The rear support is a large cast member bolted to the flywheel bousing, which has a trunnion formed on each side, and these fit into brackets, that in turn are bolted to hangers riveted to the frame side rails. This gives the engine somewhat greater freedom, and permits taking the torque reaction on the rear member.
The Signal truck has an unusual engine mounting (Fig. 107), which is also covered by patent. In this construction, swivel supports are also used on the rear arms, for with such a layout the torque reaction must all go to the rear arms, but no frame distortion can by any possibility put a stress upon the crank ease. A bracket developed into spherical shape is bolted to the arms extending from the flywheel housing and supported by brackets bolted to the frame members. The forward support is of the pivoted type, similar to the Riker, having a drop-forged member that is supported by coil springs and brackets attached to the frame members. A long stud supports the springs above and below the frame brackets, so that the springs relieve the engine of severe shocks and vibration.
The Diamond T-trucks also have a swivel rear support of the ball-and-socket type, and the front support is of the pivoted type, supported from a channel section cross member, which is also used to support the radiator.
Fig. 196. Simple Method of Support used on the Union Trucks.
Fig. 197. Three Views of the Patented Mounting on the Signal Truck.
One of the chief difficulties encountered in combining the engine and transmission in a single unit is due to the fact that the flywheel is located between them and to enclose it requires a great deal of metal, adding both to the weight and the cost. In commercial car practice the four-cylinder engine seems to have become the standard and with these there is a tendency to use a flywheel of inadequate capacity, when it is to be enclosed, which detracts somewhat from the steady running qualities of the vehicle. To overcome this, two expedients may be resorted to. One is to place the flywheel at the front end of the engine, but there are a number of objections to this practice. The purpose of this flywheel is to equalize the torque of the engine before it is transmitted to the transmission and its logical place therefore seems to be between these two units. The forward location also places it in a position where it can easily be injured, while the strains on the tires are increased and the clearance between the engine and front axle is materially reduced.
On the Dorris commercial cars all the features of an open flywheel are retained as illustrated in Fig. 198, by joining the engine and gear box by a large yoke which permits the use of a large flywheel and also affects a considerable saving in weight.
The method of mounting the engine in the United States motor trucks is illustrated in Fig. 109. The engine is mounted on a subframe, the front cross member of which extends into the side members of the frame. This cross member has ends that form a yoke into which are placed heavy coil springs, retained by a long bolt, passing through a bracket riveted to the frame, thus utilizing the springs to absorb severe shocks and vibration.
A 5-in. spherical bearing riveted to the rear of the subframe forms the rear support. This rests on a large cast cross member, which is dropped considerably at the center. The support is on the upper side of this cross member, thus providing a very flexible mounting.
The larger sizes of Kissell Car trucks also have the power plant mounted on springs at both ends, with provision for flexible mounting incorporated in the rear supports as depicted in Fig. 200. The engine is mounted upon a pressed steed subframe having cross members at both ends, which are dropped considerably at their center. The front cross member has two pressed steel brackets which rest on heavy coiled springs placed inside of the front cross member of the main frame. Another spring is placed below the flange of this cross member, a bolt being used to hold both springs in position. In this way the movement of the forward end of the subframe is controlled in both directions. The rear support is formed by brackets riveted to the subframe members, which have a ball-shaped end that rest on ball sockets placed within a bracket riveted to the main frame members. These ball sockets are provided with springs, to relieve the power plant of shocks due to vibration while the ball permits a certain degree of flexibility when the frame twists. In reality this is a four-point suspension which retains all the features of a three-point suspension.
The same principles of unit power-plant mounting may be applied to vehicles in which the engine or both engine and transmission are carried on a subframe. Fig. 201 illustrates this feature applied to Mogul trucks. The frame has a front cross member which carries a bracket to form the bearing for the third point of support. The subframe is also provided with a cross member and a bearing bracket, so that a hollow pin can be inserted. This is retained by a large nut, having a hub, which together with the pin forms the bearings for the starting crank. The rear ends of the sub-frame being supported from a frame cross member.
Fig. 198. The Dorris Unit Power Plant.
Fig. 199. Sub-Frame Arrangement used on the United States Trucks.
Fig. 200. Kissel-Kar Six-Ton Sub-Frame Mounting.