You have heard sales people tell you: hydraulic vibratory hammers are cheaper than electric vibratory hammers. Yet, when you compare quotations you see a much higher upfront investment for the hydraulic hammer and what appears to be an attractive offer for an electric hammer. The cheap they are talking about is the cost savings you will realize in the short, medium and long term.
 
Let’s discuss a short term saving that has to do with the relatively low weight of a hydraulic vibro compared to an electric vibro hammer.
 
An electric hammer is weighed down by the electric motor that sits on top of the hammer. The motor rotates the eccentric weights, and a larger hammer requires a heavier motor, which in turn dampens the vibration of the hammer so that ever bigger motors need to be installed to ensure there is still amplitude left to vibrate the pile. The eccentric weights in a hydraulic hammer however, are rotated by hydraulic oil flow generated by a diesel engine (in the power pack) that sits on the ground next to the crane and not on top of your pile. The hydraulic flow allows rotation at much higher RPM which means a more powerful piling tool, running at a higher vibration speed so that you vibrate the pile and not the surrounding buildings, and all this at half the weight of an electric hammer.
 
So why is light-weight feature a short term cost saving benefit? Obviously, with a lighter hammer you can chose a smaller crane, which reduces your crane expense, and reduces your diesel consumption. But more importantly, a lighter hammer extends the reach of your crane. An extended reach means you do not lose driving time while moving the crane along your piling job. In low margin sheet piling jobs time is money, and time gained is money earned.
 
So how much difference does the lighter hammer make to your crane’s reach? Let’s take the Sany SCC500 crawler crane with 25m boom as an example. It is built to lift 50 tons at close range. Sany provides a diagram that explains the reach of the crane at different loads. It shows that the SCC500 crane can lift the 815C (7450 kg) fourteen meter distance without repositioning of the crane (https://wenku.baidu.com/view/343f51280066f5335a8121eb.html). 

A comparable electric hammer is double the weight of an 815C and gives the crane a reach of only 8 meters. In order to allow the same kind of reach the contractor should use a 100t crane for an electric hammer.