Abstract: Floor panels are shown, which are provided with a mechanical locking system including a flexible tongue in a displacement groove. The flexible tongue may be formed from the core material of the floor panels and inserted during production into the displacement groove. The locking system may be locked with vertical folding.

Abstract: The disclosure relates to an outdoor flooring assembly for securing flooring trays to improve stability and wind uplift resistance. The flooring trays each include a plurality of securement mechanisms coupled to a bottom surface thereto, the securement mechanisms designed to interconnect with one another to securely retain adjacent trays together and minimize the risk that any individual tray is dislodged.

Abstract: An adjustable suspension assembly for suspending a lower structure such as a platform from an upper structure such as a portion of a bridge. A chain, which is attachable at one end to the upper structure or to an end of a cable which is attachable at its other end to the upper structure, is attached at its other end to a device. The device, which is attachable to the lower structure, has a pair of aligned apertures in its side walls for receiving pins. The pins are spaced to receive a thickness of a chain link but not to receive a width of the link, whereby a selected link to achieve a desired lower structure height may be cinched between the pins. When the chain is attached to a cable, the cable has an eyelet formed by folding an end portion of the cable back over the cable and swaging the cable end portion to the cable. The chain is attached to said eyelet by receiving the end portion of the cable in one of the chain links before the cable end portion is swaged to the cable.

Abstract: The invention relates to water amusement facilities generating artificial waves for surfing. The technical result is a simpler and lighter design and a shorter assembly and dismantling time along with the capability to control the water flow rate and to stabilize the flow.

Abstract: The present invention provides an inflatable swimming pool convenient for drainage, which comprises an air chamber layer and a bottom pad. The air chamber layer defines an approximate rectangle with two long sides of the rectangular air chamber layer recessed inwards. The bottom of the air chamber layer is closed at a bottom plane by the bottom pad to form a pool structure, and after water is filled between the air chamber layer and the bottom pad, the two long sides of the air chamber layer can expand outwards to form a straight rectangular pool. An accommodating chamber is further arranged in the air chamber layer. The air pump is communicated with an inner cavity of the air chamber layer through an inflation communication pipe. The inflatable swimming pool of the present invention is more convenient to use, has better drainage efficiency and can be inflated automatically.

Abstract: Coping arrangements and methods for mounting coping arrangements for swimming pools and related structures are provided. The coping arrangements include an elongated base member shaped and adapted to be received by a wall of a swimming pool; and a plurality of elongated top members, each of the plurality of elongated top members are adapted to be replaceably mounted to the elongated base member, and each of the plurality of elongated top members having an exposed contour different from each of the other elongated top members. The different exposed contours of the top members of the coping arrangement may comprise different cross-sectional. Methods for changing a coping arrangement, coping arrangement kits, coping members, and methods for installing a pool are also disclosed.

Abstract: A multistorey garage for buses includes: an elevator platform; an elevator transmission system; a vehicle supporting plate; a charging device; and a steel cable set. The elevator platform is positioned on a ground floor of the multistorey garage. The elevator platform includes a storage and retrieval device and a safety leveling device. The elevator transmission system is positioned on a top floor of the multistorey garage. The elevator transmission system and the elevator platform are arranged symmetrically with respect to a horizontal central axis of the multistorey garage. The steel cable set is connected to the elevator transmission system, a counterweight, and the elevator platform. In the multistorey garage, a vehicle supporting plate is provided in each parking space. The charging device is mounted at the vehicle supporting plate. Also provided is a method of using the multistorey garage for buses.

Abstract: A tree stand hunting blind is comprised of two sides connected by a lower center portion. The blind does not have a roof and does not have a complete front wall. This allows a user to stand up and shoot a firearm or bow in any direction, including directly under the blind or directly above the blind. The bottom platform of a tree stand and the bottom portion of the blind function as a “floor” that helps hide the user from game animals below the blind. The sides of the blind break up the user's silhouette and help hide the user and the tree stand from game animals that are not directly under the blind. Each side of the blind incorporates a window with a moveable shade mechanism that allows them to be fully or partially opened or closed as needed by the user.

Abstract: A modular fence system is disclosed herein. The modular fence system includes a frame having a fence post bracing bar, an upper locking bar, a lower locking bar, an upper stationary bar, a lower stationary bar, wherein fence boards may be coupled and uncoupled from the frame when the upper and lower locking bars are in the open position. The frame may be utilized with removable fence boards or a lattice style fence. The modular fence system is useful for simple installment of aesthetic and removable fence arrangements.

Abstract: An enhanced security fence for use in high security situations is provided. The fence is made of high strength materials that are preferably welded together in a convenient location and sent as prefabricated sections to the installation location to form an all welded bracket-less perimeter barrier fence system. Posts with section hangers are provided and installed at a perimeter, and the prefabricated panels are quickly and securely attached to the posts. The panels can be friction fit to the posts and, if desired welded thereto. The invention includes a method of creating an enhanced security fence, that includes prefabrication of panels and rapid fitting and securing the panels to posts to more quickly create a secure perimeter in places having difficult environments.

Abstract: A door knob assembly that provides an interactive visual and aural assembly familiar to a room occupant and that responds to variations in the manner of rotation of the knob in a plurality of responses, depending on the direction and rate of rotation applied to the knob, providing messages appropriate to the entertainment, safety and/or training of the knob operator and/or room occupant.

Abstract: A lock with a roller deadbolt includes a driving member having a first slot and a transverse slot. The driving member is connected to a first spring, a second spring and a positioning rod. A deadbolt includes a body, an insertion member, a roller and a slide. The driving member is connected to the body. The insertion member is received in the body. The second spring biases the insertion member. The slide is restricted by the positioning rods of the driving member and has a first guide pin extending through the first slot. The slide is movable along the first slot. The guide hole includes an extension slot and an inclined slot which inclinedly communicates with the extension slot. When in a non-transmission position, the roller protrudes beyond the receiving space. When in the transmission position, the roller does not protrude beyond the receiving space.

Abstract: The invention relates to locking devices of enhanced security. primarily locks for locking dead bolt systems of safes, metal doors of residential buildings, public and other buildings and offices, as well as to padlocks, etc., where a high level of resistance to breaking is required.

Abstract: A zipper lock has two locking members to secure two zipper pulls of a suitcase and a control plate to cause the locking member to disengage from the zipper pulls. The lock has a latch engaged with the control plate, the latch positionable in a first latch position when the lock is in a locked mode or in a second latch position to open the lock. The lock has a combination mechanism using dials and clutches to control the movement of a spindle which allows the latch to move the second latch position when the arrangement of the dials matches the correct combination code. The lock also has a key-overriding mechanism using a cylinder to cause the movement of the latch when a correct key is used to turn the cylinder to open the lock. A recovery mechanism allows a user to recover the lost combination code.

Abstract: A combination lock has a body formed from a stack of plates each having various openings to form some of the channels or holes such as the locking hole to receive the short leg of the shackle, the long-leg channel, the spindle hole, the dial slots, the ratchet-pin holder slot and the bolt slots. The short leg and the long leg of the shackle each has a cutout to receive a locking bolt. The spindle has a locking surface to engage the locking bolts with the cutouts when the lock is in locked mode. The spindle also has a neck to release the locking bolts from the cutouts when the lock is in opened mode. The lock has a directional plate and a reset button near the lock's bottom end to control the rotation and the downward movement of the spindle in the reset mode.

Abstract: An apparatus for securing a wrap or sheet roll is disclosed. The apparatus includes a cable in which a first end of the cable is mounted to a structure and a second end of the cable is mounted to a base plate. The apparatus further includes a lock notch provided at the cable. The apparatus has a lock pin removably mounted to the lock notch. The apparatus also has a lock plate mounted to the cable. The apparatus includes a sheet roll mounted to the cable as well. The sheet roll is mounted to the cable by drawing the base plate through an opening provided at the sheet roll. The lock plate is placed above the sheet roll and the lock pin is mounted to the lock notch to secure position of the sheet roll between the lock plate and the base plate.

Abstract: This opening/closing body control device for vehicles comprises a lock device and a control device. The control device comprises: a reversal control unit; a reversal stopping unit; a first error detection unit that detects a first state change error in a first neutral switch, when reverse rotation of a rotating member has been stopped on the basis of a change in the on/off state of a second neutral switch during reverse control after closing control; and a second error detection unit that detects a second state change error in the first neutral switch, when reverse rotation of the rotating member is stopped on the basis of a change in the on/off state of the second neutral switch during reverse control after release control.

Abstract: A vehicle hood latching mechanism is disclosed. The latching mechanism includes a housing securable to the vehicle body, a latch member pivotally connected to the first side of the housing, the latch member includes an external surface defining an abutment surface, a fork bolt adjustably connected to the second side of the housing and movable between a fully latched position, and an actuator assembly pivotally connected to the second side of the housing. The actuator assembly includes a first lever configured to selectively abut against the engagement surface of the fork bolt and a second lever configured to selectively engage the abutment surface of the latch member. The first lever is pivotally connected proximal to a first end of the mounting plate and the second lever is pivotally connected proximal to a second end of the mounting plate.

Abstract: A latch assembly for a storage compartment in an automobile is disclosed. The latch assembly includes a latch module, including a latch bolt, and a striker. The latch bolt is moveable between an extended latched position, in which the bolt axis is coaxial with a longitudinal axis of the latch casing, and a retracted unlatched position, in which the bolt is withdrawn into, and its axis is oblique with respect to, the latch casing. When in the oblique position, the latch bolt is retained in the unlatched position within the latch casing. A spring member within the latch casing biases the latch bolt to both extend axially from the latch casing, and pivotally toward the inner retaining surface of the latch casing. Upon closure, the bolt is moved, via contact with the striker, from the withdrawn oblique retained position, and returns via spring bias to the latched extended position.

Abstract: A magnetic latch (10) for an appliance is disclosed for use with a strike plate (12). The latch includes a body (16) having two oppositely disposed side walls (18) and a bottom surface or wall (20). The body defines a magnet recess (26). An elongated handle (40) is pivotally coupled to the body. A spring loaded plunger pin (34) biases the handle. A magnet assembly (44) is positioned within the body. The magnet assembly includes a magnet (46) having a peripheral edge (48), and a pair of metal plates (54). The magnet has a peripheral cushioning sleeve (58) extending about the peripheral edges of the magnet. The peripheral sleeve is generally rectangular in shape having two oppositely disposed end walls (60) which include a cushioning projection (68). A pivot pin (74) extends through the magnet assembly to allow rocking motion.

Abstract: A lockable latch (8) is disclosed for walk-in cold rooms which includes a lockable strike (10) with an exterior strike assembly (16) and an interior release assembly (17). The exterior strike assembly includes a housing (25) and a rod holder (32) configured to releasably hold a coupling rod (35). The exterior strike assembly also has a metal anti-rotation plate (40) removably coupled to the housing. The interior release assembly includes a turn knob (53), an escutcheon plate (54), and an index washer (55). The turn knob includes two oppositely disposed alignment projections (77) and a radial array of steps (78) which includes four, re-occurring series of three steps. The index washer has a four time re-occurring series of steps (93).

Abstract: The present invention relates to a safety locking device for interlocking a safety door, having a movable part designed for being fastened to a moving part of the safety door and having a locking element, and a stationary part designed for being fastened to a non-moving part of the safety door. The stationary part includes a receiving section having an opening for the reception of the locking element, where the locking element can be inserted into the receiving section from different insertion directions when the locking element is aligned in the insertion direction. The stationary part includes a latch selectively movable from a locking position into a release position.

Abstract: A camera housing includes a simplified draw latch for securing a first portion and a second portion of the camera housing together. The draw latch can include a draw hook and a mid-linkage. The draw latch enables a user to easily open and close a camera housing, and may also allow a user to establish an air-tight or water-tight seal between the housing portions for use in various activities, including scuba diving.

Abstract: The invention relates to a hinge for connecting two securing arts for directly or indirectly securing to two furniture parts pivotable relative to each other, the securing parts being pivotably connected to each other by means of a connecting assembly. It is thereby provided that a linear guide element is disposed on each of the two securing parts, said elements interacting to form a linear guide, and that the hinge comprises a guide device implemented for displacing the linear guide depending on the pivot position of the securing parts relative to each other. The invention further relates to a method for displacing a first securing part of a hinge in an articulated manner relative to a second securing part. The hinge and the method enable a pivotable connection between furniture parts having at least a reduced risk of injury.

Abstract: A door tensioning system for an oven or other appliance includes a chain and spring assembled as a pull member attached at one end to a door and at an opposite end to a base member of the appliance in a manner maintaining spring-mediated tension between the door and the base/bulk of the appliance. The pull member is routed around a bracket-assembly-mounted pulley, where the bracket assembly includes at least one movable bracket member that is movable with the pulley in a manner that will increase or decrease tension in the pull member by increasing/decreasing its effective length between its ends.

Abstract: To provide a power slide window in which the projecting dimension of the guide rail from the panel surface is small, the guide rail (4) defines a pin guide groove (26) that includes a groove main portion (26a) extending along a panel surface (2b) and at least one groove extension portion (26b) configured to drive a slide panel (3) in a direction to approach the window glass pane (2) via a pin (16) when the slide panel reaches the vicinity of the closed position. A slider guide groove (27) provided in the guide rail 4 to allow sliding of the slider 20 which is slidingly driven in the opening and closing direction and a groove main portion (26a) of a pin guide groove (26) are formed at least partially in common with each other.

Abstract: A latch module for controlling an opening and a closing of a door of an appliance includes a latch, a spring that applies an elastic force to the latch, a motor; and a cam that contacts a contact surface of the latch and is coupled to the motor to drive the cam to pivot the latch. The cam includes a first radius, a second radius, and a third radius in a circumferential direction at an outer circumference of the cam. The latch is positioned at a first basic position when the first radius of the cam contacts the contact surface of the latch, positioned at a second basic position when the second radius of the cam contacts the contact surface of the latch, and positioned at a third basic position when the third radius of the cam contacts the contact surface of the latch.

Abstract: An exemplary door closer has an adjustable size and includes a rotatable member operable to adjust the size and an indicator mechanism configured to indicate the current size. The indicator mechanism includes a cover mounted to a housing of the door closer and a dial rotatably mounted to the cover. The dial is engaged with the rotatable member such that the dial rotates in response to rotation of the rotatable member. The cover includes an indicating region, and the dial includes a display surface including indicia relating to the sizes of the door closer. The display surface is non-perpendicular to the rotational axis of the rotatable member. When the door closer has been adjusted to a particular size, indicia relating to the particular size are indicated by the indicating region.

Abstract: The invention relates to a hinge (10) comprising a swivellable hinge part (12), a stationary hinge part (14) and a tensionable spring element (34), wherein the stationary hinge part (14) is designed with a first bearing (16) as well as a second bearing (18), wherein the bearings (16, 18) have swivel axes (S1, S2) that are offset to one another. According to the invention, the swivellable hinge part (12) is mounted on the stationary hinge part (14) via the first bearing (16) such that it can swivel about a swivel axis (S1), and the tensionable spring element (34) is arranged on the stationary hinge part (14) via the second bearing (18).

Abstract: A hinge for the rotatable movement of a closing element, such as a door, a window, a shutter or the like, includes a fixed element anchorable to a stationary support structure and a mobile element anchorable to the closing element. The fixed and movable elements are mutually coupled so as to rotate with respect to each other between an open position and a closed position. One of the fixed or movable element includes a working chamber, with a plunger disposed to slide along a longitudinal axis and operatively coupled with the other one of the fixed or movable elements so that the sliding of the plunger corresponds to a rotation of the movable element.

Abstract: Disclosed is a hinge assembly for rotatably mounting a trunk lid to a vehicle body. The hinge assembly for a trunk lid of a vehicle, includes a hinge arm configured to be coupled to the trunk lid, a hinge bracket configured to be coupled to a vehicle body and having a hinge shaft, the hinge arm being rotatably coupled to the hinge bracket, a torsion bar configured to be coupled to the hinge arm and to provide an elastic force to the hinge arm in an opening direction, and a cushion assembly provided at one end of the hinge arm adjacent to the hinge shaft and configured to adjust a rotation speed of the hinge arm in response to the elastic force of the torsion bar.

Abstract: The invention relates to a fluid damper for bodies that are movable relative to one another, said damper comprising a piston that is movably guided in a cylinder. At least one through opening is provided in the piston and/or between the piston and the cylinder for through-flowing fluid. Adjustment means are provided on the fluid damper for adjusting a limitation least of the maximum possible through-flow cross section for the fluid at least one passage opening. The piston is connected to a piston rod leading out of the cylinder. The adjustment means comprises detent connection which is pushed, in a radially non-twistable manner, onto the end of the piston rod located in the cylinder, and holds the piston in a desired position in the cylinder.

Abstract: Sliding operator assemblies and associated fenestration units, systems, and methods of use and assembly are described. Some such sliding operator assemblies transition a first, linear actuation force along a first axis (e.g., vertical) to a second actuation force along a second axis (e.g., horizontal) to cause a drive mechanism to impart opening and closing forces, respectively, on the sash. Some designs relate to belt-, twisted ribbon-, or band-drive sliding operator assemblies.

Abstract: A retaining element for a side window of a vehicle, includes a first securing section and a first contact section connected thereto for securing to a first surface of the side window, a second securing section and a second contact section connected thereto for securing to a second surface of the side window, wherein the first and second securing sections are connected to one another opposite the contact sections via a hinge section such that the first securing section together with the first contact section and the second securing section together with the second contact section is pivotable relative to one another, whereby the retaining element is openable and closable. In the closed state, the securing sections are in surface contact with one another and, together, are suitable for securing to the vehicle and the contact sections are suitable for securing to two opposing surfaces of the side window.

Abstract: A system that performs a method is disclosed. Image data from a first camera mounted on a vehicle is received, the vehicle including a first element configured to open into a first space external to the vehicle, and the image data indicative of motion of a first object during a first time period, the first object located outside of the first space. Whether the motion of the first object during the first time period indicates that the first object will interfere with operation of the first element during a second time period, after the first time period, is determined. In accordance with a determination that the motion of the first object indicates that the first object will interfere with the operation of the first element during the second time period, an action that avoids the interference is performed.

Abstract: A pinch detection device, for detecting the occurrence of pinch during closing of one pair of sliding doors, is composed of a first door front edge rubber to be attached to an edge portion in a closing movement direction of one sliding door of the one pair of sliding doors, and a second door front edge rubber to be attached to an edge portion in a closing movement direction of an other sliding door of the one pair of sliding doors. The first door front edge rubber includes a recessed portion, which is open toward the second door front edge rubber, with a linear shape pressure sensitive sensor, which is sensitive to a pressure in the event of pinch, being disposed in that recessed portion.

Abstract: A hinged-panel opening and closing system includes: an anchor designed to be located on a hinged panel; a gear motor designed to be located on a supporting structure; and a movement-enabling component capable of angularly displacing the hinged panel relative to a receiving structure. The movement-enabling component includes: (a) a movement-enabling shaft located on the supporting structure and, at one shaft end, coupled to the gear motor; (b) a spindle located on supporting structure and coupled to the movement-enabling shaft; and (c) a linear element attaching, at a first end, to the spindle and attaching, at a second end, to the anchor such that said linear element extends between the spindle and the anchor.

Abstract: A vehicle door control system is provided, and includes a body hinge member connected to the vehicle body, a door hinge member connected to the door, a brake and a control system. The brake includes a plate pack that includes a plurality of body brake plates connected to the body hinge member, and interleaved with a plurality of door brake plates connected to the door hinge member. The plate pack is positionable in a braking state in which the body brake plates and the door brake plates are frictionally engaged with one another to provide a first resistance to relative rotation therebetween so as to hold the vehicle door in a selected position, and a release state in which the body brake plates and the door brake plates provide a second resistance to relative rotation therebetween that is less than the first resistance.

Abstract: A power actuation system for a motor vehicle closure panel includes a motor operable to pivot a driven gear. At least one pawl assembly is operably supported by the driven gear for movement between a lever driving position, whereat the pawl assembly is positioned to pivot a lever coupled to the door to pivot the door concurrently with movement of the driven gear, and a lever releasing position, whereat the pawl assembly is positioned to permit free pivotal movement of the lever and door relative to the driven gear. The pawl assembly includes a roller engaged with the lever for rolling movement therealong during movement of the pawl assembly between the lever driving position and the lever releasing position, which results in minimal static and kinetic friction, thereby lending to reliable, low effort movement of the pawl assembly between the lever driving position and the lever releasing position.

Abstract: A movable barrier opener system having a brushless DC motor is provided. The movable barrier opener system may have a power supply unit with a drive circuit power module and a storage bank. The storage bank may be chargeable by the drive circuit power module and may be connectable to the drive assembly to provide electrical power to the drive assembly to move the movable barrier. The drive circuit power module may be selectably turned on and off to improve efficiency of power consumption by turning off during periods of lowered demand.

Abstract: Systems, methods, and apparatus for detecting movable barrier disengagement are provided. A movable barrier operator system includes a motor configured to be coupled to a movable barrier and move the movable barrier, a motor sensor configured to measure a load value of the motor, communication circuitry configured to receive, from a remote control, a state change request to cause movement of the movable barrier, and a processor circuit. The processor circuit is configured to cause actuation of the motor in response to receipt of the state change request, detect, based on the load value, a disengagement between the motor and the movable barrier, and cause a communication to be sent, in response to detecting the disengagement, to a remote server, the communication indicative of motor disengagement.

Abstract: A vehicle window control system is provided. The vehicle window control system includes a window switch that generates a first signal, a first computer that reads a state of the window switch and generates a second signal, and a second computer that controls movement of the vehicle window based on either the first signal or the second signal. The second computer receives the second signal from the first computer through serial communication and the first signal from the switch portion through a hardwire.

Abstract: A special detection area in which detection in accordance with an activation detection algorithm for detecting a person or an object and detection in accordance with a protection detection algorithm having a higher detection sensitivity for the person or the object than the activation detection algorithm are performed is provided. Results of the detections in accordance with the activation detection algorithm and the protection detection algorithm are individually output to an automatic door device.

Abstract: The invention relates to a method of providing vacuum insulating glass (VIG) units each comprising at least a first and a second glass pane and a plurality of support pillars distributed between opposing surfaces of said glass panes to provide a gap (8) between the glass panes. A plurality of pane elements are provided, and individual topographic representations (TOPREP_2a-TOPREP_2n) of each of said plurality of pane elements (2a-2n) are obtained based on input (4) from a measuring arrangement (3), and the topographic representations are stored in a data storage (DS). The stored topographic representations are processed and resulting surface distance characteristic between pairs of panes are estimated. Vacuum insulating glass (VIG) assemblies are thus provided based on estimated resulting surface distance characteristics. The invention additionally relates to a system for providing manufacturing layouts and a manufacturing facility.

Abstract: The present invention relates to shaker doors with solid cores and methods for making the same. The shaker doors contain different core materials at the recessed panel than the raise peripheral region to provide dimensional stability and reduced distortion when the doors are exposed to high humidity. The devices and methods also provide for easy assembly of solid core shaker doors, including fire rated doors.

Abstract: Systems and methods for rectifying excessive bottom or head clearances of door assemblies are disclosed. An example system may comprise a door cap straight component installed on a first side of a fire door; a door cap L-shaped component installed on a second opposite side of the fire door; at least one intumescent strip seal fitted with the door cap L-shaped component; and end caps installed on two narrow ends of the fire door.

Abstract: Methods of controlling tint of a tintable window to account for occupant comfort in a room of a building. Some methods include receiving weather feed data from one or more weather services (or other data sources) over a communication network, determining a weather condition based on the weather feed data, and determining a tint level for the tintable window based on the weather condition and based on whether a current time is within a time delay period at sunrise or sunset.

Abstract: A spring drive system for a window shade includes a housing, a first and a second gear engaged with each other and respectively assembled about a first and a second pivot axis, two springs respectively assembled at two opposite sides of the second gear and respectively connected with two take-up reels provided on the first gear, a first cord drum and a third gear fixedly connected with each other and assembled about a third pivot axis, the first and third gears being respectively located at different levels along the first and third pivot axes and respectively engaged with a first gear train, a second cord drum and a fourth gear fixedly connected with each other and assembled about a fourth pivot axis, the second and fourth gears being respectively located at different levels along the second and fourth pivot axes and respectively engaged with a second gear train.

Abstract: In one aspect, a cordless covering may include a roller and a shade panel configured to be wound around and unwound from the roller to move the shade panel between an extended position and a retracted position. The shade panel may include a front panel, a back panel, and a plurality of vanes extending between the front and back panels. The covering may also include a roller shaft extending through the roller and a tilt adjustment mechanism coupled to the roller shaft. The tilt adjustment mechanism may be configured to rotate the roller shaft to adjust a tilt angle of the vanes between an opened position and a closed position.

Abstract: A window blind includes an upper beam, a plurality of foldable slats, a lower beam, a fastener, a spring, a movable base, a fixed base, a first wheel set, a second wheel set, and a third wheel set. The upper beam includes a lower part and a slideway. The plurality of foldable slats is fastened to the lower part of the upper beam and includes a lower part. The lower beam is fastened to the lower part of the plurality of foldable slats. The fastener, the spring, the movable base, and the fixed base are disposed between the upper beam and the plurality of foldable slats. The fastener and the fixed base are fixed on the upper beam. The movable base is disposed in the slideway. The spring includes two ends. The fastener includes a first hook and the movable base includes a second hook.