The new Packard worm-driven trucks are equipped with front axles (Fig. 164), employing the reversed Elliot type of knuckle; however, they are arranged for left side fore and aft steering. The axle proper, however, is dropped at the center. This construction is similar to the one depicted above, with the exception of the steering arms, which are attached to the lower part of the knuckle. This permits proper clearance for the tie rod and places it in such position that it is not necessary to bend it, A feature worthy of attention on both of these axles is the provision of ball and socket connections for the tie rod and drag link in place of the more customary clevis and bolt. These ball and socket joints have springs so that the wear in the steering connections is automatically taken up.
The International Harvester Corporation trucks for some years had used the Sarven type of wheel in connection with an Elliot type of steering knuckle, in which the pivot center lies very close to the center of the wheel. This is shown in Fig. 165 and it will be noted that the hub construction resembles an ordinary vehicle wheel hub. This consists of wooden hubs with steel hub flanges, the former have steel shells which carry the wheel bearings. The outer wheel bearing is of the roller type made by the I.H.C., while the inner bearing consists of a steel and bronze shell, the latter having a taper bearing in the shell inserted in the wood hub. The bronze shell is provided with oil holes and grooves, so that the entire bearing can work in graphite and grease. The knuckle, instead of having the usual hub for the pivot pin or king bolt, as it is sometimes called, has a yoke, which fits into the axle yoke. Short pins pass through the axle and knuckle yokes to form the pivot.
The above axles all have drop forged centers, which may either be forged in one piece or the two ends may be forged separately and welded together at the center.
Fig. 164. Packard Front Axle.
Fig. 165. Axle used on some of the International Harvester Trucks.
The Reo two-ton front axle (Fig. 16G) differs from those shown above in that the center is built up from a bar of round section, pinned and brazed into cast steel ends which form the forks. The knuckles are of the Elliot type and carry the bushings for the pivot pin. The knuckle arms fit over the ends of the knuckle and are held in unison with knuckle by two keys. This axle is arranged for left-side steering and the tie is placed directly back of the axle bed. It is not necessary to bend it. since ample clearance is obtained by placing the spring seats above the wheel center. The wheels are mounted on Timken roller bearings and retained by a castellated nut and keyed washer.
Fig. 166. Reo 2-Ton Front Axle.
The Vim and Commerce trucks also employ built-up axles with Elliot knuckles, but the center or bed is made of tubular section. The Avery farm trucks employ another type of built-up front axles. A malleable casting forms the steering head to receive the Lemoine type of knuckle, which is equipped with a series of hardened steel washers to take the thrust.
On either side of the steering head extensions are riveted a couple of steel plates as shown in Fig. 167. These are straight at the spring seats and bent up slightly at the ends to attach to the steering head castings. Blocks are placed between the two axle plates directly under each spring to form the seat. The steering connections are arranged for cross steering and are located in front of the axle.
The three-wheel "Wayne Light" commercial car having a capacity of 800 lbs. also employs a built-up front axle as shown in Fig. 168. Two sections of rolled channel steel are riveted together and with drop forged yokes and Elliot type knuckles at either end.
Pressed steel centers may also be used, while combinations of the above types may also be worked out.
All American trucks are equipped with anti-friction bearings such as the ball and roller types, which are capable of carrying both a radial and thrust load. The mounting of these bearings presents no difficulty and they are usually provided with adjustments to compensate for wear. The tie rods and drag links are made of tubular section and are provided with adjustments so that the alignment of the wheels may be properly maintained. Lately there seems to be a tendency to use the ball and socket joint for these in preference to the clevis. The former will to a considerable extent take up the wear automatically and can also be more efficiently lubricated.
Fig. 167. Lemoine Type of Knuckle.
Fig. 168. Wayne Light Axle, Built-Up Type.