Large motor disassembling, hoisting and overhauling method

Abstract

The invention relates to the technical field of motor overhauling, in particular to a large motor disassembling, hoisting and overhauling method. The method comprises the following steps: firstly, preparing technical data and standard tools, then sequentially measuring and recording a gap between bearing bushes of an upper roller motor and a lower roller motor, dismantling shielding structures such as a middle connecting shaft, a platform walking board and an A-shaped frame, dismantling accessory parts of the lower roller motor and marking relative positions, and after measuring an air gap between a stator and a rotor, completing the operation of the upper roller motor and the lower roller motor. The stator and the rotor are safely decomposed and purged and checked in a manner of cooperative lifting of two 75-ton cranes and leveling of a chain block, and finally, the shim is adjusted according to original data after reverse-sequence reinstallation, so that debugging and test running are completed. According to the method, the heavy load problem is solved through double-machine cooperative hoisting, precise assembly is achieved through the processes of measurement, recording, application and adjustment, gap deviation and contact damage are avoided, the overhaul safety, stability and efficiency are improved, and the method is suitable for industrial field overhaul of the large-scale heavy-load motor.

Description

A method for disassembling, hoisting, and repairing large electric motors Technical Field

[0001] This invention relates to the field of motor maintenance technology, and in particular to a method for disassembling and hoisting large motors for maintenance. Background Technology

[0002] In industrial production, large main drive motors, as core power equipment, are widely used in heavy manufacturing scenarios such as 1700mm hot rolling mills. The motor itself weighs 124 tons, while the total lifting weight of the disassembled stator, rotor, and auxiliary components reaches 144 tons. Its operational stability directly determines production continuity and product quality. Among these, the R1 lower roll main drive motor, as a critical piece of equipment, endures harsh conditions such as heavy loads and high-speed operation for extended periods, requiring regular overall disassembly and maintenance to eliminate potential equipment hazards and ensure production safety.

[0003] Currently, although various motor maintenance methods exist in existing technologies, they are mostly aimed at small and medium-sized motors or single maintenance links. A complete and standardized disassembly, hoisting and maintenance plan applicable to this type of large main drive motor has not yet been formed, which is difficult to meet the needs of high-difficulty and high-precision maintenance operations. Summary of the Invention

[0004] In view of this, the present invention provides a method for disassembling, hoisting and repairing large motors.

[0005] Therefore, the present invention provides the following technical solution:

[0006] A method for disassembling, hoisting, and overhauling a large motor includes the following steps: S1. Prepare the technical data and tools required for implementing this method, and confirm that the performance of each tool meets the standards according to the corresponding industry standards and equipment factory requirements; S2. Measure and record the original data of the side clearance, top clearance, and back clearance of the support bearing of the intermediate shaft of the upper roller motor; then remove some of the connecting bolts at the connection between the main shaft of the upper roller motor and the intermediate shaft, leaving the remaining bolts to maintain the fixed state of the main shaft of the upper roller motor and the intermediate shaft; after the crane is in place, tie the hoisting wire rope to the intermediate shaft of the upper roller motor, remove the remaining connecting bolts, and hoist the intermediate shaft away; S3. Use the lead pressing method to measure and record the original data of the side clearance, top clearance, and back clearance of the drive side and non-drive side bearings of the lower roller motor; then remove the connecting bolts used to fix the platform walkway, and then remove all the connecting bolts used to fix the A-frame; use a crane to lift the platform walkway and A-frame away in sequence; S4. Remove the end cover fixing bolts of the drive side and non-drive side bearing seats of the lower roller motor, and remove the bearing end cover; then remove the brush holder device, encoder, and pipeline connections of the lubrication system and cooling system of the lower roller motor and temporarily seal the pipeline openings; then remove the outer cover of the lower roller motor and the stator and rotor electrical components. Connect the power source and mark the corresponding positions of the electrical terminals and the stator and rotor; S5. Remove the connecting bolts at the front end of the lower roller motor rotor, then remove the anchor bolts of the front bearing housing, the anchor bolts of the rear bearing housing, and the anchor bolts of the combined lifting tool and the stator in sequence; use a special wedge measuring tool to measure and record the air gap between the rotor and the stator; S6. Place the core-through and core-extraction storage racks in the designated positions, use a special lifting tool with two cranes to lift them simultaneously, and hang the lifting wire ropes on the two lifting beams of the special lifting tool respectively; adjust the height of the lifting wire ropes by using the hand-operated hoists at both ends of the rotor, and keep the air gap data recorded in step S5. To ensure the stability of the air gap between the rotor and stator and prevent them from contacting each other, the entire lower roller motor stator and rotor are hoisted and transferred to the storage rack area. After the stator and rotor are disassembled and cored, the stator cavity and rotor surface are purged and inspected. S7. After the equipment is overhauled or repaired, the components are reassembled in reverse order from S6 to S1. During the reassembly process, based on the bearing clearance data recorded in step S3 and the air gap data recorded in step S5, the air gap between the stator and rotor and the bearing clearance are adjusted to the design requirements consistent with the original measurement data by adjusting the shims between the motor bearing housing and the base. Finally, debugging and trial operation are carried out.

[0007] Furthermore, the cranes used in steps S2 and S3 are 75-ton hook-type bridge cranes, and in step S6, both cranes are 75-ton hook-type bridge cranes. The special lifting tool is the original lifting tool of the motor, and the manual hoist has a specification of 20 tons.

[0008] Furthermore, the diameter of the lead wire used in the lead pressing method should not exceed 2 to 3 times the gap being measured. The measuring tool is a 0 to 25 mm outside micrometer. The gap between the bearing bushes is measured using a feeler gauge. Before measurement, the oil stains on the upper surface of the bearing seat base need to be cleaned.

[0009] Furthermore, after measuring the bearing clearance in step S3, it is also necessary to use a 500V megohmmeter to measure the insulation resistance of the motor bearing housing to ensure that its value is not less than 0.5MΩ.

[0010] Furthermore, in step S5, the special wedge measuring tool is temporarily made on-site using an inclined plate, and the air gap measurement data is used for subsequent replacement and adjustment of the motor bearing housing insulation gasket.

[0011] Furthermore, in step S6, the hoisting wire rope tying method is as follows: four support points are used at the main hook of the crane, with four wire ropes at each support point; four support points are used for stator hoisting, with two wire ropes at each support point; and two ends are used for rotor hoisting, with two wire ropes at each end.

[0012] Furthermore, in step S6, when the entire lower roller motor stator and rotor are hoisted and the stator is lifted 3050mm off the ground, the remaining height that the crane main hook can lift is ensured to be no less than 259mm.

[0013] Furthermore, in step S7, before debugging and trial operation, check whether the lubrication system and cooling system pipelines are normal, and determine whether to heat the lubricating oil based on the ambient temperature and the freezing temperature of the lubricating oil; after starting the high-pressure lifting oil pump, use a dial indicator to confirm that the rotor shaft lifting range is 0.10 to 0.20 mm.

[0014] Furthermore, during step S7, when the high-pressure jacking oil pump is running, it is necessary to check whether the high-pressure jacking pipeline is leaking, whether the high-pressure oil pump is operating normally, and whether the clearance between the seal on the bearing and the shaft is appropriate; the high-pressure motor should run under no-load for no less than 2 hours, the three-phase current imbalance value should be less than 10%, and a 24-hour hot load test should be conducted.

[0015] The specifications of the wire rope used for crane lifting are selected using the following formula:

[0016] In the formula: Where F is the breaking force of the wire rope, S is the force on the wire rope, and S is the safety factor. This is the reduction factor.

[0017] The advantages and positive effects of this invention are as follows: Two cranes are used for lifting, matching the total lifting weight requirement of 144 tons. The stator and rotor are suspended by a special lifting beam, and the height is adjusted in real time by hand-operated hoists at both ends of the rotor. This not only solves the problem of insufficient lifting capacity of a single crane, but also ensures that the stator and rotor do not come into contact during the lifting process, which greatly improves the safety and stability of lifting heavy-duty large motors.

[0018] Before maintenance, the side clearance, top clearance, and back clearance of the bearing bushes are accurately measured using the lead pressing method. A specialized wedge tool is used to measure the air gap between the stator and rotor. All two types of raw data are fully recorded and archived, forming a closed-loop process of measurement, recording, application, and adjustment. During hoisting, the original air gap data is used as a benchmark to precisely adjust the relative positions of the stator and rotor, avoiding contact damage. During reassembly, the original bearing bush clearance and air gap data are used as a basis to adjust the shims between the motor bearing housing and the base, ensuring that the bearing bush clearance, stator, and rotor air gap match the design requirements. This completely changes the traditional maintenance process, which relies on manual experience and suffers from a disconnect between data and operation. It effectively avoids the risk of clearance deviation and significantly improves the motor assembly accuracy and operational stability. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 is a flowchart of a method for disassembling, hoisting and repairing a large motor provided by the present invention. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0022] This invention provides a method for disassembling, hoisting, and overhauling a large motor, as shown in Figure 1, which includes the following steps: S1. Prepare the technical data and tools required to implement this method, and confirm that the performance of each tool meets the standards according to the corresponding industry standards and equipment factory requirements.

[0023] S2. Measure and record the original data of the side clearance, top clearance, and back clearance of the support bearing bushes in the middle of the upper roller motor: Remove the locating pins of the bearing bush seat on the motor bearing, remove the upper end caps of the seals at both ends of the motor bearing, and remove the connecting bolts of the bearing bush seat on the motor base. The top clearance and back clearance of the motor bearing bushes are measured using the lead wire method. The diameter of the lead wire used in the lead wire method should not exceed 2 to 3 times the clearance being measured. The lead wire selection is: 5A (lead wire diameter 0.98mm), 10A (lead wire diameter 1.51mm), 15A (lead wire diameter 1.98mm). The measuring tool is a 0-25mm outside micrometer. The side clearance of the bearing bushes is measured using a feeler gauge. Before measurement, the oil stains on the upper surface of the bearing seat base must be cleaned.

[0024] The lead-pressing method utilizes the excellent plastic deformation properties of lead wire. After the bearing bush is tightened, the lead wire is uniformly compressed by the gaps between the journal and the bearing bush, and between the bearing back and the bearing seat. The thickness after compression is the actual gap value. By placing lead wires on the upper part of the journal and the mating surface of the bearing bush, the top gap (between the journal and the upper bearing bush) and the back gap (between the upper bearing bush and the bearing seat) can be measured simultaneously. This method is simple to operate and has high measurement accuracy, making it the mainstream method in the motor bearing bush gap measurement industry. It can effectively avoid measurement errors in confined spaces.

[0025] Measurement of the top clearance of the motor bearing bush: Remove the upper bearing bush; place lead wires of the same specification on the upper part of the journal and at the mating surface of the upper and lower bearing bushes; slowly replace the upper bearing bush and evenly tighten the two diagonal bolts; then remove the upper bearing bush and use a micrometer to measure the thickness of the compressed part of the lead wire, which is the top clearance. The measurement principle of the bearing back clearance is the same as that of the top clearance.

[0026] Then, some of the connecting bolts at the connection between the main shaft of the upper roller motor and the intermediate shaft are removed, while the remaining bolts keep the main shaft of the upper roller motor and the intermediate shaft fixed. After the crane is in place, the hoisting wire rope is tied to the intermediate shaft of the upper roller motor, the remaining connecting bolts are removed, and the crane is lifted away from the intermediate shaft.

[0027] S3. Use the lead pressing method to measure and record the original data of the side clearance, top clearance and back clearance of the roller motor drive side bearing and non-drive side bearing; after measuring the bearing clearance, it is also necessary to use a 500V megohmmeter to measure the insulation resistance of the motor bearing housing to ensure that its value is not less than 0.5MΩ.

[0028] Then remove the connecting bolts used to fix the platform walkway, and then remove all the connecting bolts used to fix the A-frame; use a crane to lift the platform walkway and A-frame away in sequence.

[0029] S4. Remove the end cover fixing bolts of the bearing housing on the drive side and non-drive side of the lower roller motor, and remove the bearing end cover; then remove the brush holder device, encoder, and pipeline connections of the lubrication system and cooling system of the lower roller motor and temporarily seal the pipeline openings; then remove the power connection of the lower roller motor cover and the stator and rotor, and mark the corresponding positions of the electrical wiring terminals and the stator and rotor.

[0030] S5. Remove the connecting bolts at the front end of the lower roller motor rotor, and then remove the anchor bolts of the front bearing housing, the anchor bolts of the rear bearing housing, and the anchor bolts of the combined lifting tool and the stator in sequence; use a special wedge measuring tool to measure and record the air gap between the rotor and the stator; the special wedge measuring tool is temporarily made on-site using a slanted pad, and the air gap measurement data is used for the subsequent replacement and adjustment of the motor bearing housing insulation gasket.

[0031] Finally, by adjusting the shims between the motor bearing housing and the base, the design requirements for air gap and shaft levelness were met.

[0032] The air gap between the stator and rotor is a crucial component of the motor's magnetic circuit. The uniformity of the air gap directly affects the motor's magnetic field distribution, operating vibration, and energy consumption. An excessively large air gap can lead to a decrease in the power factor, while an excessively small air gap may cause friction between the stator and rotor. A specialized wedge-shaped measuring tool, based on the principle of wedge thickness gradient, directly obtains the air gap value by inserting a wedge structure into the stator-rotor gap and using a scale reading. It can be temporarily fabricated on-site using inclined shims to flexibly adapt to different gap sizes, offering high measurement efficiency and low cost, meeting the needs of rapid maintenance in industrial settings.

[0033] S6. Place the core-extraction storage rack in the designated position, and use a special lifting tool with two cranes to lift it simultaneously. Hang the lifting wire ropes on the two lifting beams of the special lifting tool respectively. Adjust the height of the lifting wire ropes by using the hand-operated hoists at both ends of the rotor. According to the air gap data recorded in step S5, ensure the air gap between the rotor and stator is stable and avoid contact between the two. Lift the lower roller motor stator and rotor as a whole and transfer them to the storage rack area. After the core extraction and disassembly of the stator and rotor are completed, blow and inspect the stator cavity and rotor surface respectively.

[0034] A single 75-ton crane cannot meet the lifting weight requirement of 144 tons. Dual-crane collaborative lifting is based on the principle of uniform load distribution. By symmetrically arranging two cranes and using specialized lifting tools and beams for rigging, the force on both cranes is evenly distributed. The actual force on each crane is ≤72 tons, lower than the rated load of 75 tons. Combined with hand-operated hoists at both ends of the rotor for height adjustment, real-time compensation for lifting synchronization deviations can be achieved, ensuring stable air gap between the stator and rotor and preventing equipment damage caused by uneven force or poor synchronization.

[0035] The hoisting wire rope attachment method is as follows: four support points are used at the main hook of the crane, with four strands of wire rope at each support point, totaling 16 strands. The stator hoisting uses four support points, with two strands of wire rope at each support point. The rotor hoisting uses two ends, with two strands of wire rope at each end. When hoisting the lower roller motor stator and rotor as a whole and lifting the stator 3050mm off the ground, ensure that the remaining lifting height of the main hook is not less than 259mm.

[0036] Calculation of the stress on the wire rope at the crane's main hook: Selection of the included angle Calculated at 60°, the maximum force on a single steel rope during hoisting operations is: 144 / (16cos30°) = 10.39 tons = 101.84 kN. Calculated using the formula for the minimum breaking strength of a steel rope: =101.84×6 / 0.82≈745KN Where: F is the breaking force of the wire rope, S is the force on the wire rope, and S is the safety factor (6 for hoisting large equipment). The reduction factor is 0.82 for 6×37+1 steel rope.

[0037] Selection of wire rope diameter: According to the mechanical properties table of important purpose wire rope in GB / T 8918--2006, specification: 6×37S+FC, the selected wire rope has a diameter of φ36mm, specification: 6×37+1, tensile strength of 1770MPa, and breaking strength of 757KN > 745KN, which meets the requirements.

[0038] Determining the dimensions of the hoisting motor stator wire rope: Four-point hoisting, each point uses a double-strand wire rope, for a total of 8 strands.

[0039] Stress calculation of the wire rope at the stator: The included angle is selected as α=60° for calculation. The maximum force on a single wire rope during hoisting is: F=G / (8cosα / 2)=47 / (8cos30°)=6.78 tons=66.48KN.

[0040] Calculated using the formula for the minimum breaking tensile force of a steel rope: =66.48×6 / 0.82≈487KN.

[0041] Wire rope diameter: According to the mechanical properties table of 6×37S+FC, the selected diameter is φ30mm.

[0042] Determining the dimensions of the wire rope for hoisting the motor rotor: both ends of the hoisting shaft (shaft diameter φ750mm), each hoisting point uses a double-strand wire rope, for a total of 4 strands.

[0043] Calculation of wire rope stress: Based on direct lifting, the maximum stress on a single wire rope during hoisting is: F = G / 4 = (77 + 5) / 4 = 20.5 tons = 200.9 kN. This is calculated using the formula for the minimum breaking strength of a wire rope. ≈1470KN.

[0044] Wire rope diameter: According to the mechanical properties table of 6×37S+FC, the selected diameter is φ52mm.

[0045] S7. After the equipment is inspected or repaired, reassemble each component in reverse order from S6 to S1. During the reassembly process, based on the bearing clearance data recorded in step S3 and the air gap data recorded in step S5, adjust the shims between the motor bearing housing and the base to adjust the stator and rotor air gap and bearing clearance to the design requirements consistent with the original measurement data. Finally, conduct debugging and trial operation.

[0046] Before commissioning and trial operation, check whether the lubrication system and cooling system pipelines are normal, that is, whether there are no leaks, smooth flow, reliable connection, and parameters meet the standards. Determine whether to heat the lubricating oil based on the ambient temperature and the freezing temperature of the lubricating oil. After starting the high-pressure lifting oil pump, use a dial indicator to confirm that the rotor shaft lifting range is 0.10 to 0.20 mm.

[0047] When the high-pressure jacking oil pump is running, it is necessary to check whether the high-pressure jacking pipeline is leaking and whether the high-pressure oil pump is operating normally. That is, after the oil pump is started, there should be no abnormal noise, vibration or leakage. The system pressure should be able to rise to the rated value quickly and remain stable, with good pressure holding performance. The drive motor current should be balanced and there should be no overload. Check whether the clearance between the bearing seal and the shaft is appropriate, that is, whether the radial clearance and uniformity meet the requirements of the equipment drawings. There should be no jamming when the rotor is manually rotated. When the motor is running, there should be no leakage or friction wear marks on the seal. The high-pressure motor should run under no-load for no less than 2 hours, and the three-phase current imbalance value should be less than 10%. It should also be combined with a 24-hour hot load test.

[0048] The cranes used in steps S2 and S3 are 75-ton hook-type bridge cranes. In step S6, both cranes are 75-ton hook-type bridge cranes. The special lifting tool is the original lifting tool of the motor, and the manual hoist is 20 tons.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for disassembling, hoisting, and overhauling a large electric motor, characterized in that, The process includes the following steps: S1. Prepare the technical data and tools required for implementing this method, and confirm that the performance of each tool meets the standards according to the corresponding industry standards and equipment factory requirements; S2. Measure and record the original data of the side clearance, top clearance, and back clearance of the support bearing bush of the upper roller motor intermediate shaft; then remove some of the connecting bolts at the connection between the upper roller motor main shaft and the intermediate shaft, leaving the remaining bolts to maintain the upper roller motor main shaft and the intermediate shaft in a fixed state; after the crane is in place, tie the hoisting wire rope to the upper roller motor intermediate shaft, remove the remaining connecting bolts, and lift the intermediate shaft away; S3. Use the lead weight method to measure and record the original data of the side clearance, top clearance, and back clearance of the lower roller motor drive side bearing bush and non-drive side bearing bush; then remove the connecting bolts used to fix the platform walkway, and then remove all the connecting bolts used to fix the A-frame; use the crane to lift the platform walkway and A-frame away in sequence; S4. Remove the end cover fixing bolts of the lower roller motor drive side and non-drive side bearing seats, and remove the bearing end cover; then remove the lower roller motor... S5. Connect the brush holder device, encoder, and piping of the lubrication and cooling systems and temporarily seal the pipe openings. Then remove the outer cover of the lower roller motor and the power connection of the stator and rotor, and mark the electrical wiring terminals and the corresponding positions of the stator and rotor. S6. Remove the connecting bolts at the front end of the lower roller motor rotor, and then remove the anchor bolts of the front bearing seat, the anchor bolts of the rear bearing seat, and the anchor bolts of the combined lifting tool and the stator in sequence. Use a special wedge measuring tool to measure and record the air gap between the rotor and the stator. S7. Place the core-pulling and core-extracting storage rack to the designated position, and use a special lifting tool with two cranes to lift it simultaneously. Hang the lifting wire ropes on the two lifting beams of the special lifting tool. Adjust the height of the lifting wire ropes by the hand-operated hoists at both ends of the rotor. According to the air gap data recorded in step S5, ensure the air gap between the rotor and the stator is stable and avoid contact between the two. Lift the lower roller motor stator and rotor as a whole and transfer them to the storage rack area. After the core-pulling and disassembly of the stator and rotor are completed, blow and inspect the stator cavity and the rotor surface respectively. S7. After the equipment is inspected or repaired, reassemble each component in reverse order from S6 to S1. During the reassembly process, based on the bearing clearance data recorded in step S3 and the air gap data recorded in step S5, adjust the shims between the motor bearing housing and the base to adjust the stator and rotor air gap and bearing clearance to the design requirements consistent with the original measurement data. Finally, conduct debugging and trial operation.

2. The method for disassembling, hoisting, and overhauling a large motor according to claim 1, characterized in that, The cranes used in steps S2 and S3 are 75-ton hook-type bridge cranes. In step S6, both cranes are 75-ton hook-type bridge cranes. The special lifting tool is the original lifting tool of the motor, and the manual hoist has a specification of 20 tons.

3. The method for disassembling, hoisting, and overhauling a large motor according to claim 1, characterized in that, The lead wire used in the lead pressing method has a diameter not exceeding 2 to 3 times the gap being measured. The measuring tool is a 0 to 25 mm outside micrometer. The gap between the bearing bushes is measured using a feeler gauge. Before measurement, the oil stains on the upper surface of the bearing seat base need to be cleaned.

4. The method for disassembling, hoisting, and overhauling a large motor according to claim 1, characterized in that, After measuring the bearing clearance in step S3, the insulation resistance of the motor bearing housing must also be measured with a 500V megohmmeter to ensure that its value is not less than 0.5MΩ.

5. The method for disassembling, hoisting, and overhauling a large motor according to claim 1, characterized in that, In step S5, the special wedge measuring tool is temporarily made on-site using an inclined plate. The air gap measurement data is used for subsequent replacement and adjustment of the motor bearing housing insulation gasket.

6. The method for disassembling, hoisting, and overhauling a large electric motor according to claim 1, characterized in that, In step S6, the hoisting wire rope is attached as follows: four support points are used at the main hook of the crane, with four wire ropes at each support point; four support points are used for stator hoisting, with two wire ropes at each support point; and two ends are used for rotor hoisting, with two wire ropes at each end.

7. The method for disassembling, hoisting, and overhauling a large electric motor according to claim 1, characterized in that, In step S6, when the lower roller motor stator and rotor are hoisted as a whole and the stator is lifted 3050mm off the ground, the remaining height that the crane main hook can lift is not less than 259mm.

8. The method for disassembling, hoisting, and overhauling a large motor according to claim 1, characterized in that, In step S7, before debugging and trial operation, check whether the lubrication system and cooling system pipelines are normal, and determine whether to heat the lubricating oil based on the ambient temperature and the freezing temperature of the lubricating oil. After starting the high-pressure lifting oil pump, use a dial indicator to confirm that the rotor shaft lifting range is 0.10 to 0.20 mm.

9. A method for disassembling, hoisting, and overhauling a large electric motor according to claim 8, characterized in that, When the high-pressure jacking oil pump is running in step S7, it is necessary to check whether the high-pressure jacking pipeline is leaking, whether the high-pressure oil pump is running normally, and whether the clearance between the seal on the bearing and the shaft is appropriate; the high-pressure motor should run under no-load for no less than 2 hours, the three-phase current imbalance value should be less than 10%, and a 24-hour hot load test should be conducted.

10. A method for disassembling, hoisting, and overhauling a large electric motor according to claim 1, characterized in that, The specifications of the wire rope used for crane lifting are selected using the following formula: In the formula: Where F is the breaking force of the wire rope, S is the force on the wire rope, and S is the safety factor. This is the reduction factor.

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