drawing paper, making sure that the faces are at the proper angle. This may be done as shown at Fig. 316, B. Draw a long line through the center of the clutch cone and parallel with the hub; this being represented by the line AB in the drawing. Continue the angle of the cone by straight lines, meeting at a point in the center line. Using this point as a center and the distance from B to C and B to D as radii, describe the arcs of circles EG and FH. The distance from E to G must equal the larger circumference of

Fig. 318.-Cone Clutch Partially Disassembled to Show Important

Components.

the cone so the ends will butt together, or it may be advisable to make the strip somewhat longer than necessary to allow for fitting. The pattern thus obtained may be used to cut the new leather. A special friction leather which is made for this purpose should be used. The thickness of the facing is important, because if it is too thick it will prevent the cone from entering the flywheel as it should. The clutch leather is usually one-quarter inch thick.

Before riveting the leather in place it should be made as pliable as possible with neatsfoot or castor oil, though all repairmen are not in agreement regarding this practice. Some advocate soaking the

Clutch pedal

leather in water and applying to the cone wet so that when it dries it will shrink and hug the cone closer. Others apply it dry and oil it after it is placed. In the opinion of the writer, which is based on considerable experience, letting the leather shrink is likely to result in the friction facing pulling away from the rivets, while oiling the material after application is apt to cause expansion and

an

Brake pedal

Clutch brake

Clutch springe and
adjusting nuts

Clutch rollers
(need grease)

uneven surface. When the leather is oiled before application it is soft and pliable and there will be no trouble in the material becoming loose from its fastenings if it is properly fitted. There are two methods of fitting the clutch leather. One of these is to attach the leather at one end, holding it on the cone with a machinist's clamp or hand vise, while the holes are then drilled in the leather to coincide with those in the cone. The two holes at the extreme end are first drilled and the leather riveted in place, care being taken that the holes for the rivet heads are countersunk deep enough so the copper will be well below the surface of the leather. After the end is securely fastened the leather is pulled tightly around the cone to the next point of fastening, the facing again being retained by clamps while the holes are drilled and the rivets applied. This operation is repeated from one point of attachment to the next. This method insures that the facing will hug the cone closely instead of standing away from be

Fig. 319. Clutch Control Assembly of Overland Automobiles.

tween the rivets, as is sometimes the case when all holes are drilled in the leather before application, which is the alternative method.

After a facing is applied it should be trued in a lathe by taking a light cut off its surface or the high spots may be rubbed off by hand with sandpaper, a piece of glass or a coarse file until a a full bearing is obtained all over the clutch facing. The material ordinarily used is good oak bark tanned belting leather, though hemlock and chrome tanned leather have been used with good results. The oak tan seems to possess all the desired qualities of elasticity, durability and degree of frictional adhesion required. The other method of applying the leather is to rivet the two ends to the cone as shown at Fig. 316, C, and then to pull the leather in place and rivet at the point directly opposite that where the two ends are riveted. The other rivet holes are then drilled to correspond with those in the cone. It is not desirable to cut woven wire asbestos fabric, and when this material is used it must be obtained all ready woven to form from the car manufacturer. Special copper rivets are used for riveting the friction facing to the cone. These have broad, flat heads of medium thickness, in order that they will keep the leather firmly in place without danger of pulling through, as would be the case if the rivet heads were small. Care should be taken to countersink deep enough for the rivet heads so that these will not touch the female member until the leather is worn so much that it needs renewing.

It is not difficult to do a good job of riveting if a bolt or punch the same diameter as the rivet head is used as a support, as shown at Fig. 316, D, and the end of the rivet is burred over with a rivet set, or with the ball pein end of a machinist's hammer. The punch supports the head of the rivet and forces it positively into the countersunk hole and insures a good tight fit. On some clutch cones, notably that used in models of the White automobile, the friction facing is held on the cone by means of T-bolts, which fit into depressions cast into the cone spider. Renewal of the leather is a simple matter, as the worn facing may be removed by loosening the clamping members and a new facing easily applied. The method of making a pattern for the clutch leather of some of the Overland car models is clearly shown at Fig. 317.

It will be observed that the radius for the inner circle is 3332 inches, while that for the outer arc is 3532 inches. The length should correspond to the circumference of the clutch cone, or 44316 inches. The rough or flesh side of the leather is placed

outside.

Plate and Disc Clutches.-Multiple disc or three plate clutches are subjected to practically the same main troubles as found in the cone type, i.e., they will engage harshly or fail to transmit the engine power in a positive manner. If a multiple disc clutch of the all-metal plate type does not release properly, it is because the surfaces of the plates have become rough and tend to adhere together. The plates should be smooth and free from any rough particles or score marks, as these will always produce harsh engagement. This condition also results if there is insufficient oil or unsuitable lubricant in those types where the discs are designed to run in an oil bath. "Spinning" or continuous rotation of a multiple disc assembly often results from seizing due to gummed oil; the presence of carbon or burnt oil between the plates, and in some cases by a lack of oil between the members. When an all-metal multiple disc clutch slips, this generally results because of reduced strength in the clutch springs, distortion of the plates, or the use of too heavy lubricating oil. To secure the best results from a multiple disc clutch it is imperative that only certain grades of oil be used. If one uses a cheap or inferior lubricant it will carbonize because of the heat present when the plates slip, or it will gum up owing to the admixture of animal fats or other adulterants.

In

In a number of cases faulty multiple disc clutch action is due to "brooming," which is a name given for a defective condition that exists when the sides of the kyeway have become indented and prevent free movements of the plates, or when the plate edges become burred over and prevent full contact of the plates. most cases the adjustment of a multiple disc clutch is easily accomplished by adjusting nuts that may be easily reached if the clutch is of the dry plate type, as shown at Fig. 320, A, which is a representation of the 1914 Hupmobile clutch. The adjusting nut is indicated and there are a number of these carried around the