A similar construction (Fig. 202) is used on the Dr. Kalb commercial cars. However in this case the hinge is placed at the front end of the subframe members, while the rear end has a large drum which forms a single hinge. Fig. 203 illustrates a sectional view of this rear support and also illustrates the method of supporting the front end of the transmission from this point. The transmission is bolted to the jack shaft and has a long torque tube extended to this third point of support, which is of spherical form.
The principle of three-point suspension in the Blair trucks (Fig. 204) is even carried on to the rear axle. In this construction the subframe is hinged to the main frame in front by steel castings and heavy hardened and ground steel pins. At the rear it is hinged at right angles to the worm-drive-axle housing. It is claimed that this system renders the subframe that carries the power plant flexible to any position, maintaining perfect alignment in the transmission of power. It provides a straight-line drive under all conditions, and almost entirely eliminates universal joints in the drive.
Flexible mountings are also applied to transmissions when these arc located amid-ship. An excellent example of this is the United States mounting (Fig. 199). in which spherical or ball-and-socket joints ate used at three points, one at the forward end, and one at each side in the rear over the jack-shaft housing.
On the Packard trucks the transmission (Fig. 205) is supported by two pressed-steel cross members. The forward end is bolted to a cross member, which has a machined surface that fits over the housing, which supports the forward or main shaft of the transmission. The rear end is free and pivotally mounted in the brake anchor, which is attached to the cross member.
On the Federal truck a modified three-point support is used. The transmission case has four lugs, two at each end, and these support the transmission case, being attached to two cross members. The two lugs at the front are close together, and practically produce the same effect as a single point.
Three-point support is also used on several other trucks, the forward support being of the pivot type while the rear is either directly mounted from a cross member or by brackets attached to the transmission.
The advisability of providing a long life for the power plant will be endorsed by all users of commercial cars, and since this feature can be accomplished with little added expense, it would seem to be a step toward reducing maintenance cost. There are very few makers at present who do not provide a certain degree of flexibility in the mounting of their power plants.
These few contended that there is little to be gained through this feature; however, it is not to be denied that for commercial cars, this feature presents several advantages.
Fig. 201. Mogul Power-Plant Mounting.
Fig. 202. Three-Point Suspension of the DeKalb Sub-Frame.
Fig. 203. DeKalb Sub-Frame and Transmission Support.
Fig. 204. Sub-Frame Arrangement used on the Blair Trucks.
Fig. 205. Method of Supporting the Transmission on a Packard Truck.