If the hammer is cocked in the field and the rifle not fired, it can be lowered by holding back on its spur with a thumb while pulling the trigger, then just as you feel the hammer break
free from the sear, remove your finger from the trigger while continuing to ease the hammer forward.
A built-on BTI hydraulic hammer breaks
up oversize incoming materials.
Or, Hesseltine says, some models will reduce the force if there's no resistance, like when a breaker or hammer breaks
through the wall it's demolishing.
In an eight-hour shift, the hammer breaks
out 240-300 t of rock, which has a compressive strength of 80-120 Mpa.