Hard Rock Trenching
Hard rock trenching normally has to use labour intensive methods, such as explosives or percussion tools. Where trenching can be utilised, very large, heavy, high horsepower machines are used. The patented Mastenbroek HRT machines allow trenching in conditions where current trenching technology fails.
The main advantages of the HRT trenchers are outlined below.
Cutting tool penetration into hard rock is inherently difficult. When cutting up an inclined cutting face, as with conventional trenchers, the effort required for penetration into the rock face is enormous.
The HRT trenching process reduces the effort required by pushing only the cutting head into the trench face. The reduced numbers of contacting elements means that the average force per pick is increased and therefore deeper penetration into the rock face is achieved.
An increase in trench depth and width is also a key area when considering contact area. An increase in depth or width on a conventional trencher will significantly enlarge the contact area, but only an increase in trench width will alter the contact area on a HRT trencher.
With a reduction (with the HRT trenchers) in the contact area wear rates on not only the cutting picks but also the chain and digging boom wear plates is achieved.
The reversal of the cutting process ensures that the machine lift problem, inherent with conventionally designed trenchers is eliminated. The HRT trencher is affectively locked into position by the upward cutting motion pulling the trencher base unit on to the ground.
The upward cutting motion of a HRT trencher is at an advantage when large stones or boulders are present within the projected trench path. The HRT effectively lifts the large stones either to the surface or they are carried, on the digging chain, along the top of the boom and deposited onto the conveyor. This eliminates the possibility of the chain stalling, as can happen with conventional trenchers, when large stone becomes lodged between the digging chain and machine.
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