The feature of this arrangement used for molding the jaw clutch, Fig. 359, is that the pattern is used as a stripping plate for the hub and the clutch jaws. It was specified that there was to be no draft on these parts, and that the corners between the disk g and the jaws f must be very sharp and clean. Construction. In Fig. 360 the right-hand section is taken midway between two jaws, and the left-hand section through the center of one of the jaws.
The stripping plate is constructed to the same dimensions as used for the other castings. As described, it is fitted for one casting mounted on a square frame machine, but a round machine will do as well, or two patterns can be fitted by extending the plates a and b. The pattern hole in the stripping plate is cored and ma-chined to dimension, and the underside must be finished parallel to the top side for a space of about 1/2 inch outside the hole.
A shoulder is made on the outside of the disk pattern g to act as a stop to prevent the pattern from being raised above the height desired. The dimension i should be such that pattern g will be held rigidly between the stripping plate and the draw plate when the latter is in a raised position.
Fig. 361 illustrates the master pattern for disk pattern g. The holes through which the jaw patterns f pass are designed to be made by the metal-pattern maker, the stock not being over 1/4 inch thick. Allow a finish of 1/16 inch to 1/8 inch on all outside surfaces, but the inside is not to be machined.
The pattern for the hub e can be made of a casting or of machine steel, and is bolted to the draw plate, as shown in section in Fig. 360.
Fig. 359. Casting Molded on Double-Draw Stripping-Plate Machine.
Six castings will be required of the jaw pattern f. A sketch of the master pattern is shown in Fig. 362. A file finish is to be allowed to the upper end and a planing or milling finish of 1/16 inch allowed to the underside of the foot. These parts are to be bolted to the draw plate.
There are to be three bosses on the underside of the disk, illustrated at j in Fig. 361, and into tapped holes in these bosses 1/2-inch soft steel rods are fitted, as shown at k in Fig. 360. These bosses are located so as to come between every other jaw pattern, and holes are to be drilled in the draw plate through which the steel draw rods k will pass.
Open springs are placed on the draw rods between the pattern g and the draw plate, and they should be capable of holding the pattern g in place until the hub e with the jaws f have been stripped, when the underside of the draw plate, upon striking the nuts on the draw rods, draws the pattern g through the stripping plate. In raising the pattern the operation is reversed, the draw plate forcing the pattern g into the correct position at the end of its upward motion.
The gate pattern will be similar to that used for the flange coupling, as is seen in Fig. 298.