Multi rotary hammer is combi hammer. Chinese combihammer is very easy to drill.The world famous Bosch and Hilti hammer has recommended diameter range strictly when drill. But chinese electric rotary hammer is not rigorous. When you use Max drilling capacity of 26mm hammer. You also could drill 28mm holes.
The hammer impact device pass eccentric shaft and connecting rod to drive piston do reciprocating work in the cylinder. So there is impact frequency to knock.. The turning device and impact device work together under motor working. And achieve composite motion of turning and impact.
The rotary hammer also has safety clutch.When the hammer machine is extra working loading or drill locked, the safety clutch could track slip and protect the motor don`t be broken.