Abstract: An improved guidance device for use with an earthworking machine, more especially a drain tile laying machine, comprising a earthworking element mounted about a pivot connection. This guidance device comprises a signal emitter and two signal receivers mounted on the earthworking element of the machine. The two signal receivers are mounted on the element in a longitudinal spaced apart relation, so as to distinguish between a depth change or an attitude change in the element. The guidance device also comprises operating means including an electronic control circuit and an hydraulic operating circuit for adjusting the attitude or depth of the element depending on the indication given by the signal receivers.

Abstract: An improved plow for use in laying drain-tile. The plow has a narrow body with an elongated upright portion and a triangular portion at the bottom, front end of the upright portion. Means on the body guide a drain-tile from an inlet high in the upright portion to an outlet at the bottom, rear of the upright portion. The plow has a plow blade detachably and adjustably fixed to the leading edge of the triangular portion. A near shoe and a plow knife may also be detachably fixed to the plow. The plow knife includes means for moving earth in a manner that it fills in the drain-tile trench. Linkage means are provided for connecting the plow to a tractor in a manner that it can be easily maneouvered. The linkage means includes an adjustable link that can change the attitude of the plow. The plow may also comprise means for laying a cover strip on top of the drain-tile as it is being laid.