Hydraulic hammers: what are they?

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Hydraulic hammers are the modern descendants of pile drivers. Pile drivers are mechanical devices used to stake piles into the ground to lay the foundations for buildings. The advent of diesel, hydraulics and pneumatics helped provide the force needed to drive piles into the ground and carry out larger construction projects.
Hydraulic devices such as the hydraulic hammer are based on fluid mechanics theories and the work of Blaise Pascal and Daniel Bernoulli. A hydraulic system consists of liquid, pump, pipes, motor and output device. Hydraulics provide the driving force to activate machinery by converting the pressure exerted on a confined liquid medium into mechanical output. The pressure exerted on the enclosed incompressible liquid is transferred uniformly in all directions and areas of the hydraulic system and is transmitted unchanged to the output device, which in this case is the hammer.

According to Pascal’s law (P = F/A), applying a small force (F) to a small piston in a small area (A) creates a mechanical advantage as the resulting constant pressure (P) is redirected through the pipes towards a larger area, producing a greater force capable of moving a larger piston. This concept is illustrated in the following example:
Pascal’s Law: P = F/A
If F1 = 2 pounds (1 kg), A1 = 1 inch2 (6 cm2)
P = F1/A1 = 2 pounds/inch2 (0.1 kg/cm2)
Se F2 = x, A2 = 1000 in2 (6452 cm2)
F1/A1 = P = F2/A2
F1/A1 = F2/A2
2 libbre/pollice2 = x/1000pollice2
x = (2 libbre/pollice2) (1000 pollici2) = 2000 libbre (907 kg) = F2
Essentially, this boils down to a significant increase in power: what starts out as 2 lbs (1 kg) of force ends up being 2000 lbs (907 kg) when the area is increased.

Hydraulic hammers have versatile applications in the construction, demolition, metal forging, quarrying and piling industries. As a pile driving device, hydraulic hammers drive piles into the ground by traveling in forward and reverse direction cycles. The hammer stroke stops as the digging tool is raised and dropped in free fall. Once it hits the surface, the hydraulic hammer resumes its stroke to break up the surface. The force of the impact is governed by factors such as piston weight, piston stroke, operating pressure, flow rate, hammer weight and size, energy output, and guide tube and guide claw dimensions.

Hydraulic hammers can be mounted on the end of a swing arm and used to break up rocks and concrete. They can be powered by a dedicated diesel engine or by the extractor’s diesel engine when fitted as a boom attachment. There are various interchangeable hammer tips, such as asphalt cutter, moil tip, sheet guide, chisel tip, pusher, pile driver or chamfer that can be equipped to customize the device function.

Hydraulic hammers are more environmentally friendly than other hammers because they generate less noise and pollutants. They are preferred in areas sensitive to vibration and noise as the use of vibrating hammers could otherwise disturb the stability of existing structures or audibly disrupt communities.

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