To readily stop the motion of the paper drum of an indicator, to change the cards or for other purposes, without disconnecting the operating cord the improvement shown in the accompanying illustration has been patented by Henry J. Parchman, of Cedar Falls, Wis. A frame is secured to the engine or other support, near the cord connecting the pantograph with the indicator, and on the frame are studs carrying pulleys around which the cord passes, one of the studs being mounted on a slide moving in a slot in the frame, the slide being locked in adjusted position by stops, one of which has a handle to facilitate moving the stop in the slot. The cord, after leaving the pantograph, not shown, passes under a pulley and around the pulleys on the frame, and thence over another pulley to the indicator, so that the several pulleys are rotated on the forward and backward movement of the cord. On one of the studs on the frame are fulcrumed levers pivotally connected with other levers fulcrumed on the other stud, a spring connecting the central pivots of the levers, and having a tendency to draw them together against the pull of the operating cord. While the cord is to positively connect the pantograph with the indicator, the slide is locked in place on the frame, but when the card is to be changed or the indicator stopped, a stop is loosened, permitting the slide carrying a stud and one of the pulleys to slide in the slot in the frame, the pull of the operating cord then drawing the levers toward each other in the opposite direction, against the tension of the spring. A yielding connection is thus introduced to compensate for the movement of the cord without affecting the indicator, the device working with indicators of any make, at. any speed and in any postion.
This article was originally published with the title "A Steam Engine Indicator Stop Motion" in Scientific American 73, 22, 341 (November 1895)