Trench-Digging by Machinery 



MODERN engineering require- 

 ments coupled with a persistent 

 demand for labor-saving devices 

 have brought into being several types 



Above, the endless chain type 

 of machine excavating a twelve- 

 foot trench with cutting buck- 

 ets. To the right, the wheel 

 type of machine with its driv- 

 ing mechanism at the top 



of trench-digging apparatus 

 which are of ingenious con- 

 struction. Of all manual la- 

 bor, digging trenches by hand 

 or exca\'ating on a large scale 

 by hand is the most laborious 

 and expensive method. One 

 of the largest single items in 

 a contractor's specification, 

 until the modern digging ma- 

 chines came along, concerned 



the amount of excavating to be done. 

 With the several new types of mechani- 

 cal excavators this item can be reduced 

 materially. 



In the machines recently marketed 

 two general principles seem to be used. 

 In one, cutting buckets are attached to an 

 endless chain, while in the other they are 

 mounted on the periphery of a wheel. 

 In both methods the buckets are forced 

 to bite into the ground at the end of a 

 trench, carrying the dirt up with them as 

 they rise. 



The endless chain type of machine 

 grips the dirt and hoists it to the surface 

 in the same way as chain buckets on an 

 elevator-hoist lift grain to upper bins. 

 The wheel type has a curious mechanical 

 feature in that the wheel itself has no 

 central hub. Instead, it consists merely 

 of a rim supported by four sets of rollers 

 mounted on an internal framework. 

 The reason for this is that it gets all the 

 driving machinery up near the top of the 

 wheel, enabling a deeper trench to be 

 dug with a smaller wheel than would 

 otherwise be possible. In fact both 

 types have their driving mechanism 

 located at the upper end of the chain, 

 and both also make use of a transverse 

 conveyor belt to carry the excavated 

 material to wagons as fast as it is 

 brought up. 



Behind the wheel on the wheel type 

 cf machine is located a bracket-like or L- 

 shaped framework, known as the "shoe." 



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