Synchronous telescopic arm structure and elevating fire truck thereof

Abstract

The utility model relates to the technical field of fire fighting trucks, in particular to a synchronous telescopic arm structure which comprises a first-stage arm frame, a middle arm frame and a last-stage arm frame which are sequentially connected in a sleeved mode. The winding drum is positioned at the rear end of the inner side of the first-stage boom and is driven by a driving mechanism; the first-stage pulley and the first-stage fixing seat are positioned at the front end of the bottom of the first-stage boom; the middle front pulley is positioned at the front end of the bottom of the middle boom; the middle rear pulley and the middle rear fixing seat are positioned at the rear end of the bottom of the middle boom; the middle upper fixing seat is located at the rear end of the top of the middle arm frame, the last-stage fixing seat is located at the rear end of the bottom of the last-stage arm frame, a winding steel rope is wound on the winding drum, a front pulley steel rope is wound on the middle front pulley, and a rear pulley steel rope is wound on the middle rear pulley. The internal space of the whole telescopic arm is liberated, so that a water system pipeline of the fire fighting truck is directly arranged in the telescopic arm.

Description

Technical Field

[0001] The utility model relates to the technical field of fire trucks, in particular to a synchronous telescopic arm structure and a lifting fire truck thereof. Background Art

[0002] In the fire fighting industry, the telescopic arm of the high-rise fire fighting truck is the main component for fire fighting and rescue work. The conventional telescopic arm adopts a telescopic cylinder and a plate chain or a wire rope to drive. For example, CN114870303A discloses a synchronous telescopic mechanism and a fire fighting truck thereof, including a primary arm section, a secondary arm section, a tertiary arm section, a telescopic cylinder, a secondary stretching wheel group and a secondary recovery wheel group; the tertiary arm section is sleeved in the secondary arm section, and the secondary arm section is sleeved in the primary arm section; the front end of the secondary arm section is provided with the secondary recovery wheel group, and the rear end is provided with the secondary stretching wheel group. Wheel group; the cylinder barrel of the telescopic cylinder is fixed on the third-level arm section; the cylinder rod of the telescopic cylinder is fixedly connected to the rear end of the second-level arm section; the second-level stretching wheel group includes a second-level stretching chain and a second-level stretching pulley, and the second-level recovery wheel group includes a second-level recovery chain and a second-level recovery pulley; one end of the second-level stretching chain is fixedly connected to the rear end of the third-level arm section, and the other end bypasses the second-level stretching pulley and is fixed to the front end of the first-level arm section; one end of the second-level recovery chain is fixed to the rear end of the third-level arm section; the other end bypasses the second-level recovery pulley and is fixed to the rear end of the first-level arm section.

[0003] The telescopic arm drives the telescopic cylinder to extend or retract, so that the first-stage arm section, the second-stage arm section and the third-stage arm section are synchronously extended or retracted. However, since the telescopic cylinder is installed inside the three arm sections, the internal space of the telescopic arm is occupied, and the water pipes of the water system of the fire truck need to be installed on the outside of each arm section. This affects the structural aesthetics of the entire telescopic arm on the one hand, and is not conducive to adding other rescue configurations to the telescopic arm on the other hand. In view of this, it is necessary to propose a synchronous telescopic arm structure with internally laid water pipes, so as to improve the overall vehicle parameter performance of the fire truck. Utility Model Content

[0004] In order to solve the above-mentioned deficiencies in the prior art, the utility model provides a synchronous telescopic arm structure and a fire-lifting truck thereof.

[0005] The technical scheme of the utility model is: a synchronous telescopic arm structure, including a first-stage arm, an intermediate arm and a final-stage arm, wherein the first-stage arm is sleeved on the intermediate arm, and the intermediate arm is sleeved on the final-stage arm, and also includes a drum rotatably mounted on the inner rear end of the first-stage arm and connected by a driving structure, a first-stage pulley rotatably mounted on the front end of the bottom of the first-stage arm, an intermediate front pulley rotatably mounted on the front end of the bottom of the intermediate arm, an intermediate rear pulley rotatably mounted on the rear end of the bottom of the intermediate arm, an intermediate upper fixing seat fixed on the top rear end of the intermediate arm, and a final-stage fixing seat fixed on the rear end of the bottom of the final-stage arm, wherein the first-stage arm is sleeved on the intermediate arm, and the intermediate arm is sleeved on the final-stage arm. A first-stage fixed seat is installed at a position near the first-stage pulley at the bottom of the first-stage boom, an intermediate rear fixed seat is installed at a position near the intermediate rear pulley at the bottom of the intermediate boom, a winch steel rope is wound on the drum, a front pulley steel rope is wound around the intermediate front pulley, a rear pulley steel rope is wound around the intermediate rear pulley, the recovery end of the winch steel rope is connected to the intermediate upper fixed seat, the stretching end of the winch steel rope is connected to the intermediate rear fixed seat after passing around the first-stage pulley, the rear ends of the front pulley steel rope and the rear pulley steel rope are connected to the first-stage fixed seat, and the front ends of the front pulley steel rope and the rear pulley steel rope are connected to the final-stage fixed seat. A drum and a driving mechanism for driving the drum to rotate are respectively arranged on the inside and outside of the first-stage boom to replace the conventional telescopic cylinder structure, and a pulley and a fixing seat for connecting the wire rope are installed at the bottom of each boom, so that the wire rope can be arranged between the booms, freeing up the space inside the entire telescopic arm, so that the remaining rescue configurations can be added to the outside of the telescopic arm, thereby achieving the compactness and aesthetics of the entire fire truck layout.

[0006] There are at least two intermediate booms, and each intermediate boom is sequentially sleeved in a direction away from the final boom, and an intermediate front pulley and an intermediate rear pulley are correspondingly installed at the end of each intermediate boom, and a front pulley steel rope and a rear pulley steel rope are correspondingly wound around each intermediate front pulley and each intermediate rear pulley, and an intermediate front fixed seat is provided on the intermediate boom that is not directly sleeved with the final boom, and the intermediate front fixed seat is installed at a position near the intermediate rear pulley at the bottom of the intermediate boom, and the front end of the front pulley steel rope and the rear pulley steel rope on the intermediate boom that is directly sleeved with the first-stage boom are connected to the intermediate rear fixed seat on the adjacent intermediate boom, and the rear end of the front pulley steel rope and the rear pulley steel rope on the intermediate boom that is directly sleeved with the final boom are connected to the intermediate front fixed seat on the adjacent intermediate boom.

[0007] There are two of the first pulley, the intermediate front pulley, and the intermediate rear pulley, which are symmetrically arranged along the central axis of the boom, and the axis of each pulley is skew perpendicular to the central axis of the boom. Two symmetrically arranged threaded grooves are formed on the surface of the drum, and two hoisting steel ropes are wound in each threaded groove. Steel rope pressing members for fixing one end of the corresponding hoisting steel rope are provided on the surface of the drum between the two threaded grooves and at both ends of the drum. The other ends of the two hoisting steel ropes in each spiral groove extend out of the spiral groove to form the stretching end and the retracting end corresponding to each first pulley. Two sets of hoisting steel ropes are arranged in the same drum for synchronous drive, which improves the safety factor and increases the stability of the telescopic boom at the same time.

[0008] A first wheel seat for installing the first pulley is provided on the first boom, and an intermediate front wheel seat and an intermediate rear wheel seat for installing the intermediate front pulley and the intermediate rear pulley are provided on the intermediate boom. One end of the intermediate front wheel seat is fixedly connected to the boom, and the other end is inclined outward. One end of the intermediate rear wheel seat is fixedly connected to the boom, and the other end is inclined inward. By arranging the wheel seats on the intermediate boom in an inclined manner, the lateral torsion generated by the lateral distance between the internally and externally sleeved booms on the steel rope wound around the pulley is reduced.

[0009] Fixing holes are formed in the intermediate upper fixing seat, the intermediate rear fixing seat, and the end fixing seat along the central axis direction of the boom. The retracting end, the stretching end of the hoisting steel rope, and the front ends of the rear pulley steel rope and the front pulley steel rope pass through the corresponding fixing holes and are connected to the steel strand anchor. The intermediate front fixing seat and the first fixing seat are fixing plates parallel to the boom bottom plate. A fixing pin is detachably arranged on the fixing plate, and closed cable joints are formed at the rear ends of the rear pulley steel rope and the front pulley steel rope to cooperate with the fixing pins on the fixing plate.

[0010] The steel rope pressing members at the positions on the surface of the drum between the two threaded grooves and at both ends of the drum are at least three and are arranged circumferentially along the drum. The steel rope pressing member includes a pressing plate and a fixing bolt. A pressing groove matching the hoisting steel rope is formed on the side of the pressing plate facing the drum, and the fixing bolt sequentially passes through the pressing plate and the drum in a threaded manner.

[0011] The driving mechanism is two coaxial and reversely rotating reduction motors. The two reduction motors are fixed on both sides of the first boom, and the output shafts of the reduction motors pass through the first boom and are fixedly connected to the drum. The double reduction motors are arranged on the opposite sides to synchronously drive the drum to rotate, thereby effectively improving the driving force.

[0012] The present utility model also provides an elevating fire truck, including the synchronous telescopic boom structure described above.

[0013] The beneficial effects of the present utility model are as follows: In this solution, a drum and a driving mechanism for driving the drum to rotate are respectively arranged on the inner and outer sides of the primary boom, replacing the conventional telescopic oil cylinder structure. At the same time, the pulleys and fixed seats for connecting the steel wire ropes are installed at the bottom of each boom, enabling the steel wire ropes to be arranged between the booms, liberating the space inside the entire telescopic boom, so that other rescue configurations can be added to the outside of the telescopic boom, achieving the compactness and aesthetics of the layout of the entire fire truck. Brief Description of the Drawings

[0014] Figure 1 is the structural schematic diagram of the present utility model;

[0015] Figure 2 is the longitudinal sectional view of the present utility model along the central axis;

[0016] Figure 3 is along Figure 1 the sectional view in the A-A direction in

[0017] Figure 4 is along Figure 1 the sectional view in the B-B direction in

[0018] Figure 5 is the structural schematic diagram of the intermediate boom in the present utility model;

[0019] Figure 6 is Figure 5 the partial enlarged view from another angle in

[0020] Figure 7 is the structural schematic diagram of the drum in the present utility model;

[0021] Figure 8 is the driving schematic diagram of the present utility model, Figure 8 in which (a) is the schematic diagram when the telescopic boom has one intermediate boom being stretched; Figure 8 in which (b) is the schematic diagram when the telescopic boom has one intermediate boom being retracted; Figure 8 in which (c) is the schematic diagram when the telescopic boom has two intermediate booms being stretched, Figure 8 in which (d) is the schematic diagram when the telescopic boom has two intermediate booms being retracted; Figure 8 in which (e) is the schematic diagram when the telescopic boom has three intermediate booms being stretched.

[0022] Reference numerals: 1, primary boom; 101, primary pulley; 102, primary fixed seat; 2, intermediate boom; 201, intermediate front pulley; 202, intermediate rear pulley; 203, intermediate upper fixed seat; 204, intermediate front fixed seat; 2041, fixing pin; 205, intermediate rear fixed seat; 2051, fixing hole; 2052, steel strand anchor; 206, intermediate front wheel seat; 207, intermediate rear wheel seat; 3, final boom; 301, final fixed seat; 4, drum; 401, thread groove; 5, reduction motor; 6, steel rope pressing member; 7, hoisting steel rope; 701, recovery end; 702, stretching end; 8, hinge shaft. Detailed implementation mode

[0023] To enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings. Other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present invention.

[0024] As Figures 1 - 4 shown, the present invention provides a synchronous telescopic boom structure, including a primary boom 1, an intermediate boom 2 and a final boom 3. The primary boom 1 is sleeved on the intermediate boom 2, and the intermediate boom 2 is sleeved on the final boom 3. The primary boom 1, the intermediate boom 2 and the final boom 3 are all welded box structures. As Figure 8 shown in (a), through the connection and telescopic mode of the primary boom 1, an intermediate boom 2 and the final boom 3, the synchronous telescopic structure of the smallest unit is formed. According to the actual height requirements, such as Figure 8 shown in (c) and Figure 8As shown in (e), the number of intermediate boom sections is increased. Taking an intermediate boom 2 as an example, the telescopic boom structure also includes a drum 4 rotatably installed at the inner rear end of the first boom 1 and connected via a driving mechanism, a first pulley 101 rotatably installed at the front end of the bottom of the first boom 1, an intermediate front pulley 201 rotatably installed at the front end of the bottom of the intermediate boom 2, an intermediate rear pulley 202 rotatably installed at the rear end of the bottom of the intermediate boom 2, an intermediate upper fixing seat 203 fixed at the top rear end of the intermediate boom 2, and a final fixing seat 301 fixed at the rear end of the bottom of the final boom 3. The first fixing seat 102 is installed at a position near the first pulley 101 at the bottom of the first boom 1. An intermediate rear fixed seat 205 is installed at the bottom of the frame 2 near the intermediate rear pulley 202, a hoisting steel rope 7 is wound on the drum 4, a front pulley steel rope is wound around the intermediate front pulley 201, and a rear pulley steel rope is wound around the intermediate rear pulley 202. The recovery end 701 of the hoisting steel rope 7 is connected to the intermediate upper fixed seat 203, and the tensioning end 702 of the hoisting steel rope 7 is connected to the intermediate rear fixed seat 205 after passing the first-stage pulley 101. The rear ends of the front pulley steel rope and the rear pulley steel rope are connected to the first-stage fixed seat 102, and the front ends of the front pulley steel rope and the rear pulley steel rope are connected to the final-stage fixed seat 301. The driving mechanism drives the drum 4 to rotate forward, as shown in FIG. Figure 8 As shown in (a), the stretched end 702 of the hoisting steel rope 7 is recovered along with the drum 4, thereby driving the intermediate boom 2 connected thereto to extend the first-stage boom 1 in the extending direction, and the intermediate front pulley 201 at the front end of the intermediate boom 2 synchronously drives the final-stage boom 3 to extend the intermediate boom 2 through the front pulley steel rope, thereby completing the extension operation of the telescopic arm; conversely, the driving mechanism drives the drum 4 to rotate in the opposite direction, as shown in (b), the recovered end 701 of the hoisting steel rope 7 is recovered along with the drum 4, thereby driving the intermediate boom 2 connected thereto to retract in the first-stage boom 1, and the intermediate rear pulley 202 at the rear end of the intermediate boom 2 synchronously drives the final-stage boom 3 to retract in the intermediate boom 2 through the rear pulley steel rope, thereby completing the retraction operation of the telescopic arm.

[0025] A drum 4 and a driving mechanism for driving the drum 4 to rotate are respectively arranged inside and outside the first-stage boom 1 to replace the conventional telescopic cylinder structure, and a pulley and a fixing seat for connecting the wire rope are installed at the bottom of each boom, so that the wire rope can be arranged between the booms, freeing up the space inside the entire telescopic arm, so that the remaining rescue configurations can be added to the outside of the telescopic arm, thereby achieving the compactness and aesthetics of the entire fire truck layout.

[0026] Taking two intermediate booms 2 as an example, the intermediate booms 2 are sleeved in sequence along the direction away from the final boom 3, and are denoted as the first intermediate boom and the second intermediate boom. Intermediate front pulleys 201 and intermediate rear pulleys 202 are correspondingly installed at the ends of the intermediate booms 2. Front pulley steel ropes and rear pulley steel ropes are correspondingly wound around the intermediate front pulleys 201 and the intermediate rear pulleys 202. For the intermediate boom 2 that is not directly sleeved with the final boom 3, that is, the second intermediate boom, there is an intermediate front fixing seat 204, and the intermediate front fixing seat 204 is installed at a position on the bottom of the second intermediate boom close to the intermediate rear pulley 202. For the intermediate boom 2 that is directly sleeved with the first boom 1, that is, the second intermediate boom, the front ends of the front pulley steel rope and the rear pulley steel rope are connected to the intermediate rear fixing seat 205 on the adjacent first intermediate boom. For the intermediate boom 2 that is directly sleeved with the final boom 3, that is, the first intermediate boom, the rear ends of the front pulley steel rope and the rear pulley steel rope are connected to the intermediate front fixing seat 204 on the adjacent second intermediate boom. The intermediate upper fixing seat 203 is located at the rear end of the top of the second intermediate boom. The steel rope connection method at other positions is the same as the telescopic boom connection method of one intermediate boom 2, that is, the recovery end 701 and the stretching end 702 of the hoisting steel rope 7 are respectively fixed on the intermediate upper fixing seat 203 and the intermediate rear fixing seat 205 of the second intermediate boom. The rear ends of the front pulley steel rope and the rear pulley steel rope on the second intermediate boom are connected to the first fixing seat 102 on the first boom 1. The front ends of the front pulley steel rope and the rear pulley steel rope on the first intermediate boom are connected to the final fixing seat 301 on the final boom 3. As shown in Figure 8 As shown in (c), the stretching end 702 of the hoisting steel rope 7 is recovered by the reel 4, thereby driving the second intermediate boom connected thereto to extend out of the first boom 1 along the extending direction. The intermediate front pulley 201 at the front end of the second intermediate boom synchronously drives the first intermediate boom through the front pulley steel rope. The intermediate front pulley 201 at the front end of the first intermediate boom synchronously drives the final boom 3 to extend out in sequence through the front pulley steel rope, completing the extending operation of the telescopic boom; conversely, the driving mechanism drives the reel 4 to rotate in the reverse direction. As shown in (d), the recovery end 701 of the hoisting steel rope 7 is recovered by the reel 4, thereby driving the second intermediate boom connected thereto to retract into the first boom 1 along the retracting direction. The intermediate rear pulley 202 at the rear end of the second intermediate boom synchronously drives the first intermediate boom through the rear pulley steel rope. The intermediate rear pulley 202 at the rear end of the first intermediate boom synchronously drives the final boom 3 to retract in sequence through the rear pulley steel rope, completing the retracting operation of the telescopic boom.

[0027] Taking two intermediate booms 2 as an example, as Figure 8As described in (e), the intermediate first boom, intermediate second boom, and intermediate third boom are sequentially recorded in the direction away from the last-stage boom 3. At this time, the intermediate boom 2 that is not directly sleeved with the last-stage boom 3, that is, the intermediate second boom and the intermediate third boom, are provided with intermediate front fixing seats 204. The front ends of the front pulley steel wire rope and the rear pulley steel wire rope on the intermediate third boom, which is the intermediate boom 2 directly sleeved with the first-stage boom 1, are connected to the intermediate rear fixing seat 205 on the adjacent intermediate second boom. The rear ends of the front pulley steel wire rope and the rear pulley steel wire rope on the intermediate first boom, which is the intermediate boom 2 directly sleeved with the last-stage boom 3, are connected to the intermediate front fixing seat 204 on the adjacent intermediate second boom. The front ends of the front pulley steel wire rope and the rear pulley steel wire rope on the intermediate second boom are connected to the intermediate rear fixing seat 205 on the intermediate first boom, and the rear ends are connected to the intermediate front fixing seat 204 of the intermediate third boom. The intermediate upper fixing seat 203 is located at the rear end of the top of the intermediate third boom. The steel wire rope connection methods at other positions are the same as those of the telescopic boom of an intermediate boom 2, that is, the recovery end 701 and the stretching end 702 of the hoisting steel wire rope 7 are respectively fixed on the intermediate upper fixing seat 203 and the intermediate rear fixing seat 205 of the intermediate third boom. The rear ends of the front pulley steel wire rope and the rear pulley steel wire rope on the intermediate third boom are connected to the first-stage fixing seat 102 on the first-stage boom 1. The front ends of the front pulley steel wire rope and the rear pulley steel wire rope on the intermediate first boom are connected to the last-stage fixing seat 301 on the last-stage boom 3. The driving principle will not be elaborated here. Similarly, when there are more than two intermediate booms 2, each boom can be connected with reference to the above connection method.

[0028] As Figure 3 and Figure 4 shown, there are two of each of the first-stage pulley 101, the intermediate front pulley 201, and the intermediate rear pulley 202, which are symmetrically arranged along the central axis of the boom and the axes of the pulleys are skew perpendicular to the central axis of the boom. As Figure 3 and Figure 7As shown, two symmetrically arranged threaded grooves 401 are formed on the surface of the drum 4. Two hoisting steel ropes 7 are wound in each threaded groove 401. On the surface of the drum 4 between the two threaded grooves 401 and at both ends of the drum 4, there are steel rope pressing members 6 for fixing one end of the corresponding hoisting steel rope 7. The other ends of the two hoisting steel ropes 7 in each spiral groove extend out of the spiral groove to form the stretching end 702 and the recycling end 701 corresponding to each primary pulley 101. Two groups of hoisting steel ropes 7 are arranged in the same drum 4 for synchronous drive, so as to improve the safety factor during the operation of the telescopic boom and increase the stability of the telescopic boom. Further preferably, there are at least three steel rope pressing members 6 at the positions on the surface of the drum 4 between the two threaded grooves 401 and at both ends of the drum 4, which are arranged circumferentially along the drum 4. The steel rope pressing member 6 includes a pressing plate and a fixing bolt. A pressing groove matching with the hoisting steel rope 7 is formed on one side of the pressing plate facing the drum 4. The fixing bolt sequentially passes through the pressing plate and the drum 4 in a threaded manner, so that the pressing plate presses and fixes one end of the hoisting steel rope 7 on the drum 4.

[0029] In order to reduce the lateral torsion generated by the lateral distance between the inner and outer sleeved boom frames on the steel rope wound around the pulley, as Figure 3 , Figure 4 and Figure 5 shown, a primary wheel seat for installing the primary pulley 101 is provided on the primary boom frame 1. An intermediate front wheel seat 206 and an intermediate rear wheel seat 207 for installing the intermediate front pulley 201 and the intermediate rear pulley 202 are provided on the intermediate boom frame 2. One end of the intermediate front wheel seat 206 is fixedly connected to the boom frame, and the other end is inclined outward. One end of the intermediate rear wheel seat 207 is fixedly connected to the boom frame, and the other end is inclined inward. By arranging the wheel seats on the intermediate boom frame 2 to be inclined,

[0030] as Figure 6As shown, the middle upper fixing seat 203, the middle rear fixing seat 205, and the final-stage fixing seat 301 are provided with fixing holes 2051 along the central axis direction of the boom. Specifically, the number of fixing holes 2051 on the middle upper fixing seat 203 and the middle rear fixing seat 205 on the middle boom 2 directly sleeved with the final-stage boom 3 is 2 each, and the number of fixing holes 2051 on the final-stage fixing seat 301 and the middle rear fixing seat 205 on other middle booms 2 is 4 each. The recovery end 701, the stretching end 702 of the hoisting steel rope 7, and the front ends of the rear pulley steel rope and the front pulley steel rope pass through the corresponding fixing holes 2051 and are connected to the steel strand anchor 2052. The middle front fixing seat 204 and the first-stage fixing seat 102 are fixing plates arranged parallel to the boom bottom plate, and fixing pins 2041 are detachably mounted on the fixing plates. Specifically, the number of fixing pins 2041 on the middle front fixing seat 204 and the first-stage fixing seat 102 is 4 each. Closed cable joints are formed at the rear ends of the rear pulley steel rope and the front pulley steel rope to cooperate with the fixing pins 2041 on the corresponding fixing plates. Through the cooperation of the closed cable joints and the fixing pins 2041, and the cooperation of the steel strand anchor and the fixing holes 2051, it is convenient to install each steel rope. The steel strand anchor and the closed cable joint are prior arts in the field of steel strands, and their specific structures will not be elaborated.

[0031] As Figure 3 and Figure 7 shown, in order to improve the driving force for the driving mechanism to drive the drum 4 to rotate, the driving mechanism is two reduction motors 5 rotating in opposite directions coaxially. The two reduction motors 5 are fixed on both sides of the first-stage boom 1 through flanges, and the output shafts of the reduction motors 5 penetrate through the first-stage boom 1 and are fixedly connected to the drum 4. By the synchronous rotation of the left and right reduction motors 5 in a forward and reverse manner, the drum 4 is jointly driven to rotate.

[0032] The present utility model also provides an elevating fire truck, including the above-mentioned synchronously telescopic boom structure. Specifically, the rear end of the first-stage boom 1 is connected to the turntable of the fire truck through a hinge shaft 8, and a luffing oil cylinder for adjusting the lifting angle of the first-stage boom 1 is installed on the turntable. Since there are no telescopic oil cylinders and pulleys occupying the internal space in this telescopic boom structure, the water pipes of the waterway system of the fire truck can be laid inside the telescopic boom, thereby changing the structural layout of the existing fire truck and meeting the requirements of layout compactness and aesthetics.

Claims

1. A synchronous telescopic boom structure, comprising a first-stage boom, an intermediate boom and a final-stage boom, wherein the first-stage boom is sleeved on the intermediate boom, and the intermediate boom is sleeved on the final-stage boom, characterized in that: The cam is connected to the rear frame via a transmission mechanism, and the cam is connected to the rear frame via a transmission mechanism. The cam is connected to the rear frame via a transmission mechanism, and the cam is connected to the rear frame via a transmission mechanism.

2. A synchronous telescopic arm structure according to claim 1, characterized in that: There are at least two intermediate booms, and each intermediate boom is sequentially sleeved in a direction away from the final boom, and an intermediate front pulley and an intermediate rear pulley are correspondingly installed at the end of each intermediate boom, and a front pulley steel rope and a rear pulley steel rope are correspondingly wound around each intermediate front pulley and each intermediate rear pulley, and an intermediate front fixed seat is provided on the intermediate boom that is not directly sleeved with the final boom, and the intermediate front fixed seat is installed at a position near the intermediate rear pulley at the bottom of the intermediate boom, and the front end of the front pulley steel rope and the rear pulley steel rope on the intermediate boom that is directly sleeved with the first-stage boom are connected to the intermediate rear fixed seat on the adjacent intermediate boom, and the rear end of the front pulley steel rope and the rear pulley steel rope on the intermediate boom that is directly sleeved with the final boom are connected to the intermediate front fixed seat on the adjacent intermediate boom.

3. A synchronous telescopic arm structure according to claim 2, characterized in that: There are two of the first-stage pulley, the middle front pulley and the middle rear pulley, which are symmetrically arranged along the central axis of the boom and the axis of each pulley is perpendicular to the central axis of the boom in different planes. The surface of the drum is provided with two bidirectionally symmetrically arranged thread grooves, and two hoisting steel ropes are wound in each thread groove. The surface of the drum between the two thread grooves and both ends of the drum are provided with steel rope clamping parts for fixing one end of the corresponding hoisting steel rope. The other ends of the two hoisting steel ropes in each spiral groove extend out of the spiral groove to form the stretching end and the recovery end corresponding to each first-stage pulley.

4. A synchronous telescopic arm structure according to claim 3, characterized in that: The first-stage arm is provided with a first-stage wheel seat for installing the first-stage pulley, and the middle arm is provided with an intermediate front wheel seat and an intermediate rear wheel seat for installing the intermediate front pulley and the intermediate rear pulley. One end of the intermediate front wheel seat is fixedly connected to the arm, and the other end is inclined outwardly; one end of the intermediate rear wheel seat is fixedly connected to the arm, and the other end is inclined inwardly.

5. A synchronous telescopic arm structure according to any one of claims 2 to 4, characterized in that: The intermediate upper fixing seat, the intermediate rear fixing seat and the final fixing seat are provided with fixing holes along the central axis direction of the boom; the recovery end, the stretching end and the front ends of the rear pulley steel rope and the front pulley steel rope of the hoisting rope are connected with the steel strand anchor after passing through the corresponding fixing holes; the intermediate front fixing seat and the first-stage fixing seat are fixing plates arranged parallel to the bottom plate of the boom; the fixing plates are provided with detachable fixing pins; the rear ends of the rear pulley steel rope and the front pulley steel rope are formed with closed rope nodes that match the fixing pins on the corresponding fixing plates.

6. A synchronous telescopic arm structure according to claim 3 or 4, characterized in that: There are at least three steel rope clamping parts located on the drum surface between the two thread grooves and on both ends of the drum, which are arranged along the circumference of the drum. The steel rope clamping parts include a pressure plate and a fixing bolt. The pressure plate is provided with a pressure groove matching the hoisting steel rope on the side facing the drum, and the fixing bolt is threaded through the pressure plate and the drum in sequence.

7. A synchronous telescopic arm structure according to any one of claims 1 to 4, characterized in that: The driving mechanism is two coaxial reduction motors rotating in opposite directions. The two reduction motors are fixed on both sides of the first-stage arm frame, and the output shafts of the reduction motors penetrate the first-stage arm frame and are fixedly connected to the reel.

8. A fire truck, characterized in that: It comprises the synchronous telescopic arm structure as described in any one of claims 1 to 7.

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