This consists of two members, one fixed on the flywheel or other rotating part of the engine, the other fixed to the transmission shaft. The latter usually slides upon the shaft so as to allow engagement and disengagement. A spring holds the two together or apart, according to the type of clutch used.
When the smaller-diameter member is spoken of, it is usually called the male member, while the part of larger size is spoken of as the female member.
The cone type is found to be made in two different varieties; the one in which the male member enters the female naturally at the open end is called the direct cone type. In the other form, the male is set within the structure of the female and is pressed outward toward the open end to engage it. This is called the inverted, or sometimes the reversed, cone clutch. A great disadvantage of the inverted form is that the spring must be carried between the two cones, which means that it is inside where it cannot be reached for adjustment. Fig. 42 shows this clearly. This form causes trouble in assembling because the male cone A must be put in place with the spring between it and the flywheel C, before the female B can be set into its place and bolted up. These two big sources of trouble have caused designers to turn to the direct type more freely, as it lends itself readily to an external adjustment. If the spring is outside, it is easily put into place and as easily taken out. Fig. 43, which illustrates this, is a section through the Bayard (French) clutch, and the spring is seen to be entirely outside the clutch proper. Its location is such as to permit the adjustment of the tension at any time, by means of a screw collar C, which may be done with no more trouble than lifting up the footboard of the car and turning the collar forward a few turns.
Not all designers have hit upon as happy a solution of the clutch problem as this. Thus, in the Studebaker clutch, shown in Fig. 44, the spring B is external to the clutch but so placed that it is necessary to disconnect the universal joint AA, take it off the car, loosen a set screw, adjust, and then repeat the other operations in reverse order. A similar state of affairs is found in the Benz, illustrated in Fig. 45, in which it is necessary to take out the bolts connecting the shifting collar to the male member, and then, through carried even farther than this, the leather being put on in sections, so that in case of unequal wear a single, worn-out section may be replaced without disturbing the others. An even later idea emanates from England, and is nothing less than putting these sections onto the cone by means of dovetails. In this way a worn section can be replaced in the length of time that it takes to tell about it.
Fig. 42. Typical Reversed Cons Clutch.
Fig. 43. Bayard (French).
A prominent German maker has been very partial to the double-cone form of clutch, particularly for large and high-powered cars. This has generally consisted of a pair of single direct clutches set back to back, and coupled up in such a way that pressure on the pedal acted upon the two progressively; that is, they were engaged one after the other. Conversely, the initial declutching pressure worked gradually upon one until that was entirely out of engagement, when a continued pressure would gradually throw out the other. For very large motors, this has a distinct advantage in that the speed can be temporarily reduced by applying the clutch pedal part way. In this case one of the two clutches is thrown out, and the one left, not being able to carry all the motor power, slips and thereby reduces the speed. A quick pick-up and very rapid acceleration can then be had, when the need for reduced speed is removed, by simply dropping in the second clutch.
Somewhat the same idea is presented in the triple cone clutch shown in Fig. 47. This has three different sizes of cones, each one meshing, or contacting, with a smaller section of the cone housing. All three are on the same splined shaft, and the arrangement is such that each part has its own spring, and thus is self-contained. When the clutch collar is pushed to the left, the smaller cone is disengaged. A further movement of about 3/16 inch and its hub come3 in contact with the hub of the middle-sized cone, a continued movement disengaging it. Similarly with the third cone.
The reverse action takes place on engagement, the larger part clutching first, then the intermediate, and lastly the small cone. In this way, a smooth and gradual action is obtained. The facing is plain metal, which contacts with metal on a 4-degree taper. It runs in oil. The over-all length is but 11 7/8 inches for a 35-horsepower unit.
Fig. 46. Male Portion of Clutch Using Narrow Leather to Carry Load.
Fig. 47. New Type of Triple Cone Clutch.