Abstract: A control mechanism for selectively positioning an upright earth working tool carried by a portable vehicle having a source of pressurized hydraulic fluid. The control mechanism includes a shaft rotatably carried on a horizontal base plate at the front end of the vehicle, and pivotally connected to a carrier member for the earth working tool for tilting movement of the carrier member laterally of the vehicle. A first hydraulic cylinder assembly for longitudinally tilting the working tool is pivotally connected at its rearward end on the shaft and at its forward end to the carrier member. A second hydraulic cylinder assembly for tilting the carrier member transversely of the vehicle has one end pivotally mounted on the base plate and is pivotally mounted at its other end to the shaft so that on rotation of the shaft the carrier member is tilted transversely.