rotary hammer drills with torque limiting at the same time

[woolyhead]

would rotary drills with torque limiting and hammering at the same time be of any use to people? Ordinary rotary hammer drills forego torque limiting when on hammer and forego hammer while on torque limiting. Would we like to have both functions at the same time? What for?

 

[HERTS P&D]

No.

Andy

 

[woolyhead]

Are you telling me no from experience of using a hammer drill, Andy? only according to John Cowan they can break your wrist without torque limiting.

 

[joinerjohn]

Most SDS+ drills have a clutch which prevents the drill from twisting your arm off or breaking your wrist.

 

[foxhole]

The SDS have clutch slip which prevents them jamming.

 

[woolyhead]

Most SDS+ drills have a clutch which prevents the drill from twisting your arm off or breaking your wrist.

Tracing backwards from the chuck, where is the clutch in the power train? The hammer mechanism is inside the big gear wheel, so the clutch must be somewhere so that it doesn't have to allow hammering motion to pass, since a clutch cannot do that, sp far as I know. Am I wrong? The power train breaks at a clutch so that the input and output shafts can rotate at different speeds. Such a break will obviously not transmit an axial hammering motion. Can you tell me what happens exactly, please?

OK people. I discovered the answer for myself. The clutch is not like a car clutch because it works on the full rotation /slip only with nothing inbetween. It doesn't need to give smooth transmission. When the control ring on the drill is turned to maximum torque the clutch doubles as the hammer ring. It's constructed from an indented plate or plates and ball bearings that run in or are trapped by, the indented plate. A helical spring pushes the balls into one of the plates under the control of the torque setting ring. For torque limiting action one of the plates is driven by gears and it takes the other plate round through the balls being unable to compress the spring far enough at that setting /torque for it to climb out of the indents.. For hammering the plates and gears are reconfigured so that only one of the plates is driven and the other one held stationary. As the indents/balls pass each other the moving plate goes back and forth along the chuck's axis and thus creates the hammering action.
That was simple enough, wasn't it? I don't know why I couldn't have figured it out for myself!