Abstract: The embodiment of the present application provides a balance mechanism and a mounting bracket. Wherein, the balance mechanism includes: a mounting part; a sliding part, which is slidably connected to the mounting part; a spring, the first end of the spring is fixed to the sliding part; an adjuster, which has a third end and a fourth end opposite to the third end, wherein the third end is connected to the mounting part, and the fourth end is connected to the second end of the spring. The adjuster is configured to adjust the spring, so as to stretch and compress the spring. The embodiments of the present application can reduce the cost of the balance mechanism and thereby reduce the cost of the mounting bracket.

Abstract: A stand in which professional television cameras are placed includes a compact and easily storable and transportable stand for professional television cameras comprising a plurality of supporting legs pivotable upon the fixed base, and between a folded position, in which the stand is positioned coupled to a corresponding slot, and an open position, in which the stand is positioned substantially in parallel to the fixed base and thereby able to be placed on a surface. When the stand is in storage or transport, the stand may be brought into a folded position, in which each supporting leg is coupled to a corresponding slot, reducing the form factor of the stand while folded and having higher easiness in transportation.

Abstract: A device may include a base, a transmission assembly, and a response assembly. The transmission assembly may be configured to move a component of a medical device. The transmission assembly may include a cable and a wheel connected to the base. An end of the cable may be connecting to a part of the component of the medical device. The response assembly may be connected to the transmission assembly. The response assembly may be configured to generate a response in response to a break of the cable.

Abstract: The LED desk light has more than one function which has area illumination by LED light source and incorporate with at least one but not limited other functions select from charge other electric device(s) from built-in USB port(s) or USB-unit(s) or USB-module(s), a display of light beams from the LED, projection of an image, projection of a time image, clock functions, illumination of an area, playing of music, serving as a source of alternating current (AC) power or electric signals, display of photos, wire or wireless transmission of digital signals, providing air flow at a desired temperature, generating moisture, steam, or smells, dispensing liquid, brewing coffee/tea, preparing food, and displaying charging status, night light with desired LED light variety light performance, functions, effects including but not limited for changing color, brightness, dimmer, moving effects, chasing which available from market place by IC or circuit design and powered by Outside Transformer DC power source or Inside Trans

Abstract: A trampoline includes a stand which has a peripheral frame, a plurality of legs and a bounce mat which is elastically suspended on the frame. At least one guide is secured to the stand. A bar is received in a height adjustable manner in the guide. An inner piece is movably received in the guide. The bar is fixed by a relative movement between the inner piece and the guide.

Abstract: A lamp includes at least one LED, an at least partially optically transmissive enclosure, a heat sink connected to the enclosure for dissipating heat from the LED, and a reflector for reflecting light along the longitudinal axis of the lamp either toward or away from the heat sink.

Abstract: A bicycle seatpost assembly comprises a first tube, a second tube, and a positioning structure. The second tube has a distal end to be attached to a bicycle seat and a proximal end opposite to the distal end. The second tube is configured to be telescopically received in the first tube. The positioning structure is configured to position the first tube and the second tube relative to each other. The positioning structure comprises a fluid chamber. The fluid chamber comprises a first chamber, a second chamber, and a movable piston. The first chamber is filled with a first liquid. The second chamber includes a second liquid and gas. The second chamber is disposed closer to the distal end of the second tube than the first chamber. The movable piston divides the fluid chamber into the first chamber and the second chamber. The movable piston is movable within the fluid chamber.

Abstract: A bicycle seatpost structure mainly provided with a shock absorber includes a sealed chamber, a buffer element and a gas. The gas is filled in the sealed chamber to change a gas pressure in the sealed chamber. The buffer element is elastic and installed in the sealed chamber for providing an upward elastic support force to an up tube of the seatpost. When a rider sitting on the saddle presses at the saddle, a shock damping force is produced, and the shock damping force and flexibility may be adjusted by the gas pressure and changed anytime according to the rider's body weight or preference.

Abstract: Provided is an operation handle mechanism with which a handle can be conveniently operated to move a movable section, thereby ensuring smooth operation and movement at any time regardless of an operation position of the handle. An operation handle section 121 includes a handle lever 67, which is used to operate movement of a support frame section 23 capable of moving up and down, and left and right transmission rods 123a and 123b, which are joined to the handle lever. The transmission rods can only move a predetermined distance in a movement direction thereof relative to the support frame section, and start to move together with the support frame section after going beyond that distance.

Abstract: An automatic balancing structure of a medical balancing stand has stoppers arranged on a turn plate. In a normal state, the stoppers are in contact with and hold a contact part of a lever so that the lever and turn plate follow a rotative motion of a lateral arm. If the lateral arm causes an imbalance, a strain occurs on the lever to which a strain sensor is attached. The strain sensor detects the strain and outputs a signal to an adjustment unit so as to cancel the imbalance of the lateral arm. The strain sensor helps downsizing the automatic balancing structure and making the balance adjustment easier.

Abstract: Embodiments include a balance mechanism having a first cam and a second cam configured to convert a variable force exerted by the energy storage member into a substantially constant force applied to a mounting portion. The balance mechanism may be useful for balancing forces such that a user can set the height of an electronic display and/or other equipment attached to the balance mechanism at a number of heights within the range of travel allowed by the mechanism. Lift mechanisms, display positioning apparatuses, and height adjustable desks incorporating a multi-cam balance mechanism are also provided. A method of positioning a display is also provided.

Abstract: A detachable lifting module includes a fixing support, a sliding unit, a mounting unit, and at least one fastening element. The fixing support has a first track defining a first space and a second track defining a second space. The sliding unit includes a first sliding element detachably disposed on the first track and a second sliding element detachably disposed on the second track. The first sliding element has a first pressing portion received in the first space, and the second sliding element has a second pressing portion received in the second space. The fastening element is capable of connecting the first and second sliding elements. The first and second pressing portions are respectively received by the first and the second spaces and respectively engaging the first and second tracks to lock the sliding unit by adjusting the fastening element.

Abstract: A television mount assembly suitable for mounting a television to a wall, especially over fireplaces and other obstacles. The mount assembly secures a television (TV) to a wall via two arms and a spring mechanism thereby allowing it to extend away from the wall while at the same time allowing the television to swivel. It includes a mechanism to straighten the television as it is positioned close to the wall. The spring mechanism is calibrated by means of a calibration screw, spring block, and locking screws. A handle enables a user to grasp the mount assembly for changing the position of the television. A temperature gauge on the handle displays ambient temperature proximate to the television to warn users if the temperature is too high for the television to safely operate. A means of setting a maximum extension prevents the television from extending beyond a point set by the user.

Abstract: An antenna apparatus which has the centroid close to a base and which has a less constraint for placement of a counter weight. The antenna apparatus includes a base fixed to a moving object or a structural object, an antenna unit disposed at a side of the base and supported by the base, and a counter weight unit disposed at a side of the base opposite to the antenna unit and supported by the base.

Abstract: Embodiments of a stand are provided with continuous adjustability within a range of travel. In one embodiment, a stand includes a movement mechanism adapted to allow a tray to move along a range of travel relative to a stand base. The movement mechanism is in some embodiments further adapted to position the tray at an infinite number of locations along the range of travel.

Abstract: The present invention provides a foldable display support, wherein when a support arm is in a standing state, a limiting sheet is located in a limiting part of a screen support rack for blocking, so only the forward/backward tilted angle of a screen can be adjusted, thereby preventing being unstable and falling due to the gravity center being overly backward. When the support arm is folded to a horizontal state, the gravity center is lowered, and a protrusion of a first cam abuts a protrusion of a second cam, such that the second cam axially moves and pushes the limiting sheet to be released from the limiting part of the screen support rack, at this moment, the screen is enabled to be backwardly rotated and folded to a horizontal state for reducing the occupied space, thereby ensuring the folding process to be smooth and stable and preventing from falling.

Abstract: A tripod head comprising a resilient force adjusting mechanism which includes a rotating operation part, a cam which is coupled to the rotating operation part and slides with the rotation of the rotating operation part, and a cam follower coming into contact with cam surfaces of the cam, wherein the cam follower is supported by a counterbalancing mechanism, and the counterbalancing mechanism is configured in such a manner that the magnitude of a resilient force to be imparted on the spring is variable in accordance with a position where the cam follower comes into contact with the cam.

Abstract: A floor stand with an angled arm is provided for use with a microscope. The angled arm allows the floor stand and microscope to fit within a small or crowded examination room while also allowing a physician and his assistant space to maneuver around the floor stand and examine a patient.

Abstract: The instant disclosure relates to a height-adjustable stand for supporting and controlling the position of a monitor. The stand is for disposing on a working surface and includes a base, a slidable frame, a plurality of springs, and a plurality of force members corresponding to the springs. The base is disposed on the working surface, and the frame is slidably disposed on the base. One end of each spring is fixed to the base, and each force member is connected to the corresponding spring and selectively engaged to the frame. When the frame slides with respect to the base, the engaged force member moves with the frame. The displacement of the force member allows the corresponding spring to create a counter force for maintaining the frame at any position between a first position and a second position.

Abstract: The invention includes a display positioning assembly comprising a support, a display supported by the support, and a balance mechanism carried by the display and operatively connected to the support. The invention also includes an article for selectively exposing a display comprising a generally planar support surface having a first side and a second side opposite the first side. A balance mechanism operatively connected to a display may be positionable between a storage position proximate the first side of the generally planar support surface and an exposed position proximate the second side of the generally planar support surface. The invention also includes an assembly for arresting the free fall of an object. The assembly may comprise an outer slide in sliding or rolling engagement with an inner slide, and a brake comprising at least one pivot member may be coupled to the inner slide.

Abstract: A height adjustable holding apparatus for holding an object is provided. The height adjustable holding apparatus includes a support, a moving part, a holding unit, an elastic member, and a linking unit. The moving part is movable along the support, wherein the object connects to the moving part to be movable along the support. The holding unit is disposed at a top end of the support. The elastic member is disposed at a bottom end of the support. One end of the linking unit connects to the moving part and the other end extending around the holding unit to connect to the elastic member. When moving the object along the support to a desired position, the object substantially remains balanced at the desired position by the cooperation of the holding unit, the elastic member and the linking unit.

Abstract: A stand for supporting an object. The stand includes a base, a support member coupled to the base, and a movement mechanism adapted to allow the object to move along a range of travel relative to the base. The base includes a planar surface for resting on a support surface. The planar surface includes a first portion and a second portion. The first portion includes a pad for providing frictional resistance between the base and the support surface on which the base is placed. The second portion includes at least first and second wheels, for rotating the base about the pad such that the object is rotated about the pad when the base is rotated about the pad.

Abstract: A counterbalance mechanism counterbalances an eccentric mass on a rotating shaft supported by a frame. A first pulley is coupled to and concentric with the shaft. An arm is coupled to the shaft to rotatably support a second at a first distance from the first pulley. A third pulley is fixedly coupled to the frame at a second distance from the first pulley. A fourth pulley is rotatably coupled to and concentric with the third pulley. A spring is fixed at a first end to the frame and has a second end that is coupled to the fourth pulley such that the spring provides a restoring force as the fourth pulley is rotated. A first cable has a first end that is coupled to the fourth pulley and a second end that is coupled to the frame through the third pulley after passing over the first and second pulleys.

Abstract: A vertical linear actuator mechanism for positioning a load at a desired elevation above a support surface is described. The vertical linear actuator mechanism in one aspect thereof comprises an electric motor having a drivable shaft. The drivable shaft is coupled to a linear extendable mechanism having a load connector at a top end thereof. A potentiometer detects the position of the load connector relative to the support surface and provides position signals to a motor controller circuit which monitors the position of the load connector and controls the operation of the electric motor. In another aspect thereof the vertical linear actuator is comprised by a pair of gas spring cylinders interconnected together. The vertical linear actuator mechanism is secured inside a telescopic pedestal and extends and retracts the pedestal.

Abstract: An exemplary display device includes a display panel and a height-adjustment assembly. The height-adjustment assembly includes a rail unit defining a rail, a sliding unit, and a spring member. The sliding unit is configured to slide along the rail. The display panel is fixed to the sliding unit. The spring member is fixed to the rail unit, and is configured to provide an elastic force applied to the sliding unit to the sliding unit when the sliding unit slides along the rail.

Abstract: A monitor lift mechanism that can be utilized in connection with a desk having a stationary work surface. The monitor lift mechanism is movable between a retracted position in which a monitor is positioned beneath the work surface, and an extended position in which the monitor is positioned above the work surface for viewing. The monitor lift mechanism includes a lift bar that is movable between a retracted position and an extended position through the use of a block and tackle pulley and lift cylinder arrangement. A latch mechanism holds the lift bar in the retracted position and can be released upon depression of a monitor door coupled to the lift bar.

Abstract: A support frame with an adjustable mechanism includes a fasten base, a displacement cylinder and an air pressure bar. The fasten base has a guiding cylinder. The displacement cylinder is sleeved with the guiding cylinder and has a relative motion relative to the guiding cylinder. One end of the air pressure bar is fastened with the fasten base and is located in the guiding cylinder. The displacement cylinder is fastened with another end of the air pressure bar and moves as the length of the air pressure bar changes.

Abstract: A support mechanism includes a base and a lifting mechanism mounted on the base. The base defines a limiting slot. The lifting mechanism includes a first arm, a second arm, a connecting mechanism including a rod, and an elastic member. The first arm has a first end and a second end and includes a limiting member slidably received in the limiting slot. The second arm has a second end and a first end adjacent to the first end of the first arm and away from the second end of the first arm. The connecting mechanism includes a rod. The elastic member is connected to the first end of the first arm and the first end of the second arm. The first end of the first arm and the rod are pivotally connected to the base, and the first end of the second arm pivotally connects to the rod.

Abstract: An exemplary flat panel display (200) includes a display body (21) and a height adjusting member (23). The height adjusting member includes a supporting member (25) and a base (26). The supporting member includes a slider (30) and a sidewall (272). The slider is attached to the display body, and the slider abuts against but is slidable up and down along the sidewall. The slider is configured to be adjustable to vary an amount of friction between the slider and the sidewall such that a height of the display body is adjustable by applying external force to the display body and moving the display body to a new height.

Abstract: A counterbalance apparatus for use in a workstation to raise and lower a work surface of the workstation. The counterbalance apparatus compensates for the load on the work surface. The counterbalance apparatus includes an inner column telescopingly mounted in an outer column. A base member is positioned at one end of the outer column. A grooved member positioned between the inner column and the base member and a force mechanism between the grooved member and the inner column or the work surface. The grooved member moves in and out of the inner column and base member to raise and lower the work surface.

Abstract: A device comprising a monitor and a monitor support stand. The monitor support is configured to hold the monitor in a plurality of fixed locations. The monitor support includes a spring, a spring counterweight balance, and a cam. The spring is configured to support a weight of the monitor. The spring counterweight balance is coupled to the spring, and is configured reduce a force required to adjust a tension of the spring. The cam is coupled to the spring counterweight balance, and has a plurality of positions, wherein each of the plurality of positions is configured to adjust a weight range of the monitor that the spring can support.

Abstract: A system and method for stocking and/or restocking shelves. The system includes a support member and a top platform coupled to the support member. The top platform is configured to receive at least one of a container of product and individual items to be at least one of stocked and restocked. The system includes a base portion coupled to the support member, wherein the base portion is configured to facilitate positioning the system relative to a shelf to be at least one of stocked or restocked. A height of the top platform is configured to be adjusted to a user-selected height and fixed at the user-selected height prior to receiving the at least one of the container of product and the individual items.

Abstract: A supporting rack having a compensating mechanism includes a rack body, an action force compensating assembly, a transmission element and a supporting plate. The rack body has a base and support arms. The action force compensating assembly is provided in the rack body. The elastic element is firmly connected to the base. One end of the dragging piece is connected to the hooking plate. The rotating piece is provided on a distal end of the support arm. The other end of the dragging piece is connected to the rotating piece. One end of the transmission element is firmly connected to the rotating piece and pivoted on the support arm. Via the above arrangement, an appropriate force can be applied to the supporting plate. When the user intends to adjust the supporting plate, the elastic element can generate an effect for compensating the action force, thereby providing a better operation feeling.

Abstract: The present invention pertains to extension arm apparatuses that are adapted to support user devices throughout a range of positions. A given apparatus may include one or more arms that position the user device remotely from a support position. An extension and retraction device such as a gas cylinder is received within each arm, and provides a force to support the user device as the arm is placed into a given position. A variable force clevis is connected to the extension/retraction device within the arm. The variable force clevis is connected to a pair of locations in the arm as well. As the arm moves, for instance up or down, the variable force clevis rotates within the arm and dynamically adjusts the force provided by the extension/retraction device. Thus, the arm may be positioned as desired, as such force adjustment stabilizes the arm.

Abstract: A motorized elevator unit for adjusting the height of counter tops has right and left elevator assemblies under control of a primary control switch. Each elevator assembly includes top and bottom frames which may be formed from T-slotted framing with the top frame sliding vertically along the bottom frame on rollers received in the bottom frame. A movable counter top is mounted on the top frames and a motor drive assembly raises and lowers the top frames in unison. The elevator unit may be housed in a standard base cabinet and may be integrated with other standard base cabinets having stationary counter tops.

Abstract: A stand includes a frame, a sliding member, and two torsion springs. The frame has two guide rail subassemblies. The sliding member is slidably attached to the guide rail subassemblies. A first end of each torsion spring is connected to the frame, and a second end of each torsion spring is connected to the sliding member to provide an elastic force to overcome the total weight of the sliding member and a load.

Abstract: A stand for a display device that adjusts the height and tilt of the display device in a variety of ways to increase user convenience is provided. The stand includes a sliding portion, a supporting portion, and a base. The sliding portion extends toward a rear surface of the display device. The supporting portion slidably supports the sliding portion. The base extends the supporting portion upward. The sliding portion and the supporting portion are formed to extend in mutually different directions.

Abstract: A force adjustment assembly for use within a telescoping subassembly that includes a first elongated member and a second elongated member that is supported by the first elongated member for sliding motion along an extension axis, the subassembly further including a force equalizer assembly that includes a strand having first and second ends that are supported by the second and first elongated members, respectively, the adjustment assembly comprising a preloader supported by at least one of the first and second elongated members and supporting at least a portion of the strand, the preloader applying a preload force via the strand when the second elongated member is in a fully extended position and an adjuster for adjusting the preload force applied by the preloader.

Abstract: A device comprising a monitor and a monitor support stand. The monitor support is configured to hold the monitor in a plurality of fixed locations. The monitor support includes a spring, a spring counterweight balance, and a cam. The spring is configured to support a weight of the monitor. The spring counterweight balance is coupled to the spring, and is configured reduce a force required to adjust a tension of the spring. The cam is coupled to the spring counterweight balance, and has a plurality of positions, wherein each of the plurality of positions is configured to adjust a weight range of the monitor that the spring can support.

Abstract: The invention relates to an arrangement for at least partially compensating a torque caused by gravitational forces acting on a mass body (2), which is rotatably supported on an axis of rotation (3). The arrangement includes a gas pressure spring (5) for providing a linear force. This linear force is transformed into a torque by means of a converter unit (7). The mass body (2) and the converter unit (7) can be coupled to each other in a way which allows for adjusting the amplitude and the phase of a compensating torque.

Abstract: An exemplary adjustable support mechanism (50) includes a main bracket (51), an adjustable suspension member (52) slidably mounted to the main bracket and an elastic member (53). The main bracket forms at least two guide rails (516) including a first guide rail and a second guide rail disposed opposite to each other. The adjustable suspension member includes two crossed connected suspension frames (524, 525), at least two wheels (522) engaging the guide rails, and at least one stretching member (526, 527). The suspension frames are rotatably connected to each other. The at least two wheels are disposed at ends of the suspension frames. Two ends of each stretching member are connected to the suspension frames correspondingly. The elastic member has two ends fixed relative to the main bracket and the adjustable suspension member correspondingly.

Abstract: An exemplary adjustable stand (20) for displays includes a main support (22), a movable rack (25), an adjusting system (26) and a balance mechanism (28). The movable rack is slidably mounted on the main support. The adjusting system includes at least one pinion gear (266) rotatably attached on the movable rack and at least one rack gear (267) fixed to the main support. The at least one pinion gear meshes with the at least one rack gear. The balance mechanism is mounted between the main support and the movable rack for balancing gravity of the movable rack and components fixed relative to the movable rack. The present invention further discloses a stand (10) including a support bracket (30), a base (40) and the adjustable stand for connecting the support and the base.

Abstract: A supporting rack having a compensating mechanism includes a rack body, an action force compensating assembly, a transmission element and a supporting plate. The rack body has a base and support arms. The action force compensating assembly is provided in the rack body. The elastic element is firmly connected to the base. One end of the dragging piece is connected to the hooking plate. The rotating piece is provided on a distal end of the support arm. The other end of the dragging piece is connected to the rotating piece. One end of the transmission element is firmly connected to the rotating piece and pivoted on the support arm. Via the above arrangement, an appropriate force can be applied to the supporting plate. When the user intends to adjust the supporting plate, the elastic element can generate an effect for compensating the action force, thereby providing a better operation feeling.

Abstract: A height adjustment mechanism for electronic equipment is disclosed. The height adjustment mechanism includes a first sliding component that includes a first set of mechanical structures for engaging a second set of mechanical structures, a first mechanical sub-component coupled to the first sliding component and coupled to a second mechanical sub-component that includes the second set of mechanical structures and a second sliding component coupled to the first sliding component. The first set of mechanical structures and the second set of mechanical structures are configured to mesh. A movement of the first sliding component causes either an expansion or a retraction of the first mechanical sub-component.

Abstract: A movable arm includes a base secured to a mounting surface; a movable body pivotally attached to the base to rotate about the base and carrying an object; and a restoring body for biasing the movable body to a home position. An elastic modulus of the restoring body, a deformation amount of the restoring body in the home position and dimensions of individual parts are determined to ensure that the gravity acting on the movable body and the biasing force exerted by the restoring body are balanced regardless of the position of the movable body. Therefore, the position of the movable body can be maintained by the elastic force of the restoring body regardless of the frictional force and thus the movable arm is hardly affected by the wear, attaining a greater life span than in a case of maintaining the movable body by the frictional force.

Abstract: A display strut adjusting structure is located on a base seat of a display, comprises an altitude adjusting device and an angle adjusting device. An arc-shaped suppressing plate is located on a sliding plate of the altitude adjusting device, which can push the torsion member of an outer frame component with stability thus enhance the smoothness of the altitude adjusting operation. A braking bar at the end of the outer frame component restricts rotation, and allows strengthening of the stability of the adjusted angle between the display strut adjusting structure and the base seat. A concave ring is designed on the braking bar, when depressed the braking bar causes the concave ring to align with the pivot end, the outer frame component will rotate through the concave ring in relation to the pivot end, thus, adjusting the angle of the display strut adjusting structure and the base seat.

Abstract: A pedestal assembly for supporting a seat including a first cylinder having an inner surface with a plurality of longitudinally-extending channels, and a second cylinder having an inner surface with a plurality of longitudinally-extending channels and an outer surface with a plurality of longitudinally-extending grooves. The assembly also includes a first bushing that is operably coupled to one end of the second cylinder by a plurality of fasteners received within an end of the channels of the second cylinder, and a second bushing that is operably coupled to one end of the first cylinder by a plurality of fasteners received within an end of the channels of the first cylinder. The second bushing includes a plurality of tabs slidably received within the channels on the inner surface of the first cylinder and is adapted to telescopingly guide the second cylinder within the first cylinder.

Abstract: The invention relates to a stand having a pivotable support arm (2) and a balance weight (AG), in which the balance weight (AG) acts via a cable pull (24) for the weight compensation of the load (G), the balance weight (AG) being arranged in the area of the vertical upright column (21) of the stand.

Abstract: A mechanical assembly includes an arm and an extension link that rotate about a pivot point, a yoke, and a force generating device. The yoke includes a first slot in which a pin of the link resides. The yoke translates in a plane responsive to rotation of the counterbalance extension link pin about the pivot point. The force generating device is connected between the counterbalance extension link pin and a fixed point on the yoke to exert a force on the counterbalance extension link pin. The orientation and magnitude of the force produced by the force generating device remains constant as the yoke translates. The force generating device and extension link produce a torque that is equal and opposing to the torque produced by the force of gravity acting on the arm so that the arm is in static equilibrium. The static equilibrium condition is independent of the rotational position of the arm.

Abstract: A lifting base for a LCD monitor includes a frame, a lifting device and a pair of clamping members. The frame has two rails extending from two sides respectively. The lifting device has a pair of sliding parts and a pair of guiding plates. The sliding parts are connected at the bottom ends with the top ends spreading apart like the shape of an English letter V. Two outer edges of each sliding part are bent to form a guiding rail thereat. The sliding parts are secured with the guiding plates connected to a monitor. The guiding plates are inserted within the rails of the frame. The clamping members are two torque springs in an opposite position. Each clamping member has one end secured to the frame and another end connected with a roller to engage with the rail of each sliding part of the lifting device for locating purpose.