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Time To Disassemble: 3 Hours, 40 Minutes, 29 Seconds

Notes: The first U.S. patent for a "percussion rock drill" was awarded to Joseph J. Couch in 1849. His drill, invented for mining, was powered by a steam engine and repeatedly threw a bit, javelin-style, at rocks. In 1895, a patent for a tool most of us would recognize as a jackhammer was awarded to Charles Brady King (incidentally, also the first guy to build a car in Detroit). Like many pavement breakers in use today, it was pneumatic, tethered to a hose that delivered compressed air. In comparison, other modern pavement breakers, like the DeWalt D25980 pictured here, are downright refined: electric, relatively lightweight, and compressor-free. So the next time the noise of a jackhammer brutally wakes you at 6:30 on a Saturday morning, think: It could be much worse.

The jackhammerer holds the handles like the handles of a bike. The left handle (1) is hollow. The right handle (23) is filled with electronics, including the paddle (22) that turns the unit on and off. Squeezing the paddle triggers an electrical switch that starts the 15-amp brushed electric motor (2). The motor is electronically governed to get up to speed slowly, so the jackhammer doesn't bounce off the ground before it finds purchase. After a few low-energy impacts gouge the surface, intensity ramps up and the tool digs in. At full speed, the pavement breaker delivers 900 blows per minute.

A pavement breaker is a sealed column of air with a piston engine on top and a chisel on the bottom. A drivetrain of reciprocating parts contained in the front housing (20), which bolts below the motor housing (24), does the work. The piston (9), connected to the motor via the crankshaft (21), points straight down and drives a series of thumping devices that ultimately reach the bit. To reduce wear, a column of air separates the piston from the first of these pieces, a heavy weight of hardened high-carbon steel called the ram (8). The piston pushes air through the column to move the ram, which in turn hits the beat piece (19). A green rubber bumper (17) that dampens impact buffers the beat piece. A white felt seal (16) keeps in lubrication and three O-rings (6, 18) keep dust out, so it moves smoothly.

Finally, the beat piece slams into the bit (15), which is secured by the holder assembly (11). Bits come with two types of attachment mechanisms: ring or notch. To accept the former, the retainer (10) flips down to grab the bit under the lip of the ring. To accept the latter, it flips up to squeeze the notch. There are also lots of different tips. Of the three pictured here, the bull, or moil-point chisel (13), is for general demolition, while the 1-inch cold chisel (14) and the 3-inch scaling chisel (12) are for finer work, like removing only one panel from a sidewalk.

Essentially, what a pavement breaker does is repeatedly slam a chisel into the ground, which should not be pleasant for the guy holding the other end. To manage vibration, the handles are attached to the tool with a plate assembly (25) consisting of two rubber brackets for padding and a long metal bolt. The bolt passes through the body of the tool so that the handles can float independently of it. Complementing this is a counterweight system: As the beat piece drives the bit into the ground, coil springs (7) pull a die-cast steel counterweight (4) up the outside of an aluminum cylinder (5) that surrounds the drivetrain. Guides (3) stabilize the counterweight, and no one breaks any bones.

This story appears in the February 2016 issue of Popular Mechanics.