Method for replacing a piston seal of a servo motor of a hydraulic lifting and lowering machine

Abstract

The present invention relates to the field of servomotors and, in particular, to a method for replacing a piston seal of a servomotor in a hydraulic lifting and lowering machine. The method for replacing a piston seal of a servomotor in a hydraulic lifting and lowering machine comprises the following: disconnecting a piston rod of the servomotor from a gate on a dam and retracting the piston rod to its highest position using a hydraulic system; draining hydraulic fluid from the servomotor and attaching a spreader for the subsequent downward movement of the servomotor's piston rod; lowering the servomotor's piston rod and removing a lower end cap of the servomotor; replacing the servomotor's piston seal and inspecting the replaced servomotor piston.The method provided by the present invention for replacing the piston seal of a servomotor of a hydraulic lifting and lowering machine facilitates the replacement of the servomotor piston and reduces time and labor costs.

Description

Technical area

[0001] The present invention relates to the field of servomotors and in particular to a method for replacing a piston seal of a servomotor of a hydraulic lifting and lowering machine. Background technology

[0002] The hydraulic lifting and lowering machine of a hydroelectric power plant is a lifting and lowering machine that uses fluid as the power transmission medium to push the boom and pull the gate wings. The hydraulic lifting and lowering machine primarily consists of an electrical control system, a hydraulic transmission system, and other components, operating via hydraulic piping, hydraulic servo motors, hydraulic pump stations, electrical components, and so on. The servo motor of a hydraulic lifting and lowering machine is a key component. It is typically used to control the movement of the lifting and lowering machine, ensuring that it opens and closes smoothly and precisely.

[0003] Due to high-frequency movements and the aging of the servo motor piston of the hydraulic lifting and lowering machine of a hydroelectric power plant, the piston seal of a servo motor is often worn or damaged, causing the contactor to drop excessively, which impairs the normal operation of the contactor and, in severe cases, even the safe and stable operation of the hydroelectric power plant.

[0004] The current procedure for replacing the piston seal of a servo motor in a hydraulic lifting and lowering machine installed at a gate in large hydroelectric power plants involves disassembling the entire servo motor from the hydraulic system, lifting it out of the gate area, positioning it horizontally, disassembling it, and replacing the piston. The servo motor is then lifted over the gate and tilted to install it on the hydraulic system. This process is time-consuming, labor-intensive, and results in high maintenance downtime and labor costs. Contents of the invention

[0005] The present invention aims to at least partially solve one of the prior art technical problems. To this end, embodiments of the present invention provide a method for replacing the piston seal of a servo motor of a hydraulic lifting and lowering machine, which simplifies the replacement of the servo motor piston and reduces time and labor costs.

[0006] The embodiment of the present invention provides a method for replacing a piston seal of a servomotor of a hydraulic lifting and lowering machine, characterized in that it comprises: disconnecting a piston rod of the servomotor from a gate on a dam and retracting the piston rod to the highest position using a hydraulic system; draining hydraulic fluid from the servomotor and attaching a spreader for the subsequent downward movement of the piston rod of the servomotor; lowering the piston rod of the servomotor and removing a lower end cap of the servomotor; replacing the piston seal of the servomotor and checking a replaced piston of the servomotor.

[0007] The method for replacing the piston seal of a servomotor of a hydraulic lifting and lowering machine according to the embodiment of the present invention facilitates the replacement of the servomotor piston and reduces time and labor costs.

[0008] In some embodiments, separating a servo motor piston rod from a sluice gate at a dam and retracting the piston rod to its highest position using a hydraulic system comprises the following steps: Closing the gate, disconnecting a piston rod lifting head pin from the gate eyelets, arranging several first ground anchors on a dam near the hydraulic system for installing a first manual pull component, the first manual pull component being connected to the servo motor piston rod; bringing the servo motor into a vertical position by means of the first manual pull component, retracting the servo motor piston rod to the limit position by means of the hydraulic system and closing a valve of a lower chamber of the servo motor.

[0009] In some embodiments, a buffer cushion is provided at the dam, wherein the buffer cushion corresponds to the position of the dam which corresponds to the pivoting direction of the piston rod of the servomotor in the vertical position of the servomotor.

[0010] In some embodiments, draining hydraulic fluid from the servo motor and attaching a spreader for the downward movement of the servo motor's downstream piston rod comprises the following steps: Opening the valve of the upper chamber of the servo motor, releasing the oil in the upper chamber, verifying that the upper chamber of the servo motor is depressurized, and removing an upper end cap of the servo motor; Setting up a second ground anchor and a second hand-operated pulling component connected to the second ground anchor at the dam near the hydraulic system, the second hand-operated pulling component lifting the servo motor by means of a lifting ring; and removal of the first hand-operated component.

[0011] In some embodiments, lowering the servo motor piston rod and removing the servo motor's lower end cap comprises the following steps: opening the connecting valves of the upper and lower chambers of the servo motor, which interact with the use of the second hand-operated pull component to lower the servo motor's piston rod; after the top of the piston rod is in contact with the lower end cap, moving the piston rod upward by 8 mm to 15 mm using the second hand-operated pull component, arranging support blocks on the underside of the piston rod to support the servo motor, arranging a lifting basket on the lower end cap of the servo motor, and removing the lower end cap of the servo motor.

[0012] In some embodiments, the piston of the servo motor is replaced and the piston of the replaced servo motor is checked.

[0013] In some embodiments, when the valve of the upper chamber of the servomotor is opened to drain the oil in the upper chamber, the oil in the upper chamber is pumped into an oil tank using an oil pump device.

[0014] In some embodiments, the first hand-pulling component and the second hand-pulling component are a hand chain hoist, hand rope hoist, or a manual winch.

[0015] In some embodiments, a dam valve is set to a fully closed position before the piston rod of the servo motor is disconnected from the sluice gate on the dam.

[0016] In some embodiments, a scaffold is erected to remove the upper end cap of the servo motor. Figures Fig. Figure 1 is a schematic representation of a second hand-operated pull component in an embodiment of the present invention. Fig. Figure 2 is a schematic diagram of a dam and a gate in a method for replacing a piston seal of a servomotor of a hydraulic lifting and lowering machine in an embodiment of the present invention. Fig. Figure 3 is a schematic representation of a second ground anchor in an embodiment of the present invention. Fig. Figure 4 is a schematic diagram of a first ground anchor in an embodiment of the present invention. Fig. Figure 5 is a schematic representation of a first hand-operated pull component in an embodiment of the present invention. Fig. Figure 6 is a flowchart of a method for replacing a piston seal of a servomotor of a hydraulic lifting and lowering machine in an embodiment of the present invention. Reference symbols in the figures:

[0017] First hand pull component 1, second hand pull component 2, Dam 3, gate 4, servo motor 5, piston rod 51, upper end cap 52, lower end cap 53, Buffer pad 6, First ground anchor 7, Second ground anchor 8, Hydraulic system 9. Specific embodiments

[0018] The following section describes in detail exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The exemplary embodiments described below with reference to the drawings are merely illustrative and serve only to explain the present invention; they are not to be construed as limitations of the present invention.

[0019] With reference to Fig. Figures 1 to 6 describe the method for replacing a piston seal of a servomotor of a hydraulic lifting and lowering machine in the embodiment of the present invention, wherein the method for replacing a piston seal of a servomotor of a hydraulic lifting and lowering machine comprises the following steps: Step S100: Disconnecting a piston rod 51 of the servomotor 5 from a gate 4 on a dam 3 and retracting the piston rod 51 to the highest position using a hydraulic system 9; Step S200: Draining hydraulic fluid from the servomotor 5 and attaching a spreader for the subsequent downward movement of the piston rod 51 of the servomotor 5; Step S300: Lowering the piston rod 51 of the servomotor 5 and removing a lower end cap 53 of the servomotor 5; Step S400: Replacing the piston seal of the servomotor 5 and checking a replaced piston of the servomotor 5.

[0020] The method for replacing the piston seal of a servomotor 5 of a hydraulic lifting and lowering machine according to the embodiment of the present invention facilitates the replacement of the piston of the servomotor 5 and reduces time and labor costs.

[0021] In particular, as in the Fig. As shown in Figures 1 to 6, the gate 4 of the hydroelectric power plant is now closed to prevent the piston rod 51 of the servomotor 5 from being disconnected from the gate 4 at the dam 3. The force acting on the gate 4 in the up and down directions is too small, causing the gate 4 to fall down. After the piston rod 51 of the servomotor 5 has been disconnected from the gate 4 at the dam 3, the existing hydraulic system 9 installed at the dam 3 retracts the piston rod 51 to its highest position. That is, the piston rod 51 extends and contracts in the up and down directions, and the highest position can be understood as the highest position of the upward-moving piston rod 51, with the up and down directions being the directions of gravity.

[0022] The hydraulic fluid in the servomotor 5 is drained, and a spreader is installed to lower the piston rod 51 of the servomotor 5. Simultaneously, a spreader is installed and connected to the piston rod 51 to lower the piston rod 51 slowly during the subsequent lowering process. At the same time, the upper end cap 52 of the servomotor 5 is removed so that the oil in the upper chamber of the servomotor 5 can then be drained.

[0023] The lower end cap 53 of the servomotor 5 is then removed by lowering the piston rod 51 of the servomotor 5 through the spreader.

[0024] The piston of servomotor 5 is replaced, and after the piston replacement, a pressure test is performed on servomotor 5. For example, after completion of the piston replacement work, the piston rod 51 is reinstalled, and a pressure test is carried out with 1.25 times the nominal operating pressure of servomotor 5, and no leakage may be present.

[0025] The method for replacing a piston seal of a servomotor 5 of a hydraulic lifting and lowering machine according to the embodiment of the present invention does not require the servomotor 5 to be disassembled from the hydraulic system 9 at the dam 3 and lifted separately to the maintenance location when replacing a piston seal. The piston can be replaced above the gate 4 without positioning the servomotor 5 horizontally, which saves labor and material resources and maintenance time. In some embodiments, disconnecting a piston rod 51 of the servomotor 5 from a gate 4 at a dam 3 and retracting the piston rod 51 to its highest position using a hydraulic system 9 comprises the following steps: Closing the gate 4, disconnecting a lifting head pin of the piston rod 51 from the eyelets of the gate 4, arranging several first ground anchors 7 on a dam 3 near the hydraulic system 9 for installing a first manual pull component 1, wherein the first manual pull component 1 is connected to the piston rod 51 of the servo motor 5; bringing the servo motor 5 into a vertical position by means of the first manual pull component 1, retracting the piston rod 51 of the servo motor 5 to the limit position by means of the hydraulic system 9 and closing a valve of a lower chamber of the servo motor 5.

[0026] In particular, as in the Fig. Figures 1 to 6 show several first ground anchors 7 below the hydraulic system 9 or at the same level for installing the first manual pull component 1. The lower part of the first manual pull component 1 is connected to the piston rod 51 of the servo motor 5 to prevent the piston rod 51 from leaking internally and falling. Release the lifting head pin under the piston rod 51 from the eyelets of the contactor 4, creating a specific angle of inclination between the piston rod 51 of the servo motor 5 (which is not yet disconnected from the contactor 4) and the up-and-down direction. With the lifting head pin under the piston rod 51 disconnected from the eyelets of the contactor 4, slowly push the piston rod 51 of the servo motor 5 through the first manual pull component 1, parallel to the up-and-down direction, i.e., the servo motor 5 is now in a vertical position.This facilitates the subsequent attachment of the servomotor 5 and prevents the servomotor 5 from swinging strongly to the left and right after being disconnected from the contactor 4, which would cause the piston rod 51 to hit the side wall of the dam 3.

[0027] The hydraulic system 9 at the dam 3 is used to raise the piston rod 51 of the servomotor 5, thereby reducing the size of the servomotor 5 in the up and down directions and preventing it from oscillating and striking the side wall of the dam 3. It should be noted that when the servomotor 5 is not disconnected from the gate 4, the first manual pull component 1 is connected to the piston rod 51 of the servomotor 5 to facilitate its subsequent vertical positioning. The piston rod 51 of the servomotor 5 is then retracted to its limit position by means of the hydraulic system 9, and the valve in the lower chamber of the servomotor 5 is closed to facilitate the subsequent draining of the oil from the servomotor 5.

[0028] The method for replacing a piston seal of a servomotor 5 of a hydraulic lifting and lowering machine according to the embodiment of the present invention facilitates the position limitation and guidance of the piston rod 51 of the servomotor 5, which has separated from the gate 4, by arranging the first ground anchor 7 and several first hand-operated pull components 1 to prevent the piston rod 51 of the servomotor 5 from swinging left and right and striking the side wall of the dam 3, thereby improving the safety and stability of the repair and maintenance of the piston rod 51 of the servomotor 5. It is not necessary to disassemble the servomotor 5 from the hydraulic system 9 at the dam 3 and lift it separately to the maintenance location to replace the piston. The piston can be replaced above the gate 4 without having to position the servomotor 5 horizontally, which saves manpower and material resources and reduces maintenance time and labor costs.

[0029] Furthermore, a buffer pad 6 is provided at the dam 3, the position of which corresponds to the pivot direction of the piston rod 51 of the servomotor 5 in the vertical position of the servomotor 5. When the hydroelectric power plant is installed, the servomotor 5 can pivot left and right to open and close the gate 4 by extending and contracting the servomotor 5. Additionally, when the gate 4 is disconnected from the servomotor 5, the servomotor 5 pivots left and right. Due to the arrangement of the buffer pad 6, the buffer pad 6 extends upwards and downwards to prevent the servomotor 5 from directly impacting the dam 3 after being disconnected from the gate 4 and causing damage to the servomotor 5.

[0030] In some embodiments, draining hydraulic fluid from the servomotor 5 and attaching a spreader for the subsequent downward movement of the piston rod 51 of the servomotor 5 comprises the following steps: Opening the valve of the upper chamber of the servomotor 5, releasing the oil in the upper chamber, verifying that the upper chamber of the servomotor is depressurized, and removing an upper end cap 52 of the servomotor 51; Setting up a second ground anchor 8 and a second hand-operated pulling component 2, which is connected to the second ground anchor 8 on the dam 3 near the hydraulic system 9, wherein the second hand-operated pulling component 2 lifts the servo motor 5 by means of a lifting ring; and removing the first hand-operated pulling component 1.

[0031] In particular, as in the Fig. As shown in Figures 1 to 6, the piston rod 51 of the servomotor 5 is retracted to its limit position, meaning the piston rod 51 is pulled back to its highest position in both the up and down directions. At this point, the valve of the upper chamber of the servomotor 5 opens to drain the oil from the upper chamber. For example, use a special hose to connect the oil line of the upper chamber to the oil return tank.

[0032] The upper end cap 52 of the servomotor 5 is then removed, allowing the upper end of the servomotor 5 to be connected to one of the several second hand-operated components 2 to facilitate the subsequent downward movement of the servomotor 5. The second hand-operated component 2 is positioned directly above the servomotor 5. While the first hand-operated component 1 is connected to the lower end of the piston rod 51 of the servomotor 5 on the side wall of the dam 3, the second hand-operated component 2 is directly connected to the upper end of the servomotor 5 to facilitate its upward and downward movement. The arrangement of the second hand-operated component 2 allows the servomotor 5 to be moved more smoothly and with greater stability during this movement.

[0033] In some embodiments, lowering the piston rod 51 of the servo motor 5 and removing the lower end cap 53 of the servo motor 5 comprises the following steps: opening the connecting valves of the upper and lower chambers of the servo motor 5, which interact with the use of the second hand-operated component 2 to lower the piston rod 51 of the servo motor 5; after the top of the piston rod 51 is in contact with the lower end cap 53, moving the piston rod 51 upward by the second hand-operated component 2 by 8 mm to 15 mm, arranging support blocks on the underside of the piston rod 51 to support the servo motor 5, arranging a lifting basket on the lower end cap 53 of the servo motor 5, and removing the lower end cap 53 of the servo motor 5.

[0034] In particular, as in the Fig. 1 to Fig.Figure 6 shows the upper side of the second hand-operated component 2 connected to several second ground anchors 8. The lower side of the second hand-operated component 2 is connected to the piston rod 51 of the servo motor 5 in order to subsequently move the piston rod 51 downwards, thus moving the servo motor 5 downwards.

[0035] The connecting valves of the upper and lower chambers of the servomotor 5, which interact with the second hand-operated component 2, are opened to lower the piston rod 51 of the servomotor 5. When the top of the piston rod 51 of the servomotor 5 comes into contact with the lower end cap 53 of the servomotor 5, the second hand-operated component 2 moves the piston rod 51 upwards by 8 mm to 15 mm to prevent it from contacting the bottom and wobbling during piston replacement. Furthermore, support blocks are positioned on the underside of the piston rod 51 to support the servomotor 5, and a lifting basket is simultaneously positioned to manually remove the lower end cap 53 of the servomotor 5 and replace the piston.

[0036] The method for replacing a piston seal of a servo motor in a hydraulic lifting and lowering machine facilitates the movement of the servo motor 5 in the raising and lowering direction and the movement of the piston rod 51 in the raising and lowering direction by means of the arrangement of the second manual pull component 2, in order to fix the piston rod 51 in a certain manner. At the same time, the support blocks are designed to interact with the second manual pull component 2 and, through the interaction of the gravity of the servo motor 5, the supporting force of the support blocks, and the tensile force provided by the second manual pull component 2, exhibit a certain degree of fixation to facilitate the replacement of the piston.

[0037] Furthermore, a replaced piston of the servomotor 5 is inspected after the piston has been replaced. For example, the piston rod 51 is reinstalled, and a pressure test is performed at 1.25 times the rated operating pressure of the servomotor 5. No leakage should be present. First, ensure that the piston rod 51, the piston, and the relevant internal parts of the servomotor 5 are thoroughly clean and free of contaminants, rust, or damage. Apply an appropriate amount of lubricating oil to the contact surface between the piston rod 51 and the piston to reduce friction and wear. Properly mount the piston rod 51 to the piston according to the manufacturer's guidelines or drawings and ensure that all connecting parts are tight.If necessary, adjust the position or angle of the piston rod 51 to ensure its movement is smooth and meets the design requirements. Ensure that the servo motor 5 is properly installed and connected to the hydraulic system 9, and that all valves and lines are closed. Slowly pressurize the servo motor 5 using a hydraulic pump or other suitable device until it reaches 1.25 times its rated working pressure. During the pressure build-up process and after reaching the target pressure, carefully observe whether hydraulic fluid is leaking from the servo motor 5 and its connecting parts. At the same time, check whether the housing and connecting parts of the servo motor 5 are unusually deformed or damaged. After completing the pressure test, slowly release the pressure and again check for damage or leakage from the servo motor 5 and its associated parts.

[0038] Furthermore, when the valve of the upper chamber of the servomotor 5 is opened to drain the oil, the oil in the upper chamber is pumped into an oil tank by means of an oil pump device. This increases the oil delivery rate, reduces the time required for piston repair and replacement, and improves maintenance efficiency.

[0039] Furthermore, the first hand-operated component 1 and the second hand-operated component 2 are a hand chain hoist, hand rope hoist, or manual winch. In addition, the first hand-operated component 1 and the second hand-operated component 2 can also be used with wire ropes or lifting rings to connect and lift the piston rod 51 or the servo motor 5.

[0040] Furthermore, a valve of the dam 3 is set to a fully closed position before the piston rod 51 of the servomotor 5 is disconnected from the contactor 4 on the dam 3. If the piston rod 51 of the servomotor 5 is disconnected from the contactor 4 on the dam 3 and the contactor 4 is not in a fully closed state, the contactor 4 tends to move downwards. This disconnects the contactor 4 from the piston rod 51 of the servomotor 5, and it then moves downwards, causing the contactor 4 to collide with the dam 3.

[0041] Furthermore, when removing the upper end cap 52 of the servomotor 5, a scaffold is erected to facilitate the removal of the upper end cap 52. This reduces the difficulty for personnel in disassembling the upper end cap 52 from the servomotor 5. In describing the present invention, it is necessary to point out that an azimuth or position relationship, referring to terms such as "center," "longitudinal," "transverse," "length," "width," "thickness," "top," "bottom," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," "outside," "clockwise," "counterclockwise," "axial," "radial," "circumference," and the like, has an azimuth or position relationship based on the drawing.They are intended to facilitate and simplify the description of the present invention, rather than indicating or implying that the device or component in question must have a specific orientation, be designed and operated in a specific orientation. Therefore, they must not be understood as limiting the present invention.

[0042] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or suggesting a relative meaning, nor as implicitly specifying the set of the technical features mentioned. Therefore, features defined as "first" and "second" may explicitly or implicitly include one or more of these features. In the description of this invention, "several" means at least two, for example, two, three, etc., unless expressly and specifically limited otherwise.

[0043] In the present invention, the terms "install," "connect," "link," and "fasten" are to be understood in a broad sense unless expressly stated otherwise or limited. For example, it may be a permanent connection, a detachable connection, or a connection in one piece; it may be a mechanical connection, an electrical connection, or mutual communication; it may be a direct connection or an indirect connection via an intermediate medium; and it may be a connection within the two elements or an interaction between the two elements. For general technical personnel in this field, the specific meaning of the above terms in the present invention may be understood according to the specific circumstances.

[0044] In the present invention, unless expressly stated otherwise and limited, a first feature being “above” or “below” a second feature can mean that the first and second features are in direct contact or that the first and second features are in indirect contact via an intermediate medium. Furthermore, the expression that the first feature is “above,” “above,” and “below” the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature has a greater horizontal height than the second feature. The expression that the first feature is “below,” “below,” and “below” the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature has a lesser horizontal height than the second feature.

[0045] In the present invention, reference to the terms “an embodiment”, “some embodiments”, “example”, “specific example”, or “some examples”, or the like, means that certain features, structures, materials, or properties associated with the embodiment or example are included in at least one embodiment or example of the present invention. In this description, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the described specific features, structures, materials, or properties may be combined in any suitable manner in one or more embodiments or examples.Furthermore, technical personnel may combine different embodiments or examples and features of different embodiments or examples described in this description, provided they do not contradict each other.

[0046] Although the embodiments of the present invention have been shown and described above, it should be understood that these embodiments serve only for illustration and should not be construed as limitations of the present invention. General technical personnel may make changes, modifications, substitutions, and variations to the embodiments described above within the scope of the present invention.

Claims

[1] Method for replacing a piston seal of a servomotor of a hydraulic lifting and lowering machine, characterized by , that it includes the following: Separating a piston rod of the servo motor from a contactor at a dam and Retracting the piston rod to its highest position using a hydraulic system; Draining hydraulic fluid from the servo motor and attaching a spreader for the subsequent downward movement of the servo motor's piston rod; Lowering the piston rod of the servo motor and removing a lower end cap of the servo motor; Replacing the piston seal of the servo motor and checking a replaced servo motor piston. [2] Method for replacing a piston seal of a servomotor of a hydraulic lifting and lowering machine according to claim 1, characterized by, that separating a servomotor piston rod from a sluice gate at a dam and retracting the piston rod to its highest position using a hydraulic system involves the following steps: Closing the gate, disconnecting a piston rod lifting head pin from the gate eyelets, arranging several first ground anchors on a dam near the hydraulic system for installing a first manual pull component, the first manual pull component being connected to the servo motor piston rod; bringing the servo motor into a vertical position by means of the first manual pull component, retracting the servo motor piston rod to the limit position by means of the hydraulic system, and closing a valve of a lower chamber of the servo motor. [3] Method for replacing a piston seal of a servomotor of a hydraulic lifting and lowering machine according to claim 2, characterized by, that a buffer cushion is provided at the dam, wherein the buffer cushion corresponds to the position of the dam which corresponds to the pivoting direction of the piston rod of the servo motor in the vertical position of the servo motor. [4] Method for replacing a piston seal of a servomotor of a hydraulic lifting and lowering machine according to claim 2, characterized by , that draining hydraulic fluid from the servo motor and attaching a spreader for the downward movement of the servo motor's downstream piston rod comprises the following steps: Opening a valve of an upper chamber of the servo motor, releasing the oil in the upper chamber, verifying that the upper chamber of the servo motor is depressurized, and removing an upper end cap of the servo motor; Setting up a second ground anchor and a second hand-operated pulling component connected to the second ground anchor at the dam near the hydraulic system, the second hand-operated pulling component lifting the servo motor by means of a lifting ring; and removing the first hand-operated pulling component. [5] Method for replacing a piston seal of a servomotor of a hydraulic lifting and lowering machine according to claim 4, characterized by, that lowering the servo motor piston rod and removing the servo motor's lower end cap comprises the following steps: opening the connecting valves of the servo motor's upper and lower chambers, which interact with the use of the second hand-operated component to lower the servo motor's piston rod; after the top of the piston rod is in contact with the lower end cap, moving the piston rod upwards by 8 mm to 15 mm using the second hand-operated component, arranging support blocks on the underside of the piston rod to support the servo motor, arranging a lifting basket on the lower end cap of the servo motor, and removing the lower end cap of the servo motor. [6] Method for replacing a piston seal of a servomotor of a hydraulic lifting and lowering machine according to claim 5, characterized by Replacing the piston of the servo motor and checking the replaced piston of the servo motor. [7] Method for replacing a piston seal of a servomotor of a hydraulic lifting and lowering machine according to claim 6, characterized by , that when the valve of the upper chamber of the servomotor is opened to drain the oil in the upper chamber, the oil in the upper chamber of the servomotor is pumped into an oil tank by means of an oil pump device. [8] Method for replacing a piston seal of a servomotor of a hydraulic lifting and lowering machine according to claim 4, characterized by that the first hand-pulling component and the second hand-pulling component are a hand chain hoist, hand rope hoist or a manual winch. [9] Method for replacing a piston seal of a servomotor of a hydraulic lifting and lowering machine according to claim 5, characterized by , that a dam valve is set to a fully closed position before the piston rod of the servo motor is disconnected from the sluice gate on the dam. [10] Method for replacing a piston seal of a servomotor of a hydraulic lifting and lowering machine according to claim 4, characterized by , that when removing the upper end cap of the servo motor, a scaffold is erected to remove the upper end cap of the servo motor.

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