Barmac aggregate impact crusher; Machine #1, Wellington

Engineering Plant (eg railway, locomotive, car, plane)


The Barmac Crusher was invented by Jim Macdonald when he was deputy city engineer, Wellington. After a period of development and patenting, in partnership with Bryan Bartley then of Winstones, Auckland, production of Barmac crushers has been licensed worldwide. The name for the machine is a combination the first three letters of Bartley and MacDonald.

The Barmac rock-on-rock crushing principle uses a central "spinner" on a vertical shaft to project incoming aggregate outward onto a "scree" of the same aggregate, so that nearly all crushing energy is used in stone-to-stone impact crushing and attrition. They tend to produce a cubical product & quality sand. By heavily decreasing mechanical wear of conventional impact crushers, while avoiding the very large quasi static crushing forces of conventional jaw crushers, the Barmac has radically changed material reduction options, offering a crusher type that produces excellent reduction at a low operating cost. 

In 2003 the tally of units was over 3500, operating in aggregate and mineral processing installations around the world. It was estimated at this time that about a further 1200 had been produced as copies. The largest unit operated 22 hours per day to crush over a million tons per year and was driven by electric motors totalling 800kW (about 1100HP).

Machine #1, which first operated in 1970, is preserved on site at Wellington City Council's Kiwi Point Quarry in Ngauranga Gorge, SH1, Wellington.

In the 1970s the original design was refined in an attempt to reduce wear and enhance the quality of the product further.



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Wellington City 'Kiwi Point' quarry, in Ngauranga Gorge.

Wellington / Kapiti

Access Info
Call first at quarry office. Crusher is adjacent. Foot, cycle and vehicular access from northbound carriageway of State Highway 1 (Centennial Highway) partway up the ascent from Ngauranga towards Johnsonville.

Nature of Engineering
New Zealand Innovations, Manufacturing and Industrial Processing


(Click image to enlarge )

(Click image to enlarge )

Lat: -41.237694 Long: 174.805