An unplanned breakdown in a critical crane or hoist used in production can lead to a significant loss of production and potentially delay deliveries of product to customers. The unplanned breakdown can be catastrophic to both deliveries and your bottom line when there is no backup crane and the required crane and hoist parts are weeks or months away.
Once it is determined that a crane or hoist is critical to production, an analysis must be performed to identify which spare parts must be maintained in MRO inventories.
Some of the factors to take into account in this determination are:
- The quality and frequency of maintenance inspections.
- The age of the crane or hoist and breakdown history.
- Repair parts usage history.
- Current parts inventories.
- The availability and delivery time of required spare parts from the crane and hoist manufacturer.
Quality maintenance inspections performed monthly will identify critical wear on many long lead time components such as crane and trolley wheels, drums, hooks, sheaves, hoist wire rope assemblies and load chain so that they can be ordered well in advance for planned replacement. Proper lubrication done in conjunction with the maintenance inspections will also prolong the life of wear parts such as bearings and gears.
When a crane or hoist ages, there is a higher chance of failure of longer lead time items such as motors, bearings, and gears. Many of these parts are also not easy to fully inspect during routine maintenance inspections. Many older cranes and hoists have custom motor mounts and machining on bearings that preclude them from being cross-referenced and outsourced. Hoist gearing parts lead times on older hoists could be months; and reverse engineering, taking weeks, must be done to ensure safety prior to having any load bearing parts machined by a qualified machine shop.
Parts that have a history of multiple failures and common wear parts such as wire ropes, load chains, collector shoes, and brake discs should obviously be maintained in inventory in case they require immediate replacement due to normal wear or damage from use.
The availability of critical parts and components is probably the biggest question mark in determining what parts to stock within MRO inventories. Common replacement parts with current production off-the-shelf hoists are usually not a problem in getting fast deliveries from the factory. Be very careful with research on parts availability for hoists and crane components where critical items or mechanical parts are manufactured off-shore. Lack of domestic inventory may force you into overseas air shipment or complete replacement of the equipment in a critical breakdown where parts are months off.
Parts for high capacity built up hoists and cranes are very likely to be custom or special order. This is also the case for older hoists and end truck assemblies that are no longer manufactured. Quite often support of replacement parts is limited to five or ten years after the production of a hoist model is discontinued.
Spare parts consideration varies based upon the crane component and features
Hoists & Trolleys
Wear parts such as wire ropes, load chain, hook latches, and brake discs should always be stocked for quick replacement. Rope guides on many European style hoists should also be kept in stock as they can be easily damaged during use.
Hoist Drums, hooks, sheaves, and trolley wheel wear should be identifiable well in advance of a required repair allowing planned purchase. Hoist and trolley motors with complete brake assemblies often have long lead time and are a wise addition to MRO stock on critical cranes.
Stock of hoist and trolley gearbox parts, as well as bearings and seals, is warranted on older units that have not been rebuilt recently. Lead times on older hoist gearbox parts can be very long.
Crane End Trucks and Drives
Wear parts such as crane wheels can be determined in advance of repair. Bearings, however, should be stocked in case of failure. Note that bearing failure may result in wheel damage as well. So it might be wise to stock one complete wheel assembly with bearings. Bridge motors with complete brake assemblies often have long lead time and are a wise addition to MRO stock on critical cranes.
Hoist and Bridge Control Components
It is always smart to stock critical electrical components such as all required fuses, transformers, and contactors as well as replacement limit switches. Hoist, bridge and trolley Variable Frequency Drives are also a wise investment in the case of drive failure.
Runway and Bridge Electrification Components
Replacement collector shoes and arms, as well as replacement sections of conductor bar, should always be stocked for potential damage to electrification system from normal use. Extra wires should be available in well-planned festoon systems, however, if there are no spare wires present, replacement festoon cable is recommended in case of wire failure and subsequent short.
CRANE 1 specializes in crane and hoist asset management. If you are unsure about what spare parts you should maintain for your overhead crane and hoist units…we can help.