Originally Posted by blueshifty
Hmm... so in order to not further derail the thread I'll leave it at saying that that the impact energy is also not the most important aspect in "perceived impact" because impact area is also not covered by joules. Also curious... (serious question btw) but do any pneumatic jackhammers get rated in joules or only the electric ones?
Jackhammers are most normally identified by weight, i.e. 60 lb, 90 lb, etc. Which is a statement of the weight of the tool. The problem with that type of identification is that it gives no indication as to how hard the tool hits; it leaves out the statement of its capable "force". And as you reference, there are various types of jackhammers: Electric, Pneumatic, but you left out Hydraulic. There are hydraulic hand-held, and hydraulic mounted (on skid steers, backhoes, or excavators).
Since they are completely drive systems, with hydraulics being non-compressible, pneumatics only working because of compressibility, and electrics working based on magnetic fields, and they have dramatically different levels of efficiency.
In the 60 lb class, a standard issue Bosch Brute (64 working lbs) electric will deliver roughly 28-32 joules of energy per blow; a Sullair 60 lb (65 working lbs) pneumatic will deliver 65-75 joules of energy per blow; and a Hycon 60 (61 working lbs) hydraulic will deliver 85-90 joules of energy per blow.
Of course there is tremendous variation based on the age and condition of the tool, as well as environmental characteristics, such as humidity and temperature. Also, the material being affected, probably concrete or rock, will affect the effectiveness of the tool, because, the quicker the engagement, the faster the energy transfer.
The rating for jackhammers being joules, assumes 3000-3500psi cured concrete, and a moil point, and takes the average over some amount of time. I admit, I do not know the amount of time. However, it does factor in both area and time, so I think it was a proper use of the word.
Nothing against newtons. Them's is pretty badass. I like the Fig ones's.