Four-pit electric hammer means that the number of grooves at the drill handle of electric hammer is four pits, which are divided into two keyways and two steel ball grooves, and are applied to four-pit electric hammer. This kind of drill is generally used on medium-sized electric hammers. Five pits: it means that the number of grooves at the drill handle of electric hammer is five pits, which are divided into three keyways and two steel ball grooves. It is suitable for five pits electric hammer. This kind of drill is generally used on heavy electric hammers.
Wukeng is a patent of Bosch. You have to buy a Bosch patent to produce this kind of electric hammer. Four pits are everywhere, and every family can produce. In fact, there are several differences: Sikeng is the longest used in the market now. There are some small places in the five pits where drills will not be installed.
Five pits are generally used on large electric hammers, above 38, because large electric hammers have large torsion, and relatively speaking, the stress structure of five pits is more reasonable.