A pile hammer is a device used to drive concrete and steel pilings into the ground to be used as support for building projects. There are several types of pile hammer, or pile driver as it is more commonly known. These hammers can be diesel- or steam-powered and some designs are hydraulically operated. Mechanical drawings and remnants of pile hammer machines have been found dating back 5,000 years.
The diesel pile hammer is nothing more than a very large two-cycle diesel engine. The piston of this machine acts as the weight which hammers the piling into the earth. The part of the pile hammer that surrounds the piling acts as the cylinder, which is held in place over the piling by a crane. The weight or piston is drawn up into the cylinder by a cable attached to the crane. The weight is dropped by releasing the cable and compressing the air within the cylinder to the point of diesel fuel combustion. Diesel fuel is injected into the pile hammer and explodes, sending the weight back up into the cylinder and driving the piling downward. The cycle repeats itself until the machine runs out of fuel or is stopped by the crew.
The hydraulic pile hammer operates by sending hydraulic fluid at high pressure into a rotary type hammer. The hammer is forced down at very high speed, striking the piling. The hammer returns to the raised position and is once again driven downward. This type of hammer is typically attached to a large crane or track excavator. This hydraulic hammer is much quieter than traditional diesel or steam hammers.
In soft or unsteady ground where the pounding of a piling may lead to collapse of the work site, the hydraulic press hammer is used. This machine typically uses large hydraulic ram, attached to a framework positioned over the piling, to press the piling down in a single steady motion. This type of hammer eliminates the vibrations found in conventional hammer designs.
The vibratory pile hammer is not only used to set pilings in a work site — it is also used to remove them. The large vibrating hammer is held over a piling and allowed to sink it into the earth by the repeated vibration and hammering. Conversely, it is placed onto a set piling to vibrate it loose from the earth while another crane pulls the piling from the ground.