CN107013158B

CN107013158B - Practical and safe three-leg ladder for orchard

Info

Publication number: CN107013158B
Application number: CN201710311516.1A
Authority: CN
Inventors: 杨淮清; 杨莹; 贾威
Original assignee: Shenyang University of Technology
Current assignee: Shenyang University of Technology
Priority date: 2017-05-05
Filing date: 2017-05-05
Publication date: 2020-06-19
Anticipated expiration: 2037-05-05
Also published as: CN107013158A

Abstract

The practical and safe three-leg ladder for the orchard comprises pedal ladder legs, supporting ladder legs, a treading ladder surface and ladder foot pads; the upper ends of the pedal ladder legs and the upper ends of the supporting ladder legs are connected with the tread surface in a way of adjusting the angle, and the lower ends of the pedal ladder legs and the lower ends of the supporting ladder legs are connected with the orthogonal shaft joints and the ladder foot pads in a way of realizing steering and up-and-down translation; two step ladder legs and a support ladder leg jointly form a triangular support structure relation to the step ladder surface. The invention has simple, reliable and reasonable structure and complete functions, not only maintains the original efficacy and characteristics of the simple three-leg ladder, but also adds the warning notice of keeping the tread level and adjusting, supporting the rotation constraint of the ladder legs, touching the ground of the whole area of the ladder foot pads and possible overturning, thereby fundamentally preventing the occurrence of personal injury events caused by slippage and overturning, greatly improving the safe use limit of different crowds, and greatly expanding the adaptability of various geographic environments.

Description

Practical and safe three-leg ladder for orchard

Technical Field

The invention relates to a practical and safe three-leg ladder for an orchard, which can be applied to the orchard and can also be applied to ascending and climbing indoors or in other common environments.

Background

At present, the simple three-leg ladder widely applied to climbing and climbing in various orchard environments has numerous hidden dangers, and especially, the simple three-leg ladder is outstanding in that the personal safety of a user is lack of effective guarantee. People of different age groups, sexes and social experiences often work simultaneously with both hands in the orchard, and change self position, gesture from time to time according to actual conditions needs, in case take place the focus unbalance and lead to the ladder to topple and easily appear the health injury. Operators often stand on the top end of the ladder, are difficult to find around the ladder depending on objects and objective reality such as loose and slippery soil, and the like, so that frequent ladder overturning events are facilitated, branches are dense, irregular growth is easy to cause that the ladder overturning process cannot be effectively avoided, and the damage degree is aggravated. If the simple three-leg ladder is changed into other occasions, the opening and closing angles of the ladder legs are different, the top stepping ladder surface is welded with the pedal ladder legs due to the fact that the fixed angles are tied, therefore, the top stepping ladder surface cannot be adjusted to be level according to needs, and the lower ends of the ladder legs are only welded with angle irons, so that the simple three-leg ladder is easy to slide and overturn by point contact. The lifting platform, the herringbone ladder, the drawing ladder and the like are difficult to be widely used in the orchard due to various limitations of cost, space requirements, complex operation and the like.

Disclosure of Invention

The purpose of the invention is as follows: the invention relates to a practical and safe three-leg ladder for an orchard, which aims to solve the problem that a simple three-leg ladder cannot adjust and level the tread of a tread, and utilizes a ratchet ring, a ratchet cup, a sliding plate, a spring and a bolt to tightly connect the tread of the tread with the pedal ladder legs and adjust and level the tread at intervals as expected to meet the requirements of users; in order to reduce and prevent slippage and overturn, the ladder foot pad is contacted with the ground in a whole area all the time through the orthogonal coupling on one hand, and the antiskid effect is further enhanced in the soft soil deeply pricked by the nails on the antiskid foot plate on the other hand. Besides, the force measuring potentiometer is used for continuously detecting the distance change of the ladder foot pad relative to the ladder foot, and the single chip computer gives warning of possible overturn of the ladder according to stress distribution. Therefore, the personal safety of orchard application is effectively ensured, and meanwhile, the orchard application can be applied to other various places with confidence.

The technical scheme is as follows: the invention is realized by the following technical scheme:

practical safe three-leg ladder in orchard, its characterized in that: the three-leg ladder comprises pedal ladder legs, supporting ladder legs, a pedal ladder surface and ladder foot pads; the upper ends of the pedal ladder legs and the upper ends of the supporting ladder legs are connected with the pedal ladder surface in an angle-adjustable manner, and the lower ends of the pedal ladder legs and the lower ends of the supporting ladder legs are connected with the orthogonal shaft joints and the ladder foot pads in a steering and up-and-down translation manner through ladder feet; two step ladder legs and a support ladder leg jointly form a triangular support structure relation to the step ladder surface.

A bolt fixing shaft is arranged at the top end of each pedal ladder leg, a ratchet ring is welded on the coaxial line of the bolt fixing shaft, and the treading ladder surface penetrates through the ratchet ring to realize connection and rotation with the pedal ladder legs; the end surface of the ratchet ring is buckled and pressed with a ratchet cup, and the ratchet ring and the ratchet cup are meshed and positioned by means of the end surface ratchets; the outer side of the bottom of the ratchet cup is fixedly connected with a sliding plate, the other side of the sliding plate is pressed with a compression spring, the other end of the sliding plate is limited by two pin shafts parallel to the axis of a bolt fixing shaft and is connected to the tread ladder surface, the bolt fixing shaft penetrates through a central circular hole in the bottom of the ratchet cup, the sliding plate and the compression spring and is locked by nuts, and therefore rotation and locking between the ratchet ring and the ratchet cup are achieved.

The left side and the right side of the top end of each supporting ladder leg are provided with transverse bolt rotating shafts penetrating through the tread ladder surface, and the outer sides of the transverse bolt rotating shafts are locked and compressed by nuts.

The step ladder legs and the bottom ends of the supporting ladder legs are all provided with ladder feet, the ladder feet are hinged with the ladder foot pads through orthogonal coupling joints, and the ladder feet and the ladder foot pads are connected in a mode that the ladder foot pads are always in full-area contact with the ground.

The ladder foot is provided with a transverse long hole with a vertical eccentric axis on the central line of the side surface of the ladder leg, namely the extension of the transverse round hole in the up-down direction, and a pin shaft passes through the ladder foot long hole and the orthogonal coupling, so that the rotation and up-down translation hinge joint between the ladder foot and the orthogonal coupling is realized; the plane of the eccentric shaft of the long hole of the ladder leg is orthogonally provided with a through round hole, a position detection rod is inserted in the round hole, the upper end of the position detection rod is fixed with a positioning sheet, the positioning sheet is pushed by a compression spring to be tightly propped against the pin shaft, the positioning sheet drives a sliding type force measuring potentiometer fixed on the support to indirectly measure the bearing change of the ladder leg pad when acting, and the force measuring potentiometer is connected with a single chip computer.

The force measuring potentiometer converts the stress of the ladder foot pad into resistance value parameters at any time, and the single chip computer warns and informs of overturning in time according to the stress distribution change of each leg when exceeding a preset threshold value.

The lower end of the orthogonal coupling is rotatably connected to the ladder foot pad through a rotating shaft, so that the rotary hinge is realized.

The bottom end of the ladder foot pad is provided with an anti-skid foot plate.

The bottom of the anti-skid foot plate is provided with anti-skid nails.

The advantages and effects are as follows: the invention provides a practical and safe three-leg ladder for an orchard, which mainly comprises pedal ladder legs, supporting ladder legs, a treading ladder surface, ladder feet, orthogonal coupling joints, ladder foot pads and optional anti-skid foot plates, wherein the pedal ladder legs are connected with the supporting ladder legs through the supporting ladder legs; the treading ladder surface is connected with the supporting ladder legs through a transverse bolt rotating shaft, and is connected with the pedal ladder legs through a pin shaft, a sliding plate, a ratchet cup, a ratchet ring and a pressing spring and a bolt fixing shaft; the ladder leg pad is respectively connected with the bottom ends of the step ladder legs and the supporting ladder legs by virtue of the orthogonal coupling and the ladder feet, the ladder leg pad is always kept in full-area contact with the ground under the help of the orthogonal coupling, and the anti-skid foot plate can be selected to further weaken, so that slipping and overturning events possibly occurring in the use of soft ground in an orchard can be avoided; the ladder foot utilizes the long hole to be hinged with the orthogonal coupling round hole through the pin shaft, the eccentric shaft plane of the long hole of the ladder foot is orthogonally penetrated through the round hole upwards, the position detection rod is inserted in the round hole, the sliding type force measurement potentiometer is linked to indirectly reflect the gravity borne by the ladder foot pad through the change of resistance parameters under the pushing of the compression spring, and finally, the single chip computer gives out the warning of possible overturn in due time according to the preset or learning threshold value according to the stress distribution of each leg.

On the premise of inheriting various advantages of the simple three-leg ladder, the defect that the tread cannot be adjusted and leveled along with the difference of the opening and closing angles of the ladder legs is overcome by introducing the connection of the tread with the ladder legs of the pedal through the sliding plate, the ratchet cup, the ratchet ring and the bolt fixing shaft; meanwhile, the original characteristics of free opening and closing and free rotation are kept by treading the transverse bolt rotating shaft between the ladder surface and the supporting ladder legs, the random degree of rotation is limited, and the use safety guarantee is further improved; the combined action of the orthogonal coupling, the ladder foot pad, the anti-skidding foot plate, the sliding force-measuring potentiometer, the single chip computer and the like adds the anti-skidding, anti-overturning and overturning warning functions which are not possessed by the simple three-leg ladder, and the simple three-leg ladder can be safely used in different types of environments, can be widely applied to people at all ages and with physical ability and agility, and even opens up the application possibility for people suffering from a certain slight disability.

The invention has simple, reliable and reasonable structure and complete functions, not only maintains the original efficacy and characteristics of the simple three-leg ladder, but also adds the warning notice of keeping the tread level and adjusting, supporting the rotation constraint of the ladder legs, touching the ground of the whole area of the ladder foot pads and possible overturning, thereby fundamentally preventing the occurrence of personal injury events caused by slippage and overturning, greatly improving the safe use limit of different crowds, and greatly expanding the adaptability of various geographic environments.

Description of the drawings:

FIG. 1 is a schematic diagram of the main structure and layout of the present invention;

FIG. 2 is a side view of FIG. 1;

FIG. 3 is a schematic view of the connection structure of the tread, the supporting ladder legs and the step ladder legs of the present invention;

FIG. 4 is a side view of FIG. 3;

FIG. 5 is a schematic view of the connection structure of the same ladder leg, the orthogonal shaft joint, the ladder foot pad, the anti-skid foot plate and the force measuring potentiometer of each ladder leg of the present invention;

fig. 6 is a side view of fig. 5.

The specific implementation mode is as follows: the invention is further described below with reference to the accompanying drawings:

the practical and safe three-leg ladder for the orchard comprises pedal ladder legs 1, supporting ladder legs 2, a stepping ladder surface 3 and ladder foot pads 16; the upper ends of the step ladder legs 1 and the support ladder legs 2 are connected with the step ladder surface 3 in an angle adjustable manner, and the lower ends of the step ladder legs 1 and the support ladder legs 2 are connected with the orthogonal shaft joints 12 and the ladder foot pads 16 in a steering and up-and-down translation manner through ladder feet 11; two step ladder legs 1 and one support ladder leg 2 jointly form a triangular support structure relation to the tread 3.

A bolt fixing shaft 8 is arranged at the top end of the pedal ladder leg 1, a ratchet ring 5 is welded on the coaxial line of the bolt fixing shaft 8, and the stepping ladder surface 3 penetrates through the ratchet ring 5 to realize connection and rotation with the pedal ladder leg 1; the end surface of the ratchet ring 5 is buckled and pressed with the ratchet cup 6, and the ratchet ring 5 and the ratchet cup 6 are meshed and positioned by means of end surface ratchets; the outer side of the bottom of the ratchet cup 6 is fixedly connected with a sliding plate 9, the other side of the sliding plate 9 is pressed with a compression spring 7, the other end of the sliding plate 9 is limited by two pin shafts 10 parallel to the axis of a bolt fixing shaft 8 and is connected to the tread ladder surface 3, the bolt fixing shaft 8 penetrates through a central circular hole in the bottom of the ratchet cup 6, the sliding plate 9 and the compression spring 7 and is locked by nuts, and therefore rotation and locking between the ratchet ring 5 and the ratchet cup 6 are achieved.

The left side and the right side of the top end of the supporting ladder legs 2 are provided with transverse bolt rotating shafts 4 penetrating through the tread ladder faces 3, and the outer sides of the transverse bolt rotating shafts are locked and compressed by nuts.

The bottom ends of the step ladder legs 1 and the bottom ends of the support ladder legs 2 are all provided with ladder feet 11, the ladder feet 11 are connected with ladder foot pads 16 through orthogonal coupling joints 12, and the ladder feet 11 and the ladder foot pads 16 are connected in a mode that the ladder feet 16 are always in full-area contact with the ground.

The ladder foot 11 is provided with a vertical long hole on the central line of the side surface, namely the extension of a transverse round hole in the up-down direction, and the pin shaft 13 passes through the long hole of the ladder foot 11 and the orthogonal coupling 12 to realize the rotation, up-down translation and hinge joint between the ladder foot 11 and the orthogonal coupling 12; the orthogonal direction of the long holes of the ladder legs 11 is provided with a through round hole, a position detection rod 19 is inserted in the round hole, the upper end of the position detection rod 19 is fixed with a positioning piece 20, the positioning piece 20 is pushed by a pressing spring 21 to be tightly propped against the pin shaft 13, the positioning piece 20 drives a sliding type force measuring potentiometer 23 fixed on a support 22 to indirectly measure the bearing change of the ladder leg pad 16 when acting, and the force measuring potentiometer 23 is connected with a single chip computer 24.

The lower end of the orthogonal coupling 12 is rotatably connected to a ladder foot pad 16 by a rotary shaft 14, thereby realizing a rotary hinge.

The bottom end of the ladder foot pad 16 is provided with an anti-skid foot board 17.

The bottom of the anti-skid foot plate 17 is provided with an optional anti-skid nail 18.

As shown in figure 1, the invention provides a practical and safe three-leg ladder for an orchard, which mainly comprises pedal ladder legs 1, supporting ladder legs 2, a tread surface 3 and an overturning early warning single-chip computer 24; the step ladder leg 1 is used for climbing up and down by a user, and is formed by welding (riveting) a left step leg, a right step leg and a plurality of cross beams which are arranged according to a certain interval and are provided for being stepped by the user, the step ladder leg or the step cross beam can adopt an angle shape, a groove shape, a square shape or a rectangle shape, and can also be randomly selected among iron, aluminum magnesium, aluminum titanium and stainless steel, and an actual product is determined after comprehensive and balanced according to various factors such as strength, quality, cost, durability, corrosion resistance, market purchasing convenience and the like; the supporting ladder legs 2 belong to single-leg type upright posts, the function of the supporting ladder is only to support the ladder to stand and not fall when the ladder is not leaned on, and the type and the material of the cross section are selected to be similar to those of the pedal ladder legs 1; the shape of the main body of the tread 3 is a rectangular frame, the frame can be welded, riveted and bolted together, the middle of the tread is welded (riveted) with a beam for increasing the strength, a plate-shaped or net-shaped covering piece can be welded (riveted) on the tread in order to prevent a user from carelessly extruding feet between the beam and the frame, the types and the materials of the cross sections of the frame and the beam of the tread 3 are selected, and the material of the top covering piece is selected to be similar to that of the tread ladder leg 1; the tread ladder surface 3 is connected with the tread ladder legs 1 and the support ladder legs 2 in a bolt rotating shaft mode, one step is realized by the rotation of the support ladder legs 2 relative to the tread ladder surface 3 to realize the opening and closing change, and the other step is realized by the rotation of the tread ladder legs 1 relative to the tread ladder surface 3 to keep the tread ladder surface 3 flat and adjusted; the single chip computer 24 continuously detects the parameter changes of the force measuring potentiometers at the bottom ends of the step ladder legs 1 and the support ladder legs 2 and gives warning information of possible overturn in due time. The overturn warning threshold is generated through analysis and prediction on the basis of the memory reference of the quickness of restoring the gravity center unbalance of the recent user through presetting, practical application experience accumulation, stress distribution of each leg, stress change rapidity, development trend and the like.

As shown in fig. 2, a schematic view of the connection structure between the tread 3 and the supporting legs 2 and 1 is given. Firstly, an angular, groove or square cross beam which is slightly shorter than the width of the tread ladder surface 3 is welded (riveted) in the orthogonal vertical direction of the top ends of the supporting ladder legs 2, transverse bolt rotating shafts 4 which are used for penetrating through the tread ladder surface 3 and playing a connecting role are welded at the corners of the left side and the right side of the cross beam, and locking compression is realized by nuts at the outer sides of the transverse bolt rotating shafts 4. The beam does not follow the current common inner and outer circular tube sleeving thought, and the basic purpose of the beam is to provide necessary settable tightening adjustment according to the will of a user while keeping the relative rotation characteristic between the support ladder legs 2 and the tread ladder surface 3, so that the potential safety use hazard caused by the original random rotation is overcome. For the convenience of processing and the avoidance of galvanic reaction, the material of the cross beam should be the same as that of the supporting ladder legs 2. Secondly, in order to ensure that the outer edges of the step ladder legs 1 and the step ladder faces 3 are not greatly different from each other, angular transition bodies are welded at the top ends of the upright posts of the step ladder legs 1 on the left side and the right side, one side face of each angular transition body is welded on the cross section of each step ladder leg 1, and the other side of each angular transition body is suspended and used for being connected with the step ladder faces 3 through bolt fixing shafts 8 of round holes in the other side. The unsettled face of angular form transition body has the thorn ring 5 to having welded on the round hole concentric shaft of trampling ladder face 3 one side, and the thorn ring 5 passes 3 frames of trampling ladder faces and erects a face round hole and realize supporting and trampling ladder face 3 to reach and let footboard ladder leg 1 can rotate for trampling ladder face 3 around bolt fixed axle 8, thereby satisfy and trample ladder face 3 and keep flat the adjustment. In order to ensure the locking of the corner between the step ladder leg 1 and the step ladder surface 3, a ratchet ring 5 is buckled with a ratchet cup 6 with a cup bottom center round hole penetrating through a bolt fixing shaft 8, the bolt fixing shaft 8 at the other side of the ratchet cup 6 is sleeved with a compression spring 7, the tail end of the compression spring 7 is locked by a nut, and the elastic tension of the compression spring 7 is adjusted by the nut. In order to achieve the expected target of the ratchet cup 6, the outer side of the bottom end surface of the ratchet cup is welded (riveted) with a sliding plate 9, and the other end of the sliding plate 9 is tightly connected with the tread ladder surface 3 through pin shafts 10 which respectively penetrate through two round holes of the sliding plate and maintains the mutual pose and angle unchanged. In order to prevent the slide plate 9 from separating from the pin shaft 10 and falling off the ladder, the pin shaft 10 should be of a perforated type and limited by a cotter pin. When the leveling angle of the tread ladder surface 3 is adjusted, the ratchet cup 6 and the sliding plate 9 are lifted together along the axial direction of the pin shaft 10, so that the ratchet ring 5 and the ratchet cup 6 are disengaged, after the adjustment is finished, the ratchet cup 6 and the sliding plate 9 are released, and the original ratchet ring 5 and the ratchet cup 6 are engaged and locked again under the pushing of the compression spring 7. The ratchet ring 5 is a simple variation of ratchet wheel with ratchet changed from circumferential generatrix to circular section, and the ratchet cup 6 is similar to the ratchet ring 5 except that the former provides the action support surface for the compression spring 7 and the bottom of the opposite end surface of the ratchet is provided with a cup bottom with a central circular hole. The tooth shapes of the ratchet ring 5 and the ratchet cup 6 can be triangular, trapezoidal or rectangular, and the key selection is the harmony and compromise between the tooth pitch, the tooth height, the locking safety, the leveling transformation convenience and the like. The pitch is of primary concern here because it directly determines the fineness and resolution of the tread 3 leveling but is not so preferential as to impede overall performance improvement due to constraints imposed by several other factors. In fact, the combination of the ratchet ring 5, the ratchet cup 6, the sliding plate 9 and the pressing spring 7 does not constitute the only way to achieve the objective of leveling adjustment and locking, and can be replaced by a conventional ratchet wheel and a conventional pawl if desired.

As shown in fig. 1 and 3, the bottom ends of the left and right ladder legs of the supporting ladder legs 2 and the pedal ladder legs 1 are welded (riveted) with ladder feet 11, the ladder feet 11 are provided with horizontal strip holes with vertical eccentric axes on the central line of the side surface, namely, the vertical extension of the horizontal round holes, and the vertical strip holes are seen from the side surface, the strip holes penetrate through the ladder feet 11 so as to allow the pin shafts 13 penetrating through the ladder feet to do vertical translation movement under the action of bearing pressure, and the pin shafts 13 are of an opening type and are inserted and bent by split pins to prevent the falling. The pin 13 passing through the long hole of the ladder foot 11 and the top round hole of the orthogonal coupling 12 realize a rotary hinge, the orthogonal coupling 12 is orthogonal relative to the axis of the top round hole and is welded with a rotating shaft 14 which is downward, and the orthogonal coupling 12 and the ladder foot pad 16 are tightly connected together with the help of a rotating shaft buckle cover 15. The landing side of the ladder foot pad 16 can be selectively and temporarily connected with an anti-skid foot plate 17 through bolts, and anti-skid nails 18 on the anti-skid foot plate 17 ensure that the soft ground of the orchard is used without slipping and overturning. The number and length of the antiskid nails 18 on the antiskid foot plate 17 can be changed in a wide range according to the geological species and the user's will, but in consideration of the stress balance and the visual beauty, the paired and symmetrical arrangement is recommended as much as possible. The cross-sectional size and the material selection also have a great convolution space, for example, the selection can be made between cast iron, low-carbon steel, high-carbon steel, even manganese steel and the like in the aspect of the material. Of course, proper material positioning must still allow for durability, hardness, brittleness, cost and ease of procurement, etc., but not for that matter. The orthogonal coupling 12 and the rotating shaft 14 on the orthogonal coupling are used for the purpose of adapting the ladder foot pad 16 to the unevenness of the ground, and finally, the ladder foot pad 16 is ensured to face the ground within a large enough inclination range and maintain contact with the ground in a full area all the time, so that the antiskid overturning and the rat cave collapse and falling are further improved. In addition, the rotating shaft buckle cover 15 which is used as the responsibility for compressing and locking the rotating shaft 14 and the ladder foot pad 16 on the orthogonal coupling 12 not only has the connecting function, but also has the non-random and self-adaptive ground inclination characteristic without special adjustment due to the left and right distribution and tight screwing of the two sides.

As mentioned above, the pin 13 passing through the elongated hole of the ladder leg 11 not only connects the ladder leg 11 and the orthogonal coupling 12, so that the orthogonal coupling 12 can rotate, but also provides a motion support for the position detecting rod 19 and the force measuring potential 23 connected thereto. The pin 13 is tightly fixed on the orthogonal coupling 12, the two are almost immovable, and the structure that the pin 13 passes through the vertical strip hole of the ladder foot 11 drives the orthogonal coupling 12 and the pin 13 to do up-and-down translational motion relative to the ladder foot 11 along with the stress change of the ladder foot pad 16, and the pin 13 is circular, so the orthogonal coupling 12 rotates relative to the ladder foot 11 around the axis of the pin 13. The position detecting rod 19 is fixed with a positioning plate 20 at the outer side of the ladder foot 11, the positioning plate 20 is pushed by a pressing spring 21 and tightly propped against the pin shaft 13, and the other side of the pressing spring 21 turns towards the bottom plate by depending on a fixed support 22 to form the coordination of assembly and stop. The positioning plate 20 drives the sliding force-measuring potentiometer 23 fixed on the bracket 22 to indirectly convert the pin shaft 13 movement caused by the bearing stress change of the ladder foot pad 16 into the resistance parameter change, and further the collected bearing, distribution and development trend of each ladder leg is comprehensively considered by combining various factors and the above factors, and necessary warning and informing are carried out at a proper time. The force measuring potentiometer 23 is connected with the positioning plate 20, and can adopt a clamping mode and a sleeving mode, and relatively speaking, if the sliding arm of the potentiometer is thick enough, the clamping mode has a little advantage in the aspects of assembly, clearance adaptation and the like.

Claims

1. Practical safe three-leg ladder in orchard, its characterized in that: the three-leg ladder comprises pedal ladder legs (1), supporting ladder legs (2), a pedal ladder surface (3) and ladder foot pads (16); the upper ends of the step ladder legs (1) and the support ladder legs (2) are connected with the step ladder surface (3) in an angle-adjustable manner, and the lower ends of the step ladder legs (1) and the support ladder legs (2) are connected with the orthogonal shaft joints (12) and the step foot pads (16) in a steering and vertical translation manner through ladder feet (11); the two step ladder legs (1) and the supporting ladder leg (2) jointly form a triangular supporting structure relation to the step ladder surface (3);

a bolt fixing shaft (8) is arranged at the top end of each pedal ladder leg (1), a ratchet ring (5) is welded on the coaxial line of the bolt fixing shaft (8), and the pedal ladder surface (3) penetrates through the ratchet ring (5) to realize connection and rotation with the pedal ladder legs (1); the end surface of the ratchet ring (5) is buckled and pressed with the ratchet cup (6), and the ratchet ring (5) and the ratchet cup (6) are meshed and positioned by means of end surface ratchets; a sliding plate (9) is fixedly connected to the outer side of the bottom of the ratchet cup (6), a compression spring (7) is pressed on the other side of the sliding plate (9), the other end of the sliding plate (9) is limited and connected to the tread ladder surface (3) through two pin shafts (10) parallel to the axis of a bolt fixing shaft (8), the bolt fixing shaft (8) penetrates through a central circular hole in the bottom of the ratchet cup (6), the sliding plate (9) and the compression spring (7) and is locked through nuts, and therefore rotation and locking between the ratchet ring (5) and the ratchet cup (6) are achieved.

2. An orchard practical safety three-leg ladder according to claim 1, characterized in that: the left side and the right side of the top end of each supporting ladder leg (2) are provided with transverse bolt rotating shafts (4) penetrating through the tread ladder surface (3), and the outer sides of the transverse bolt rotating shafts are locked and compressed by nuts.

3. An orchard practical safety three-leg ladder according to claim 1 or 2, characterised in that: the bottom ends of the pedal ladder legs (1) and the supporting ladder legs (2) are provided with ladder feet (11), the ladder feet (11) are connected with ladder foot pads (16) through orthogonal coupling joints (12), and the ladder feet (11) and the ladder foot pads (16) are connected in a mode that the ladder feet (11) are always in full-area contact with the ground.

4. An orchard practical safety three-leg ladder according to claim 3, characterized in that: a vertical long hole is formed in the central line of the side surface of the ladder foot (11), and a pin shaft (13) penetrates through the long hole of the ladder foot (11) and the orthogonal coupling (12) to realize the rotation and up-and-down translation hinge joint between the ladder foot (11) and the orthogonal coupling (12); a through round hole is formed in the rectangular hole of the ladder leg (11) in the orthogonal direction, a position detection rod (19) is inserted into the round hole, a positioning piece (20) is fixed at the upper end of the position detection rod (19), the positioning piece (20) is pushed by a compression spring (21) to be tightly abutted onto the pin shaft (13), the positioning piece (20) drives a sliding type force measurement potentiometer (23) fixed on the support (22) to indirectly measure the bearing change of the ladder leg (16) when acting, and the force measurement potentiometer (23) is connected with a single chip computer (24).

5. An orchard practical safety three-leg ladder according to claim 4, characterized in that: the lower end of the orthogonal coupling (12) is rotatably connected to the ladder foot pad (16) through a rotating shaft (14), thereby realizing rotary hinge.

6. An orchard practical safety three-leg ladder according to claim 1, characterized in that: the bottom end of the ladder foot pad (16) is provided with an anti-skid foot plate (17).

7. An orchard practical safety three-leg ladder according to claim 6, characterized in that: the bottom of the anti-skid foot plate (17) is provided with an optional anti-skid nail (18).