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wire is sprung around the nut and the point entered into a suitable drill hole which goes through the nut into the shaft as indicated. Another method having much in its favor is shown at E. In this a double row ball bearing is pressed against the shoulder by a
Fig. 334.—Diagram Showing Construction of National Three Speed
clamping nut which is separated from the bearing inner face by a locking washer of the form shown at E'. This has one projection on its inner periphery designed to engage a keyway cut in the shaft. The projection on the outer periphery is intended to be bent around one of the facets of the nut to hold it in place after it has been firmly seated against the locking washer and bearing inner race. Complete instructions for the maintenance and instal
lation of ball bearings and other anti-friction forms will be found in Chapter IX., which deals with rear axle construction.
The construction of a typical three speed forward and reverse selective transmission showing ball bearings and gear shift members is clearly shown at Fig. 334. This has the gear shaft and emergency brake levers carried by a suitable supporting casting forming part
Fig. 335.—Three Speed Sliding Gearset, Forming Part of Rear
Construction of Overland Automobiles.
of the gear case cover. In this gear box single row ball bearings are used at all points, except to support the telescoping end of the main shaft, which fits into the primary shaft and which rotates on a roller bearing. The primary shaft is supported by two single row bearings, the outer one being clamped so it holds the shaft steady while the inner and larger one has a floating outer race. When a ball bearing is clamped on both inner and outer races it
will take end thrust as well as radial load. A thrust is usually an endwise load, while a radial stress is a load applied from an up-and-down direction or sidewise. In this gearset the bearing inner races on the countershaft are pushed on tightly, these being a force fit on the shaft ends. No retention means are provided. The general construction of this gear box, which is that used on National cars, is so clearly shown that further description is unnecessary.
A three speed and reverse sliding gear set that forms part of the rear construction on Overland cars is clearly shown at Fig.
335. In this the primary shaft is carried on single and double row ball bearings, while the end of the main shaft to which the bevel driving pinion is secured is supported by a large double row bearing which is capable of taking end thrust and radial load in combination. The single row bearings on the end of the countershaft are subjected to radial loads only as the countershaft is kept from end movement by simple thrust members composed of a steel ball fitting into an adjustable screw plug. The gear shifting forks
are attached to the gear shifting shafts by means of taper pins which may be driven out to release the forks and permit of taking the transmission apart by removing pipe plugs in the side of the gear case which gives access to the retaining pins when the sliding gear members are in the neutral position as indicated.
In some gear boxes, especially those used on high-priced auto
mobiles, the gears are in the form of rings which may be bolted to the shifting members and to flanges on the countershaft as shown at Fig. 336. The point advanced in favor of this construction is that it is possible to renew only the defective toothed ring instead of replacing an entire shifting member as is necessary when the gears and hubs are formed integrally. It is also contended that the use of bolts to hold the gears firmly against flanges machined integrally with the countershaft makes for more secure attachment than the cheaper method of keying. The gear box design shown is used only on high-powered cars, where secure means of retaining the gears are absolutely necessary. A gear box of this design is very costly to manufacture, but it is cheaper to keep it in repair than the simpler forms.
The change speed gearing is often combined on the rear axle, as shown at Fig. 337. This outlines a top sectional view through the rear construction and a side sectional view showing the disposition of parts very clearly. It will be observed that the bevel pinion carried on the back of the main shaft drives the bevel ring gear attached to the differential housing directly. As the gear box is part of the rear construction it is possible to secure exact alignment between the driving gears, and no power is lost due to faulty alignment between these members as may sometimes occur when the gear box and rear axle are separate components and the frame is distorted due to rough roads.
A four speed gear box having clutch integral, a somewhat uncommon construction, is shown at Fig. 338. This design is used on some models of the Winton automobile. Three shifting yokes are used, shift member A controlling the direct drive, which in this case is a third speed, and the second speed. Shift member B gives the first or lowest forward speed and the reverse ratio. Shift member C is used to engage the fourth speed, which is a high ratio obtained through speeding up gears instead of reduction gears. With gear sets of this character all normal driving is intended to be done on the third speed or direct drive. The geared-up fourth speed is called upon only when conditions are favorable and high vehicle speed is desired. This gearset is a form in which but little clearance obtains between the shifting members and the non-shift