We have already learned about working principle of diesel pile hammer in previous two part of this topic. In this part we will finish this topic. So we were on preloaded force.
We have learned that while piston falls, it blocks exhaust system to entrap air. This entrapped air is compressed by the weight of piston. The compressed air produces a preloaded force of around 44,000 lbs.
The preloaded force holds firmly the impact block against pile through driving cap. While the piston exerts force the pile becomes mobilized from it position overcoming inertia and skin friction. Now our aim is to exert extra pressure by the explosion of fuel in the diesel engine.
From the previous topics of relative efficiency we have learned that the blow interval develops inertia and friction resistance which have to overcome by next blow and after overcoming the pile get mobilized. Here we have advantage of initial mobilization of pile by preload force and when fuel energy results pressure, pile moves without overcoming this resistance. Obviously in the next blow this resistance is again developed.
When piston strikes impact block, atomizing fuel pump and exerts downward movement to pile due to impact. The compressed air at ignition temperature of fuel results explosion which exerts greater force than that of impact and generates further downward energy to already moving pile.
The pile results rebounds on the piston and it moves towards upward. While moving up back, the exhaust system which was previously blocked in compression stroke is released. Thus the gases and explosion force is released to atmosphere.
This system again draws air to its cylinder and when energy of upward movement is diminished, the piston falls again and the cycles are continued.
Dear reader the topic is finished here, we will discuss about vibratory hammer in the next post.