Handbook of construction plant, its cost and efficiency (1914)
Dana, Richard Turner, 1876-1928 · Chicago, The M. C. Clark Publishing Co. · leaf 250
able.This leakage is provided for by compensating valves on thepulsator, adjusted to automatically maintain a constant averagepressure in the circuit. The drill is practically a cylinder con-taining a moving piston and rotation device, without valves,chest, buffers, springs, side rods and pawls.… … Fig. 86. Electric Air Drill at Boutwell Milne and VarnumQuarry, Barre, Vt. discharge valves nor water jackets. It is geared to a motorwhich may, of course, be of either direct or alternating current,and is mounted on a wheeled truck for convenience in handlingThe pulsator and drill are connected by…
Contractors' operations · Building
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