Improved Means for Automatically Controlling the Reversal of Electrically Driven Machine Tools.

摘要

21,803. Beardmore & Co., W., and Sykes, J. A. Sept.24. Switches, actuating.-The switches for reversing and controlling a motor which drives machine tools are actuated by a tumbler weight, the falling of which is controlled by a dash - pot. 'r h e lever A is engaged by tappets on the moving table &c. during its forward and return strokes, and carries a toothed arc B gearing with an arc of smaller radius on a lever C mounted loosely on a shaft D. A pin E4 on the lever C works in a slot in a tumbler lever G, which is fast to the shaft D and has a slotted head H with a rolling tumbler weight J. The tumbler lever is connected to the piston of a dash-pot M, the admission of air to which is controlled by a valva P, preferably regulatable. As the lower end of the tappet lever A, Fig. 3, is moved, for example, to the left at the end of the cutting-stroke, the tumbler weight J is raised, and the switchoperating shaft D is turned. When the tumbler weight J has passed its dead-point, it commences to fall on the opposite side and continues the operation of the parts under the control of the dash-pot. Switches, quick-action.-Two auxiliary switches A2, B2 in the control circuits are operated by a projection O1 on another switch arm N1. These switches each comprise two spring - controlled quadrants S', T', the lower ones carrying the switch arms A2, B2 and projecting tappets W1, while the upper ones T' carry two pins X' which engage between the tappets with considerable lost motion. The arm N', O1 engages the pins X' to operate the switches in one or other direction, the springs and lost-motion ensuring a quick-action.