1995
V O L U M E 2 4 , NO. 12, D E C E M B E R 1 9 5 2
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disks, the perforated ones on top, are held to the shaft between nuts. The base plate, C, 8 inches square, with rounded corners, and the bearing support, D, are cut from 3/*-inch steel. I n the lathe, the cups to accept ball bearing sets for 3/*-inch shaft are cut and 13/32-inch holes are drilled completely through the plates. The bearing support, D, is held rigidly above the base plate by pillars cut from */p-inch shaft. Tapped holes in each end allow the pillars to be bolted directly between the two plates. The shaft is inserted through the bearings and secured by a collar and setscrew below the bearing support. The driving force is obtained from an alarm clock spring, E, attached, as explained above, to the shaft and secured to a steel pedestal bolted to the bearing support. The stainless steel escapement wheel, F , is turned to 3.875-inch diameter and 0.25inch thickness. Fifty teeth of the shape shown in the figure are milled in its edge. I t is attached to the shaft by a taper pin through its hub. A ratchet, G, pivoted on a pedestal bolted to the base plate, allons one notch of the escapement wheel to pass each time the solenoid functions. The inertia of the moving assembly driven by the spring returns the solenoid, H , to its out position while the ratchet halts the motion as a fresh test tube is centered under the delivery funnel (not shown in Figure 1). Sufficient vertical length is allowed in the ratchet pivot and the link to the solenoid to permit the ratchet to be lifted above the escapement wheel for rewinding, which is accomplished by merely rotating the test tube platform in the clockwise direction with the ratchet in the elevated position. .k spring normally holds the ratchet in its lower position. The apparatus has been in use in this laboratory for several months and. Tithin the limits imposed by its small number of tubes, has proved very satisfactory. With proper allowances the same driving and control arrangements could be used with a murh larger apparatus.
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Figure 3.
Front and Horizontal Sectional Views of Fraction Collector A. B. C. D. E. F. G. H.
.Main shaft Test t u b e supporting disks Baseplate Bearing support Driving spring Escapement wheel Rntchet Solenoid
fi,orn one end. Tlic 0.5-inch diameter section is threaded for a length of 1.25 inches a t the end and for 2.25 inches above the shaulder. Beginnirig at R point 3.125 inches from the smaller end, two grooves 1/8-inch apart, */8-inchwide, and 1/,6-inch deep are cut. The remaining ridge brtxeen the grooves is filed away so as to leave only inch. This projection is so undercut, with a small file, as to grip securely the clock spring mentioned below. Three eirrular disks, R, of 9.375 inches radius are cut from standard 19.25 X 19.12
