongate blade having a tang portion formed with an integral normally unstressed cantilever spring. A cam pin is provided within the blade receiving space within the handle which is disposed along a curvilinear path defined by a locus of points traveled by a free end of the spring as the blade pivots from the closed to the open positions. The cam pin serves to engage and obstruct the free end of the spring between a first point on the curvilinear path when the blade approaches the open position and a second point on that path when the blade reaches the fully open position. The spring, while obstructed is deflected by the cam pin toward the blade into a gap defined by an end edge of the blade and the spring. Such deflection enables the spring to move past the cam pin.

Abstract: A guide for attaching to a router to form arcuate cuts in a workpiece. The router guide has a circular mounting plate which replaces a lower plate of a router. The guide has an elongated arm extending from the mounting plate with a slot extending along the longitudinal center line of the guide arm. An anchoring mechanism slidably carried in the slot includes an anchor fastener such as a wood screw or nail to anchor the anchoring mechanism to the workpiece and define a pivot point for the router and guide. The anchoring mechanism further includes a locking mechanism to releasably lock the anchoring mechanism in place along the slot to define the radius of travel of the router and guide about the pivot point.

Abstract: An apparatus for measuring the shape of a frame of spectacles is provided wherein the shape of a frame is measured with a measuring element which is held in contact with a groove in a rim of the frame while being moved along the groove. To accurately position the measuring element with respect to the groove of the frame before the start of measurement, a positioning device is provided which moves the measuring element horizontally toward the frame, presses the measuring element against the frame with a biasing force, and positions the measuring element at a measurement position. Further, to permit smooth vertical movement of the measuring element and to achieve accurate shape measurement, a thrust device is provided which pushes the lower end face of a measuring element supporting shaft upward at a location displaced from the axis of the shaft.

Abstract: A laser beam plane generator is provided and supported from a datum line vehicle body reference point measuring jig for generating either a vertical longitudinal laser beam plane parallel to the vertical centerline plane of the vehicle body, a vertical transverse laser beam plane normal to the datum line, or a horizontal laser beam plane. A hand-held wand type probe is used in conjunction with either of these laser beam planes to check and/or verify the spacing of specific vehicle reference points relative to a selected laser beam plane.

Abstract: A measuring device allows simultaneous determination of the length and diameter of elongated fasteners such as bolts, screws and the like. The device has a body member with a plurality of variously-sized holes extending from a gauge surface. The body member is preferably marked to indicate the hole size. A panel member is attached to or integral with the body and defines a plane extending parallel to the hole axes and spaced therefrom. The panel member carries indicia which indicate length from the gauge surface. Insertion of a bolt into the smallest hole which will accept it identifies the bolt diameter while comparing its end with the panel member indicia indicates its length.

Abstract: A device 22 for measuring the curvature of an object, such as a tapered shaft 24, includes a support plate 26 and a clamping mechanism 32 for supporting the shaft at one end 34 thereof a holding mechanism 60 retains an opposite end 78 of shaft 24 in a position such that the shaft is in a curved state. The curved state of shaft 24 can be attained by physically moving holding mechanism 60 or by placing a weight 80 on the mechanism. A first transducer 82 includes a slide 88 which is movable along a guide bar 86. A second transducer 98 includes slide 102 which is movable along a guide bar 100. Guide bar 100 is connected to slide 88 for movement therewith. A locator mechanism 114 is mounted on slide 102 for movement therewith and includes a pair of spaced pulleys 144 and 146 biasingly urged against opposite sides of shaft 24 and toward the axis thereof.

Abstract: A gage for splitting annular seals by establishing two points on a seal's outer edge for cutting lines, and planes through which the cuts should extend. The gage includes two pivotally connected arms equipped with collar assemblies. The collar assemblies include contact edges and offset angle plates. The seal abuts against the contact edges to properly orient the gage and seal. The offset angle plates establish the cutting lines. The gage includes feet which position the gage to stand over the seal.

Abstract: An improved measuring, marking, and cutting tool comprising a tape measuring device within a housing which contains a guide and brake, and a pencil/knife holding attachment affixed to the distal end of the extensible, flexible measuring tape. The guide is a rigid, straight structure running along the bottom of the housing, and provides for a method of smoothly following along the straight edge of a workpiece, thereby facilitating long, straight, perpendicular marks or cuts. The brake mechanism is engaged by the guide structure, allowing the user to engage the brake and fix the measuring length of the tape by merely pushing down on the housing. The pencil/knife holding attachment is comprised of two Velcro (.TM.) straps that can be wrapped around and affixed to a standard pen, pencil, utility knife, and the like.

Abstract: A substrate transporting system is presented which can prevent contamination within a sealed box, and which does not bring in contaminants from the outside environment when installing substrates in a processing apparatus connected to a clean tunnel. The substrate transporting apparatus according to the present invention includes a box for installing one or more substrates in a clean sealed atmosphere, and a box transporting apparatus for transporting the box by loading it on a carrier and through a clean sealed space of a tunnel shape, and further includes a box transfer apparatus arranged in the tunnel-shaped sealed space for transferring the box from the exterior of the sealed space to the carrier, and a substrate transfer apparatus for transferring substrates installed within the box to a substrate processing apparatus connected to the sealed space. It has a cleaning apparatus arranged within the tunnel-shaped sealed space for cleaning the outer surface of the box.

Abstract: In a papermaking machine, the drying section includes a vacuum based system which serves to guide the web and supporting felt (15) from a first drying cylinder (11) to a transfer vacuum roller (10), which has perforations (13) through which a vacuum is communicated into the interior of the roller 10 from of an external suction box (14). The suction box (14) includes lengthwise extending sealing strips (28, 29) located adjacent and bounding the free circumferential surface of the transfer roller (10), which is not overlapped by the felt of the drying section. The sealing strips extend from the suction box 14 to the roller mantel (10a) of the roller 10. These strips are further designed in the style of a doctor blade and are flexibly mounted on the suction box (14) so that they are flexible and biased against the roller 10 by spring action. They extend approximately tangentially to the surface of the roller mantel (10a), contacting it gently.

Abstract: An apparatus and method for operating a rotatable drying drum are disclosed herein. The drying drum has a burner for generating hot gases of combustion for flow through the drum to dry aggregate. The drum includes identical drying flights each having a generally U-shaped body having side walls extending from opposite edges of a base and terminating in first and second edges having different configurations and consequent different veiling effects in the dryer by securing the flights in one of a plurality of orientations within the drum. By reorienting the identical flights within the drying zone of the rotary drum dryer, the veiling patterns of the aggregate across the drum may be altered, hence adjusting the exhaust temperature.

Abstract: The present invention disclosed and claimed herein comprises an apparatus and method for curing and drying coatings on nails of the human hand. A housing (12) is provided having two elongated solid sides (14), one elongated solid top (15), two solid ends (16), and an elongated underneath side (18) having a length. Restrictive air vents (22) are provided along the length of the elongated underneath side (18) of the housing (12), such that the housing (12) and air vents (22) define a substantially closed air pressure chamber (34). An ultraviolet light source (20) is disposed along the underneath side (18). A flat surface (26) running the length of the underneath side (18) is disposed a distance beneath the restrictive air vents (22) and the ultraviolet light source (20).

Abstract: A ventilation system for footwear having an upper and sole assembly in which perforations or openings in the sole assembly connect the interior of the shoe through a duct or passage into a pumping chamber or air bag. A pair of one-way valves connect the duct to the chamber or air bag and from the chamber or air bag outwardly through a single valve in the rear of the heel of the shoe for movement of air rearwardly through the shoe. The air bag is preferably 23.3 percent in volume of the total volume of the interior of the shoe.

Abstract: A road and/or airport runway scraping blade for use with a ground supported vehicle, which scraping blade includes a frame for attaching the scraping blade to the vehicle. The scraping blade has a front facing side, a rearward facing side, a top edge and a bottom edge, both edges extending laterally of a longitudinal axis of the vehicle when coupled to the vehicle. Coupling structure is provided for facilitating a coupling of the frame to the vehicle with the rearward facing side facing the rear of the vehicle. An elongated conduit and a fastening structure is provided for fastening the conduit to the rearward facing side of the blade intermediate the coupling structure and the bottom edge of the blade. A longitudinal axis of the conduit extends generally parallel to the lower edge. A plurality of laterally spaced spray nozzles are provided and are oriented along a length of the conduit and communicating with an interior of the conduit.

Abstract: An excavating hoe or bucket includes a hoe or bucket body which is movable across an excavation area, and a structure for providing the hoe body or bucket body with a variable load capacity. The variable load capacity may be provided by a network of flexible line members such as chains, which may be disconnected from each other and reattached at different attachment or insertion locations, to increase or decrease the load capacity of the hoe or bucket.

Abstract: A rake attachment for use on a skid steer, which can be used for multiple lawn and grounds preparation activities, such as grading, filling, leveling and scarifying. The rake attachment of this invention combines several useful attachment functions into a single compact design. The rake attachment includes a support frame that has spaced side support members to define an opening through which a skid steer operator may view the soil being worked. Scarifying teeth extend from the support frame to penetrate the ground for scarifying. The support frame includes tines which work and level the soil as it is being scarified by the scarifying teeth.

Abstract: A coupling device for connection between the operating arm of an excavator and an implement (e.g. bucket) has upper and lower supports and a tilting device having a hinge with a tilt central axis and a transmission gear mounted to the upper and lower supports for tilting of the implement and the lower support part. The gear is a worm gear which has a segment of a worm wheel which is rigidly connected to the upper support and has its center coinciding with the tilt central axis, and a worm screw rotatably journalled to the lower support and rotated by a reversible hydraulic motor to effect tilting about the tilt central axis.

Abstract: An apparatus and method are provided for transferring a flatwork article. A transfer mechanism grips a leading edge portion of the article between leading corner portions thereof and moves the article from a loading station to a pickup station. A positioning device locates a trailing edge portion of the article at the pickup station for engagement with a moving mechanism. A moving mechanism picks up the trailing edge portion of the article at the pickup station and moves the article to a desired location.

Abstract: A protective jacket for use in a method of framing a picture. The jacket is designed to fit within the existing frame of the picture, allowing the picture to be viewed under near optimal conditions whilst affording protection against fire or impact damage. The jacket comprises a fire-resistant laminated glazing material for viewing the picture and a metal sub-frame for providing impact resistance. The jacket may also be air-tight or water-tight.

Abstract: A frame for framing a poster or similar on a wall is disclosed. The frame requires no rigid backing element since the wall itself serves to support the poster. The frame includes a top piece, at least two side members and a plurality of corner pieces for connecting the top piece and the side members to form an enclosing frame. Each of the side members has a front portion and a rear portion, with these portions being connected together to form an inwardly facing groove for receiving edge portions of the poster. The rear portion is in the form of a thin flange having opposed front and rear surfaces with the front surface partially delimiting the groove.

Abstract: An adjustable picture frame includes a generally polygonal frame having a plurality of elongated side sectional pieces, each side sectional piece including a first end face having a longitudinally projecting dowel and a second end face having a dowel receiving socket. The frame also includes a plurality of right angled corner sectional pieces for completing the frame, each corner sectional piece including a first elongated arm section having a first section end face with a longitudinally projecting dowel and a second elongated arm section including a second section end face opposite and perpendicular to the first section end face and including a dowel-receiving socket. The first and second arm sections are connected to each other to form a generally L-shaped right angle corner sectional piece. The corner sectional pieces are adapted to contact adjacent side sectional pieces with the dowel on one sectional piece fitting into the dowel-receiving socket of another thereby completing the polygonal frame.

Abstract: A book scroll device is provided, which consists of a housing having a transparent main compartment, with a book scroll assembly. A structure is for carrying the book scroll assembly within the main compartment. A first facility is for unwinding the book scroll assembly within the main compartment, so that it can be viewed therefrom. a second facility is for rewinding the book scroll assembly within the main compartment, so that it can be removed therefrom.

Abstract: A plastic price channel for attachment along the front edge of a merchandise display shelf to carry labelling pertaining to articles on the shelf has a main body panel and a see-through cover joined to the body panel along its bottom edge so that non-adhesive labels can be fitted between the body panel and the cover. The top edge of the cover can be engaged behind a resilient top lip on the body panel to releasably lock the cover in place and a forwardly extending channel-shaped formation is provided along the top edge of the cover in which the top lip is received. The channel-shaped formation has an upwardly extending outer limb forming a gripping element by which the top edge of the cover can be disengaged from behind the top lip by finger pressure exerted downwardly on the gripping element.

Abstract: A trigger shield sandwiches the trigger guard and trigger of a weapon between a base plate and a cover plate to prevent accidental discharge of the weapon. The base plate is slotted and a slide plate is slideably mounted in the slot. A pair of upstanding posts are mounted to the slide plate. A trigger guard is positioned between the upstanding posts when the device is in use. The slideability of the posts enables the structure to accommodate trigger guards of many differing sizes and shapes. A locking device has a ratchet mechanism that enables quick attachment of the cover plate to the base plate, and a safety device prevents inadvertant or accidental release of the locking device. A quick release device enables quick separation of the cover and base plates when access to the trigger of the weapon is required, but the operation of the quick release device is not obvious to a child or other individual unfamiliar with such operation.

Abstract: Household Safety Lock device includes two different screw thread connecting parts separately connecting to a regular lock and a household ware. They can join together or divide separate easily with a bar. So every dangerous household ware is easily locked for protecting children.Gun Lock Guard device includes regular trigger lock section and permanent lock section. The device will lock or unlock the trigger temporarily whenever using the real key. But it will lock the trigger permanent deadly whenever trying unlock the trigger with counterfeit key or destroying the lock. This device increases safety for guns.

Abstract: Apparatus for providing a decorative cover for a flower pot comprising a collar wherein the collar clamps a sheet of material to the flower pot or wherein the sheet of material is connected to the collar and the collar is connectable to the flower pot.

Abstract: A firearm having a laser beam capacity for aiding in sighting positioned within the firearm for adjustment therein and having an on-off switch operated by the firearm operator's trigger finger of the trigger finger hand is in position on the firearm grip. The switch can be assembled for operation by finger pressure from a selected side of the firearm.

Abstract: A rod has a region at a selected place between its upper and lower ends formed into a helical spring in one embodiment. A part of the rod extends upwardly from the spring through a decoy body and a part of the rod below the spring is pushed into the ground to support the decoy. A spherical bead on the rod, even if the helical spring is not formed in the rod, serves as a thrust bearing allowing the decoy to swing about the vertical axis of the rod like a weather vane to simulate natural body and head lateral and frontal movements and to tilt when a mild breeze impinges on the body of the decoy.

Abstract: A limit line linear fish catching device having an elongated barrel and a coaxially disposed internal elastic spring humanely allows hooked fish to remain in the water until harvested. Preferably the elastic tube spring extends between a pair of spaced apart guiding elements coaxially centered within the device. A limit line interconnects both ends of the tube spring and limits the elongation of the spring. The limit line extends from the support through the device to the fishing line and interconnects the components of the device. The device is cocked by stretching the spring tube. The tube functions as a linear spring. The limit line from the bottom end of the barrel is secured by captivating a stop in a slot defined in the barrel end. When a fish strikes, the stop is dislodged from the slot, freeing the line. This action activates the spring which contracts and hooks the fish.

Abstract: A fishing strike indicator apparatus includes a ballast portion, a fishing line receiving portion connected to the ballast portion, and a cam portion connected to the fishing line receiving portion. The ballast portion includes the center of gravity of the apparatus. Portions of the ballast portion, the fishing line receiving portion, and the cam portion are arrayed along a longitudinal axis. A free-end, pole-contacting portion of the cam portion extends laterally to a first side of the longitudinal axis; and an intermediate, pole-contacting portion of the cam portion extends laterally to a second side of the longitudinal axis. The fishing line receiving portion includes a line cam surface adapted to slide against a taut fishing line. Also, the fishing line receiving portion includes notch portions adapted to engage a portion of a slack fishing line. The notch portions of the fishing line receiving portion extend longitudinally along the longitudinal axis.

Abstract: Apparatus for releasably attaching a tackle box (20) to a fishing pole (22) with the tackle box (20) being held in a desired position relative to the fishing pole (22). The tackle box (20) may include a container (34) a lid (63), and a handle (80). A channel (30) may be formed in one surface (32) of container (34) to releasably attach to the pole (22). The rotation of the tackle box (34) about the pole (22) may be prevented by a retainer (28). Methods of manufacturing and using a tackle box (20) are also presented.

Abstract: A fishing pole casing consists of a tubular sheath of plain or canvas backed, smooth, solid plastic sheeting with a longitudinal, stitched or welded seam, and an elastic loop; only the portion of the rod ahead of the reel is inserted into the sheath and the elastic loop engages the reel of the pole to urge the rod into the sheath.

Abstract: A trap for small noxious animals, such as mice, and comprising a holder (1) in form of a frame for holding a tightening element (3) in form of a shield. The trap (1) is arranged to be able to take a first, non-tightening position and at least a second, tightening position (12). The holder (1) shows a support (4) for a bait (20). The element (3), consisting of a sheet-metal, shows a setting-tongue (5) cut in the element (3), which tongue is arranged preloaded in the trap (1). In the said first position of the trap (1), the setting-tongue (5) is arranged at a distance from the support (4) and in the said second position (12) of the trap (1), an end portion (7) of the setting-tongue (5) is arranged to extend over the outer end (14) of the support (4) and touch the bait (20), while a second end portion (9) of the setting-tongue (5) is arranged to touch a stop in the holder (2).

Abstract: A mosquito killer including an upper cover having a center hole, a handle having a lower end extending downwardly through the center hole of the upper cover to engage with a stopper, a lower cover, a collapsible cross frame having upper ends slidably connected with the upper cover and lower ends slidably connected the lower cover, a lamp seat slidably installed on the cross frame, a protective net disposed between the upper cover and the lower cover, and an electric net arranged within the protective net.

Abstract: A floral container having a water-impermeable external layer for a floral grouping comprising a holding material and having a water-impermeable external surface layer. The holding material is constructed of a material capable of receiving a portion of a floral grouping, botanical item or propagule and supporting the botanical item, floral grouping or propagule. A sheet of material may be extended about a portion of the holding material and a crimped portion or bonded portion is formed in the sheet of material with the crimped portion or the bonded portion cooperating to hold the sheet of material about the holding material to provide a decorative cover. A bond or other tying device may also be used to bond the sheet of material to the flower pot.

Abstract: An improved ground stake apparatus for the support of small garden fences used to protect flower beds, seedlings and the like. The invention is comprised of a stake adapted with a plurality of incrementally spaced apertures through which one or more removable U-shaped bridge members are inserted to form channels for the retention of horizontal wires of conventional fencing. Hour-glass shaped clips are also provided to secure the bridge members in place at the desired elevation along the elongate shaft of the stake. Additional features of the invention include an enlarged head having elevated nubs to reduce hammer slippage while driving the stake and a ventral fin attached along the bottom of the shaft for the prevention of both axial and lateral movement of the stake once inserted into the ground.

Abstract: A vacuum infusion system and method provides for the introduction of desired chemical or treatment fluid directly into functional water conducting elements of a tree without the introduction of air and the subsequent embolization and dysfunction of part of the trees normal transpirational stream and method. With the present system, an orificed-needle is passed through a previously evacuated chamber containing a liquid medium which has been degassed. The insertion of the orificed-needle through this degassed liquid prevents the introduction of air into the tree while the treatment fluid is being pulled into the tree's transpirational stream by the normal xylem tension.

Abstract: Apparatus for providing a decorative cover for a flower pot comprising a collar wherein the collar clamps a sheet of material to the flower pot or wherein the sheet of material is connected to the collar and the collar is connectable to the flower pot.

Abstract: The present invention relates to the propagation and growing of plants, and particularly concerns an apparatus for growing large numbers of plants in a small area, with optimized use of available and artificial light, and to reduce the effect of plants competing for light.

Abstract: A door operating system is disclosed which includes a remotely or manually controlled fluid supply system (10) which pressurizes a reciprocable striker release assembly (50), and activates an opening cylinder assembly (30) functionally mounted to a door (17) and door frame (18) for opening the door.

Abstract: A gate assembly includes a sliding gate, a drive having a motor and motor pinion gear for driving the sliding gate, and a force transmission element for transmitting a driving force from the drive to the sliding gate. The force transmission element includes at least one threaded bolt having a bolt head, and a toothed rack engaged with the motor pinion gear. The toothed rack includes a toothed element having a base defining a first side having teeth attached thereto, and a second side opposite to the first side and forming a groove extending in a longitudinal direction of the toothed element for accommodating the bolt head. The groove defines a groove width corresponding to a width of the bolt head. The toothed rack further includes a support element connected with the sliding gate using the at least one bolt, and that is adapted to receive the toothed element. The support element includes at least one through bore for receiving the at least one bolt.

Abstract: The invention relates to a device for fastening a window of a motor vehicle in the guide device of a window lifter, consisting of retaining legs disposed on opposite sides of the lower area of the window, at least one of said retaining legs having an opening which can be engaged by a connecting element for retaining the window, wherein at least one upper part of at least one retaining leg is embodied to be resilient and supports an insertion section oriented in the direction of the lower edge of the window and essentially extending parallel with it. One feature of the invention is that the opening can comprise two cutouts, instead of one, in order to reduce the number of variations of catches required for use with window lifters. Another feature of the invention is that a connecting element for retaining the window in the guide device of a window lifter is already connected with the window prior to the window's insertion into the gap between the retaining legs.

Abstract: There is disclosed herein a double hung window assembly which includes a frame and a pair of vertically moveable pane carrying sash members. The frame is a multi-chambered structural plastic extrusion with provision for carrying interior decorative members. The frame includes elongated jamb liners of different colors. The sash includes wooden members carried by the plastic extrusion and constructed to define a stop whereby a pane is secured along its edges to the frame and between the stop and the plastic extrusion. The sash plastic members are essentially identical and the wooden stop members are identical for both sashes. The sash includes grooves to engage the jamb liners. Both the frame and sash carry interior wooden members constructed to be received and held in position relative to the plastic members and conceal the plastic members from interior view.

Abstract: A starter corner for use in constructing a shingled roof is provided. The starter corner is adapted to be positioned in the corner of a roof during construction for the purpose of preventing ice formation and backup damage to the finished roof.

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.