Abstract: The invention provides a self-mounting counterweight device which is mounted to one end of the chassis frame of the vehicle. The counterweight is U-shaped having two vertical sides and an outward wall defining an internal enclosure. The counterweight includes a rod mounted to the top of the counterweight for suspending it from a boom and includes lateral threaded bolts to releasably mount the counterweight to blocks on the chassis frame. The lifting boom has an inward end journalled to the frame and an outward end with tackle for releasably connecting the boom outward end to the counterweight suspending rod. A hydraulic cylinder provides mechanical lift with an inward end journalled to the frame and an outward end pivotally connected to the boom. The combination of the boom and lift provides a scissor-like lever for selectively raising and lowering the counterweight between a lowered and mounted position.