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Title: |
1902 Article-Brown & Sharpe Mfg. Co., Vertical Milling Machine |
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Source: |
Cassier's Magazine Dec 1902 pg 163 |
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Insert Date: |
6/2/2012 9:01:34 PM |
The Brown & Sharpe machine shown in Fig. 8, is especially interesting in the method employed for increasing the number and range of spindle speeds, and the feed-changing mechanisms. The spindle can be driven at twelve different speeds, six of which are obtained through the usual medium of double countershaft pulleys in connection with the three-stepped cone pulley on the back of the machine, from which the speeds are transmitted to the spindle by the main driving belt which passes from the pulley on the cone shaft over the idlers at the top of the machine and drives the large pulley on the spindle. For each of these six speeds an additional faster speed is obtained through the use of two auxiliary belts, one of which runs on the large driving pulley, passing underneath the main driving belt which rides on it to the small step of the pulley on the vertical shaft at the rear of the machine, while the other runs from the large step of the pulley at the back of the machine and drives the]"small driving pulley. When the spindle is driven at these higher speeds by the auxiliary belts, the large driving pulley is disconnected and runs free. On the other hand, when the spindle is being driven at the slower speeds, the top auxiliary belt must, of course, be taken off. The vertical shaft serves to drive the feed mechanism which is almost entirely enclosed in the column of the machine.
The feed changes are secured by a single lever movement, causing a sliding gear to be brought into mesh with
the proper unit of the nest of gears of different diameters which forms the feed varying device. Motion is carried from this sliding gear to the table through spur gears and the usual universal joint shaft. Since the belt which drives the vertical shaft is of the same size as the main driving belt, being virtually the main driving belt when the higher speeds are used, it is evident that the feed of this machine is positive to the full extent of the meaning of that term as at present applied to machine tool feeds. |
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Fig. 8, 1902 Brown & Sharpe Mfg. Co., Vertical Milling Machine
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