1.1 Overall Installation Process Flow for Chain Bucket Elevators

Basic inspection and acceptance → Pre‑assembly of the drive unit → Installation of the upper sprocket assembly → Installation of the lower sprocket assembly → Sectional assembly of the housing → Installation of the intermediate guide sprockets → Assembly of the traction chain and buckets → Installation of auxiliary components → Alignment of the inlet and outlet openings → Commissioning and trial operation of the complete machine

Overall machine structure: upper maintenance top cover, head sprocket assembly, motor–reducer drive unit, maintenance operating platform, discharge outlet, middle standard housing, plate-chain traction assembly, lower housing, feed inlet, tail sprocket, and counterweight tensioning device.

1.2 Standardized Installation Procedures for Chain Bucket Elevators

1.2.1 Pre-Installation Preparations

(1) On-site Arrangements and Logistics Preparation

1. Site Cleanup: Thoroughly sweep the equipment foundation and all floor-level work areas, removing construction debris and miscellaneous items to ensure adequate space for lifting and assembly operations.
2. Equipment configuration: Complete set of installation and inspection tools, including cranes, electric winches, manual hoists, electric welders, gas‑cutting equipment, theodolites, precision levels, steel tape measures, plumb bobs, and more.
3. Personnel Allocation: A specialized work crew comprising certified fitters, riggers, welders, electricians, and other qualified trades is assigned. All personnel are thoroughly familiar with equipment drawings and installation standards.

1.2.2 Equipment Foundation Recheck and Acceptance

(1) Acceptance Criteria

The equipment foundation’s external dimensions, positioning accuracy, and concrete construction quality shall comply with the current national standard, “Code for Construction and Acceptance of Reinforced Concrete Structures.” The contractor shall provide complete foundation acceptance records and work‑handover certificates. In strict accordance with the bucket elevator foundation shop drawings and handover documentation, all relevant parameters of both the upper and lower equipment foundations shall be verified individually.

(II) Measurement and Testing Methods

1. Elevation Survey: Using the floor elevation datum as the reference, short‑distance elevations are measured with a communicating tube, while long‑distance elevations are determined using a precision level.
2. Axial alignment inspection: Use a theodolite to verify that the centerlines of the upper and lower foundations coincide.
3. Coordinate positioning: Using the centerlines of floor columns and wall reference lines as references, adopt… Φ0.35 ~ 0.5mm Steel wire tensioning is verified on-site using a plumb bob and a steel tape measure.
4. Data Verification: Conduct a line-by-line comparison between the measured data and the basic handover checklist; for any deviations exceeding the allowable tolerance, a corrective action plan must be prepared and rework carried out.
5. Foundation Flatness: Permissible Deviation of the Overall Levelness of the Foundation ≤1/1000 。

(3) Reference Table of Permissible Deviations for Basic Dimensions

1.2.3 Installation of the Main Equipment of the Bucket Elevator

1. Component Inventory and Inspection Unbox and inspect all equipment and components, checking for deformation, damage, or missing parts incurred during transportation and storage. Any damaged or defective parts must be replaced or repaired in advance before installation can proceed.

2. Install the tail base in position. Use a level to level the foundation and verify all dimensions of the foundation and anchor bolts. Lift and position the tail assembly onto the foundation, ensuring that the horizontal deviation of the upper flange at the tail end is less than 1/1000; shims may be used for fine leveling. Once completed, tighten all anchor bolt nuts.

3. Sectional assembly of the middle casing An asbestos sealing gasket is installed on the tail‑end flange, and the first section of the access door is positioned in the mid‑section of the casing. Using the outer wall of the tail‑end casing as the reference coordinate system (X₀, Y₀), the axial and radial misalignments of each individual casing segment are measured; the allowable deviation for each segment is less than 2 mm. Any deviations can be corrected by adding or removing asbestos shims or by packing asbestos rope. Once the alignment has been verified, the flange bolts are tightened. Subsequent casing sections are assembled upward, one by one, following the same procedure, with careful attention to the positioning of adjustment sections and non‑standard sections to ensure that all flange joints remain accessible for future maintenance and disassembly.

4. Control of Overall Accumulated Deviations in the Housing Assembly For each assembled shell section, verify the offset between adjacent sections (less than 2 mm per section), and simultaneously check the cumulative deviation of the entire assembly relative to the tail‑end datum. The total cumulative deviation of the complete assembly must not exceed the limits specified in the table below:

5. Alignment of the head housing with the spindle installation   The assembly and verification standards for the head housing are the same as those for the mid‑section housing. After the housing is installed, open the upper maintenance cover and use a level to calibrate the horizontal alignment of the spindle; the allowable deviation is… ≤0.3/1000 . Verify the coaxiality of the upper and lower sprockets, ensuring that axial and radial misalignments comply with the tolerances specified in the table below. If the deviations exceed the limits, make adjustments in stages: first, slightly loosen the bolts on the head bearing housing to fine‑tune the main shaft; if the requirement still is not met, adjust the tail‑shaft assembly or loosen the head housing flange and reposition the entire assembly for correction.

6. Reinforcement of the Housing Support Lateral support frames are installed vertically along the vessel body to prevent tilting and displacement during operation. These supports are typically spaced 5–8 m apart, with the uppermost frame securely anchored to the mid‑section of the shell that connects to the upper casing. The supports are reliably welded to the building structure, closely abutting the outer surface of the shell, while providing adequate vertical expansion clearance to accommodate free thermal expansion and contraction of the equipment.

7. Installation of maintenance platforms and guardrails The three separate platforms are pre-assembled into a single unit using bolts, then lifted and securely fastened to the upper casing. Additional support channel steel is welded to reinforce both the platforms and the mid‑section of the casing. Upon completion of the platforms, guardrails and maintenance access ladders are welded in place.

8. Assembly of the Drive Unit and Coaxiality Alignment Equipment transportation can easily cause misalignment of the motor and reducer’s coaxiality; therefore, alignment is mandatory prior to installation. Precision control is implemented according to three distinct transmission configurations:

• General coupling transmission: radial displacement between the motor shaft and the reducer shaft. ≤0.2mm , angular displacement error ≤30′ ; Axial clearance of the pin-type coupling 3 ~ 5mm (The hydraulic coupler conforms to the standard.) Before installation, briefly jog the motor to verify that the rotation direction is correct, then secure the base.
• Chain drive configuration: Parallelism between the main shaft and the reducer output shaft < 0.5/1000 ; Coplanarity deviation of the centerlines of the driving and driven sprockets ≤1mm ; Adjust the sag of the slack side after chain installation. 10 ~ 30mm ; The drive base and the maintenance platform are fully welded in place; the lower half of the sprocket guard is installed, and internal lubrication is applied. 10# Machine oil, with the oil level submerging the chain. 6 ~ 12mm , and finally seal the top cover.
• ZL Elastic pin-type gear coupling direct connection: radial displacement between the spindle and the reducer output shaft. ≤0.3mm , angular displacement ≤30′ , coupling axial clearance 6 ~ 8mm。
• Hollow‑shaft direct‑drive reducer structure: Prior to assembly, the inner diameter of the hollow shaft bore is measured with an internal diameter gauge, and the outer diameter of the main shaft is measured with an outside micrometer; the fit tolerance grade must meet H7/h6 Clearance fit or H7/m6 Minimum interference fit; if the fit is excessively tight, only grinding, filing, or sandpaper finishing of the spindle is permitted—machining of the reducer’s hollow shaft is prohibited.

9. Assembly of the traction chain and hopper  

• (1) Chain Pre‑treatment: The chains are delivered from the factory in sections of approximately 3 m each. Prior to installation, verify the smooth rotation of the hinges; any sticking or binding points should be cleaned with gasoline or kerosene to remove rust. Deformed buckets must be straightened and reshaped in advance.
• (2) Chain Installation: Open the mid‑section maintenance section and the tail‑end maintenance cover, then lift and install the chain in sections. Use a hand chain hoist to pull two sets of chains upward along the casing, routing them over the head sprocket and lowering them to the tail end. Raise the tail sprocket assembly to the uppermost position of its travel, aligning the chain ends for splicing. After lowering the tail sprocket, ensure that the remaining tensioning travel is no less than 50% of the total travel; if the travel is insufficient, add or remove two chain links to adjust it. For weight‑type tensioning mechanisms, distribute the counterweight blocks evenly; for spring‑type tensioning systems, adjust the screws on both sides to maintain balanced tension between the two springs.
• (3) Hopper Assembly: After the chain links are joined, install the hoppers, tightening the bolts, flat washers, and spring washers evenly to avoid over‑tightening. Ensure that all hopper inlets face the equipment’s feed side. Once all hoppers are assembled, manually rotate the drive sprocket to verify that the sprocket and chain engage smoothly, without binding, impact, or unusual noises.

10. Enclosure Cleaning and Lubrication Clean all tools and debris from the interior of the machine, then close the head cover and the tail access door. Lubricate all bearing locations, transmission pairs, gearboxes, and other lubrication points with the specified grade of lubricant; upon completion, proceed to the commissioning phase.

1.2.4 Operating Procedures for Full-Machine Trial Operation

Test driving is divided into No-load trial run 、 Load test run During both phases, dedicated on-site commanders will be assigned throughout the entire operation, and all operators and patrol personnel must follow unified dispatch instructions; unauthorized departure from duty is strictly prohibited.

(1) Pre-Test Inspection

1. Internal inspection: Thoroughly remove any tools or debris left inside the enclosure.
2. Lubrication and Oil Filling: Lubricate all bearings, gear reducers, drive chains, and hydraulic couplings according to the oil level indicators.
3. Tensioning mechanism inspection: Verify that the tensioning device operates smoothly and is free of binding or obstruction.
4. Direction verification: Confirm that the check valve’s locking direction, the motor’s rotation direction, and the equipment’s lifting direction are properly matched.

(2) No-load trial run

1. Pre‑operation inspection: Manually rotate the drive system; only energize and perform jog operation after confirming there are no jams, impacts, or abnormal friction noises throughout the entire cycle. Perform a jog test to circulate the chain for at least two full cycles, and proceed to continuous no‑load operation only if no abnormalities are detected.
2. Data Monitoring: During no-load operation, continuously record motor current and voltage; monitor in real time the temperature rise of the head and tail bearings as well as the reducer bearings; inspect the condition of the machine housing, drive unit, and sprockets; and immediately shut down for maintenance upon detecting abnormal noises or overheating exceeding allowable limits.
3. Operating duration requirement: continuous no-load operation 2 hours After shutdown, re-tighten all hopper mounting nuts and apply spot welding to prevent loosening; intermittent start–stop operation. 2  More than once, then continue running under no-load conditions. 4h Only after all indicators have been verified as compliant may the equipment proceed to loaded trial operation.
4. No-load acceptance criteria: The electrical control system operates sensitively and reliably; the motor runs smoothly, with vibration velocity… ≤6mm/s ; The drive unit exhibits no abnormal vibration, impact, or oil leakage; all bearings show normal temperature rise. ≤65℃ ; The chain and hopper operate without jamming, misalignment, or abrasion. Operational records are maintained throughout the entire process.

(3) No-load trial run

1. Feeding operation: Start the equipment under no-load conditions; once it is running smoothly, feed material in three equal batches, gradually increasing the feed rate to the design‑rated conveying capacity.
2. Operational inspection: Monitor in real time the noise level of the drive unit, the motor’s operating current (which must not exceed the rated current), and the stability of the electrical control system; observe the uniformity of material filling in the hopper to prevent unilateral overloading.
3. Operating duration and shutdown inspection: cumulative loaded operation of no less than 16h , with intermittent shutdowns during this period. 4  At least once, inspect for loose fasteners, bearing temperature rise, and the reliability of the backstop brake.
4. Load acceptance criteria: the actual lifting displacement meets the design specifications; material backflow is negligible; and the maximum bearing temperature rise is within acceptable limits. ≤70℃ ; The entire unit exhibits no persistent abnormal noise; all operating parameters are fully recorded.