Fig. 19
Fig. 20
Fig. 21
In the method illustrated in [Fig. 20], the rear and front wheels have the same tread, but the rear axle is longer than the front and has rollers a on each side. These strike the track b, and while the front wheels follow the curved track c these rollers run on the track b and thus raise the rear end of the skip.
20. Skip Cage.—Where a self-dumping skip is to be used in a vertical or highly inclined shaft and it is desired to use safety catches, the skip a is mounted in a cage or frame b, [Fig. 21], similar to the self-dumping cage, [Fig. 11]. The skip being pivoted at c one side of the center, and resting on the frame of the cage, tends to remain upright until it reaches the dump; but for safety it is sometimes locked in place by the latch d, which hooks over the pin e. When near the top, the roller f on the end of the latch d comes in contact with a bar that depresses the roller and thus unhooks the latch. The roller g enters and travels along the guide rails h, tipping the skip. There are two rollers g, one on either side of the skip. The nose i is temporarily caught on the roller j, thus stopping the movement of the skip sidewise and away from the upright guide.