In traveling position the howitzer is retracted and locked to the cradle, the cradle locked to the trail, the spade revolved and secured to the bottom of the trail. The lower end of trail rests on the carriage limber, which is used to carry the proportionate share of the load of the howitzer and carriage in traveling position. The limber is equipped with a connecting pole for motor traction. The carriage and limber wheels are rubber tired and considered able to negotiate any roads suitable for field artillery. Howitzer Description. The howitzer, consists of a tube and jacket. =The jacket= is shrunk over, approximately, the rear half of the =tube= and screwed to it by a short thread near the rear end of the tube. The rear end of the tube is prepared for the reception of the breechblock. On the right of the jacket at its rear are two lugs which receive the hinge pintle of the operation lever. A flat seat with two transverse slots is machined on the top of the jacket at the rear end for receiving the counterweight. =The counterweight= is securely fastened to the jacket by six screws, and two lugs which engage the slots in the jacket. =The bridle= is fitted to the underside of the jacket near the rear end and held in place by four screws. The breech key passes through the bridle and holds the howitzer in its seat on the sleigh. On the underside of the jacket just forward of the bridle seat are seven square threads which engage corresponding threads on the sleigh. A holding-down band which encircles the jacket at its forward end also secures the howitzer to the sleigh. On the top surface of the counterweight are two nickel silver leveling plates. Vertical and horizontal axis lines are cut on the breech and muzzle faces. A line showing the actual center of gravity with the breech mechanism in place is cut on the upper side of the jacket marked C. of G. The name and model of the howitzer are stamped on the left side of the jacket just below the counterweight. The name of the manufacturer, year of manufacture, serial number of the howitzer and the weight of the howitzer, including the breech mechanism, are stamped on the muzzle face. [Illustration: _155 M.M. HOWITZER MODEL OF 1918_ (_SCHNEIDER_) _BREECH MECHANISM ASSEMBLY_] [Illustration: _155 M.M. HOWITZER MODEL OF 1918_ (_SCHNEIDER_) _BREECH MECHANISM ASSEMBLY_] =The breech mechanism= is of the plastic obturator, interrupted screw type having four plain sectors and four threaded sectors. The block can be loaded with one-eighth of a turn. Two of the plain sectors are relieved to permit the breechblock to enter the breech recess. The breechblock is screwed into the block carrier and rides on the hub of the latter. _The block carrier_ is hinged to the right side of the jacket by means of the pintle hinge of the operating lever. _The pintle hinge_ is fitted at the lower end with an operating lever collar and detent. The dead weight of the breech is carried by the block carrier hinge plate.