Replacing the
reducer of a bridge crane is a major maintenance operation involving the core components of the lifting equipment, which must be carried out in strict accordance with safety regulations and technical standards. The following are detailed replacement steps and precautions:
I. Preliminary preparation
(1) Technical data verification
Check the crane drawings to confirm the reducer model, installation dimensions, connection method (such as flange connection, coupling type, etc.) and lubrication requirements.
Check whether the technical parameters of the new reducer (speed ratio, torque, power) match the original machine.
(2) Preparation of tools and equipment
Lifting equipment (such as hand hoists and truck cranes, ensure that the rated load is ≥ 1.5 times the weight of the reducer).
Special tools (hydraulic pullers, torque wrenches, dial indicator alignment instruments).
Consumables (sealants, grease, cleaning agents, gaskets).
(3) Safety measures
Disconnect the power and lock out the tag (LOTO), and hang a "No Operation" warning sign.
Set up a warning area to prevent cross-operation.
II. Disassembly of the old reducer
(1) Disconnect the power connection
Disconnect the motor power cord and mark the wiring position.
Remove the coupling bolts or brake wheel connectors, and use a puller to separate the mating surfaces.
(2) Lifting and fixing
Hold the reducer housing with a wire rope or sling (do not hang the shaft end), and pre-tighten it slightly.
Remove the anchor bolts or flange fixing bolts, and check whether there are hidden connection points.
(3) Remove the old reducer
Slowly move it to the maintenance platform, check the gear wear and bearing clearance and record them, and analyze the cause of the fault.
III. Installation of new reducer
(1) Foundation treatment
Clean the rust and burrs on the installation surface, and check the flatness of the motor/wheel assembly base (≤0.1mm/m).
(2) Alignment and adjustment
The coupling alignment requirements (radial/axial deviation ≤0.05mm, angular ≤0.02mm/m), use a dial indicator for fine adjustment.
When the gear is driven, the tooth side clearance needs to be checked (using the lead pressing method, the clearance value refers to the JB/T 9003 standard).
(3) Tightening and sealing
Tighten the anchor bolts to the rated torque (reference bolt grade 8.8 or 10.9) in three steps.
Apply sealant (such as Loctite 587) to the joint surface, and the vent cap should face upward.
IV. Commissioning and acceptance
(1) No-load test run
Test the steering by jogging, and monitor the temperature rise for 30 minutes (≤40℃ ambient temperature rise).
Vibration value detection (≤ISO 10816-3 standard limit).
(2) Load test
Load to 110% of the rated load in stages, and check for abnormal noise and oil leakage.
Brake linkage test (braking distance must comply with GB/T 3811 requirements).
(3) File archiving
Update the equipment file, record the replacement time, spare parts batch, and test data.
V. Key points
(1) Lubrication management: Lubricating oil needs to be replaced after the first 500 hours of operation (to remove metal chips during the running-in period).
(2) Welding taboos: It is forbidden to weld temporary lifting ears on the reducer housing to avoid material annealing.
(3) Emergency plan: Prepare support tools such as hydraulic jacks to prevent parts from falling suddenly during disassembly.
