Abstract: A compact, easily maneuverable lift that may be readily positioned and operated by one person, that is quickly and accurately adjustable to the desired height, and that is particularly applicable to servicing heavy parts such as aircraft batteries. The lift is easy to manufacture and may include a load platform configured to fit into tight spaces. Other embodiments are disclosed.

Abstract: The present invention provides a wind-turbine rotor-blade hoisting apparatus that enables attachment and removal of wind-turbine rotor blades without using a plurality of heavy machines and that enables attachment and removal of wind-turbine rotor blades on a site having a complex land shape with little flat land, a method for attaching a wind-turbine rotor blade, and a method for constructing a wind power generator.

Abstract: A portable hoist assembly is provided for lifting a hitch to be installed on the underside of a vehicle platform. The hitch has a hitch ball hole and the vehicle platform has a hole to be aligned with the hitch ball hole when the hitch is installed. The hoist assembly includes a hoist frame and a winch for paying out and drawing in a cable. The winch is supported by the frame above the vehicle platform hole. An elongated member is attached to the cable. The elongated member can be oriented in a first position wherein it can pass through the vehicle platform hole and the hitch ball hole. Also, the elongated member can be oriented in a second position wherein it cannot pass through the hitch ball hole. The elongated member can be lowered through the vehicle platform hole and the hitch ball hole in the first orientation and can secure the cable to the hitch in the second orientation.

Abstract: A system for servicing a water well including a well pipe having a pump and a motor at a bottom thereof. The well head has a platform to support a winch thereon. Also supported on the platform is an upstanding mast having a return wheel at a top thereof. One end of a cable is attached to the winch and another end is attached to a top of the well pipe after having been trained over the return wheel at the top of the mast. Activating the motor on the winch will pull the well pipe from the deep well including the pump and the motor.

Abstract: A lifting apparatus for extending upwardly out of a commercial building roof hatch, including a ladder docking device surrounding the roof hatch and optionally including roof hatch grab bars for ease of emergence through the roof hatch. The roof hatch ladder docking device is rapidly and removably attached to a permanent vertical ladder attached to the interior of the building. The lifting apparatus includes a winch post, a pulley mounted on the winch post and the ladder attachment device includes a fixed lower ladder attachment bracket along with a sliding upper ladder attachment sleeved over the winch post.

Abstract: A hoisting machine for an elevator includes a motor having a motor body and a rotary shaft rotatable with respect to the motor body and a boss, which is a handle fit/removal member and is fixed to the rotary shaft. A manually operated handle for manually rotating the rotary shaft can be removably fitted on the boss. The boss is provided with a rotation prevention portion for preventing, when the manually operated handle is fixed to the boss, the manually operated handle from rotating with respect to the boss in a rotational direction of the rotary shaft.

Abstract: An arrangement for raising and lowering relative light weight objects from a ground position to a high storage position. A bracket is secured to the high storage position and supports a vertical rotatable shaft, with a pair of horizontal reels and an automatic lock position. A rod is detachably attached to the shaft and extends horizontally downwardly to the ground position. Rotation of the shaft around its central axis causes rotation of the reels. The reels are affixed to two lines which extend generally horizontally from the reels, with the free ends of the lines extending over spaced pulleys and extending downwardly for attachment to the ground level. Rotation of the shaft allows raising and lowering of the object. A spring loaded mechanism associated with the shaft causes automatic locking of the reels in any position, and locks the reels upon raising to the high storage position.

Abstract: A dual drive winch system for efficiently providing a winch operable either manually or via an external motor. The dual drive winch system generally includes a rotatable spool adapted to have an elongated member wound thereon, a first drive unit mechanically connected to the spool and a second drive unit mechanically connected to the spool. The first drive unit rotates the spool via a manual force applied to the first drive unit and the second drive unit rotates the spool via a powered force applied to the second drive unit.

Abstract: A storage apparatus is disclosed. The storage apparatus comprises a mounting mechanism, a hoist system and a storage member. The hoist system, which is attached to the mounting mechanism, comprises at least one pulley. A hoist wire is disposed within each of the at least one pulleys. A hoist wire mount receives a first end of each of the hoist wires and also includes a power source. Finally, the storage member is affixed to a second end of each of the hoist wires.

Abstract: A tree stand hoist includes a holder frame with stop bars and harnesses for fastening to a tree, a bracket provided at the back side of the holder frame to support a cable wheel, a cable pulley assembly provided with a rope for fastening to the tree at a high place, a steel cable, which has one end fastened to the cable wheel and the other end inserted through the cable pulley assembly and terminating in a hook for hooking a tree stand, and a crank handle for rotating the cable wheel through a gear transmission mechanism to roll up the steel cable so as to lift the tree stand for setting up on the tree.

Abstract: An embodiment of the invention is directed to a system having a pulley attached to a building. A closed loop of cable is installed around the pulley. The loop is of sufficient length so as to reach, when deployed outside of the building, below the pulley to where emergency personnel gather in an area next to a base of the building (when responding to a disaster situation in the building). A winch around which the loop is to be operatively installed is located in the area next to the base. Other embodiments are also described and claimed.

Abstract: The invention relates to a winch (6) for raising and lowering persons, of the type that comprises a housing with an attachment member (16), an electric motor (39) driving a reel (27), a lifting strap (7) connected to the reel for winding and unwinding the lifting strap whereby the lifting strap is guided through one of two openings (17,19) formed in the housing.

Abstract: A lifter including tongs; an electric motor having a stator, a rotor, and one or more windings and a shaft operatively coupled with the first tongs for actuating the first tongs to an open position for receiving a load and actuating the first tongs to a closed position for engaging the load; and a vector drive controller electrically coupled to the electric motor for controlling the operation of the electric motor. A method of handling a load with a motorized lifter including at least one set of tongs and an electric motor coupled to the tongs, the method including moving the tongs of the motorized lifter to a home position by operation of the electric motor, wherein the electric motor is controlled by a vector drive controller; moving the tongs out of the home position; placing the tongs over the load; and positioning the tongs against the load by operation of the vector drive controlled electric motor so as to frictionally engage the load with the tongs.

Abstract: Winch for a vehicle and method for coupling and/or uncoupling an anchoring device to and/or from a positionally fixed anchor part The invention relates to a winch for a vehicle, in particular for a piste maintenance vehicle, with an elongate flexible traction means which is assigned to a drive device which is configured for the introduction of tractive forces to the traction means, and with a guide device which is provided for feeding the traction means to the drive device, and also with an anchoring device which is mounted on a free end region, facing away from the drive device, of the traction means and is configured so as to be adjustable between an opening position and a locking position, in order to allow a positive anchoring of the traction means on a positionally fixed anchor part, and also to a method for coupling and/or uncoupling an anchoring device to and/or from the fixed anchor part.

Abstract: A multiple-rope or multiple-cable pulling device is provided for positioning a load. The device can include an electronic controller that interprets a user's input from an interface such as a trigger or a joystick, and activates electronically controlled motors that drive one or more rope pulling mechanisms, such as winches. When the winches pull in or pay out cable in accordance with the controller's demand, the load is moved along the desired trajectory as specified by the user through the device interface.

Abstract: The invention enables the routine remote deployment of multi-function sensors from unmanned air ground platforms, such that a special assembly containing one sensor can be mounted and operated by remote control. The invention includes a circular frame with attached legs to grip the sensor during transport and recovery. The legs are stabilized (locked open or shut) by means of a threaded metal band/wire being retracted by means of a gear assembly pulling the threaded band and removing all slack. The legs' rotating point (fulcrum) is located between the circular frame and the top of the leg. The metal band is located nearer to the bottom of the legs and when it (band) is tightened, the legs are squeezed together sufficiently enough to grip the sensor inside their perimeter.

Abstract: A device for lifting and lowering a cover from a lower surface of a roof includes four lines connected to the ends of a top panel of the cover. The lines pass through eyes on the cover at the midsection of the top panel, then through pulleys on the lower surface of the roof, then to a cleat on a wall. Pulling the lines lifts the cover off the vehicle.

Abstract: A wind turbine has a nacelle frame and a first hoist substantially permanently mounted on the frame. The method comprises the processes of hoisting a second, more powerful hoist and crane on the frame with the first hoist; removably mounting the second hoist and the crane on the nacelle frame; hoisting a winch using the second hoist and the crane on the frame, and removably mounting the winch on said frame; performing operations involving handling heavy parts employing said winch; and removing and lowering said winch, crane, and second hoist from the frame.

Abstract: A hoist system for raising, lowering, or applying a pulling force to an object or equipment attached thereto. The hoist system has a hoist, a hoist adapter unit attached to the hoist, and a pull pin assembly. The hoist has a frame and a line, cable, or chain which is used to raise, lower, or manipulate an object attached thereto. The hoist adapter unit is removably attached to the frame of the hoist, and it is configured to contact either the object to be manipulated or a stationary object. The pull pin assembly is removably attached to the line of the hoist and to the object other than the object in contact with the hoist adapter.

Abstract: An apparatus includes a bi-directional DC motor; a gear reducer connected to the DC motor; a pulley mounted on an output of the gear reducer; an anti-back drive brake mounted on the output of the gear reducer; a reel wound with cable; a second pulley attached to the reel wound with cable; a belt for connecting the pulley and the second pulley; a water measuring device attached to an end of the cable wound on the reel; at least one shaft encoder attached to the motor for measuring the speed and direction of the motor; a DC power source connected to the DC motor; a microprocessor control electronics module connected to the at least one shaft encoder and the DC motor; and a remote control in communication with the microprocessor control electronics module.

Abstract: An engine frame and counter-roller support assembly provides for adjustable positioning of the support with respect to the engine frame, thus allowing differing cable-line spacing to be accommodated. The support includes a pair of carrier elements. The counter-roller is supported on an axle in the bore holes of the carrier elements. The carrier elements are identical and each are in the form of a plate with a headliner and reinforcement ribs. The headliner has a contact surface with a number of two-stage bore-holes which serve for the fastening of the counter-roller support to the engine frame. The bore-holes are arranged such that the counter-roller support can be fastened in different positions, according to the required cable-line spacing between cab cables and counterweight cables.

Abstract: The invention is a method for lifting and transporting a heavy load by using a heavy lift vessel with at least two heavy lift cranes adapted to operate simultaneously; mounting fly-jibs on the heavy lift crane to increase reach and height of the heavy lift crane; picking up a load from a first location using the fly-jib modules simultaneously; shifting the load from the first location to over a second location on the heavy lift vessel; placing the load on the second location; moving the heavy lift vessel to a second position; using a mooring system to maintain the heavy lift vessel at the second position; picking up the load from the second location using the fly-jib modules simultaneously; shifting the load from a second location to over a third location; and placing the load on the third location.

Abstract: A fixture for suspending banners, signs and the like on the sides of multistory buildings, includes a U-shaped bracket adapted to engage the sides and end of a vertical parapet or a horizontal overhang. The fixture supports a powered winch over which cables connected to the banner or the like are arranged so as to allow the raising and lowering of the banner by powering the winch. Clamps on the U-shaped brackets securely retain the fixture in position on the building.

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. Further disclosed is a base assembly support system which is connectable to the hitch receiver portion of a tow bar assembly on a vehicle such as a pickup truck.

Abstract: A portable dynamometer station with a vehicle mounted lifting assembly is disclosed. It comprises (a) a vehicle, such as a bus, for transporting the dynamometer, (b) a dynamometer with associated monitoring equipment, and (c) a lifting assembly mounted in the vehicle, for transporting the dynamometer from the vehicle to the ground.

Abstract: An apparatus includes a sleeve sized to receive a bar, the sleeve having a nub. The apparatus includes a movable assembly including a spindle, a drive axle to receive the chuck of a drill, and a bracket, the bracket sized to fit over either of the bar and the nub. A power relay of the apparatus receives a power cord of the drill and applies power from an electrical source to the power cord of the drill upon the operation of a power relay switch. A retainer, separate from the movable assembly, retains a drill power switch in an ON position.

Abstract: A lift, a system and a method for elevating a trailer are provided. The lift may have an “A” frame for supporting the trailer. The trailer may be placed on the lift and secured to the lift. A cable attached to the lift is used to pull the lift and the trailer towards a wall. The cable, with the use of a pulley system, pulls the trailer in an upward direction towards the wall such that the lift and the trailer may be elevated in a vertical direction. The lift with the trailer may be attached to the bracket on the wall and locked into place. The lift and the trailer may be removed from the wall by releasing a lock.

Abstract: A lift, a system and a method for elevating a trailer are provided. The lift may have an “A” frame for supporting the trailer. The trailer may be placed on the lift and secured to the lift. A cable attached to the lift is used to pull the lift and the trailer towards a wall. The cable, with the use of a pulley system, pulls the trailer in an upward direction towards the wall such that the lift and the trailer may be elevated in a vertical direction. The lift with the trailer may be attached to the bracket on the wall and locked into place. The lift and the trailer may be removed from the wall by releasing a lock.

Abstract: A collapsible apparatus is disclosed for lifting and transporting objects, such as toilets and similar plumbing fixtures. The toilet lifter has a support structure and a strap system attached thereto. The support structure has three vertical legs with wheels on the bottoms and horizontal support structures connecting the legs at the tops. The strap system includes a loop strap that engages a bowl of the toilet and rear straps that engage a back or middle portion of the toilet. The strap system is supported by the support structure above the toilet in use and passes across a pivot point on the support structure to raise and lower the toilet. The straps are connected to a toilet, and the strap system is retracted to lift the toilet. The support structure may be locked into a folded position for transportation.

Abstract: A lifting device for lifting and moving objects with minimal effort and a method for using the same is provided. The lifting device has a cable attachable to an object and a handle on the cable. Sensors in the handle may sense vertical pressure exerted on the handle and may put out a current to a variable-speed motor in a housing of the lifting device. The motor may release or may retrieve the cable at a speed dependent upon the amount of pressure applied, thereby raising or lowering the object. Pressure of three to five pounds is sufficient to lift any object. The operator may move the object in any direction up to a radius determined by the length of the cable from the object to the housing. The housing may have an upper portion that may slide forward relative to a lower portion. Consequently, this lengthens the radius of movement allowed to the operator.

Abstract: A hoisting device for spreader supporting slide member of a sunshade includes first and second ratchet combinations each including a first ratchet, and a second turning ratchet. The ratchet combinations are positioned to face two opposite sides of the sunshade shank with the second ratchets being positioned between corresponding first ratchets and the shank. The ratchet combinations are biased towards the shank with springs. A shaft is passed through the shank plus the ratchet combinations, and is joined to a handle for effecting rotation thereof. The shaft is joined to a reel, which contacts the second ratchets at two end disk portions. Friction of the second ratchets against the end disk portions counteracts gravity on the slide member to prevent the sunshade from unwontedly folding from spread position once the sunshade is spread.

Abstract: Apparatus and methods for preventing overlap of coils on a cable of a rotatable winch drum have a rotatable roller which is mounted at a certain location with respect to the axis of rotation of the winch drum. The rotatable roller has an outer surface which is engageable with a side surface of the incoming coil of the cable as the incoming coil is being formed. The rotatable roller exerts a sufficient force through the roller and the body of the cable at the incoming coil to maintain the roller engaged portion of the incoming coil at the location of the rotatable roller and to shift all previously formed engaging adjacent coils of the cable sufficiently longitudinally on the surface of the winch drum in a direction along the axis of rotation of the winch drum so as to make room for the formation of the incoming coil directly on the surface of the winch drum.

Abstract: A door operating apparatus is provided for safely and efficiently opening and/or closing a side door of a railway boxcar by moving a door engagement member laterally.

Abstract: A portable hoist primarily for mounting on the ground at a manhole or similar location for lifting a load such as a person entering the manhole includes a base with a generally Y-shape defining a rear leg and two diverging front legs for mounting on the ground with the front legs either side of the hole. A jib portion is mounted on a vertical post portion of the base and extends upwardly and forwardly therefrom to a cable guide at an upper end overlying the hole. The jib portion is formed by a tubular body extending substantially from the bottom end at the base to the upper end which is smoothly curved with a constant radius of curvature. The body is formed in two parts with one siding inside the other and of the same curvature. Each part has a straight end portion where it attaches to the base and the cable guide respectively. A winch mounting for a winch for the cable is attached to the lower portion at its upper end. The front legs are also formed similarly as two inter-fitting curved parts.

Abstract: An apparatus for the controlled lowering to the ground of a cut portion of a tree includes a rope and an anchor having an arrangement of guiding protuberances, each guiding protuberance including a bearing surface frictionally engaging and redirecting the rope without the rope fully encompassing any portion of the anchor including any of the guiding protuberances. Three guiding protuberances define a triangular arrangement. Of the three, a first guiding protuberance is disposed in proximity to an intermediate guiding protuberance defining a segment of a rope path therebetween, and a second guiding protuberance is disposed in proximity to the intermediate guiding protuberance defining another segment of the rope path therebetween without the segments crossing. A mounting member is attachable to the tree and a guiding member is pivotally connected to the mounting member along a pivot axis and includes an arrangement of guiding protuberances generally extending to each side thereof.

Abstract: A lifting device for lifting and moving objects with minimal effort and a method for using the same is provided. The lifting device has a cable attachable to an object and a handle on the cable. Sensors in the handle may sense vertical pressure exerted on the handle and may put out a current to a variable-speed motor in a housing of the lifting device. The motor may release or may retrieve the cable at a speed dependent upon the amount of pressure applied, thereby raising or lowering the object. Pressure of three to five pounds is sufficient to lift any object. The operator may move the object in any direction up to a radius determined by the length of the cable from the object to the housing. The housing may have an upper portion that may slide forward relative to a lower portion. Consequently, this lengthens the radius of movement allowed to the operator.

Abstract: A portable hoist primarily for mounting on the ground at a manhole or similar location for lifting a load such as a person entering the manhole includes a base with a generally Y-shape defining a rear leg and two diverging front legs for mounting on the ground with the front legs either side of the hole. A jib portion is mounted on a vertical post portion of the base and extends upwardly and forwardly therefrom to a cable guide at an upper end overlying the hole. The jib portion is formed by a tubular body extending substantially from the bottom end at the base to the upper end which is smoothly curved with a constant radius of curvature. The body is formed in two parts with one siding inside the other and of the same curvature. Each part has a straight end portion where it attaches to the base and the cable guide respectively. A winch mounting for a winch for the cable is attached to the lower portion at its upper end. The front legs are also formed similarly as two inter-fitting curved parts.

Abstract: A combined utility cart and lifting device, the cart having a tongue adapted to receive an elongated rod containing a winch and cable. The cart can be placed to position the rod and winch in a vertical position enabling a cable on the winch to move vertically to act as a lifting device.

Abstract: A device and method to assist a person to walk up a flight of stairs is provided. The device includes a winch that is suitable for mounting at the top of the stairway having a winch cable of sufficient length to provide walking assistance along the length of stairway desired. A winch controller is attached to the winch cable that is adapted for grasping by the person to be assisted. The winch controller may include a switch operable by the hand of the user to selectively cause the winch to operate and provide assistance to the user.

Abstract: Apparatus for hoisting and suspending a pick-up truck cap adjacent the ceiling of a storage structure. The apparatus includes a slotted, aluminum beam and plural lifting straps. The lifting straps are removably secured at two positions on the beam. Plural storage cables are attached to the ceiling of the storage structure and extend around the truck cap. Each storage cable is adapted to be removably positioned on hooks disposed in the ceiling of the storage structure. A conventional worm gear winch and pulley system is provided for hoisting.

Abstract: There is disclosed a lifting device for lifting and moving heavy and/or cumbersome objects such as tree stumps, large rocks, logs, landscaping rail road ties, manhole covers, and the like. The device has a central housing and a plurality of support legs pivotally secured adjacent their upper ends to the housing. The lower ends of the support legs are mounted on wheels equipped with brakes to facilitate moving and stabilizing the device. A winch is mounted to one of the support legs and a pulley is suspended from the housing. One end of a first flexible means is wound about the winch, its other end is provided with a lock means and its intermediate length is threaded over the pulley. One end of each of a plurality of second flexible means is secured to the lock means while the other end of each is provided with means to engage a heavy and/or cumbersome object.

Abstract: A recovery device particularly useful in confined space and remote rescues. The recovery device includes a base plate, a winch coupled to the base plate, and an anchoring plate coupled to the base plate to detachably couple the base plate to an object that will support the recovery. A cord is attached to the winch to raise or lower the load to or from the recovery device or object. A guide roller assembly is coupled to the base plate to guide the cord and reduce the amount of friction on the cord that occurs when raising a load with the winch.

Abstract: The present invention provides a portable pulling apparatus suitable for mounting in an exit pit during installation of a pipeline. A portable pulling apparatus of the invention includes an elongated stake having a lower end portion configured for insertion into the ground and an upper end portion. A winch including a pulling cable is mounted on the upper end portion of the stake by a suitable fixture. The winch can then operate to exert a horizontal pulling force on a cable and is secured against movement when the lower end portion of the stake is inserted into the ground. Such a pulling apparatus can be used in a method of installing an underground pipe according to the invention.

Abstract: A two wheeled trailed vehicle intended to be towed by a conventional frontal hitch attachment to the rear of an all terrain vehicle (ATV) or other relatively lightweight four wheel drive vehicle has a fixed, rigid, rear vertical hoist supporting an electric winch operated lift cable run through a snatch block at the top end of the hoist. Power is supplied by either a battery or other suitable source such as a small gasoline powered electrical generator on board the two wheeled vehicle and the winch is preferably controlled remotely as well as manually. A cinch attached at either end to a pair of lateral support points well below the snatch block is utilized to secure the end of the load elevated with operation of the winch upon the lift cable through the snatch block and attached to a choker chain which is removed after the load has been taken up by the cinch.

Abstract: An extensible boom or strut has a telescoping action easily adjusted for appropriate length, and further is capable of attachment to a fixed point such as on a ceiling or wall at one end, and a lighting fixture or such at the other end. A torque tube is engaged with a cable winding device for playing out and winding up the cable which pulls on the innermost segment of the boom to shorten it or relaxes to allow gravitational force to lengthen it.

Abstract: A hoist apparatus is provided for a vehicle, such as an all terrain vehicle (ATV) and includes a support bracket assembly for mounting on the vehicle. The support bracket assembly includes a horizontal support plate and a hoist-axle-reception channel depending downward from the horizontal support plate. A hoist assembly is provided and is supported by the support bracket assembly. The hoist assembly includes a hoist axle received in the hoist-axle-reception channel and includes a hoist base plate supported by the horizontal support plate. Game, such as a deer, can be supported by the hoist assembly and rotated around the support bracket assembly on the hoist axle and the hoist base plate. In accordance with one embodiment of the invention, the support bracket assembly includes mounting plates for mounting on the rear of the vehicle. In accordance with another embodiment of the invention, the support bracket assembly is mounted on a side of the vehicle.

Abstract: A load lifting device of the hoist type, comprises a flat strip 5 arranged to form two hoist runs on opposite sides of a connection member 6 for a load. The two runs of the strip 5 are simultaneously wound up on, or unrolled from, a single reel. A spacing roller 20 forms in the strip 5 a substantially horizontal upper run. This improves the stability of the load by spacing apart the upright runs 21, 22 of the hoist.

Abstract: A holding device for storing a hard-top including a belt system into which the hard-top can be placed in such manner that the weight of the hard-top is supported essentially entirely by the belt system. The belt system enables the hard-top to be fixed in the holding device and attached thereby to a wall or a ceiling of a room. A protective cover into which the belt system is sewn, can also be provided. The holding device is suitable for hard-tops with attachment pins as well as for hard-tops without attachment pins.

Abstract: A recovery device particularly useful in confined space and remote rescues. The recovery device includes a base plate, a winch coupled to the base plate, and an anchoring plate coupled to the base plate to detachably couple the base plate to an object that will support the recovery. A cord is attached to the winch to raise or lower the load to or from the recovery device or object. A guide roller assembly is coupled to the base plate to guide the cord and reduce the amount of friction on the cord that occurs when raising a load with the winch.

Abstract: The present invention relates to a collapsible device for assisting a construction worker in erecting a framed wall. The device includes an elongated telescoping arm having a planar foot member at a first end thereof for vertically securing the arm to a floor. A first end of an elongated nylon strap is attached to a retraction mechanism on the arm. A second end of the nylon strap has a bracket thereon for securing to the top of a wall. The telescoping arm has a weight indication means for indicating to a user the weight of a wall being erected thereby. Accordingly, the strap may be secured to a horizontally oriented wall and the nylon strap is retracted causing the wall to pivot to a vertical position. The telescoping arm allows the device to be easily collapsed for transport or storage.