Abstract: A dump truck is provided with a dump body having a tailgate. A lever arm having a first end and a second end is pivotably attached to the dump body. The first end is fixedly attached to the tailgate and the second end is attached to a latching device which locks the position of the lever arm. When the dump body is raised, the latching device is deactivated and the position of the lever arm is unlocked. When the dump body is lowered, the latching device is activated and locks the position of the lever arm, thereby locking the position of the tailgate.

Abstract: A duty cycle data acquisition system for a truck having an elevatable dump body, a hydraulic hoisting mechanism, throttle and transmission controls, and a retarder further including a microprocessor having an analog imput corresponding to ground speed of the truck and which records the amount of time the ground speed remains in any of a plurality of increments corresponding to the speed range of the truck in one of eight histogram output memories selectively determined by the inputs of a plurality of on-off switches corresponding to throttle position, transmission forward or reverse position, retarder position, and a one-shot timer switch activated by a loaded dump body actuating circuit, the latter circuit including a switch sensing body position relative to the frame disposed in series with a pressure switch located in the hoist mechanism, the pressure switch being calibrated to close only when a loaded body is lifted.