public boolean moveBack(float tpf) {
        if (this.getLocalTranslation().z < (-2.2f - 13 / 6)) {
            this.move(0, 0, tpf * (15 / 3.6f / 3)); // (15 km/h) / (3.6 = m/s) / 3 our scale 
            return false;
        } else { // return true if Crane reached its destenation
            return true;
        }
    }