The transmission is made up of a planetary gear set.
The hammer mechanism is located behind a spring in the gear-case assembly.
Hammer drill-drivers are major tool manufacturers’ most-prized and most-sought-after drills. They have a powerful 18v Li-ion battery, a beefy 1/2-in. chuck, variable speed and torque settings to match a broad range of tasks, and a hammer function that helps to punch through extrahard materials. Simply put, they are a must-have tool for anyone who works on a house.
In the tool test article, "18v Li-Ion Hammer Drills
", senior editor Justin Fink and contributors Andy Beasley and Kit Camp sort through seven hammer drill-driver models to find the top performer. Each manufacturer has a slightly different take, but their approach to the tool is essentially the same. If you’re looking to buy a hammer drill-driver or if you’re looking to get optimum performance from your current drill, you should understand the features and components that make it useful. Here’s how it works.