When contractors need to break rock, they’ll often turn to a traditional hydraulic hammer. But when the rock in question is glacial granite boulders, something more powerful is required.
Ambrose Brothers Inc. had such a need at its gravel pit in Sandwich, N.H., and found a solution in the Surestrike rock breaker.
Located near the White Mountain National Park, not far from Lake Winnipesaukee, the site — a natural gravel deposit of mostly granite — is approximately 200-acres and is part of a 600-acre site owned by Ambrose Brothers.
Much of the site has large and mid-sized naturally formed granite boulders, which date back in formation to the ice age and were created by glaciers. These boulders are extremely difficult to break, not only because they are made of granite, but because they were formed naturally and are round, with no seams. It is the seams, cracks or fractures that make the breaking of a rock relatively easy with the use of a hydraulic hammer, according to Ambrose Brothers.
“Over the years we have tried to break these boulders with hydraulic hammers. If we were able to break them at all the amount of time it took and the amount of wear that it put on the hammer and the excavator was not worth the effort to continue trying. We could put a 5,000-foot-pound hydraulic breaker on these boulders for hours and make little or no progress. Whitney and Son introduced us to the Surestrike model 4000 52,000-foot-pound rock breaker. This breaker is very strong. It hits with a lot of impact and can strike the rock up to 20 times per minute,” said Bob Ambrose, owner.
“The Surestrike has been breaking these granite boulders nearly effortlessly. With this ready supply of boulders scattered across our pit that we were previously unable to harvest, our production numbers increased significantly. The only way we could have harvested these rocks previously was by blasting them, which was not very practical.”
“Much of the sand we had been producing in the pit was sandy gravel. Breaking this hard granite we are able to mix the hard granite with the sandy gravel, which helps us make a product with the required specifications,” Ambrose continued.
“We purchased the Surestrike in May 2009, so it has been operating for well over a year. Thus far we have only needed to replace the large nylon strap inside the unit every couple of hundred hours,” he added.
The Surestrike operator, Joe Ballou, an employee of Ambrose Brothers, also is impressed with the Surestrike.
“I have never seen anything like it. We have tried all sorts of approaches to breaking these granite boulders. The Surestrike is the only thing we have seen that gets the job done,” he said.
Surestrike Model 4000
The Surestrike model 4000 is rated for crushing extremely hard materials. It is effective for handling glacial rock, granite, trap rock, basalt, slag and heavy-duty concrete demolition, according to the manufacturer.
The breaker has an operating weight of 15,900 lbs. (7,212 kg), an overall height of 23 ft. (7 m), an overall width of 30 in. (76 cm) and an overall depth of 52 in. (132 cm).
It has a single blow impact energy of 52,000 lbs. and a cycle time of three seconds. The striker pin diameter is 8 in. (20 cm) and the striker pin length is 33 in. (83.8 cm).
Back to Nature
A natural reclamation process is taking place inside the areas of the Ambrose pit where gravel is no longer being harvested. Due to a very high water table, there is a natural underground aquifer just below the surface in the gravel pit. The holes that have been left from excavating are quickly filled with a tremendous quantity and quality of water. As area birds have visited these ponds their droppings, which contain cranberry seeds from other regions of the state, have started a natural organic cranberry bog.
About Ambrose Brothers
David and Edward Ambrose founded Ambrose Brothers Inc. as D.E. Ambrose and Son after World War II. They had developed their construction trades doing construction work such as building runways in the Army during World War II. Their sons, Paul (Bud) and David, ran the second generation of the company; and today their children, Bob and Ed, along with Bob and Ed’s children, Rob and Paul, run the company.
The company does site work, both commercial and residential, and it operates a quarry and a gravel pit. The aggregate products are sold to both private and municipal customers around the Lakes Region of New Hampshire (Lake Winnipesaukee and the lake areas north of Lake Winnipesaukee).
The company has 35 employees and a fleet of equipment that includes 10 trucks, seven excavators, three dozers and five wheel loaders. The earthmoving fleet is made up of Caterpillar and Komatsu machines. For crushing purposes it owns a Nordberg crusher that it purchased from Whitney and Son in the mid 1980s from sales representative Doug Baker.
For more information, visit www.surestrike.biz or www.whitneyandson.com.
(This story also can be found on Construction Equipment Guide’s Web site at www.constructionequipmentguide.com.) CEG
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