Before bridge crane purchasing, there are many factors needs to be considered to buy an ideal bridge crane machine. Your purchase is typically to improve productivity and safety within your facility. Therefore you really need to take several things into account prior to the bridge crane purchasing. Lowest bid does not work in the bridge crane industry. There are too many bridge crane variations, safety requirements, and technological features available. Before you invest your money into a new bridge crane, take into account these ten items that will not only save you money but you will invest in the best bridge crane for your application.
Typical double girder bridge crane
1. Know Your Application
This is the most important thing to know over anything else. Depending on the application could change many of the deciding factors on what kind of bridge crane you will need.
For example certain chemicals can make plastic brittle or accelerate metal corrosion. Cutting oils can make neoprene and PVC brittle. Heat and moisture can cause your motors to overheat. You will not pick the right bridge crane without the crane company knowing what the application is. Your crane will need to come with certain components depending on its application. To know your application you will need to know what you’re picking up, and the environment in which the bridge crane will be used. Added components will be required for areas with heavy dust, humid, high or low temperatures, outdoor, indoor, chemical exposure, Light, and even altitude can affect the bridge crane. Outside of the standard range, additional components will be required.
Look out for these items on your application.
- Standard Altitude is Below 3280ft (Altitude can affect cooling of electronic components and not allow heat dissipation)
- Standard Temperature Range is 32˚F to 104˚F
- Standard Humidity is below 90%
- Outdoor Applications will require features to prevent damage during rain, snow, ice, heat, wind, and ultraviolet radiation.
- Corrosive or Explosive Chemicals/ Fumes will require added features
- Heavy dust environments from cutting will require protective added features
- Heat can liquefy lubricants, and affect motors, and electrical components
- Cold can freeze lubricants, crack plastic components, and electrical parts
• Drastic temperature changes can cause condensation and short out electrical components and cause corrosion
2. Duty Cycle
The bridge crane’s duty cycle is going to depend partly on the application. If the crane is a production bridge crane it will probably need a heavy duty cycle. If it is a maintenance bridge crane or a bridge crane used for shipping then the cycle may be shorter. You will need to ask yourself how often will this bridge crane will get used every hour and how often will it be lifting near full capacity? Depending on this, different components will be used to make your customized bridge crane. Electric motors have duty cycles and you want to make sure that your bridge crane has the right motor for the job. Picking a severe duty motor for a light duty application will just cause you to spend well over what is required for the application.
There are two standards bridge crane manufacturers go by when picking out the right duty cycle. FEM and CMAA. CMAA is the Bridge Crane Manufacturers Association of America and FEM is Federal European De La Manutention. This is the standards for design and manufacturing internationally of overhead traveling bridge cranes. Both specifications are written based on the input from the larger bridge crane companies. The difference is that FEM is worldwide while CMAA is the United States only. FEM will also separate each main part of the bridge crane (hoist, trolley, and bridge) while CMAA specs classify the bridge crane as a whole. To understand these classifications you will also need to understand what a lift or work cycle is. A work cycle is lifting the load, having a rest period where the trolley or bridge is moving, lowering the load, having a rest period again where the trolley or bridge may be moving, and then returning the hook to the starting position.
FEM Class Definitions
1Bm
- Light Loads less than two hours per day (Occasional full loads, usually light load, Small fixed load)
- •Medium loads less than one hour per day (Occasional full loads, usually light load, Average fixed load)
1Am
- Light Loads less than four hours per day (Occasional full loads, usually light load, Small fixed load)
- Medium loads less than two hours per day (Occasional full loads, usually light load, Average fixed load)
- Heavy loads less than one hour per day (Repetitive full loads, usually average load, Heavy fixed load)
2m
- Light loads less than eight hours per day (Occasional full loads, usually light load, Small fixed load)
- Medium Loads less than four hours per day (Occasional full loads, usually light load, Average fixed load)
- Heavy loads less than two hours per day (Repetitive full loads, usually average load, Heavy fixed load)
- Very heavy loads less than one hour per day (usually almost full loads, Very heavy fixed load)
3m
- Light loads less than sixteen hours per day (Occasional full loads, usually light load, Small fixed load)
- Medium Loads less than eight hours per day (Occasional full loads, usually light load, Average fixed load)
- Heavy loads less than four hours per day (Repetitive full loads, usually average load, Heavy fixed load)
- Very heavy loads less than two hours per day (usually almost full loads, Very heavy fixed load)
4m
- Medium Loads less than sixteen hours per day (Occasional full loads, usually light load, Average fixed load)
- Heavy loads less than eight hours per day (Repetitive full loads, usually average load, Heavy fixed load)
- Very heavy loads less than four hours per day (usually almost full loads, Very heavy fixed load)
5m
- Heavy loads continuous use per day (Repetitive full loads, usually average load, Heavy fixed load)
- Very heavy loads continuous use per day (usually almost full loads, Very heavy fixed load)
CMAA Class Definitions
- CLASS A (STANDBY OR INFREQUENT SERVICE)
This service class covers bridge cranes which may be used in installations such as power houses, public utilities, turbine rooms, motor rooms and transformer stations where precise handling of equipment at slow speeds with long, idle periods between lifts are required. Capacity loads may be handled for initial installation of equipment and for infrequent maintenance.
- CLASS B (LIGHT SERVICE)
This service covers bridge cranes which may be used in repair shops, light assembly operations, service buildings, light warehousing, etc. where service requirements are light and the speed is slow. Loads may vary from no load to occasional full rated loads with two to five lifts per hour, averaging ten feet per lift.
- CLASS C (MODERATE SERVICE)
This service covers bridge cranes which may be used in machine shops or paper mill machine rooms, etc., where service requirements are moderate. In this type of service the bridge crane will handle loads which average 50 percent of the rated capacity with 5 to 10 lifts per hour, averaging 15 feet, not over 50 percent of the lift at rated capacity.
- CLASS D (HEAVY SERVICE)
This service covers bridge cranes which may be used in heavy machine shops, foundries, fabricating plants, steel warehouses, container yards, lumber mills, etc., and standard duty bucket and magnet operations where heavy duty production is required. In this type of service, loads approaching 50 percent of the rated capacity will be handled constantly during the working period. High speeds are desirable for this type of service with 10 to 20 lifts per hour averaging 15 feet, not over 65 percent of the lifts at rated capacity.
- CLASS E (SEVERE SERVICE)
This type of service requires a bridge crane capable of handling loads approaching a rated capacity throughout its life. Applications may include magnet, bucket, magnet/bucket combination bridge cranes for scrap yards, cement mills, lumber mills, fertilizer plants, container handling, etc., with twenty or more lifts per hour at or near the rated capacity.
- CLASS F (CONTINUOUS SEVERE SERVICE)
This type of service requires a bridge crane capable of handling loads approaching rated capacity continuously under severe service conditions throughout its life. Applications may include custom designed specialty cranes essential to performing the critical work tasks affecting the total production facility. These cranes must provide the highest reliability with special attention to ease of maintenance features.
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