Three-point linkage categories are standardized based on tractor power and hitch pin sizes, ranging from Category 0 to 4. These categories help ensure compatibility between tractors and implements. The pin diameter of the top link is a key differentiator between categories. Here's a more detailed breakdown:

 

Category	Typical usage
0	Typically found on very small, compact tractors and lawn tractors.
1	Suitable for smaller tractors (20-45 hp) and implements.
2	Used for tractors with a higher horsepower range (40-100 hp).
3	Designed for larger tractors (80-225 hp) and heavier implements.
4	For the most powerful tractors (180 hp and up) and the heaviest implements.

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