Abstract: A linkage system for a loader vehicle of the type comprising a pair of parallel lift arms having a first upper end pivotally connected to upper end portions of a vertical bracket member secured to the frame of the vehicle and a second lower end pivoted to an associated lower back portion of a bucket, a pair of bellcrank levers, the central portions of which are pivotally connected to corresponding upper end portions of the lift arms, a pair of connecting links having one or a first end pivotally connected to a lower end of the bellcrank levers and its other end pivotally connected to associated intermediate portions of the bracket members secured to the frame and a pair of bucket cylinders for control of rotation of the bucket about its lower end portion, having a head end pivotally connected to a corresponding upper end of the bellcrank levers and a rod end pivotally connected to an associated upper back end portion of the bucket.

Abstract: A signalling device operatively coupled between the side arm or lifting boom of a pipe layer and the frame thereof in a predetermined fixed position such that movement of the signalling device relative to the fixed position, which occurs in response to the operational load, is directly related to the critical or rolling load for any lateral position of the side arm or lifting boom.