Impact wrenches are divided into two broad categories based on the source of power used to produce the torque. There are electric-powered wrenches and air-powered wrenches. Air powered impact wrenches are often referred to as pneumatic impact wrenches. The electric powered wrench category is further divided into corded impact wrenches and the cordless wrenches. The three types of impact wrenches vary in strengths, structure, weakness, functions, key features and are of best fit.
Pneumatic Impact Wrench. These types of impact wrenches are powered by compressed air. They are the oldest impact wrench design and most widely recognized. The pneumatic wrench has to have a source of compressed air to power it. This type of wrench exists in five different sizes. There is the 0.25, 0.375, 0.75 and 1 inch sizes. A drive, in this case, refers to the amount of torque of 3000feet/lbs. Higher drives in impact wrenches produce higher torques. The best part about working with pneumatic wrenches is that they don’t need electricity for power rather all they need is compressed air. They are also the smallest of all impact wrenches and therefore more maneuverable.
Corded Electric Impact Wrench. As the name suggests, they are powered by a direct source of electricity. Corded Impact wrenches are becoming rare and less used in the market as manufacturers shift to the corded models. The most common drives of corded impact wrenches are the 0.5 and the 0.75 inches. They are longer and larger than pneumatic wrenches due to the extension cord. Their main advantage is that they can function for hours on end, as long as there is a constant power source. The power levels can be regulated to adjust the torque depending on the role. Their dependence on electricity sources makes them virtually unusable in an area with no electric power or erratic energy sources.
Cordless Electric Impact Wrench. This model of electric impact driver is powered by rechargeable batteries. The primary form of cells are NiCad and Li-ion The batteries have power ranging between18 and 28 volts though they can be higher or lower. They are the most common form of all impact wrenches in the market. They also exist in different models, price ranges and levels of drive. They are popular because they are portable and have internal power sources. The disadvantage is that they are less powerful than the other two types. That is because the batteries tend to run out pretty quickly especially during heavy use.
In a nutshell, none of the impact wrenches is more advantageous than the other. Each one of them has its main strength as well as its weaknesses. You have to choose the type that you need based on your needs, power sources and amount of work need to be performed.