Practical Hand Book of Gas, Oil and Steam Engines / Stationary, Marine, Traction; Gas Burners, Oil Burners, Etc.; Farm, Traction, Automobile, Locomotive; A simple, practical and comprehensive book on the construction, operation and repair of all kinds of engines. Dealing with the various parts in detail and the various types of engines and also the use of different kinds of fuel.

by John B. Rathbun

(45) Four Cylinder Vertical Auto Motor.

A common type of four cylinder vertical motor is shown by Fig. 19, which is of the type commonly used on automobiles. In order to show the general construction of the cylinder, each cylinder is cut through at a different point. The cylinder at the extreme left is shown in elevation, or as we would see it from the outside. In the second cylinder from the left, the section is taken through the valve chamber, which projects from the side of the cylinder. A section through the center of the cylinder is shown on the third cylinder, and the fourth cylinder is in elevation.

On cylinder No. 1, (left) is seen the exhaust pipe (32) and the inlet pipe (31) entering to valve chamber and connected to the exhaust valve and inlet valve respectively. The pipes are held in place by the clamp or “crab” (33). The exhaust pipe connects with the exhaust valve of each cylinder, and terminates at the fourth cylinder as shown by (32). Screwed into the top of the valve chamber on cylinder No. 1 are the two spark plugs (34) and the relief cock (35).

Referring to cylinder No. 2, the inlet valve (42) is shown at the left of the chamber and the exhaust valve also shown by (42) is shown at the right. Above the valves are the spark plugs (34) which project into the space above the valves. Pressing against the lower ends of the valve stems and holding the valves tight on their seats are the springs (44) which fit into the washers (45) fastened to the stems. The valve stems terminate in a nut at (48). The valve stem guides (43) form a support for the valves and at the same time form an air tight connection for the stems to slide in.

Immediately beneath the stems are the push rods (46) which are provided with an adjustment (48) at the upper end, and a roller (49) at the lower end. The rollers (49) rest directly on the cams mounted on the cam shaft (27), and as the irregular cams revolve, the push rods are moved up and down which in turn act on the valve stems and raise the valves at the proper moment. The cams raise the valves and the springs close them. The two cams (exhaust and inlet) appear as two rectangular enlargements on the shaft (27). The bearings (53), support the cam shaft, one being supplied for each cylinder.

At the extreme left of the crank shaft is shown the half time gear (20) which meshes with the gear on the crank-shaft and drives the cams. Next to this gear is the large cam shaft bearing 26. It should be noted that the section through the valve chamber taken on cylinder No. 2 is at a point considerably back from the center line of the cylinders and not in the same plane as the section shown on cylinder No. 3, which is taken through the center line of the cylinders.

Fig. 19. Cross-Section Through Typical Four Cylinder Automobile Engine. Courtesy of the Chicago Technical College.

In the section of cylinder No. 3, we see the water space surrounding the upper portion of the cylinder with the opening (37) connected to the water manifold (36), through which the water leaves the cylinder and passes to the radiator. At the lower end of the stroke is the piston, one-half of which is shown in section and one-half in elevation so that internal and external appearance may be readily seen. The piston pin (60) is located approximately in the center of the piston to which it is secured by means of the set-screw (61).

By means of the connecting rod (56), the motion of the piston is transmitted to the crank-shaft throw (54), both ends of which are provided with bronze bushings (59) and (58), fitting on the piston pin and crank-pin respectively. Between each crank throw are the main crank shaft bearings (55) which are provided with the bronze bushings (54). Below the connecting rod ends is the small drip trough containing oil into which the pipes on the rod ends dip when passing around the lower end of the stroke. When the pipes enter the oil puddle a small amount of lubricating oil is driven into the crank-pin bearing because of the force of impact, this force also causing oil to splash about in the crank case for the lubrication of the main crank shaft bearings and cam shaft. In order to maintain a constant level of oil in the puddle so that the bearings shall receive a constant supply of oil, a small overflow opening is placed in the center of the puddle which allows an excess of oil to overflow into the return oil sump below.

This excess of oil drains by gravity back to the oil circulating pump (73), at the right which again forces the oil to the various bearings. In this way, the same oil is used over and over again until it becomes unfit for lubricating purposes because of dirt or decomposition. The oil pump is driven from the cam-shaft through the level gears (66) and the vertical shaft (72). To the right of the oil pump is the fly-wheel (75) which furnishes the power for the idle strokes of the engine.

At the upper end of the vertical shaft that drives the oil pump is an extension (68) which passes through the bearing (70) and drives the ignition timer shown at the top of the housing (69). The timer controls the period of ignition in the cylinders in regard to the piston position so that the spark occurs at the end of the compression stroke. At the extreme left of the engine is the radiator fan (1) which is driven from the crank-shaft pulley (16), the belt (10), and the fan pulley (1122). This fan increases the amount of cold air that is drawn through the radiator, (mounted to the left of the engine) and increases its capacity for cooling the jacket water of the engine. The water circulating pump is located on the opposite side of the motor.

Fig. 19-a. Buda Four Cylinder Automobile Motor. Carburetor Side.

Fig. 19-b. Buda Motor, Pump Side, Cylinders “En Bloc.”

In this motor both the inlet and exhaust valves are located on the same side of the cylinder which arrangement classifies the engine as an “L” type, the extended valve pockets forming an “L” with the center line of the cylinder. In the motor shown by Figs. F-14-F-15, the inlet and exhaust valves are on opposite sides of the cylinder as shown in the cross-section, which classifies the motor as a “T” type, as the valve chambers together with the cylinder forms a “T.” The latter type of motor has several advantages over the “L” type, but as it requires two cam shafts, one for the inlet and one for the exhaust valves, it is not adopted by the builders of the cheaper grades of automobiles. Since the exhaust valves are on the opposite side of the cylinder, in the “T” type, the inlet air is not expanded nor the output diminished by the heat of the exhaust passages. The piping is less complicated which permits of a more effective arrangement of the carburetor and magneto. Since the piping in the latter type can be arranged to better advantage, less back pressure is the result.

Fig. F-14. Cross-Section Through Wisconsin Truck Motor. “T” Type.

Fig. F-15. Longitudinal Through Wisconsin Truck Motor.

As in the previous case, the valves are acted on directly by the cams and push rods, one cam shaft being provided on each side of the cylinders. In order to reduce the noise made by the push rods and springs, all of the springs are enclosed by sheet metal housings or tubes. The circulating pump is shown at the left nearly on a line with the left hand cam shaft, the pump outlet being inclined toward the cylinder so that it enters the water jacket under the exhaust valves. Water leaves the jacket by the pipe shown on the cylinder tops.

From the longitudinal section it will be seen that the cylinders are cast in pairs, two cylinders to the pair, instead of singly as in the previous case. The large pipe crossing at about the center of the cylinders is the exhaust pipe (shown in front of the left pair), and the pipe shown under the exhaust is the water inlet pipe from the circulating pump. It will be seen from the longitudinal section that the main crank-shaft bearings are fastened to the upper half of the crank case, and are entirely independent of the lower half which acts simply as an oil shield. This construction allows the oil shield (lower half) to be removed without disturbing the adjustment of the bearings, when it becomes necessary to inspect the internal mechanism.

Six Cylinder Rutenber Automobile Motor, with Cylinders Cast in Pairs.

Large removable plates cover the top of the water jackets so that it is a simple matter to clean out the water space in case that it becomes coated with deposits from the water. This is an important feature as a great many of the heating troubles may be overcome by having access to the interior of the water jacket. The water outlet pipes connect with the jacket covers. Both cam shafts are driven by the gears at the right which connect with the crank shaft pinion. Fan is belt driven from an extension to the cam shaft.

All bearings are supplied with oil by a high pressure force feed pump, the crank pins receiving their supply through channels drilled in the crank shaft and pin, which in turn are connected to the oil supply of the main bearings, no dependence being placed on a splash system. After leaving the bearings, the oil drops into the crank case and drains into the sump shown at the left of the longitudinal section. From the sump, the oil returns to the oil pump from which point it is returned to the circulating system under high pressure.