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Full text of "Modern Mechanical Engineering Vol-I"

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ESSENTIAL  MACHINES AND  APPLIANCES

167

of guides that rigidly control the downward movement of the pattern away
from its mould, or the upward lift of the box off its pattern.   A little rapping

Fig. 73.—Bottom Box rammed over Pattern, then tabled, turned over, and mould delivered

E

Fig. 74.—Top Box rammed over Pattern, embedded in Plaster of Paris, then turned over and delivered

)E

Fig. 75-—Mould Closed and Completed
Figs. 73-75.—Cone Pulley moulded on a Darting & Sellers' Machine
A, Pattern.     B, Its mounting,    c, Table of machine,    D, Bottom box.    E, Top box.
is done, which does not sensibly enlarge the mould, like lateral hand rap-
ping, but loosens the contact of the sand slightly. Either a hand mallet is
used, striking blows on the table, or a pneumatic piston produces vibration.