Abstract: A system and associated methods and software for loading a stock roll onto a center-driven winder/unwind device, or other devices, is described. The system may comprise a bridge crane coupled to two J-hooks operative to hold a stock roll; a chucking system, which engages a stock roll while the stock roll is held by the J-hooks, the chucking system being part of a center-driven winder/unwind device; and, an operating program, running on a computer, providing signals that direct the bridge crane to move the stock roll to a position within the manufacturing environment.

Abstract: A crane apparatus is installed on a pier, wharf, bulkhead wharf or other foundation extending into the water for directly transshipping containers from a vessel moored alongside the foundation to another transportation mode without necessity of ground placement of the containers. The crane apparatus includes a parent crane displaceable along the foundation for unloading containers from a vessel moored alongside the foundation and placing the containers on a first platform of the parent crane, and a sibling crane displaceable along the foundation beneath the parent crane independently of displacement of the parent crane for loading containers from the first platform onto over-the-ground vehicles.

Abstract: A portable jib for movably mounting to a crane girder includes a base frame configured for traveling along a girder and a support member coupled to the base frame, wherein the support member extends substantially upward from the base frame. A boom is coupled to a free end of the support member and the boom extends substantially radially outward from the support member. The base frame, the support member and the boom are assembled and mounted to the girder for use and disassembled and removed from the girder after use.

Abstract: A mobile lift crane includes a carbody having moveable ground engaging members; a rotating bed rotatably connected to the carbody such that the rotating bed can swing with respect to the ground engaging members; a boom pivotally mounted on a front portion of the rotating bed; a mast mounted at its first end on the rotating bed; a backhitch connected between the mast and a rear portion of the rotating bed; a moveable counterweight unit; at least one hydraulic cylinder; and at least one arm pivotally connected at a first end to the rotating bed and at a second end to the hydraulic cylinder. The arm and hydraulic cylinder are connected between the rotating bed and the counterweight unit such that extension and retraction of the hydraulic cylinder changes the position of the counterweight unit compared to the rotating bed.

Abstract: An inventory storage and retrieval system and method are provided for a shipping or storage facility. In an embodiment, the system includes: (a) a mobile computer and radio on a load-handing vehicle; (b) sensors on the vehicle to determine the ground location and orientation of the vehicle; (c) encoders that determine the position of a lifting mechanism relative to a chassis of the vehicle; and (d) a base computer and radio that communicates with the vehicle. The system maintains an inventory database of items and their respective storage locations in three dimensions as a result of the loading activity of the vehicle. The data can be used to guide the vehicle for ground movement generally to a storage location, appropriately orient the vehicle, and then to move the lifting mechanism of the vehicle to deposit or retrieve the item at a particular storage location.

Abstract: A mounting system and method for a portable hoist assembly usable in the load-carrying portion of a vehicle includes a post base and a surface support base. The post base including a tubular support post and a plurality of support rings attached thereto. The surface support base includes a substantially flat plate having a hole formed therein with a receiver sleeve extending therefrom. The tubular support post of the post base is inserted into the receiver through the hole in the substantially flat plate. The portable hoist assembly is inserted through the plurality of support rings. Hardware is used to affix the surface support base to the floor of the load-carrying portion of the vehicle.

Abstract: A method for controlling a boom construction and a tool articulated thereto, said boom construction comprising a first boom and a first actuator controlling the same, a second boom articulated to the first boom, and a second actuator controlling the same, as well as a third actuator controlling the position of the tool, wherein in the method: the first actuator is controlled manually; and/or the second actuator is controlled manually and the third actuator is also controlled at the same time automatically to control the position of the tool. For example, the first actuator is controlled by means of a first set point; and/or the second actuator is controlled by means of a second set point; and in addition, the third actuator is controlled simultaneously by using for the control a variable dependent on at least one of said set points.

Abstract: A method and a device for determining the rotary oscillation of a load suspended from a lifting gear are disclosed. The lifting gear includes a trolley equipped with a camera that can be oriented towards the load. The load includes at least two spaced apart markers, with one marker located on or near the axis of rotation, which extends in the lifting direction. A rotary oscillation of the load can be determined from the position of two markers, whereby at least one marker is recorded by the camera and its position is determined. At least at certain points in time, the rotary oscillation is determined by including a virtual position of a marker.

Abstract: A method for controlling the orientation of a crane load is described, wherein a manipulator 416 for manipulating the load is connected by a rotator unit to a hook suspended on ropes 410 and the rotational angle ?L of the load is controlled by a control unit using the moment of inertia JL of the load as most important parameter. The control unit is an adaptive control unit wherein the moment of inertia JL of the load is identified during operation of the crane based on data obtained by measuring the state of the system.

Abstract: A mandrel segment loader provides a reliable means of assembling the segments of a large multi-piece mandrel designed for the lay-up of composite materials in the manufacture of large structures such as one-piece fuselage barrels for wide-body aircraft and can also be used for removing the mandrel from the finished fuselage barrel by disassembling the segments. The mandrel segment loader provides transport and multi-axis positioning for the segments, which may weigh as much as 25,000 pounds, with linear positioning resolution in the realm of 0.002 inch and rotational positioning resolution in the realm of 0.005 degree. The mandrel segment loader is also more generally useful as a material handling system that can perform many useful manufacturing functions, such as loading passenger floors into a fuselage barrel when assembling an aircraft. Self-locking grippers prevent accidental self-release of a load.

Abstract: The present invention substantially relates to a method for erecting and disassembling an at least two-piece main boom for a lattice-boom crane. The erecting and disassembling procedure results in that the geometric kinematic properties of the main boom (1, 2) are used in such a manner that during the erecting and disassembling, the effective lever arm (1?) of the main boom (1, 2) is reduced. This results from the main boom (1, 2) being bent at the hinge point (A), at which at least two boom portions (1, 2) are connected to each other, and thus an angle position is produced between the two boom portions (1, 2). Further, the invention relates to a main boom (1, 2), which can be erected by the method as well as a lattice-boom crane having such an main boom (1, 2).

Abstract: In a method for maintaining a position of a load on a lifting gear, a position of a load, which is suspended from a trolley of a lifting gear via at least four cables, is determined and a swinging motion of the load is counteracted by selectively adjusting the length of at least one of the cables.

Abstract: A method for nonintrusive scanning of cargo containers quay side while the containers are being transferred between ship and land transportation utilizing a mobile cargo container handling buffer crane having a bridge crane mounted thereon for transferring cargo containers between a ship and land transportation with an intermediate transfer position whereby a suspended container can be noninvasively inspected by a longitudinally reciprocating container traversing radiation emitter apparatus.

Abstract: A steering system (10) for a vehicle, such as a gantry crane (12). The gantry crane (12) generally includes a support structure (14) having a first front wheel (32) and a second opposing front wheel (36) connected proximate a front portion of the crane (12), and a first rear wheel (30) and a second opposing rear wheel (34) connected proximate a rear portion of the crane (12). A control system connected to the crane includes a user interface (111) electronically coupled to a command potentiometer (114) and a programmable controller responsive to the command potentiometer for controlling the angular position of each of the first front wheel (32), the second front wheel (36), the first rear wheel (30) and the second rear wheel (34) to effect a steering mode selected through the user interface (111).

Abstract: The present invention provides an apparatus for suspending and transporting articles, and is provided with a wobble prevention member that is capable of moving between a support position where it abuts against a lateral surface of an article and a release position, and in the support position keeps the article from wobbling in at least one direction. The wobble prevention member has a roller capable of rotation about a vertical shaft, and by the roller abutting against the article when the wobble prevention member is in the support position, wobbling of the article is reduced.

Abstract: An intelligent assist method and apparatus are disclosed. The intelligent assist method includes imparting a manual force to a suspended object, determining an angle at which the suspended object is manually forced, generating motorized power to move the object in accordance with the angle at which the suspended object is forced, and inputting a signal to continue the motorized power and enable the object to continue moving on accordance with the angle at which the suspended object is manually forced.

Abstract: A steering system (10) for a vehicle, such as a gantry crane (12). The gantry crane (12) generally includes a support structure (14) having a first front wheel (32) and a second opposing front wheel (36) connected proximate a front portion of the crane (12), and a first rear wheel (30) and a second opposing rear wheel (34) connected proximate a rear portion of the crane (12). A control system connected to the crane includes a user interface (111) electronically coupled to a command potentiometer (114) and a programmable controller responsive to the command potentiometer for controlling the angular position of each of the first front wheel (32), the second front wheel (36), the first rear wheel (30) and the second rear wheel (34) to effect a steering mode selected through the user interface (111).

Abstract: A lifting apparatus includes a plurality of preferably four carriages, each carriage supporting a lifting boom. Two booms are pinned together to define a first pair, a second two booms being pinned together to define a second pair. Each pair of booms and connected carriages are placed on a preferably common travel path. Rigging can include a horizontal beam that extends between the first pair of booms and the second pair of booms. The beam can be attached to the pinned connection of each pair of booms with a sling. A powered motor-driven winch is used to power a cable that is wound between sheaves on the lower end portions of a pair of booms that are connected together. During use, the winches are simultaneously or nearly simultaneously operated to elevate the first pair of the booms and the second pair of booms at about the same time. The horizontal beam that spans in between booms is elevated.

Abstract: A control system for reducing cargo pendulation. The control system calculates a correction factor and adds the correction factor for the operator input motions in addition to the motion of the platform in order to provide a reference position of the suspension point of the hoisting cable. The reference position is then provided to a tracking controller so that the crane can be forced to track the needed motions for reducing the cargo pendulation.

Abstract: Methods and apparatus for eliminating instability in intelligent assist devices are disclosed. The intelligent assist device includes an overhead motorized moveable trolley, a support that extends downwardly from the trolley to a payload, and a sensor operatively coupled to the support to sense a characteristic of motion imparted by a human operator to the device. A controller is operatively coupled with the sensor and the trolley to control movements of the trolley. The controller estimates an amount of oscillation in the support that does not correspond to the motion imparted by the human operator and adjusts movements of the trolley based thereon.

Abstract: An automatic guidance system and method are provided for a gantry crane to permit accurate tracking along a path, including a curved path. The position of the crane is determined from two spaced apart GPS receivers fixed to the crane. A guidance controller determines a plurality of error measurements from respective front, center and rear points of the crane relative to a current tracking line, which is a line tangent to the path at a current position of crane. In an embodiment, the system includes a base station that can be used to transmit data to the crane to specify a particular destination location of the drive path, or to transmit data representing the drive path itself.

Abstract: This crane control apparatus and method with swing control and variable impedance is intended for use with overhead cranes where a line suspended from a moveable hoist suspends a load. It is responsive to operator force applied to the load and uses a control strategy based on estimating the force applied by the operator to the load and, subject to a variable desired load impedance, reacting in response to this estimate. The human pushing force on the load is not measured directly, but is estimated from measurement of the angle of deflection of the line suspending the load and measurement of hoist position.

Abstract: A stability measurement system is provided for a lifting vehicle including a vehicle frame, a turntable secured to the vehicle frame and supporting lifting components of the vehicle frame, and a turntable bearing disposed between the vehicle frame and the turntable. The stability measurement system includes a plurality of load sensors secured to the turntable bearing that measure vertical forces on the turntable bearing. A controller calculates a rotational moment applied to the vehicle frame from the turntable by processing the vertical forces on the turntable bearing measured by the plurality of load sensors. The forces are directly related to the stability of the machine. By monitoring the resulting moment according to a predetermined upper bound and lower bound, operation of the lifting machine can be controlled to substantially eliminate a tipping hazard.

Abstract: A collapsible, portable hoist that can be assembled and operated by a single individual, for lifting and conveying heavy objects onto and off of trucks, especially pickup trucks. When not in use, the hoist collapses down to a flat storage configuration that rests on, and is secured to, the truck's cargo walls without any portion extending beyond the truck. In order to deploy the hoist, one rotates its support frame up from the stowed position and then suspends from it the rail along which a trolley or other implement used to convey the object will travel. When the hoist is fully deployed, the trolley rail is mounted high above the bed, permitting tall objects to be manipulated. The hoist is constructed so as to be readily removable from the truck.

Abstract: A programmable control system for a crane that senses a hydraulic pressure of the lift mechanism, and controls the movements of the crane apparatus as a function of the magnitude of the hydraulic pressure. As the status conditions of the crane change, sense switches relay such information to a programmable controller and error codes are generated and presented to the operator. The control system can respond to the states of the sense switches and override wireless command inputs to the control system.

Abstract: A measurement system uses dual axis force sensor pins to effectively assess the tipping moment of a load-bearing vehicle and anticipate imminent tipping in any direction. The pins are installed in the pivot points of the boom of a lift vehicle and its main lift cylinder, substituting the standard structural pins presently used. For non-traditional boom support arrangements, one sensor pin for each moving part attachment to non-moving turntable is required. Each of the sensors provides the actual force components acting on the sensor in two perpendicular axes. The output signals are then utilized to assess vehicle stability and detect when the machine is approaching instability in order to warn the operator and/or restrict vehicle movements.

Abstract: A system and process are provided for controlling motion of a grappler of a gantry crane to avoid damaging an object to be lifted. In an embodiment, a speed of grappler movement is automatically reduced when in close proximity to the object. Furthermore, the grappler automatically stops when positioned appropriately to permit a latching mechanism to engage the object for lifting. Normal speed grappler motion is restored when the latching mechanism is fully engaged. In a particular embodiment, the grappler includes a plurality of height sensors at various positions along the grappler to determine the respective height of the grappler above a top of the object. Vertical motion of front and rear ends of the grappler are independently actuated and controlled to permit appropriate control when the grappler and/or the object are not level.

Abstract: A davit arm system includes a base that supports a davit arm and engages an underlying ground surface. The system components are preferably designed for arrangement in alternative ways to accommodate different installation environments, and/or for packaging in a bag that may be carried by a single person. The relative positions of the components are preferably adjustable relative to the base to further accommodate different applications. Yet another desirable option is to mount the davit arm on the support base in a manner that allows rotation about both a vertical axis and a horizontal axis. A winch is preferably mounted on the davit arm in a manner that counterbalances the davit arm relative to its vertical axis of rotation.

Abstract: A crane provided with a trolley, a hanging member, a rope member, and a hoisting device. The crane includes a horizontal position displacement detection unit which detects a horizontal positional displacement between at least two corners of the cargo and a landing place of the two corners; and a horizontal position displacement correction unit which corrects a horizontal positional displacement between the at least two corners of the cargo and the landing place of the two corners when the two corners have landed based on a detection signal from the horizontal position displacement detection unit. The horizontal position displacement correction unit corrects the position of a corner of the cargo so that the corner lands at the landing place of the corner, and then corrects the position of another corner so that the corner lands at the landing place of the corner.

Abstract: Crane apparatus is equipped with a container security scanning system for scanning containers for radioactive material, such as neutron or gamma ray emissions. The crane apparatus has a crane for unloading containers from a marine vessel and placing the containers on a deck located at the portal girder level of the crane and for transferring the containers from the deck to another location. The container security scanning system comprises one or more scanning units disposed on the deck, each scanning unit having one or more scanning platforms for supporting a container such that a bottom of the container is vertically spaced from the deck. A scanning device is movable beneath the container in a space between the underside of the scanning platforms and the deck for scanning the container to detect whether radioactive material is present. Existing cranes can be retrofitted with the container security scanning system, and newly manufactured cranes can be upgraded to include such a system.

Abstract: A system and method for moving a canister of spent nuclear fuel from a first location, which may be within a nuclear power generation facility to a second location such as a storage cask that is used for short-term or long-term storage of spent nuclear fuel includes a first lifting mechanism for engaging a transfer cask and a second lifting mechanism for engaging and lifting the canister of spent nuclear fuel. Preferably, the method is practiced by first positioning a canister of spent nuclear fuel within the transfer cask and then engaging the transfer cask with the first lifting mechanism. The canister is engaged with the second lifting mechanism. The transfer cask having the canister positioned within is moved to the vicinity of a storage cask, and the canister is lowered from the transfer cask into the storage cask by the second lifting mechanism without disengagement of the first lifting mechanism from the transfer cask.

Abstract: An improved method and system for a liftcrane in which a load is lifted through the combined action of first and second hoist drums. The method and system use a first rope wound on one hoist drum and a second rope wound on the second hoist drum. The ends of the ropes opposite the hoist drums are linked together to transmit tension between them. The load is coupled to the ropes. If the take up speed of one of the ropes exceeds the take up speed of the other, the linked ends of the ropes will shift. This condition is detected and the operation of at least one of the first and second hoist drums is modified to bring the take up rates into balance. This system is advantageously used with a hoist block sheave arrangement. This system can also be used with a single rope in which each of the ends of the single rope are wound on a separate one of the hoist drums and the load is coupled to the middle of the rope.

Abstract: A method of assembling a heavy duty mobile crane having a load handling boom that has a boom base section and other component parts. The method includes positioning the component parts adjacent said crane, such as on a truck, raising the parts from the truck bed in sequence with a self-contained lifter associated with said base section, lowering and placing each part in a position adjacent ground level for connection to said crane, and then connecting the parts to the crane so as to provide a complete working crane. The method applies particularly to assembling the boom sections and connecting them to the crane. Extension sections of the boom are handled by placing them at ground level and preassembling the sections to form an upper boom, and then connecting the upper boom to the base section. The method steps are reversed to disassemble the crane. The method also includes transporting the crane to a work site with the boom base section connected to the mobile crane.

Abstract: An apparatus and method of self-raising a mast for a crane having an upper works rotatably mounted on a lower works and a boom pivotally mounted on the upper works, the boom being supported by boom hoist rigging and a mast pivotally connected to the upper works. The crane further includes a self-raising mast assembly for controlling the position of the mast when the mast is not connected to the boom and is not supportable by the boom hoist rigging. The self-raising mast assembly comprises a mast raising yoke pivotally connected to the upper works, a hydraulic mast raise cylinder pivotally connected between the upper works and the mast raising yoke, and a hydraulic system for controlling the mast raise cylinder.

Abstract: A railroad car wheel changer assembly (10), adapted to be mounted on a gantry crane (12), is provided. The railroad car wheel changer assembly (10) includes a base assembly (60), a beam member (62) and a grappler assembly (64). The base assembly (60) is adapted to be attached to the gantry crane(12). The beam member (62) is attached to the base assembly (60). The grappler assembly (64) is adapted to engage a railroad car wheel assembly (100) and is attached to a first end of the beam member (62). The beam member (62) is articulatable to move the wheel assembly (100).

Abstract: The invention relates to a method for controlling the operation of a crane brake, the crane comprising an electric motor (2) controlled by means of a frequency converter (10) for hoisting and lowering movements of the crane; an electromechanical brake (9) having an impact on said movements, the brake being opened when the motor is started for a hoisting or lowering operation; a load sensor (8) weighing a load (7) to be handled; and an overload protection connected to the sensor, the frequency converter (10) being used for calculating the torque of the motor (2), which information is compared with the load information, or weight, obtained from the load sensor (8).

Abstract: A method for handling containers in which containers are stacked using a moveable crane with a travelling part such as a trolley (8) arranged to lift, move and land a container (7) on a stacking target (15) in a stack comprising a least one ground container (1). The method is characterised by the steps of measuring the horizontal position of the stacking target (15), determining the horizontal position of the ground container (1), and comparing the relative positions of stacking target (15) and ground container (1). An overlap is developed from the relative positions of the stacking target (15) and the ground container (1), and compared to predetermined limits. If the overlap is within limits a desired landing position (25) on the stacking target (15) is selected for the container (7). Advantages include automatic stacking, faster stacking, safer stacks and dense packing of stacks in a container terminal.

Abstract: An apparatus for controlling stacking of a load by a crane estimates a periodical displacement of a horizontal position of a tool. A speed with which the tool descends is controlled such that the tool or a load held by the tool lands on a desired position when the amplitude of the periodical displacement becomes maximum.

Abstract: A method for buffer crane operation for supplementing a quay crane operation and formed to operate thereunder with a landing deck for supporting a multiple of cargo containers in buffer operation above dockside cargo transport operations and for moving cargo containers therebetween by means of a dedicated crane engaged with said landing deck.

Abstract: A locking and latching system for use with a telescoping boom assembly in a crane or other lifting device is provided. The system may include complementary devices for latching and unlocking a selected boom section for telescoping movement relative to a next-adjacent boom section using an extension cylinder. Preferably, the devices are activated in a predetermined sequence using a single motive device. The motive device may include a single cylinder for performing both the locking and latching function. The locking and latching cylinder may be axially aligned with the extension cylinder to create a relatively compact locking and latching system that easily fits within the confines of the innermost boom section in a conventional boom assembly.

Abstract: A lifting apparatus includes a plurality of preferably four carriages, each carriage supporting a lifting boom. Two booms are pinned together to define a first pair, a second two booms being pinned together to define a second pair. Each pair of booms and connected carriages are placed on a preferably common travel path. Rigging can include a horizontal beam that extends between the first pair of booms and the second pair of booms. The beam can be attached to the pinned connection of each pair of booms with a sling. A powered motor-driven winch is used to power a cable that is wound between sheaves on the lower end portions of a pair of booms that are connected together. During use, the winches are simultaneously or nearly simultaneously operated to elevate the first pair of the booms and the second pair of booms at about the same time. The horizontal beam that spans in between booms is elevated.

Abstract: The invention concerns a process for the orientation of the load in cranes, in which the load hung from cables is rotated by a predetermined absolute angle using rotating gear between cable and load. Under the invention, here a regulating device is provided for the rotating gear with which torsion oscillations of the load are suppressed, where, as input values, the absolute rotating angular speed and the angular position of the rotating gear are measured and fed back to the setting input.

Abstract: A system is disclosed for eliminating sway of a load in a crane or crane-like system subject to operator's command. The load is suspended by a cable from a horizontally movable trolley and can be hoisted vertically. The system uses the principle of cancellation to eliminate sway even when the crane has simultaneous horizontal trolley and vertical hoisting motions. The system takes into account the full dynamical effect in computing cancellation signals. The use of a family of ordinary differential equations for the computation of the cancellation controls is a key component of the invention. In computing these controls, the differential equations are solved in real time using sensory measurement of the cable length and its time derivative.

Abstract: A method for buffer crane operation for supplementing a quay crane operation and formed to operate thereunder with a landing deck for supporting a multiple of cargo containers in buffer operation above dockside cargo transport operations and for moving cargo containers therebetween by means of a dedicated crane engaged with said landing deck.

Abstract: This pendant responsive crane control system has a sensor pendulum arranged above a hoist for the crane and a load sensor for determining the load lifted by the hoist. The sensor pendulum serves as a swinging link between the hoist and a crane drive for moving the hoist. Lateral movement sensors generate signals in response to lateral movement of the sensor pendulum. A crane control means directs lateral movement of the crane drive in response to the signals generated by these sensors. The load sensor used is preferably a load cell or strain gauge incorporated into the sensor pendulum.

Abstract: A loading device for ISO containers in a container terminal with a container bridge for the loading and unloading of ships and with automatic incoming and outgoing transfer of the containers by means of automatic guided vehicles, with at least one container load suspension device in the form of a spreader and devices for the intermediate positioning of the container within the loading device to allow the installation or removal of the twistlocks, and with platforms for the workers performing this task. The loading device consists of a polar bridge crane, which can rotate around its center vertical axis, and which is designed as a bridge crane with a trolley capable of traveling on a crane bridge supported on a circular track located in the rear area of the land-side rail of the container bridge.

Abstract: The invention provides a load measurement in a crane hoist system. A parameter adaptation process uses a model of the system in order to measure the lifted load. A controller monitors hoist speed and hoist torque feedbacks that are input into the model and processed using a filter, as well as a previously determined load value. The model adapts automatically to determine the weight of the lifted load.

Abstract: A method for synchronously retracting and extending a jib of a crane having a plurality of telescoping lengths, preferably in a vehicle crane, extending and retracting being with driving means which is one of a hydraulically-driven, multistage telescoping cylinder and a plurality of single-stage telescoping cylinders operated in parallel.

Abstract: A portable hoist system includes a base assembly which includes a pintle. Slidably mounted over the pintle is a hoist support assembly. The hoist support assembly includes a substantially vertical tube which is connected at its top portion to a support arm. The support arm is supported with respect to the substantially vertical tube by an angled brace member. On the top of the support arm is located a lifting strap control assembly. The lifting strap control assembly includes a windlass and a guide bar.

Abstract: A boom assembly for a crane or other lifting device is provided. The boom assembly includes a plurality of telescoping boom sections, each having an at least partially rounded portion, and a plurality of corresponding wear pads for reducing friction between the adjacent boom sections during relative telescoping movement. The rounded portion includes a plurality of equiangular breaks. Each wear pad is substantially identical and includes a contoured engagement surface for positioning adjacent to one of the plurality of breaks at the lower front end of each boom section. The identical wear pads are interchangeable, which eliminates the need for keeping a plurality of substantially different shapes or sizes of wear pads on hand for positioning at the lower front ends of adjacent boom sections. Spacers may also be provided between the wear pads positioned adjacent to the breaks on outer boom sections to prevent shifting during the relative telescoping movement.