CN210515774U

CN210515774U - Show shelf for analyzing applied mathematics difficult problem

Info

Publication number: CN210515774U
Application number: CN201920910464.4U
Authority: CN
Inventors: 汤华丽
Original assignee: Chongqing Industry Polytechnic College
Current assignee: Chongqing Industry Polytechnic College
Priority date: 2019-06-17
Filing date: 2019-06-17
Publication date: 2020-05-12
Anticipated expiration: 2029-06-17

Abstract

The utility model discloses a show shelf for resolving applied mathematical problems, which comprises a base, wherein a height-adjusting rod is arranged on the surface of the base, a bearing block is arranged at the lifting end of the height-adjusting rod, the bottom surface of the bearing block is provided with a mounting groove, rotary rods are arranged at the two ends in the mounting groove through rotary shafts, and a positioning component for fixing the angle of the rotary rod is arranged on the front side surface of the bearing block; the rotary rod bottom surface is provided with T type groove, T type inslot portion slidable mounting has T type piece, the mount is installed to T type piece bottom surface, the mount leading flank is provided with compressing tightly the subassembly, the mount dorsal surface be provided with be used for right the mount carries out the fixed locking Assembly of locking. Has the advantages that: the rotary folding of the rotary rod can be realized, the occupied space is greatly reduced, and the storage is convenient; the position that can realize the mount removes and fixes, and the cooperation compresses tightly that the subassembly can satisfy not unidimensional drawing compress tightly and hang, and application scope is wide.

Description

Show shelf for analyzing applied mathematics difficult problem

Technical Field

The utility model relates to a mathematical education device technical field, concretely relates to use analytic show shelf of using a mathematical problem.

Background

In the mathematical education process, in order to facilitate explaining the problem solving thought to the students, the teacher writes the specific problem solving thought to be displayed on the drawing, the teacher is not required to write on site, and the teaching efficiency is improved. However, the conventional drawing showing stand for solving the problems cannot be folded, occupies a large space and has an unsatisfactory use effect; meanwhile, the display requirements of drawings with different sizes cannot be met, and the application range is limited.

SUMMERY OF THE UTILITY MODEL

The purpose of the utility model is to provide a display rack for resolving the mathematical problems, so as to solve the problems that the prior art drawing display rack for solving the problems can not be folded, occupies large space and has unsatisfactory use effect; meanwhile, the display requirements of drawings with different sizes can not be met, and the application range is limited. The rotary folding device has the advantages that the optimized technical scheme in the technical schemes can realize rotary folding of the rotary rod, so that the occupied space is greatly reduced, the storage is convenient, the operation is simple and convenient, and the using effect is good; the position that can realize the mount removes and fixes, and the cooperation compresses tightly the subassembly and can satisfy compressing tightly of not unidimensional drawing and hang, and application scope extensively waits technological effect, sees the explanation below in detail.

In order to achieve the above purpose, the utility model provides a following technical scheme:

the utility model provides a show shelf for analyzing difficult problems of applied mathematics, the on-line screen storage device comprises a base, height-adjusting rods are installed on the surface of the base, the lifting ends of the height-adjusting rods are vertically upward and are provided with bearing blocks, the bottom surfaces of the bearing blocks are provided with mounting grooves, the mounting grooves run through the two side surfaces of the bearing blocks in the length direction, the two ends in the mounting grooves are provided with vertically rotating rotary rods through rotating shafts, and the front side surfaces of the bearing blocks are provided with positioning components for fixing the angles of the rotary rods;

the utility model discloses a paper fixing device, including rotary rod, T type groove, mount leading flank, the rotary rod bottom surface is provided with T type groove, the inside slidable mounting in T type groove has T type piece, wear out T type piece bottom surface T type groove just installs the mount, the mount is "n" style of calligraphy structure, the mount leading flank is provided with and is used for fixing the paper pressure fastening the inside subassembly that compresses tightly of mount, the mount dorsal flank is provided with and is used for right the mount carries out the fixed locking Assembly of locking.

By adopting the display rack for analyzing the applied mathematical problem, when the device is used, the height of the bearing block can be adjusted by adjusting the length of the height-adjusting rod, so that different hanging height requirements can be met; when the drawing needs to be hung and displayed, the rotary rod is rotated through the rotary shaft, so that the rotary rod is in a horizontal state, the rotary rod is fixed through the positioning assembly, the position of the fixing frame is adjusted according to the specific size of the drawing, when the fixing frame is adjusted, the fixing frame is locked and fixed through the locking assembly in a contact mode, the T-shaped block slides in the T-shaped groove, the distance between the two fixing frames is adjusted, the distance between the two fixing frames meets the size of the drawing, the fixing frame is locked and fixed through the locking assembly, soil needing to be hung and displayed is inserted into the fixing frame, the drawing is pressed and fixed in the fixing frame through the pressing and fixing, and the hanging and displaying of the drawing are achieved; when the device is not used, the fixing of the positioning assembly on the rotating rod is released, the rotating rod is rotated to be in a vertical state through the rotating shaft, the rotating rod can be rotated and folded, the occupied space of the device is greatly reduced, and the device is convenient to store; through T type piece T type groove with locking Assembly can realize the position control and the fixing of mount can satisfy the demand that hangs of the drawing of unidimensional, and easy operation is convenient, and application scope is wide.

As preferred, the pole of increaseing is including fixed pipe, fixed pipe is vertical to be installed the base surface, fixed outside of tubes runs through and is provided with the lift groove, the lift groove along the axial extension of fixed pipe, the fixed intraduct is installed through the bearing and is born the weight of the cover, wear out on bearing the weight of the cover fixed pipe and install adjusting nut, adjusting nut installs elevating screw through the screw thread is inside, elevating screw upper end with the carrier block is connected, the elevating screw bottom stretches into fixed intraduct, and installs the guide block, the guide block is followed the inside wearing out of lift inslot.

Preferably, the back side surface of the rotating rod is provided with a plurality of locking holes, the locking holes are uniformly distributed along the length direction of the rotating rod, the locking assembly comprises a bearing frame, the bearing frame is arranged on the back side of the fixing frame and is of an L-shaped structure, a guide pipe is arranged on the vertical side surface of the bearing frame, which is far away from the rotating rod, the guide pipe corresponds to the locking holes, a guide groove is arranged on the outer side of the guide pipe in a penetrating manner, the guide groove axially extends along the guide pipe, a locking column is slidably arranged in the guide pipe, a deflector rod is arranged at the outer end of the locking column, the deflector rod penetrates out of the guide groove, the inner end of the locking column extends into the bearing frame and extends towards the locking holes, a baffle is arranged on the outer side of the locking column, and the, and a locking spring is sleeved outside the locking column and is positioned between the baffle and the inner wall of the bearing frame.

Preferably, the locking post is in clearance fit with the locking hole.

Preferably, a limiting groove penetrates through the outer side of the guide pipe, the limiting groove is close to the bearing frame, the limiting groove extends along the radial direction of the guide pipe, and the limiting groove is communicated with the guide groove.

As preferred, the rotary rod leading flank is provided with the locating hole, the locating hole is provided with a plurality ofly, and uses the rotation axis is central circumference evenly distributed, the bearing block leading flank runs through and is provided with the mounting hole, the mounting hole with the locating hole is corresponding, locating component includes the reference column, reference column slidable mounting be in inside the mounting hole, the reference column inner to the locating hole extends, the arm-tie is installed to the reference column outer end, reference column outside cover is equipped with the location extension spring, the both ends of location extension spring respectively with the arm-tie with the bearing block is connected.

Preferably, the positioning column is in clearance fit with the positioning hole.

Preferably, the fixing frame front side is provided with a guide hole in a penetrating mode, the pressing assembly comprises a sliding column, the sliding column is slidably mounted inside the guide hole, the outer end of the sliding column is provided with a pulling block, the inner end of the sliding column extends into the fixing frame, a pressing plate is mounted inside the fixing frame, a pressing spring is sleeved on the outer side of the sliding column, and the pressing spring is located between the pressing plate and the inner wall of the bearing frame.

Preferably, pull rings are arranged on the surfaces of the pull plate and the pull block.

Preferably, the bottom surface of the base is provided with a self-locking universal wheel.

Has the advantages that: 1. the rotary rod can be rotated and folded, so that the occupied space is greatly reduced, the storage is convenient, the operation is simple and convenient, and the using effect is good;

2. the position that can realize the mount removes and fixes, and the cooperation compresses tightly that the subassembly can satisfy not unidimensional drawing compress tightly and hang, and application scope is wide.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic perspective view of the present invention;

FIG. 2 is an enlarged schematic view of the internal structure of the height-adjusting rod of the present invention;

fig. 3 is a schematic rear perspective view of the present invention;

FIG. 4 is an enlarged schematic view of portion A of FIG. 3;

fig. 5 is an enlarged schematic view of the right-view structure of the pressing assembly and the locking assembly of the present invention;

fig. 6 is an enlarged schematic view of the right-view structure of the positioning assembly of the present invention.

The reference numerals are explained below:

1. a self-locking universal wheel; 2. a base; 3. a height adjusting rod; 301. a fixed tube; 302. a lifting groove; 303. a guide block; 304. lifting a screw rod; 305. a bearing sleeve; 306. adjusting the nut; 4. a positioning assembly; 401. pulling a plate; 402. positioning a tension spring; 403. a positioning column; 5. a compression assembly; 501. pulling the block; 502. a compression spring; 503. pressing a plate; 504. a sliding post; 6. rotating the rod; 601. a T-shaped groove; 602. a locking hole; 603. positioning holes; 7. a bearing block; 701. mounting holes; 702. mounting grooves; 8. a locking assembly; 801. a carrier; 802. a guide tube; 803. a guide groove; 804. a deflector rod; 805. a locking spring; 806. a baffle plate; 807. a limiting groove; 808. a locking post; 9. a fixed mount; 901. a guide hole; 10. a T-shaped block; 11. a rotating shaft.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below. It is to be understood that the embodiments described are only some embodiments of the invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

Referring to fig. 1 to 6, the utility model provides a show shelf for resolving application mathematics difficult problem, including base 2, base 2 surface mounting has heightening pole 3, heightening pole 3's lift end is vertical upwards and is installed bearing block 7, bearing block 7 bottom surface is provided with mounting groove 702, mounting groove 702 runs through bearing block 7's length direction both sides face, mounting groove 702 inside both ends all install vertical rotatory rotary rod 6 through rotation axis 11, bearing block 7 front side is provided with locating component 4 that is used for fixing rotary rod 6 angle;

the bottom surface of the rotating rod 6 is provided with a T-shaped groove 601, a T-shaped block 10 is slidably mounted in the T-shaped groove 601, the bottom surface of the T-shaped block 10 penetrates out of the T-shaped groove 601 and is provided with a fixing frame 9, the fixing frame 9 is of an n-shaped structure, a pressing component 5 used for pressing and fixing paper in the fixing frame 9 is arranged on the front side surface of the fixing frame 9, and a locking component 8 used for locking and fixing the fixing frame 9 is arranged on the back side surface of the fixing frame 9.

As an optional embodiment, the height-adjusting rod 3 includes a fixed tube 301, the fixed tube 301 is vertically installed on the surface of the base 2, a lifting groove 302 is penetratingly disposed on the outer side of the fixed tube 301, the lifting groove 302 extends along the axial direction of the fixed tube 301, a bearing sleeve 305 is installed inside the fixed tube 301 through a bearing, the upper end of the bearing sleeve 305 penetrates through the fixed tube 301 and is installed with an adjusting nut 306, a lifting screw 304 is installed inside the adjusting nut 306 through a thread, the upper end of the lifting screw 304 is connected with the bearing block 7, the bottom end of the lifting screw 304 extends into the fixed tube 301, and is provided with a guide block 303, the guide block 303 penetrates out of the lifting groove 302, when the length of the height-adjusting rod 3 needs to be adjusted, the adjusting nut 306 is screwed, the elevation screw 304 is guided in a limited manner by the guide block 303 and the guide groove 803, and the elevation screw 304 is elevated inside the fixed pipe 301 by screw transmission, thereby realizing the length adjustment of the height-adjusting rod 3.

The back side of the rotating rod 6 is provided with a plurality of locking holes 602, the locking holes 602 are uniformly distributed along the length direction of the rotating rod 6, the locking assembly 8 comprises a bearing frame 801, the bearing frame 801 is installed on the back side of the fixing frame 9 and is in an L-shaped structure, the vertical side of the bearing frame 801 far away from the rotating rod 6 is provided with a guide pipe 802, the guide pipe 802 corresponds to the locking holes 602, the outer side of the guide pipe 802 is provided with a guide groove 803 in a penetrating manner, the guide groove 803 extends axially along the guide pipe 802, a locking column 808 is installed inside the guide pipe 802 in a sliding manner, the outer end of the locking column 808 is provided with a deflector rod 804, the deflector rod 804 penetrates out from the inside of the guide groove 803, the inner end of the locking column 808 extends into the bearing frame 801 and extends towards the locking holes 602, the outer side of the locking column 808 is provided with a baffle 806, the baffle, when the position of the fixing frame 9 needs to be adjusted, the elasticity of a locking spring 805 is overcome, a locking column 808 is pulled through a shifting rod 804 until the shifting rod 804 is separated from a guide groove 803, the locking column 808 is rotated to enable the shifting rod 804 to deviate from the guide groove 803, the shifting rod 804 is limited through a guide pipe 802, the inner end of the locking column 808 is in a state of being completely separated from a locking hole 602, the locking and fixing of the fixing frame 9 are released, when the fixing frame 9 needs to be locked and fastened, the locking column 808 is coaxial with the locking hole 602, the locking column 808 is rotated to enable the shifting rod 804 to correspond to the guide groove 803, the baffle 806 is pushed by the elasticity of the locking spring 805, the baffle 806 drives the locking column 808 to move, the locking column 808 is inserted into the locking hole 602, and the fixing frame 9 is locked.

The locking columns 808 are in clearance fit with the locking holes 602, so that the locking columns 808 can be fully contacted with the locking holes 602, and the locking and fixing stability of the fixing frame 9 is ensured.

The outside of stand pipe 802 runs through and is provided with spacing groove 807, spacing groove 807 is close to and bears frame 801, spacing groove 807 radially extends along stand pipe 802, and spacing groove 807 is linked together with guide way 803, set up like this, when locking post 808 inserts locking hole 602 inside, driving lever 804 is located the intercommunication department of spacing groove 807 and guide way 803, screw in driving lever 804 inside spacing groove 807, carry on spacingly to driving lever 804 through spacing groove 807, thereby can prevent that locking post 808 from breaking away from locking hole 602 inside, help guaranteeing the fixed steadiness of locking to mount 9.

Preferably, the inner wall of the limiting groove 807 is provided with anti-slip threads, so that the friction force between the limiting groove 807 and the shifting rod 804 can be increased, and the shifting rod 804 is prevented from being separated from the limiting groove 807.

The front side surface of the rotating rod 6 is provided with a plurality of positioning holes 603, the positioning holes 603 are uniformly distributed around the axis of the rotating shaft 11, the front side surface of the bearing block 7 is provided with a mounting hole 701 in a penetrating manner, the mounting hole 701 corresponds to the positioning holes 603, the positioning component 4 comprises a positioning column 403, the positioning column 403 is slidably mounted in the mounting hole 701, the inner end of the positioning column 403 extends towards the positioning hole 603, the outer end of the positioning column 403 is provided with a pull plate 401, the outer side of the positioning column 403 is sleeved with a positioning tension spring 402, two ends of the positioning tension spring 402 are respectively connected with the pull plate 401 and the bearing block 7, when the angle of the rotating rod 6 needs to be adjusted, the tension of the positioning tension spring 402 is overcome, the positioning column 403 is pulled by the pull plate 401, the inner end of the positioning column 403 is completely separated from the positioning holes, the pulling plate 401 is pulled by the pulling force of the positioning tension spring 402, so that the pulling plate 401 drives the positioning column 403 to move, and the positioning column 403 is inserted into the positioning hole 603, thereby fixing the rotating plate.

The positioning column 403 is in clearance fit with the positioning hole 603, so that the positioning column 403 can be fully contacted with the positioning hole 603, and the fixing stability of the rotating rod 6 is ensured.

The front side surface of the fixing frame 9 is provided with a guide hole 901 in a penetrating way, the pressing component 5 comprises a sliding column 504, the sliding column 504 is slidably arranged in the guide hole 901, the outer end of the sliding column 504 is provided with a pulling block 501, the inner end of the sliding column 504 extends into the fixing frame 9 and is provided with a pressing plate 503, the outer side of the sliding column 504 is sleeved with a pressing spring 502, the pressing spring 502 is positioned between the pressing plate 503 and the inner wall of the bearing frame 801, when the display drawing is required to be pressed and fixed in the fixing frame 9, the elastic force of, the sliding column 504 is pulled through the pulling block 501, so that the sliding column 504 drives the pressing plate 503 to move, a gap exists between the pressing plate 503 and the inner wall of the fixing frame 9 far away from the pressing spring 502, the display drawing is inserted between the pressing plate 503 and the inner wall of the fixing frame 9, the pulling block 501 is slowly loosened, the pressing plate 503 is pushed by the elasticity of the pressing spring 502, and the display drawing is pressed and fixed inside the fixing frame 9 by the pressing plate 503.

Pull plate 401 and pull block 501 surface all install the pull ring, and the setting is convenient for through pull ring pulling pull plate 401 and pull block 501 like this.

The self-locking universal wheel 1 is installed on the bottom surface of the base 2, so that the self-locking universal wheel 1 is arranged to facilitate movement and fixation of the device, and the use flexibility of the device is improved.

By adopting the structure, when the device is used, the height of the bearing block 7 can be adjusted by adjusting the length of the height adjusting rod 3, so that different hanging height requirements can be met; when a drawing needs to be hung and displayed, the rotating rod 6 is rotated through the rotating shaft 11, the rotating rod 6 is in a horizontal state, the rotating rod 6 is fixed through the positioning assembly 4, the position of the fixing frame 9 is adjusted according to the specific size of the drawing, when the fixing frame is adjusted, the fixing frame 9 is locked and fixed through the locking assembly 8 in a contact mode, the T-shaped block 10 slides in the T-shaped groove 601, the distance between the two fixing frames 9 is adjusted, the distance between the two fixing frames 9 meets the size of the drawing, the fixing frame 9 is locked and fixed through the locking assembly 8, soil needing to be hung and displayed is inserted into the fixing frame 9, the drawing is pressed and fixed in the fixing frame 9 through pressing and fixing, and hanging and displaying of the drawing is achieved; when the folding device is not used, the fixing of the positioning component 4 on the rotating rod 6 is released, the rotating rod 6 is rotated to be in a vertical state through the rotating shaft 11, the rotating rod 6 can be rotated and folded, the occupied space of the folding device is greatly reduced, and the folding device is convenient to store; the position of the fixing frame 9 can be adjusted and fixed through the T-shaped block 10, the T-shaped groove 601 and the locking assembly 8, the hanging requirements of drawings of different sizes can be met, the operation is simple and convenient, and the application range is wide.

The above description is only for the specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto, and any person skilled in the art can easily think of the changes or substitutions within the technical scope of the present invention, and all should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. The utility model provides an use analytic show shelf of mathematical problem which characterized in that: the lifting device comprises a base (2), wherein a height adjusting rod (3) is installed on the surface of the base (2), a bearing block (7) is vertically installed upwards at the lifting end of the height adjusting rod (3), an installation groove (702) is formed in the bottom surface of the bearing block (7), the installation groove (702) penetrates through two side surfaces of the bearing block (7) in the length direction, a vertically rotating rotary rod (6) is installed at two ends inside the installation groove (702) through a rotating shaft (11), and a positioning assembly (4) used for fixing the angle of the rotary rod (6) is arranged on the front side surface of the bearing block (7);

rotary rod (6) bottom surface is provided with T type groove (601), T type groove (601) inside slidable mounting has T type piece (10), wear out T type groove (601) and install mount (9) T type piece (10) bottom surface, mount (9) are "n" style of calligraphy structure, mount (9) leading flank is provided with and is used for compressing tightly the drawing to be fixed the inside subassembly (5) that compresses tightly of mount (9), mount (9) dorsal plane is provided with and is used for right mount (9) carry out locking fixed locking Assembly (8).

2. The display rack for resolving the application mathematics difficult problem as set forth in claim 1, characterized in that: heightening pole (3) are including fixed pipe (301), fixed pipe (301) are vertical to be installed base (2) surface, fixed pipe (301) outside is run through and is provided with lift groove (302), lift groove (302) along the axial extension of fixed pipe (301), fixed pipe (301) are inside to be installed through the bearing and to bear cover (305), bear cover (305) upper end and wear out fixed pipe (301) and install adjusting nut (306), adjusting nut (306) are inside to install lift lead screw (304) through the screw thread, lift lead screw (304) upper end with carrier block (7) are connected, lift lead screw (304) bottom is stretched into inside fixed pipe (301), and install guide block (303), guide block (303) are followed lift groove (302) are inside to be worn out.

3. The display rack for resolving the application mathematics difficult problem as set forth in claim 1, characterized in that: the utility model discloses a locking assembly, including rotary rod (6), locking assembly (8), bearing frame (801) are installed the mount (9) dorsal part, and are "L" style of calligraphy structure, bearing frame (801) is including bearing frame (801), bearing frame (602) is installed the length direction evenly distributed of rotary rod (6), and it has stand pipe (802) to bear the vertical side-mounting that the rotary rod (6) was kept away from in bearing frame (801), stand pipe (802) with locking hole (602) is corresponding, the stand pipe (802) outside is run through and is provided with guide way (803), guide way (803) along guide way (802) axial extension, inside slidable mounting of stand pipe (802) has locking post (808), driving lever (804) are installed to locking post (808) outer end, driving lever (804) follow inside wear out of guide way (803), locking post (808) inner stretches into bear frame (801) inside and to locking hole (602) extend, baffle (806) are installed to locking post (808) outside, baffle (806) are located rotary rod (6) with bear between the frame (801) inner wall, locking post (808) outside cover is equipped with locking spring (805), locking spring (805) are located baffle (806) with bear between the frame (801) inner wall.

4. The display rack for resolving the application mathematics puzzle according to claim 3, characterized in that: the locking post (808) is in clearance fit with the locking hole (602).

5. The display rack for resolving the application mathematics puzzle according to claim 3, characterized in that: the outer side of the guide pipe (802) is provided with a limiting groove (807) in a penetrating mode, the limiting groove (807) is close to the bearing frame (801), the limiting groove (807) extends along the radial direction of the guide pipe (802), and the limiting groove (807) is communicated with the guide groove (803).

6. The display rack for resolving the application mathematics puzzle according to claim 3, characterized in that: the utility model discloses a positioning assembly, including rotary rod (6), locating hole (603) and locating component (4), locating column (403) slidable mounting be in inside mounting hole (701), locating column (403) inner to locating hole (603) extend, arm-tie (401) are installed to locating column (403) outer end, locating column (403) outside cover is equipped with location extension spring (402), the both ends of location extension spring (402) respectively with arm-tie (401) with bearing block (7) are connected.

7. The display rack for resolving the application mathematics difficult problem as set forth in claim 6, characterized in that: the positioning column (403) is in clearance fit with the positioning hole (603).

8. The display rack for resolving the application mathematics difficult problem as set forth in claim 6, characterized in that: the front side face of the fixing frame (9) is provided with a guide hole (901) in a penetrating mode, the pressing assembly (5) comprises a sliding column (504), the sliding column (504) is installed inside the guide hole (901) in a sliding mode, a pulling block (501) is installed at the outer end of the sliding column (504), the inner end of the sliding column (504) stretches into the fixing frame (9) and is provided with a pressing plate (503), a pressing spring (502) is sleeved on the outer side of the sliding column (504), and the pressing spring (502) is located between the pressing plate (503) and the inner wall of the bearing frame (801).

9. The display rack for resolving the application mathematics puzzle according to claim 8, characterized in that: pull rings are arranged on the surfaces of the pull plate (401) and the pull block (501).

10. The display rack for resolving the application mathematics difficult problem as set forth in claim 1, characterized in that: the bottom surface of the base (2) is provided with a self-locking universal wheel (1).