The History of NPK Hydraulic Breakers
The NPK hydraulic breaker is made in Japan. NPK stands for Nippon Pneumatic Machinery as they began business making pneumatic tools, such as impact wrenches. The first series of hydraulic hammers sold into the United States were the “H” series, likely for “hydraulic” to differentiate the new line from their pneumatic impact products. The H series is also known as the X series as the model numbers all end in X, XA or XB. This was followed by the “E” series NPK, and then the current “GH” and “PH” series of hydraulic breakers that are currently offered today. They are nearly always orange in color from the factory, with black side buffers.
The Design of NPK Hydraulic Hammers
Most NPK hydraulic breakers are a side plated type of cradle design, which sandwiches the power cell, or main body, between two large plates that are held together with large double ended cross bolts. Most all NPK models use two large square side buffers on each side of the breaker to absorb vibration and reduce power cell movement. The hammer top cap, or mounting bracket, bolts to the top of each side plate, enabling the skid steer, mini excavator, backhoe or full-sized excavator to pin on to the entire hydraulic hammer assembly. All NPK hydraulic breakers utilize the standard nitrogen fired, or nitrogen assisted design. In this design, there is a nitrogen filled chamber at the top, or back head of the hydraulic hammer, which acts as a bowstring. When the foot pedal or trigger of the carrier is energized, it sends high pressure hydraulic power through the hydraulic breaker, lifting the strike piston against the “bowstring”. When it reaches a certain point in its upward travel, a valve switches, forcing the strike piston into its downward stroke using both hydraulic power from the carrier and the nitrogen assist of the charged chamber, or back head.
What Makes NPK Hydraulic Breakers Different?
There are some peculiarities to the NPK hydraulic hammer. Unlike most nitrogen fired hydraulic hammers, they do not feature on board accumulators of any kind. NPK hydraulic breakers also use two sets of hydraulic hoses to bring oil into the cylinder. They use the traditional long inlet and outlet hoses utilized by all hydraulic breakers that bring oil to and from the skid steer, backhoe, mini excavator or full sized excavator, but with NPK, those long hoses go to hydraulic attachment points on the top bracket. A second set of “jumper hoses” carry oil to and from the inlet and outlet of the hydraulic hammer’s cylinder. A final difference with NPK’s hydraulic breaker design is that they utilize an upper and lower sleeve-known as the “A” and “B” sleeve-between the piston and the cylinder. There are a few other hydraulic breaker manufacturers that use this, but most utilize the traditional “piston in bore” design.
Discover More of NPK at Gorilla Hammers
As Gorilla has been repairing NPK hydraulic breakers for over 80 years, our Gorilla Service Team™ knows how to properly polish the A and B sleeves within their tolerances, and rebuild these very complicated breakers. We also offer demolition chisels, moil, blunt tools and even long lasting self-sharpening extreme duty carbide core tools to fit NPK as well as the parts you need to keep running.