Scientific American
Supplement.
No. 404

BIETRIX'S VERTICAL AND HORIZONTAL COMPOUND ENGINE.

Compound engines are tending to come more and more into use, inasmuch as they present many advantages over other kinds, especially as regards the saving they effect in fuel, and their great regularity, due to the adjusting of the cranks at right angles.

It is not surprising, then, to see our large manufacturers, who desire to maintain a reputation, seeking to create new types based upon this principle. But, in multiplying the parts, as is done in these motors, the engine is rendered more complicated, and the cost of installation is increased. Hence the difficulty of placing these motors, notwithstanding the saving in fuel that is gained by employing them.

Messrs. Bietrix & Co., of St. Etienne, however, have devised a type in which these two inconveniences seem to have been in a great measure overcome, and which we illustrate in the annexed engraving.

COMBINED VERTICAL AND HORIZONTAL COMPOUND STEAM ENGINE.

Description of the Engine.—The engine as a whole is represented in longitudinal elevation in Fig. 1, in plan in Fig. 2, and in side view in Fig. 3. Fig. 4 shows the condenser in transverse section.

The motor consists of a small vertical cylinder, A, and of a large horizontal one, C, both projecting over a strong hollow frame, B, which connects them and carries the guides, g g', and the pillow block, P, of the driving shaft, p. The condenser, D, is in a line with the large cylinder, and the piston, D², of its pump is mounted upon the prolongation, d', of the piston rod, a, of the cylinder, C. The expansion gear is controlled by the regulator, and the admission may vary from ¹/₁₉ to ¹/₈₅. Steam is admitted into the small cylinder through the pipe, s, and its entrance may be regulated at will by acting upon the hand wheel, s', which controls the maneuvering rod, s². After expanding, the steam, in escaping from the smaller cylinder, passes through the pipe, r, into the feed-water heater, R, and then acts in the larger cylinder, c, in order to pass afterward to the condenser, D, through the pipe, d.

The frame, B, is in two parts, the vertical part being adjusted by keys upon the horizontal one, and strong bolts concurring with such a coupling to make the whole strong and solid. This frame carries plane slide bars, g g', with beveled counter guides.

The pistons are of the Swedish type, of hollow iron, with steel rods. The segments are of cast iron. The horizontal connecting rod, M', is connected directly with the crank pin, m, but the vertical one is fixed to the head of the former, as may be seen in Figs. 3, 8, and 9.

The bearing of the horizontal connecting rod is in three parts, each having an anti-frictional bushing, and their play being regulated by bolts, m². Friction being slight in the bearing of the vertical rod, M, inasmuch as the latter's axis has but a short travel at each revolution of the driving shaft, it is not provided with an anti-frictional bushing.

The Small Cylinder (Figs. 5 and 6).—The small cylinder is shown in detail in Figs. 5 and 6, the valve box cover being removed in the latter. The diameter of this cylinder is 380 millimeters, the stroke of the piston is 650 millimeters, and the thickness of the sides is 25 millimeters. It is provided with a steam jacket; and the two ports are 45 millimeters in width by 200 in length. The exhaust is effected through an orifice 84 millimeters in diameter.

The distribution is a variable one, according to the Meyer system, the expansion being caused to vary automatically in the small cylinder, by means of a regulator, so as to proportion the motive to the resistant power.

The distributing slide valve, t, contains two steam inlets, whose orifices facing the cylinder are formed by two horizontal, parallel rectangles, while the inlets debouch toward the opposite surface (in contact, consequently, with the expansion slide valve, t'), according to two parallelograms, whose larger sides are oblique, and form between them a sharp angle, as may be seen in Fig. 6. These inlet conduits are therefore out of true. The slide-valve, t, is moved by an eccentric, E.

The expansion slide-valve, t', has the form of a trapezium, whose two like sides are parallel with the inclined openings in the slide-valve, t. It is held by a piece, q, which carries it along in its backward and forward motion, but does not prevent it from being moved in a horizontal direction under the action of the regulator. This piece, q, is keyed upon a rod, q', which is itself jointed at its lower extremity with the rod, e', of a second eccentric, E', which causes its vertical motion.

The backs of the valve, t, and the piece, q, are provided with grooves, which are designed for giving passage to the steam, the pressure of which on these surfaces partially balances that that it exerts in an opposite direction.

Automatic Regulation (Figs 5 and 6).—The upper part of the rod, e', carries a cam, f, that plays freely between two connecting rods, f¹, and the travel of which is limited by two rollers, f² and f³, situated between the rods, f, which latter are themselves suspended from a rod, F. The latter slides in a support, F², which serves likewise as a guide to the rods, q' and t², of the slide-valves, and which is fixed upon a projection cast in a piece with the frame, B, and is suspended from the short arm of a bent lever, F', whose longer arm carries a roller that runs in a vertical groove, t³, in the back of the expansion slide-valve. The lower extremity of the connecting rods, f', is connected with the sleeve of the regulator, Q, by a lever, f⁴, and a bent lever, Q'. This latter revolves on an axis passing through its elbow and mounted at the extremity of a projection that is cast in a piece with the support of the regulator. This bent lever is prolonged beyond the sleeve, and carries suspended from its extremity a small piston-rod that plays in a dash pot, Q³, and limits the too abrupt motions of the apparatus. The regulator is driven by a belt and through the intermedium of the bevel pinions, u.

It is easy now to understand the purpose and the modus operandi of the mechanism that permits the regulator to act upon the expansion gear. When running normally the connecting-rods, f', occupy a vertical position, and the rollers, f² and f³, are placed exactly at the two extremities of the travel of the cam, f.

When the velocity exceeds the normal, the sleeve of the regulator rises and the lever, Q', tips to the right and forces the rods, f', to oscillate in the same direction around their upper joint. After that, the lower roller, f², being situated on the line of travel of the convex part of the cam, will be carried along by the latter and cause an oscillation to the right of