In: Civil Engineering
Piles are driven with hammers that are mounted on cranes. There are several commonly used hammer types to install piles. List at least two hammer types with brief explanation about its function and usage (DO NOT copy and paste contents from lecture slides. Use your own words.)
please type answer don't scan
1) single acting hammer
2) double acting hammer
SINGLE ACTING HAMMER
The single acting hammer is raised by steam or compressed air and is dropped on the pile head.
It is very heavy .
They operate at a moderate speed of about 60 to 75 blows per minute.
These hammers have improper valve timing .
It has high mechanical friction.
The blows delivered are rapid compared to a drop hammer .
These hammers provide consistent energies when the stroke is controlled.
DOUBLE ACTING HAMMER
Steam or air pressure is used to lift the ram and accelerate it down.
The blows are rapid ( 90 to 240 blows per min )
The energy delivered in each blow varies greatly with steam or air pressure.
If the number of blows per minute is equal to the rated value , then the pressure is correct.
It has high efficiency due to steam operation.
The pile is in constant motion as the blows are in quick succession , so it reduces the damage to pile head.