BENDIX BW7255 User Manual

7

Dragging brakes

See DRAGGING BRAKES

Insufficient lining-to-drum contact:
• Bell-mouthed drum condition

 Replace drum (3,6)

• Poor surface condition of drum

 Rebore or replace drum (3,6)

• Bent brake spider

 Replace spider (3,6)

• Bent or stretched brake shoe

 Replace shoe (3,6)

• Loose wheel bearing

 Torque spindle nuts and check end play (6)

• Worn or damaged camshaft

 Replace camshaft (3,6)

• Improper lining grind

 Grind linings to fit drum radius

Linings tapered across width:
• Bell-mouthed drum condition

 Replace drum (3,6)

• Poor surface condition of drum

 Rebore or replace drum (3,6)

• Bent brake spider

 Replace spider (3,6)

• Loose wheel bearing

 Torque spindle nuts and check end play (6)

Unequal shoe wear on same brake:
• Mismatched lining friction codes

 Correct as required with proper lining (5)

• Worn camshaft or bushings

 Replace camshaft or bushings (3,6)

Glazed linings:
• Unbalanced brake system

 Inspect brake system (2)

• Incorrect lining for vehicle type and service

 Install proper lining (6)

• Dragging spring brake chamber

 Inspect valves and chamber for leaks. Replace air

chamber (4,6)

Scored or grooved linings and drum:
• Improperly machined drum

 Replace or machine drum (3,6)

• Abrasive material between lining and drum

 Remove dirt and debris. Clean drum and remachine

if required (3)

Loose lining:
• Improper rivet size

 Replace rivets (5)

• Improper crimping of rivets

 Replace rivets (5)

• Enlarged rivet holes in shoe

 Replace shoe (3,6)

• Incorrect lining hole size or counterbore depth

 Replace lining (5)

Cracked lining at rivet holes:
• Dirt or rust on shoe table

 Remove dirt and debris. Clean and repaint shoe (3)

• Incorrect counterbore lining size

 Replace linings (5)

• Loose rivets

 Replace linings and check rivet process (5)