Piles are driven into the ground by means of hammer. Piling Hammer are classified into following types as shown in Fig.1
- Drop hammer
- Single acting hammer
- Double acting hammer
- Diesel hammer
- Vibratory hammer
Drop hammer – A drop hammer is lifted up by rope and dropped freely on the pile head. During the driving operation, a cap is fixed to the top of the pile and a cushion is provided in between the pile and the cap.
Single acting hammer – In a single acting hammer, a hammer is lifted up by compressed air and dropped freely. This is suitable for stiff to hard clay.
Double acting hammer – In a double-acting hammer, air pressure is used to raise the hammer. When the hammer has been raised to the required height, air pressure is applied to the other side of the piston and the hammer is pushed downward under pressure. This is suitable for granular soil.
Diesel hammer – A diesel hammer consists of a ram and a fuel injection system. In this method, the ram is first raised manually and the fuel is injected near the anvil. This is suitable for all soils except for soft clays.
Vibratory hammer – In this method, pile is driven by applying vibration. A vibratory pile driver is suitable only for sandy and gravelly soils.