. Modern mechanism, exhibiting the latest progress in machines, motors, and the transmission of power, being a supplementary volume to Appletons' cyclopaedia of applied mechanics . Fig. 6.—Bradley expansion arch cultivator. 1G4 7.— cultivator. by which it passes obstructions without the risk of breakage. The pivots a c and d arenormally nearly in line, allowing the strong spiral springs to ofiEer a very stout resistance to the flexion of the pivot c ; butwhen the limit of that resist-ance is once exceeded by collis-ion of the shovel-point withan earth-fast obst
. Modern mechanism, exhibiting the latest progress in machines, motors, and the transmission of power, being a supplementary volume to Appletons' cyclopaedia of applied mechanics . Fig. 6.—Bradley expansion arch cultivator. 1G4 7.— cultivator. by which it passes obstructions without the risk of breakage. The pivots a c and d arenormally nearly in line, allowing the strong spiral springs to ofiEer a very stout resistance to the flexion of the pivot c ; butwhen the limit of that resist-ance is once exceeded by collis-ion of the shovel-point withan earth-fast obstruction, aslight flexion of the pivot /causes collision of the nuptione with the rear shoulder of /by reason of shortening the dis-tance slightly between the cen-ter of the i)ivot d and theshoulder, throwing the pivot cback out of line with a and d,raising the jioint of attachmentof the extremity of the sjjringat b enough to nearly neutralizetiic powiT of the spring, andthus permitting the point ofthe shovel to yield backwardand (haw over any low obsta-cle, after which the tendencyof the spring to uncoil returnsthe shovel to working positionand relocks it. The nuption e,termed a break-pin. is adjusta-ble, to Ihange the amount ofres
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Keywords: ., bookcentury1800, bookdecade189, booksubjectmechanicalengineering
