The rear axle of an auto requires quite as careful work as any other part. It is not only subjected to bending strains due to vertical load, but it must also resist the pull of the chain. Then, when the hub-brake is Used a severe torsional strain is imposed and the combination of the three subjects this part to the most severe twisting and bending strains.

The Amateur Runabout IV The Rear Axle 201

The cut shows a sectional elevation of the axle with the hubs and muff enclosing the differential. The outside shell is made of 1$ in No. 12 gauge seamless drawn steel tubing. The lengths are cut to suit the work, depending on the width of tread, and are brazed into the separate halves of the muff. Two bronze bushings are forced into the ends of each half and secured by a pin. These bushings can be made of brass tubing, which can be obtained in any large city.

The sides of the muff are turned on an arbor and finished with a male and female joint. This insures a perfect alignment of the bearings. The tubing is brazed into its sockets, which makes a very strong job. The muff is provided with two openings through which the chain passes. The flanges are provided with holes for 11 3/8 in. bolts.

The shafts are of 1 in. cold rolled steel shafting fitted to the hubs and provided with a key. A nut on the ends of the shaft keeps the hub in place.

Each inside hub-flange is provided with a drum for the brake band. These are turned true and smooth. Where the shafts pass into the differential case they are provided with collars pinned in place, each half of the shaft is keyed to one of the differential gears, as will be described and detailed in the next chapter.

The spring-seats are brazed to the tubing before assembling, and their position can best be determined after the exact spring position is determined. The spring seats should have lugs to receive the ends of the radius rods, or these may be attached to separate castings brazed onto the tubing.