CN205971424U - Can climb stair helping hand floor truck - Google Patents

Abstract

The utility model relates to a stair-climbing power-assisted transport trolley, comprising a load-bearing device for carrying goods, a stair-climbing device for climbing stairs through crawler movement, a flat ground and stair conversion device for adjusting the working angle between the load-bearing device and the stair-climbing device, and a control device. The control device and power supply for the working state of the stair climbing device and the flat ground and the stair conversion device; the load-bearing device and the stair climbing device are connected through the flat ground and the stair conversion device. The stair-climbing power-assisted transport trolley of the utility model has dual functions of running on flat roads or climbing stairs, its moving speed and direction are adjustable, and the structure is simple and easy to operate, which greatly reduces the labor intensity of operators and improves work efficiency and safety. .

Description

A stair-climbing power-assisted transport trolley

technical field

The utility model relates to the field of power-assisted transporting trolleys, in particular to a stair-climbing power-assisted transporting trolley.

Background technique

In recent years, with the continuous acceleration of my country's urbanization process and the continuous increase of the proportion of cities and towns, the floors of housing in various places are getting higher and higher, and there are great difficulties in the handling of various items. And with the development of transportation service industries such as express delivery and moving, especially the delivery of more and more diversified items in the express delivery industry, many large goods need to be moved, and there are great limitations in manpower and freight elevators. At this time, a A convenient and flexible stair-climbing assisting device to complete the handling of large items. In some areas and complex terrain where mechanized equipment is not popular, a small and flexible power-assisted equipment is also needed.

The development concept of the stair climbing trolley is to use a simple mechanical device to complete the transportation of complex terrain.

About the research of stair-climbing device, abroad started relatively early, and American Bray just applied for the patent of stair-climbing wheelchair in 1892. Since then, various countries have begun to invest in this research, among which the United States, the United Kingdom, Germany and Japan are dominant, the technology is relatively mature, and some products have been put into use in the market.

Although my country's research on this type of device started relatively late, many patents in this area have also emerged in recent years. Existing stair-climbing device and patent both at home and abroad at present, its realization principle mainly is divided into compound wheel type, lever type, screw rod type. Among them, the compound wheel type has serious bumps and impacts, poor stability, cannot adapt to steps of different sizes, and has difficulty in turning; the lever type has poor stability and is prone to overturning if improperly operated; the screw type has limited load and is difficult to control.

Such as Chinese Patent Publication No.: CN 101085621 discloses a portable semi-automatic stair-climbing dolly, but the center of gravity fluctuates greatly during the work of the dolly, the movement is unstable, the load capacity is small, and it is difficult to control.

In view of above-mentioned defect, the creator of the utility model has finally obtained this creation through research and practice for a long time.

Contents of the invention

The purpose of the utility model is to provide a stair-climbing power-assisted transport trolley to overcome the above-mentioned technical defects.

In order to achieve the above purpose, the utility model provides a stair-climbing power-assisted transport trolley, including: a load-bearing device for carrying goods, a stair-climbing device for climbing stairs through crawler movement, and a flat ground for adjusting the working angle between the load-bearing device and the stair-climbing device It is connected with the stair conversion device, the control device and the power supply for controlling the working state of the stair climbing device and the flat ground and stair conversion device; the load-bearing device and the stair climbing device are connected through the flat ground and the stair conversion device.

Further, the conversion device between level ground and stairs includes a retractable push rod, a push rod cylinder and a push rod drive motor.

Further, the stair climbing device includes: a chassis, a power unit, and a transmission unit; the power unit is placed in the housing of the chassis; the transmission unit is distributed on the left and right sides of the chassis.

Further, the bottom of the push rod drive motor is welded or fixed at the center of the load-bearing device through stud nuts; the push rod cylinder and the push rod drive motor share a base, or are welded separately or fixed by screw nuts. The column nut is fixed on the load-bearing device; one end of the push rod is sleeved inside the push rod cylinder, and the other end is hinged or riveted to the upper side of the chassis.

Further, the power unit includes a worm gear reducer and a track wheel motor;

The worm gear reducer is welded or bolted to the rear inner surface of the chassis;

The track wheel motor is connected with the worm gear reducer through a transmission shaft;

The end of the crawler motor and the worm gear reducer are fixed or welded together by bolts.

Further, the transmission unit includes a first track wheel, a second track wheel, a tensioning wheel, a first driven wheel, a second driven wheel and a track;

The transmission unit also includes a reducer output shaft, a track wheel connecting shaft, a first driven wheel connecting shaft, a second driven wheel connecting shaft, and a tensioning wheel connecting shaft;

The first crawler wheel is connected through the output shaft of the reducer; the output shaft of the reducer passes through the center of the worm gear reducer.

Further, the surfaces of the first track wheel and the second track wheel are toothed and meshed with the track; the inner and outer surfaces of the track are toothed, and the contact point with the ground is lower than the left and right sides of the chassis The lowest point of the shell wall.

Further, the control device mainly includes switches and relays; the switches and relays are fixed on the upper part or the side of the switch and relay placement frame.

Further, the switch includes a power switch, a push rod drive motor switch that can adjust the telescopic length of the push rod, and a track wheel motor switch that can adjust the running speed and direction of the crawler belt; the relay passes through Lead wire is connected with described push rod driving motor and track wheel motor.

Further, the load-bearing device includes: a handle, a carrying frame and a bottom tray;

The bearing frame is a side beam welded frame structure;

Two carrying wheels are arranged on both sides of the bottom of the carrying frame;

The handle and the bearing frame are connected by screws or welded into one;

The bottom tray and the carrier frame are welded together.

Further, the bottom of the load-bearing device is hinged or riveted to the stair climbing device through a connecting device.

Compared with the prior art, the utility model has the beneficial effects as follows: the utility model uses double-toothed crawlers for anti-slip treatment, so that the trolley does not slip when it contacts with inclined roads or stairs, and it can be used in narrow and difficult-to-walk places such as corridors. The road surface can still consign items, and the working state is stable, which greatly reduces the burden on the staff; the working angle between the track wheel and the carrier is adjusted by the push rod driving motor and the retractable push rod. When the trolley is working, it can be adjusted according to Conditions change the angle to adapt to different slopes; the switch can control the running direction of the trolley, so that the trolley can not only climb stairs for transportation, but also go downstairs for transportation; Transportation tasks on flat roads and other general terrains.

The stair-climbing assisting transport trolley described in the utility model uses a simple mechanical load-carrying trolley to replace manpower to carry out the transport work in complex terrain such as stairs or when large-scale mechanical transport equipment cannot enter. This trolley is also suitable for flat roads or steep slopes, its speed is adjustable, and it can freely switch between human-powered and electric-driven. When the trolley goes up and down the stairs, the center of gravity of the trolley always moves along a straight line parallel to the line connecting the steps of the stairs, its center of gravity fluctuates little and moves smoothly. And when the trolley is running, it only needs to be lightly supported by personnel to control the speed change and forward direction of the trolley, which greatly improves work efficiency and safety.

Description of drawings

Fig. 1 is the three-dimensional structural diagram of the stair-climbing power-assisted transport trolley of the present utility model;

Fig. 2 is a side view of the stair-climbing power-assisted transport trolley of the present invention;

Fig. 3 is a top view of the chassis of the stair-climbing power-assisted transport trolley of the present invention;

Fig. 4 is a bottom view of the stair-climbing power-assisted transport trolley of the present invention.

In the figure: 1 handle, 2 load frame, 3 battery box, 4 bottom tray, 5 first track wheel, 6 tensioner wheel, 7 first driven wheel, 8 chassis, 9 track, 10 second driven wheel, 11 second Track wheel, 12 load wheel, 13 push rod, 14 push rod cylinder, 15 push rod drive motor, 16 switch and relay mounting frame, 17 reducer output shaft, 18 first driven wheel connecting shaft, 19 second driven wheel connecting shaft , 20 track wheel connecting shaft, 21 worm gear reducer, 22 track wheel motor, 23 drive shaft, 24 connecting device.

detailed description

The above-mentioned and other technical features and advantages of the present utility model will be described in more detail below in conjunction with the accompanying drawings.

Please refer to Figures 1 and 2, the utility model is a stair-climbing power-assisted transport trolley, which mainly includes: a load-bearing device, a stair-climbing device, a conversion device between flat ground and stairs, a control device and a power supply.

The load-bearing device and the stair-climbing device are hinged or riveted together through the connecting device 24; the flat ground and stair conversion device adjusts the working angle between the load-bearing device and the stair-climbing device, so as to realize the flat road and the stair-climbing device. The conversion between; the control device controls the operating angle between the load-bearing device and the stair climbing device and the rotation speed and direction of the crawler belt 9 by controlling the working state of the push rod drive motor 15 and the track wheel motor 22; The power supply of push rod drive motor 15 and track wheel motor 22 provides electric power.

The load-bearing device includes a handle 1, a carrier frame 2 and a bottom tray 4; the handle 1 is made of hard materials such as steel, iron or aluminum alloy, and a layer of commonly used plastic materials can be added to the part held by the operator. Anti-slip textures can be provided to increase friction and operating comfort; the carrier frame 2 is a side-beam welded frame structure, which is composed of a plurality of steel bars arranged at intervals in the horizontal direction, welded or connected to the carrier frame 2 through stud nuts on the frame; the handle 1 and the carrier 2 are connected by screws or the two are welded together; the length of the bottom tray 4 is slightly longer or shorter than the width of the carrier 2, and its width depends on the load The size of the article is designed. The bottom tray 4 is used to support the article so that it does not slide down; the bottom tray 4 is welded to the carrier frame 2; Described bearing wheel 12 is responsible for the operation of dolly when flat road.

The stair climbing device includes a chassis 8, a power unit and a transmission unit. The chassis 8 is a shell made of steel plate or iron plate. The front side of the chassis 8 and the side in contact with the stairs are open, and the other sides Closed by an iron plate or a steel plate, the upper side of the chassis 8 is made of a hollow iron plate or steel plate to carry the power unit and connect the flat ground and the stair conversion device at the same time.

Please refer to shown in Fig. 3, described power unit comprises worm gear reducer 21 and track wheel motor 22, and described worm gear reducer 21 is welded or is fixed on the rear side inner surface of chassis 8 by bolt, for its fixing more firmly, one side of the worm gear reducer 21 can be fixed to the inner surface of the upper side of the chassis 8 by welding or by bolts; fixed or welded together; the track wheel motor 22 is connected to the worm gear reducer 21 through the transmission shaft 23; the worm gear reducer 21 uses its internal gears to reduce the number of revolutions of the track wheel motor 22 to the trolley The number of revolutions of the work reduces the running speed and improves the work safety. Because the trolley needs to carry a certain weight, when going up and down the stairs, the track wheel motor 22 provides power, so the required torque is relatively large. Therefore, the role of the worm gear reducer 21 here is not only to convert the direction of the force and slow down the speed of the track wheel motor 22, but also to amplify the torque provided by the track wheel motor 22 to carry greater weight. It can be known from P=FV that when the power is the same, the smaller the speed, the greater the driving force that the motor can provide.

The transmission unit includes a first track wheel 5, a second track wheel 11, a tensioning wheel 6, a first driven wheel 7, a second driven wheel 10 and a track 9, a reducer output shaft 17, a track wheel connecting shaft 20, The first driven wheel connecting shaft 18 and the second driven wheel connecting shaft 19 . The two first crawler wheels 5 are connected through the reducer output shaft 17, and the reducer output shaft 17 passes through the center of the worm gear reducer 21, and the described worm gear reducer 21 is the reducer output shaft 17 The rotation provides power, the contact between the output shaft 17 of the reducer and the outer wall of the worm gear reducer 21 is connected by bearings, the two first driven wheels 7 are connected by the first driven wheel connecting shaft 18, and the two The second driven wheel 10 is connected by the second driven wheel connecting shaft 19, the two second track wheels 11 are connected by the track wheel connecting shaft 20, the output shaft 17 of the reducer, the first driven wheel connecting shaft 18. The second driven wheel connecting shaft 19 and the track wheel connecting shaft 20 pass through the left and right shell walls of the chassis 8, and the contact between the shaft and the shell wall is connected by a bearing to reduce mechanical friction.

The first track wheel 5 is close to the rear side wall of the chassis 8, and the first track wheel 5 is a driving track wheel, which is made of aluminum alloy, steel, cast iron, stainless steel or other hard and wear-resistant materials. A crawler wheel 5 has a toothed surface and meshes with the crawler belt 9. The diameter of the first crawler wheel 5 is the largest among all parts of the transmission unit.

The bottom of the first crawler wheel 5 is close to the front side of the chassis 8, and the first driven wheel 7 is arranged, and the first driven wheel 7 is made of nylon material; the outer periphery of the first driven wheel 7 is smooth, and it has tension. The function of the crawler belt 9 ensures that the contact area between the crawler belt 9 and the stairs is sufficient, so that the dolly can run smoothly.

The second track wheel 11 is close to the front side of the chassis 8, and the second track wheel 11 is a driven track wheel, which is made of aluminum alloy, steel, cast iron, stainless steel or other hard and wear-resistant materials. The surfaces of the two crawler wheels 11 are toothed and meshed with the crawler belt 9 .

The second driven wheel 10 is located between the first driven wheel 7 and the second track wheel 11, the second driven wheel 10 is made of nylon, and the second driven wheel 10 is close to the front and rear of the chassis 8 Either the side or the middle position can be used. The outer circumference of the second driven wheel 10 is smooth, and it has the function of tensioning the crawler belt 9 .

The tension wheel 6 is made of plastic or nylon to reduce the weight of the trolley; the periphery of the tension wheel 6 is smooth; the tension wheel 6 is arranged between the first track wheel 5 and the second track wheel 11 , and close to the first track wheel 5, the working height of the tensioning wheel 6 is lower than the working height of the track 9 away from the ground side, so as to ensure that it has the effect of tensioning the track 9.

The crawler belt 9 is a flexible material used for crawler belts such as rubber. The inner and outer sides of the crawler belt 9 are tooth-shaped structures, and the inner side thereof is meshed with the first crawler wheel 5 and the second crawler wheel 11. The crawler belt 9 is lower than the lowest point of chassis 8 left and right sides shell wall with ground contact place, when guaranteeing that dolly climbs stairs, only crawler belt 9 contacts with stair face in whole stair climbing device.

The working heights of the first driven wheel 7, the second driven wheel 10 and the second track wheel 11 are the same, which ensures that the crawler belt 9 of the trolley can touch the stairs smoothly, thereby ensuring a stable working state when the trolley goes up and down the stairs .

The flat ground and stair conversion device includes a push rod 13, a push rod cylinder 14 and a push rod drive motor 15, and the bottom of the push rod drive motor 15 is welded or fixed on the center position of the carrier frame 2 by a stud nut; The upper or lower part of the push rod drive motor 15 is provided with a push rod cylinder 14, and the push rod cylinder 14 and the push rod drive motor 15 share a base, or are welded separately or fixed on the center position of the carrier frame 2 slightly by a stud nut. Up or down, one end of the push rod 13 is sleeved inside the push rod cylinder 14 , and the other end is hinged or riveted on the upper side of the chassis 8 .

The control device mainly includes a switch and a relay, and the switch and the relay are fixed on the upper part or the side of the switch and the relay mounting frame 16 by bolts or other fixing methods, and the control systems of the switch and the relay are all placed on the plastic In the box, the switch and the relay are connected by wires, and the relay is connected to the push rod drive motor 15 and the track wheel motor 22 by wires. The switch mainly includes a power switch, a push rod drive motor switch and a track wheel motor. wheel motor switch, the push rod drive motor switch can adjust the operating speed of the push rod drive motor 15, and then adjust the telescopic length of the push rod 13, so as to control the working angle of the trolley when climbing stairs, so that the trolley can be rotated at different angles Working on a ramp, the track wheel motor switch rotates in different directions to control the rotation direction of the track wheel motor 22, and then adjust the rotation direction of the track wheel, that is, to control the state of going up and down the stairs of the trolley. The relay has the functions of automatic adjustment, safety protection and conversion circuit.

Described power supply is positioned at battery box 3, and described battery box 3 has two, is made up of lead storage battery of an electric vehicle respectively, and it provides power for push rod driving motor 15 and track wheel motor 22, and described battery box 3 It is welded or fixed on the opposite side of the bottom tray 4 at the bottom of the carrier frame 2 by stud nuts. The width of the battery box 3 must be less than the horizontal distance between the load wheel 12 and the first crawler wheel 5. The battery box 3 One side cannot contact the load wheel 12, and the other side cannot contact the crawler belt 9.

The utility model is a stair-climbing power-assisted transport trolley. Its working process on a flat road: the power switch, the push rod drive motor switch and the track wheel motor switch are in the off state, the push rod 13 is in the retracted state, and the crawler belt 9 is not running. , the operator moves it by operating the handle 1, and the carrier frame 2 needs to maintain an appropriate angle with the horizontal ground, so that the operator can control the direction of movement of the trolley. The whole dolly is similar to a handcart, only the carrying wheels 12 are in contact with the ground.

The utility model is a stair-climbing power-assisted transport trolley. Its working process when going up and down the stairs: the lead-acid battery of the electric vehicle provides the overall power for the trolley, turns on the power switch and the push rod to drive the motor switch, and the switch sends a signal to the push rod. The relay connected to the rod drive motor 15, the relay transmits the signal to the push rod drive motor 15, the push rod drive motor 15 runs, and then the push rod cylinder 14 connected to it works, thereby starting the push rod 13, and finally the push rod 13 turns the chassis 8 launched. According to the angle between the stairs and the ground, the operating state of the push rod drive motor 15 is controlled by the push rod drive motor switch knob, thereby adjusting the telescopic length of the push rod 13, that is, adjusting the working angle between the chassis 8 and the carrier frame 2, so that When the trolley climbs stairs to transport goods, it can save time and effort and move smoothly. After the working angle of the trolley is adjusted, turn on the track wheel motor switch, the switch sends a signal to the relay connected to the track wheel motor 22, and the relay transmits the signal to the track wheel motor 22, the track wheel motor 22 runs, and the drive shaft 23 is connected to it The worm gear reducer 21, the worm gear reducer 21 then drives the output shaft 17 of the reducer to rotate, thereby driving the first crawler wheel 5 to rotate, and the first crawler wheel 5 drives the crawler belt 9 meshed with it to move, and then the power is transmitted to and The second track wheel 11 meshed with the track 9, the first track wheel 5 and the second track wheel 11 rotate, driving the track 9 to move at a constant speed, so that the operator only needs to hold the handle 1 tightly, and then control each motor by operating the switch knob The working state finally enables the trolley to climb stairs smoothly to transport goods. The first driven pulley 7, the second driven pulley 10 and the tension pulley 6 in the transmission device play the role of tensioning the crawler belt 9, and the first driven pulley 7 and the second driven pulley 10 ensure sufficient contact between the crawler belt 9 and the stairs area, so that the trolley can move smoothly. The working state of push rod driving motor 15 and track wheel motor 22 can all be controlled by switch, and the rotation direction of track wheel motor 22 also can be controlled by switch, and the rotation direction of track wheel motor 22 controls the rotation direction of crawler belt 9, thereby realizes that dolly transition between up and down stairs.

Compared with the prior art, the stair-climbing power-assisted transport trolley provided by the utility model has at least the following advantages:

The start and stop of the trolley, the angle between the carrier frame 2 and the chassis 8, and the running direction of the trolley are all controlled by electronic control devices such as switches, relays, stair climbing devices, and level ground and stair conversion devices. There is a strict logic between each device Sequentially, through the mutual cooperation of various components, the multi-faceted control of the switch is realized, so that the trolley can not only climb stairs for transportation, but also go downstairs for transportation.

The worm gear reducer 21 decelerates the number of revolutions of the track wheel motor 22 to a certain range in order to improve work safety. Make the moving speed of the trolley along the slope of the stairs be about 0.10m/s-0.15m/s. According to field investigations, the angle of most stairs is about 32°. When the load is 50kg, for safety considerations, the speed of the trolley should not be too fast, and this speed is just suitable for this speed range.

The inner and outer sides of the crawler belt 9 are tooth-like structures, so that the trolley does not slip when moving on an inclined road surface. Due to the weight of the trolley, the crawler belt 9 is under a greater force when going upstairs, and it is easy to form a larger deformation. Therefore, a tension pulley 6 is added to the upper part to compress the deformation space, and the first driven wheel 7 and the second driven wheel 11 supports the crawler belt 9, so that the dolly can move on the stairs smoothly and at a uniform speed.

The lower part of the load-bearing device of the trolley is hinged or riveted together with the stair-climbing device through the connecting device 24, and the center position of the load-bearing device is connected with the chassis 8 through the flat ground and the stair conversion device, so that three-point positioning is formed to make the structure of the trolley and the center of gravity more stable. Stable, and the parts placed on the chassis 8 of the dolly are symmetrically distributed to prevent the center of gravity of the dolly from shifting.

The working angle between the chassis 8 of the trolley and the carrier frame 2 is determined by the telescopic length of the push rod 13. The telescopic length of the push rod 13 is controlled by the push rod drive motor switch, and its length can be freely changed between 200mm-300mm. When the length of the push rod 13 was 200mm, that is, the push rod 13 was in a non-telescopic state. At this time, the angle between the carrier frame 2 and the chassis 8 was 11 degrees, and the crawler belt 9 could not touch the ground. Make the trolley move on flat ground. Because when the chassis 8 is put away, the second crawler wheel 11 will be pushed out forward, and at the same time, it will be more downwards. At this time, it is easy to interfere with the support wheel 12, so that the support wheel 12 cannot touch the ground, and the push rod 13 The telescoping length range avoids this interference.

The above detailed description is a specific description of one of the feasible embodiments of the utility model. This embodiment is not used to limit the patent scope of the utility model. Any equivalent implementation or change that does not deviate from the utility model shall include Within the scope of the technical solution of the utility model.

Claims (10)

1. a kind of climbing stairs assist transportation dolly is it is characterised in that including carrying the load carrier of kinds of goods, passing through caterpillar drive Realize the stair-climbing device of stair climbing, adjust the level land of operating angle and stair converting means between load carrier and stair-climbing device Put, control control device and power supply pacifically with the working condition of stair conversion equipment for the stair-climbing device；Described load-bearing dress Put and be connected with stair conversion equipment by level land and described stair-climbing device between.

2. climbing stairs assist transportation dolly according to claim 1 is it is characterised in that described level land is changed with stair Device includes telescopic push rod, push rod cylinder and push rod motor.

3. climbing stairs assist transportation dolly according to claim 2 is it is characterised in that described stair-climbing device bag Include：Chassis, power unit and gear unit；Described power unit is placed in the housing on chassis；Described gear unit divides It is distributed in the chassis left and right sides.

4. climbing stairs assist transportation dolly according to claim 3 is it is characterised in that described push rod motor Bottom welding or the center being fixed on described load carrier by stud nut；Described push rod cylinder drives electricity with push rod Machine shares a base, or individually welds or be fixed on described load carrier by stud nut；Described is telescopic Push rod one end is enclosed within push rod cylinder interior, and the other end is hinged or riveting is connected in the upside on described chassis.

5. climbing stairs assist transportation dolly according to claim 3 is it is characterised in that described power unit includes snail Worm and gear decelerator and crawler belt turbin generator；

Described worm type of reduction gearing welds or is bolted the rear side inner surface in chassis；

Described crawler belt turbin generator is connected with described worm type of reduction gearing by power transmission shaft；

The described end of crawler belt turbin generator is bolted with described worm type of reduction gearing or welds together.

6. climbing stairs assist transportation dolly according to claim 5 is it is characterised in that described gear unit includes One Athey wheel, the second Athey wheel, tensioning wheel, the first follower, the second follower and crawler belt；

Described gear unit also includes reducer output shaft, Athey wheel connecting shaft, connecting shaft；

The first described Athey wheel passes through described reducer output shaft and connects；Described reducer output shaft passes through described snail The center of worm and gear decelerator.

7. climbing stairs assist transportation dolly according to claim 6 is it is characterised in that the first described Athey wheel and The surface of two Athey wheels is dentation, and is meshed with crawler belt；Inside and outside described crawler belt, two sides is dentalation, and it is connect with ground Synapsis is less than the minimum point of chassis left and right sides shell wall.

8. climbing stairs assist transportation dolly according to claim 2 is it is characterised in that described control device mainly wraps Include switch and relay；Described switch and relay are fixed on top or the sidepiece of switch and relay dispenser.

9. climbing stairs assist transportation dolly according to claim 8 is it is characterised in that described switch includes power supply opens The fortune of the crawler belt described in the push rod motor switch of the collapsing length of telescopic push rod described in pass, scalable and scalable The Athey wheel motor switch in rotary speed and direction；Described relay passes through wire and described push rod motor and Athey wheel Motor connection.

10. climbing stairs assist transportation dolly according to claim 1 is it is characterised in that described load carrier includes： Handle, carrier and bottom tray；

Described carrier is edge-beam type lead frame structure；

The both sides of the bottom of described carrier arrange two bearing wheels；

It is connected by screw between described handle and carrier or the two is welded as a whole；

Described bottom tray is welded together with described carrier.