The best speed to engage the PTO clutch is always the lowest possible speed that provides a smooth engagement for the machine. There is some misinformation published by some manufacturers that the clutch should be engaged at the fastest possible speed. This is not correct if you want to extend the life of the clutch and the drivebelt. Let's look at the following example:

The following table shows what the clutch would see from a typical three blade mower deck when it is run at full engine speed (3600 rpm) or a lower speed (2200 rpm) assuming an engagement time of around 0.2 seconds, the higher speed operation requires almost 2/3 more energy per engagement and 1/3 more torque. So, by lowering the engagement speed, it increases the overall life cycles of the clutch and reduces the forces on the belt by almost 1/3, increasing overall belt life.

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