There are actually 4 sizings of hook type fork carriages rated by the fork carriage lifting capability. Hook type blade carriages have been standardized.
The carriage bar spacing used for Class 1 is roughly 13 inches and the Class 1 carriage is rated to carry loads as much as 2000lbs. The Class 2 carriage is rated to hold loads up to 5,500lbs with carriage bar spacing of 16 inches. Class III carriages are rated for cargo up to 10,000 lbs. The carriage bar spacing for this particular class is twenty inches. Class IV carriages are rated for cargo up to 15,500 lbs. The carriage bar spacing for this capacity is 25 inches.
Pin mounted forks vary by the amount of offset between the tine and the blade eye. Some makers would vary the carriages for pin type blades. Carriage capacity would be determined by the carriage pin size and by the fork size.
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