An automobile is always equipped with two sets of brakes, as they are required by law. The functional action of the brakes is to check the motion of the car when the driver wishes to stop or reduce the rolling speed. The service brake usually operates on the external surface, or on the outside of the drum flange, and is connected to the right foot pedal through a set of linkage. The emergency brake operates on the internal surface of the drum, and connects through linkage to a hand lever operating on a notched quadrant. The service brake is used in ordinary driving to check the rolling motion and to stop the car. The emergency brake is used to assist the service brake and to hold the car, in case the driver wishes to allow it to stand on a grade.

Fig. 124 shows a set of brakes assembled on the axle ready to receive the horizontal flange of the brake drum. The brake drum is attached to the wheel; consequently when a wheel has been removed and is about to be replaced, the first operation consists of starting the drum flange into the space between the lining of the external and internal bands; care should always be exercised in making this adjustment, in order not to burr the outer edge of the lining, as a brake with an uneven frictional contact surface is of little value in checking the motion of the car.

In Fig. 124, A shows the position of the band on the inside of the drum; B shows the contracting tension coil spring which holds the bearing surfaces of the band in contact with the flat surface of the cam when the brake is not in use; C shows the cam shaft, and the flat surfaces of the double action cam, which expands the band and brings it into even contact with the inner horizontal surface of drum flange, thereby checking the motion of the wheel by frictionally grasping the drum.

The service brake shown in Fig. 124 is of the external contracting type, which operates on, or frictionally grasps the outside horizontal surface of the drum. D shows the lined band, which is held in a stationary position from the rear; E shows the leverage arrangement with its expanding coil spring, which holds the band free from the drum, when the brake is not in use; F is the lever to which the pull rod is connected; G is the lever on the internal brake cam shaft to which the hand lever is connected by the pull rod.

Fig. 125 shows a new type of internal expanding brake, which is being used on many of the late models. The brake band in this case is supported at three points and has an adjustment at the rear main point of support. The cam has been done away with, and the band is expanded by a leverage toggle arrangement which operates through a much larger area, and is more dependable as there is no danger of its “sticking” or turning over, as was often the case with the cam.

Fig. 126 shows another type of service brake which may be encountered on a few of the former models. This type of brake is usually located on the propeller shaft at the rear end of the transmission case. This type of brake operates in the same manner as the service brake at the end of the axle.

Fig. 126 shows an equalizer which allows for any difference that may occur in making adjustments.

Fig. 127 shows the complete brake assembly, and the points of adjustment on late Buick cars.

Brake Adjustment.—All types of brakes are adjustable. The service brake usually has two adjusting points, one at the drum, which is made by turning the nut on the leverage pull pin, and another on the pull rods. A long neck clevis, or a long butted turn buckle will always be found on the pull rods, or on the rod leading to the equalizer. The adjustment is made by turning either to the right to shorten, or take up, and to the left to lengthen. The clevis is always threaded to the right, while the turn buckle has a right and left thread which carries each end of the rod into the butt when it is turned to the right. The lock nuts must always be turned up tight to the butts after the adjustment is made in order to hold it.

Brake Care.—A great deal depends upon the proper operation of the brakes. They should be regularly inspected at least once a month for loose adjustments and uncleanliness. The need of adjustment usually occurs from natural wear, while an unclean frictional surface is usually the result of oil or grease seepage through the outer axle bearing. A felt washer is provided to prevent this from taking place, but as these washers are subjected to considerable pressure, they often become caked and hardened and lose their absorbing effectiveness. These washers can be purchased at any accessory store for a few cents apiece, and applied with very little trouble.

Cleaning the Surface of the Brake Bands.—This is accomplished by removing the wheel and washing the friction contact surface with gasoline, after the surfaces have become thoroughly dry. Drop three or four drops of castor or Neat’s foot oil on the contact surfaces of the drum, and replace the wheel and spin it a few times before releasing the jack.

Caution.—After you have set the gears for starting, and before you release the clutch pedal, always reach and make sure that the emergency brake lever is in the neutral position. New drivers invariably forget to do this, which results in severe strain on the bearings, and causes them to get loose; the average brake band will not stand more than fifteen to twenty minutes of continuous contact before it burns or wears beyond the point of usefulness.