WORM WHEEL; BNA 227; D3.5

The Automatic Slack Adjuster (ASA) is a vital part of the foundation brake acting as a lever, forming the connection between the actuator & the camshaft.

When the brake is applied the actuator moves the ASA forward. The worm wheel rotates the camshaft, in turn moving the brake lining toward the brake drum & diss-engages when it reaches the drum.

When the brake is released the reacting force drops & the ASA mechanism re-engages. If excess clearance (wear) is in the system, the worm wheel in the mechanism will not return to its original position – it will have indexed.