Excavator with laser position indicator

Claim 1

In a back hoe excavator of a type having an articulated digging device with a digging bucket mounted at an outer end, in which the digging bucket is capable of being set to a given cutting angle, and in which the digging bucket is moved toward a human operator of the excavator in a digging direction during a digging operation while the digging bucket is maintained at the given cutting angle, a position indicator apparatus for checking position of the digging device of the excavator relative to a digging floor which has already been formed, the position indicator apparatus being arranged in a field of view of the human operator of the excavator to provide a visual indication of the position of the digging device to the operator, the position indicator apparatus comprising: laser transmitter means for providing a laser beam in a direction parallel to the digging direction, the laser transmitter means being positioned on an opposite side of the digging bucket from the operator, so that the digging bucket moves in the digging direction toward the operator and away from the laser transmitter means during a digging operation; mounting means for mounting the laser transmitter means with respect to the digging floor which has already been formed so that the laser beam is representative of vertical and horizontal aspects of a digging floor to be dug by the excavator; and target means mounted to and carried by the digging device, the target means being at least partially transparent, and having a first surface facing the operator and a second, opposite surface for receiving the laser beam from the laser transmitter, and wherein the target means reproduces a visual image of an end point of the laser beam for parallax-free observation by the operator during an entire digging operation in which the digging bucket is set to a given cutting angle and moved in the digging direction toward the operator.