Abstract: A draft force sensor is provided for a coupling member coupled between a towing vehicle and a towed earth engaging implement, such as a scraper. The draft force sensor includes first and second bores extending through the coupling member. Each bore has a horizontal axis which extends perpendicular to a main fore-and-aft axis of the coupling member. The second bore is positioned above the first bore and spaced apart from the first bore. Each of the bores is surrounded by an outer cylindrical wall. Four electrical strain gauges are spaced apart and placed on the wall of each of the bores. A center line bisects an axis line which extends between the axes of the first and second bores. The axis of each bore is spaced apart from the center line by a distance which is less than a diameter of the bores. The strain gauges are connected electrically in a circuit which generates a draft force signal in response to draft forces applied to the coupling member.

Abstract: A cutter bar is provided for trimming debris away from the wheel-track interface of a tracked vehicle. A pivot attachment is provided wherein a knife having a cutting edge is removably mounted to a bracket by way of fasteners which will shear when a pre-selected force is applied to them. The bracket is mounted to the vehicle structure so that the knife is disposed in close proximity to the drive wheel and endless track of the vehicle. Accordingly, when a piece of tough debris is encountered by the knife edge some of the fasteners will shear and the knife pivots out of the way so that the debris can pass by without causing damage to the wheel or track. The knife and fasteners being readily serviceable with inexpensive parts.