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MULTIBESTOS HANDBOOK . FOR BRAKE SERVICE EXTERNAL BAND BRAKE Fig. I 22 THE external bead type of brake has not been generally used on new car production since 1928. How ever, it ii (till quite common, and both mechanically and hydraulically operated sys tems are in daily use. The above diagram ia typical of the mechanical type external brake and, although various shapes and designs of lever arms and anchors are used, the principle is the same. The adjustment for either mechanical or hydraulic type is practically the tame, and the clearances shown above will give best resulta tinder most conditions. The exter nal band brake require# a friction material of the type such as Multibestos Busduty or Multiduty moulded-woven brake lining. MULTIBESTOS HANDBOOK FOR BRAKE SERVICE External Band Brake Adjustments 1. Check linkage. Release until just free. Fit brake (a) Pedal rod. rods to that adjustment. (b) Cro* shafts. Check by applying flight pre>?ure to (c) Equalizers. brake pedal and adjurt at point* (B) (d) Pull rods and cables. and (C) until both ends of band ap (e) Lever arms back against stops. proach brake drum at the lame time. 2. Disconnect rods at the operating Equalize brakes by making adjuat- cams on each brake. 3. Adjust nut at point (C) until band drags slightly against drum at operattng arm end of band. C. Adjust clearance at (A), pushing J |i !.' mcnts on t?u* brake rod. The above nn-'hod of adjustment will, in all nrob.ibrb'y. give final clearances between the chum and the lining of ap* proximnieiy /.*i j". However, due to cer* band across the drum until the drag \\ tain variations, these clearances may not previously felt at operating arm end *i be equal, but by *be above adjustment of band is relieved. you are assured of an even acting brake 5. Turn nut (B) until slight drag t9 felt. j at all times. Average time required for a complete four wheel reline--4-5 hour*. Maintenance Suggestions Where hard pedal ia a chronic complaint on externa! band brake systems, it i* poaaible in (ome caBea to change over the leverage system to cure this. In the case of all four wheel external Buick brake jobs this can be easily done as follows: 1. Remove brake rod that connects brake pedal to equalizer from the lower hole at the pedal to the upper hole provided for just this purpose. 2. On levers, attached to the frame, which control the front brakes change the relative positions of the brake rods that run to the cross shaft and the cablet that run to the front brakes so that the cables are connected to the Upper hole and the rod to the cross shaft is in the lower hole of the lever. This method gives more brake on the front wheels and consequently easy pedal. Another method of accomplishing the same effect is by drilling a new hole in the equalizer one inch nearer to the left frame of the cam than the present hole. The puff rod running from the brake pedal should be connected to the new hole. A greater pull will then be exerted on the cross shaft that controls the front brake, and accordingly an easier pedal will be required to obtain a suitable atop. When brake is applied the operating lever should be in auch a position that lever arm pin and yoke clevis pin will line up with the center of the axle. See Pig. 1. Bend operating lever with wrench to aecure correct applied position and check to see that lever on each brake is in the same relative position. Tbis assures an. easy pedal. To obtain a freer hinge action always cut out lining at anchor, chamfering the ends to reduce noise. If clearance between band and drum is too small or uneven, frictional heat may expand the brake drums causing the brake to drag. Out-of-round bands cause high spots which may result in dragging brake* or squealing brakes. Always reform refined bands, taking care not to twist them. On external brakes the lining is more exposed to dirt and water and requires more frequent cleaning. Excessive squeal, chatter, and groans may be eliminated by bending the foe ends of band slightly away from drums. Oiling the mechanism at points A, B, C. and the operating fever arm pins will tend to eliminate brake noise and increase brake efficiency. Squeal is also caused by distorted backing plates or bands, too hard lining, scored or eccentric drums, dirt on lining, etc. More than .005" clearance between anchor bracket and saddle allows the band to distort when brakes are applied. Closing up to correct clearance may be done by hammering or in a vise. In certain cases where externa) band brakes have given good performance when dry and have resulted in no brake when wet. out-of-round drums with low spots on the drums have very of'en been found to be the cause of this trouble. Turning the drums, taking a slight cut only, will overcome this d'fficulfy. Poor wet weather performance is sometimes caused by the toe of *he lining forming a small pocket in which the water gathers. We suggest cutting ail enda of lining in a V shape so that the water and mud can escape. 23