page_title: Drum brake
section_title: Brake shoe
hierarchical_section_title: Drum brake / Components / Brake shoe
caption_attribution_description: English: Brake shoe assembly
context_page_description: A drum brake is a brake that uses friction caused by a set of shoes or pads that press outward against a rotating cylinder-shaped part called a brake drum.
  The term drum brake usually means a brake in which shoes press on the inner surface of the drum. When shoes press on the outside of the drum, it is usually called a clasp brake. Where the drum is pinched between two shoes, similar to a conventional disc brake, it is sometimes called a pinch drum brake, though such brakes are relatively rare. A related type called a band brake uses a flexible belt or "band" wrapping around the outside of a drum.
context_section_description: Brake shoes are typically made of two pieces of steel welded together. The friction material is either riveted to the lining table or attached with adhesive. The crescent-shaped piece is called the Web and contains holes and slots in different shapes for return springs, hold-down hardware, parking brake linkage and self-adjusting components. 
  All the application force of the wheel cylinder is applied through the web to the lining table and brake lining. The edge of the lining table generally has three “V"-shaped notches or tabs on each side called nibs. The nibs rest against the support pads of the backing plate to which the shoes are installed.
  Each brake assembly has two shoes, a primary and secondary. The primary shoe is located toward the front of the vehicle and has the lining positioned differently from the secondary shoe. Quite often, the two shoes are interchangeable, so close inspection for any variation is important. 
  Linings must be resistant to heat and wear and have a high friction coefficient unaffected by fluctuations in temperature and humidity.
  Materials that make up the brake shoe lining include, friction modifiers (which can include graphite and cashew nut shells), powdered metal such as lead, zinc, brass, aluminium and other metals that resist heat fade, binders, curing agents and fillers such as rubber chips to reduce brake noise.
  In the UK two common grades of brake shoe material used to be available.  DON 202 was a high friction material that did not require a brake power servo.  The disadvantage was that the lining was prone to fading on steep hills. A harder lining, the famous VG95 was produced but this required a brake servo.  The other snag was that the parking brake would often fail the annual MOT test unless the high friction linings were installed just for the test.
caption: Brake shoe assembly
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