We know that precast piles are driven with the help of pile driver/hammer to reach expected foundation depth. Different types of hammers are used in pile foundation construction. We have already learned about all types of pile hammer, briefly, in our previous post. Here we will discuss about diesel hammer.
The hammers used, now-a-days, have large engine of two-stroke facility. A cylindrical apparatus connects to top of pile. The weight that drives the pile, with ignition energy, consists of this apparatus and piston. As we go through the topics we will learn about the apparatus gradually.
At first the weight is raised with auxiliary means, which may be a crane or any other means. Usually a crane holds this pile driver. While raising the weight air entered in to cylinder by suction.
The weight is released quickly to drop over pile. This quick release results compression of air trapped during raising. This compression raises the temperature of air to reach ignition point of fuel.
Obviously the fuel is diesel. There have facility to inject diesel fuel to such heated air. The ignition of mixture (air and fuel) generates energy which is then transferred to pile head enhancing the driving energy.
The ignition energy not only transferred to pile head but it drives the weight to its previous falling height. So the auxiliary means to raise the weight back its position is not required after initial application. Dear reader we will finish this topics in the next post. There we will clarify the according to army manual.