dition to the usual countershaft carried below the main shaft, a quill is mounted below this which carries a differential gear. From this differential two drive shafts provided with universal joints transmit the power to two auxiliary differentials located on the front and rear axles respectively. The differentials on the axles in turn drive the wheels and as the wheels are movable to steer the vehicle, as well as rotatable to drive it, it is apparent that the final drive shafts which transmit power to the wheels must have universal joints to compensate for wheel movement when set at an angle to direct the vehicle.

A section through the universal joints employed at the wheels is clearly shown at B, Fig. 177-c. Here it will be seen that the universal joint is a regular double yoke and cross type enclosed in a housing that protects it from the dirt and grit and which permits of considerable movement of the drive shaft without allowing the lubricant with which the universal joint is packed to escape. One end of the universal joint is attached to the drive shaft which runs to the differential on the axle while the other yoke drives a spur pinion which is well supported by a taper roller bearing placed at each side. This spur drive pinion engages with an internal spur gear carried within the body of the wheel and applies the power near the wheel rim, thereby gaining the greatest driving leverage possible. The internal gear of the wheel and the pinion driving it are well housed to exclude grit and retain lubricant and this housing at the same time serves as a brake drum.

The wheels, one of which is shown at Fig. 177-d, are interchangeable. The two drive axles with their universals are duplicates of each other and the three differential gears, consisting of that in the gear box and those on the axle, are all alike. The differential is a special Wayne type which differs from the common construction in that it automatically drives the wheel which has the greatest resistance and which has traction and this feature coupled with the use of four driving wheels makes it possible to propel the truck if any one of the four wheels has traction. It is claimed that while the truck has 120 inches wheel base it will turn in a circle of twenty-two feet radius, which is accomplished by the fourwheel steering feature. There are four ample brakes, one on each

Fig. 177-c.-Components of Distinctive Design Necessary to Successfully Apply the Four Wheel Drive Principle on Rambler Trucks. A.Section of Four Speed Gearset Having Drive Through Gears on All Speeds and Incorporating a Differential Drive Assembly to Impart Motion to the Axles. B.-Universal Joint Construction Utilized to Drive Wheel.

Fig. 177-d.-Type of Wheel Used on Rambler Four Wheel Drive Truck.

wheel, and it is claimed that either set of two brakes is sufficient to hold the loaded truck on a 30 per cent grade. The wheel revolves on taper roller bearings carried by the wheel spindle. The steering knuckle is a special form of the inverted Elliot type and not only carries the wheel spindle but the frame supporting he spur drivin pinion as wel. The loaded front axle is supported by a taper roller bearing at the lower end of the steering knuckle which makes it possible to turn the wheel with minimum exertion on the part of the operator. When the wheel is moved by the steering knuckle the frame carrying the spur drive pinion turns as well, but owing to the universal joint the drive is not interrupted and the wheels are all