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