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I was told by some people from the store that there exists 2 types of percussion types regarding the rotary hammer drill: the pneumatic percussion and the mechanical percussion. I need a confirmation if this is true or not ? The second question is: What is the difference between a rotary hammer that has a pneumatic percussion system and a rotary hammer that uses a mechanical percussion system ? The 3rd question is: how can I identify (if the manual does not specify) which is pneumatic and which is mechanical ?

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  • If they both drill the hole and are the same mass & cost, what does it matter?
    – Solar Mike
    Mar 16, 2020 at 18:54
  • The life of the nerves in one's hands...
    – mongo
    Nov 30, 2020 at 14:58
  • There is a patent on (EP) electro pneumatic hammer devices, which is what all the rotary hammer drills and demo hammers I am familiar with employ...or at least something very similar. The feature is high impact with high frequency impact isolation for the operator's hands. Other vibration isolation mechanisms are normally also used to further isolate operator's hands.
    – mongo
    Nov 30, 2020 at 15:03

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I think the first step is to clear up the terms you are using. There are "rotary hammers" and there are "hammer drills". You are combining the two, causing some confusion.

In general, if a product is called a hammer drill, it will have (to simplify) a pair of ridged disks inside it that rub together and cause the bit to move in and out a little when the drill rotates. This hammer drill will have a high "beats per minute" and has a characteristic sound almost like slowly rubbing a coarse file with a nail.

A rotary hammer is normally larger and the in and out motion of the bit is performed by a pneumatic piston. They are more powerful and also absorb shock more for the user so can be used for longer periods. They also will typically have the ability to use the hammer without the bit rotating (which is not possible on a hammer drill).

So to answer your last question, if it is called a hammer drill, it uses mechanical percussion, and if it's called a rotary hammer it uses a piston. I guess a manufacturer could use the wrong term and at that point you would need to look at the manual or a parts diagram. This article from Popular Mechanics actually mentions a drill that is marketed as a hammer drill but is designed like a rotary hammer (the Rockwell).

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    Good explanation and I'll add that there is no comparison between the performance of these two. A pneumatic rotary hammer is a far superior tool and, if you have much drilling to do, is worth the extra cost. It will save you hours of drilling time.
    – jwh20
    Mar 16, 2020 at 22:35
  • It is noteworthy that the hammer drill and rotary hammer terminology have gone through changes over several decades. Similar to sabre saws, reciprocating saws, and jig saws. So old literature may refer to a hammer drill, which is really a rotary hammer by today's usage, and of course a rotary hammer which is really a hammer drill by today's usage.
    – mongo
    Nov 30, 2020 at 15:05

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