Many bridge crane parts are considered "wear parts" or "safety-critical parts," and must be replaced regularly or periodically based on their wear, aging, and relevant regulations and standards. They cannot be replaced only after complete failure.
The following is a list of major overhead bridge crane parts that require regular replacement, along with the replacement criteria and basic replacement cycle:
Replacement Criteria: Based on the number of broken wires, diameter wear, deformation, and degree of corrosion. Replacement is mandatory when any of the following conditions are present:
* The number of broken wires within one lay reaches the standard (e.g., 12 broken wires in a 6×19+FC wire rope during interlacing).
* Diameter wear exceeds 7% of the nominal diameter.
* Severe plastic deformation such as kinking, flattening, bending, or cage-like distortion occurs.
* Outer wire wear reaches 40% or severe corrosion.
Replacement Cycle Reference: There is no fixed time; it depends on usage frequency, load rate, and environment. Typically, it is 1-3 years, but daily inspections and periodic detailed checks must be consistently performed.
2. Crane Brake Friction Pads (Crane Brake Pads)
Replacement Criteria: Friction material thickness worn to 50% or less of its original thickness. Check for cracks and oil stains (oil stains greatly reduce the coefficient of friction and must be cleaned or replaced).
Replacement Cycle Reference: Inspection cycle is monthly; replacement cycle may vary from several months to several years depending on usage. Hoisting mechanism brake pads wear faster than running mechanism brake pads.
Replacement Criteria: Wear at the critical section exceeds 10% of the original dimension.
Opening deformation exceeds 15% of the original dimension.
Cracks or breaks appear (must be detected through flaw detection).
Hook torsional deformation exceeds 10 degrees.
Replacement Cycle Reference: The hook body has a relatively long lifespan, but monthly measurement and inspection are required. Bushings and pins of plate hooks need to be replaced periodically after wear.
4. Bridge Crane Pulleys and Crane Drum
Replacement Criteria: Uneven wear of the rope grooves leads to wire rope skipping or accelerated wear. When the wheel flange is damaged, cracked, or the groove bottom is worn, causing excessive clearance between the wire rope and the groove bottom (usually, when the wire rope diameter decreases by more than 1/3, the groove liner or the entire machine needs to be replaced).
Replacement cycle reference: Performed concurrently with wire rope inspection; its lifespan is usually longer than the wire rope itself.
5. Bridge Crane Wheels
Replacement criteria: Flange thickness wear exceeds 50% of the original thickness (easily leading to derailment).
Road surface (tread) wear forming severe depressions or cracks.
Diameter difference between the two drive wheels exceeds the standard (causing trolley misalignment).
Replacement cycle reference: Regular measurement; replacement cycle is long, possibly several years, depending on track condition and operating distance.
6. Crane Mechanism Bearings
Replacement criteria: Abnormal noise during operation (humming, rattling), overheating, severe vibration. After disassembly and inspection, if pitting or peeling is found on the raceway or rolling elements.
Replacement Cycle Reference: This is a preventative replacement, usually performed during major overhauls, or determined based on operating hours (e.g., 8000-15000 hours) and lubrication conditions.
7. Bridge Crane Current Collector Carbon Brushes/Slippers (for sliding contact line power supply)
Replacement Basis: Wear exceeding 1/2 or more of the original length leads to insufficient contact pressure, causing arcing or burning.
Replacement Cycle Reference: Check wear monthly; the specific replacement cycle depends on the crane's movement frequency, possibly 3-12 months.
8. Contactor/Relay Contacts
Replacement Basis: Severe contact burning, adhesion, welding, or poor contact causing overheating. Silver-based contacts may also be replaced after wear.
Replacement Cycle Reference: No fixed cycle, but should be carefully checked during regular maintenance (monthly, annual inspections), and replaced based on actual burning conditions. Main contactors require more frequent replacement than auxiliary contactors.
9. Resistor Components
Replacement Basis: Broken resistor sheet/wire, short circuit, or damaged insulating ceramic component. Excessive resistance fluctuations affect speed control performance.
Replacement Cycle Reference: Replace immediately upon discovery of damage during inspection; typically during system checks over major overhauls.
10. Limit Switches/Travel Switches
Replacement Basis: Mechanical component wear leading to malfunction, or the electrical life of the internal microswitch reaching the end of its life.
Replacement Cycle Reference: Due to their extreme importance (safety protection), even if not completely damaged, preventative replacement is recommended during major overhauls after hundreds of thousands of cycles.
11. Control Cables (Towing/Chain Systems)
Replacement Basis: Cracked or damaged outer sheath, broken core wires causing signal instability or short circuits.
Replacement Cycle Reference: Regular inspection, especially of moving and bending sections; typically replaced every 3-5 years or when signs of aging appear.
Replacement Basis: Rubber/polyurethane aging and cracking, loss of elasticity; hydraulic dampers leaking oil or failing to reset.
Replacement Cycle Reference: Monthly inspection; replace immediately upon discovery of damage. For rubber dampers, it is recommended to check for aging every 3-5 years; replacement should be considered even without impact.
13. Overload Limiter Sensors and Instruments
Replacement Criteria: Severe zero-point drift of the sensor, inaccurate display, or instrument damage. Regular calibration by a qualified organization is mandatory; failure to calibrate requires repair or replacement.
Replacement Cycle Reference: At least once a year, as required by regulations. Electronic components typically have a long lifespan, but may be damaged by harsh environments.
