CMAA Crane Duty Classifications

designs, builds, installs and services custom overhead crane systems

CMAA has established crane service classes so that the most economical crane for a particular installation may be specified in accordance with Specifications for Top Running Bridge and Gantry Type Multiple Girder Electric Overhead Traveling Cranes - No. 70; or Specifications for Top Running and Under Running Single Girder Electric Overhead Cranes Utilizing Under Running Trolley Hoist - No. 74. Crane service classifications are based on the load spectrum reflecting the actual service conditions as closely as possible. The CMAA Crane Service Classes are as follows:

Crane Classification Typical
Installation		 # Lifts
per/hr.		 Average
Lift		 Shift Typical
Workload		 Key Points
Class A
Standby or Infrequent Service		 Power Houses
Public Utilites
Turbine Rooms
Motor Rooms
Transformer Stations		 0 - 2 10 ft. Single Shift
Operation
  • Precise handling at slow speeds
    with idle periods between lifts
  • Capacity loads may be handled
    for intial installation of equipment
    and for infrequent maintenance
  • H1 Hoist
  • Maintenace crane in machine house
  • Used only occasionally
Class B
Light Service		 Repair Shops
Light Assembly Operations
Light Warehousing		 2 - 5 10 ft. Single Shift
Operation
  • Loads vary from no load to occasional full rated loads
  • H2 Hoist
  • Light service requirements
  • Slow speed
Class C
Moderate Service		 Machine Shops
Paper Mills
Machine Rooms		 5 - 10 15 ft. Single Shift
Operation
  • Average load is 50% of rated load
  • 50% of less of the lifts are at the rated capacity
  • H3 Hoist
  • Minimum 1.15 service factor on bridge motion
  • 5,000 L-10 bearing life
Class D
Heavy Service		 Heavy Machine Shops
Foundries
Fabricating Plants
Steel Warehouses
Container Yards
Lumber Mills
Stanadard Duty Bucket &
Magnet Operations		 10 - 20 15 ft. 1 - 2 Shift
Operation
  • Average loads approaching 50% are continuously handled
  • 50% of less of the lifts are at the rated capacity
  • H4 Hoist
  • Minimum 1.3 service factor on bridge motion
  • 10,000 L-10 bearing life
  • Lift the maximum capacity with 30% frequency
  • Typically faster speeds over Class C

A Built-Up Hoist is typically used in this type of application and is tailored towards a specific application with a heavy duty cycle to handle demanding needs.

Class E
Severe Service		 Magnet
Bucket
Magnet/Bucket Combo
Scrap Yards
Cement Mills
Lumber Mills
Fertilizer Plans
Container Handling		 20+ 20+ ft. 24/7
Continuously
  • Continuous use at/or near capacity
  • H4+ Hoist
  • Minimum 1.75 service factor on bridge motion
  • 20,000 L-10 bearing life
  • Continuously lifts at the maximum capacity
  • Typically faster speeds over Class C and D

A Built-Up Hoist is typically used in this type of application and is tailored towards a specific application with a heavy duty cycle to handle demanding needs.

Hoist Classification Corresponding
Crane Class		 Corresponding
Crane Class
FEM HMI ISO CMAA DIN 15018
& SIM.		 EXAMPLE
1Cm H1 M2 CLASS A H1/B2
  • Maintenace crane in machine house
  • Used only occasionally
1Bm H2 M3 CLASS B H1/B2
  • Light duty work shop crane
  • Single shift operation
  • Low average loads
  • Maximal load lifted occasionally
1Am H3 M4 CLASS C H2/B3
  • Light/Med duty work shop crane
  • Single shift operation
  • Medium average loads
  • Occasionally lifting of max load
2m H4 M5 CLASS D H2/B3
  • Heavy duty crane, 2 shift operation
  • 1 or 2 shift operation
  • Regular medium and heavy loads
3m H4 M6 CLASS D H2/B3
or
H3/B4
  • Med/heavy duty work shop crane
  • Nominal load regularly lifted
  • Traverse or other dead loads below the hook
4m H4 or H5 M7 CLASS D
or
CLASS E		 H3/B4
or
H4/H6
  • Very heavy duty crane
  • 2 - 3 shift operation
  • Grab or magnet below the hook
  • Regular heavy loads

Key:

FEM - Federation Europeenne de la Manutention (European Federation of Material Handling)
HMI - Hoist Manufacturers Institute
ISO - International Organization for Standardization		 CMAA - Crane Manufacturers Association of America
DIN - Federation Europeenne de la Manutention (German Institute for Standardization)
CMAA Crane Duty Classifications

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