Fig. 254.
Fig. 255.
The simple and primitive way, so often used in the country by drivers of heavily loaded sleds, of dropping a chain under the runner is an effective method of braking, provided you have some sure method of dropping the chain under the runners. Fig. 254 shows a method which can be worked from either the forward or rear end of the double-runner. In the plan, or top view (Fig. 254), the details of the arrangement (being beneath the seat) would ordinarily be represented by dotted lines, but in this case, on account of the small size of the drawing, they are shown by full lines, as they would look if the seat-board were transparent. A way of holding up the middle of the chain is shown in Fig. 255. A small block a, perhaps 3" long, is screwed to the under side of the seat and the chain is held against it by the pivoted bar b (which is pivoted to the seat-board by a bolt and is kept in position by the spring), and on the under side of which a piece of metal is screwed at one end, which prevents the chain from dropping. The end of the bar b is connected by a wire with the lever in front. When the lever is pushed by the steersman's foot the bar b is pulled away from the block a and the chain falls by its own weight under the runners of the rear sled, which quickly brings the double-runner to a standstill. Fig. 256 shows the bar held in position by the spring. Fig. 257 shows the position of the bar after the lever has been pressed, with the open space which allows the chain to drop. The same apparatus can be worked from the rear end of the double-runner by simply having the wire to be pulled led back (Fig. 258), where it can be worked directly by the hand or you can contrive a lever to be raised.
Fig. 256.
Fig. 257.
