| 摘要 |
In a machine for digging a trench, in which the digging apparatus comprises an elongated boom having a movable chain around its periphery and which is lowered into the ground, the problem of dislodged boulders which heretofore would be excavated into the machine where they often damaged the conveyor belt system or became stuck, is prevented by an elongate bar or drum which is attached to the frame of the machine in close proximity to the operating chain and immediately before the boulder would otherwise enter the machine. The boulder is held there until it either breaks apart or its abraded by further action of the chain to a sufficiently small size that it can safely navigate through the machine and be expelled in the normal course.
|
