The Hydraulic Hammer Drill: How Does It Work?

I would suggest you go to the hammer drill manufactures site for the technical info you require.

Item specific information is more likely to be found at sites that make or sell the items.

Done, long since.

Perhaps the info is proprietary, since there appears to be more than one way to generate the pulse required.

Thanks for your help!

I thought those hammers were pneumatic, not hydraulic. As for nitrogen cells, I think they more effectively transmit a sudden pulse from the driving end to the hitting end. It's a little slower than air (I imagine). That's why motorcycle racers have used nitrogen filled shocks for years... While the up-and-down inertia of the motorcycle is allowed to change slowly, the tires (on the other side of the cylinder) track the differences in the paved surface... But this is just a guess :-)

SOME of the large hydraulic units ARE hydraulic over air-wherein a hydraulic motor drives an airmotor - both within the drill motor.

It is done so that the impacts are not transmitted back through the hydraulics

I am not able to devine from manufacturers literature if some forego the airmotor and use the hydraulic motor with a repeating strike mechanism - AND with buffering(to save the hydraulics) being provided by those nitrogen filled chambers that some of those manufacturers use.

Most large rock drills are either exclusively air driven - or exclusively hydraulic and it is the exclusively hydraulic ones that I am looking for conceptual info about.

I knew that nitrogen was popular in shocks, tires, and other things as an air substitute - but I thought that this was mainly because oxidation won't occur if your omit the oxygen AND because it expands and contracts less with temperature change - thus giving more consistant performance over a broad temperature range. Does it really behave so much differently from AIR with regard to the RIDE of a vehicle? After all, air is 78% nitrogen.

Take a look at Rock Breakers that is the right term for Jackhammers or Peckerheads type.

http://www.rockbreaker.com/literature/pdfs/TB%20Series.pdf

Regarding the post hole digger, is a bob-cat auger type? Is rock hard rock the reason you want to soup it up?

I think it seems to. Remember that the nitrogen is under high pressure. Many of the high performance shocks have fittings on them so that they can be eventually refilled with nitrogen... Perhaps I can find something on the web about this.

The nitrogen is in an accumulator, so the pump will work at a steady speed and the pressurised hydraulic oil be stored in the accumulator, at the opposite side of a membrane from the nitrogen. This gives a nearly level pressure each stroke of the hammer, at a much higher force than could be exerted by the pump itself, but for a shorter duration.

Nitrogen is used as air becomes unstable at such high pressures, and may explode.

Especially if something like hydraulic fluid comes in contact with the pressurized air? Something like using petroleum grease on oxygen bottle fittings?

To store air at high pressure requires it first to be dried, or the container will corrode from the inside.

To obtain high working pressures of 6000psi, at least three phases of compression are used, with intercooling.

Hydraulic fluid can be compressed into an accumulator in one phase, and to 10,000psi (Tobul - highest pressure accumulators I have found)