Internal shoe drum brakes
AssigneeAutomotive Products plc
InventorDuncan W. Osborne
Life of this patent
Estimating the term…
Abstract
The invention relates to internal shoe drum brakes having an automatic adjuster to maintain a substantially constant clearance between the brake shoes and the drum, when the brakes are released. A strut having a variable overall effective length acts between the shoes for automatic adjustment of the clearance and has one end portion connected to one brake shoe through a lost motion device. The lost motion device comprises a main lost motion connection for providing a minimum clearance and a secondary lost motion connection which provides a greater clearance for de-adjusting the brake, and a first spring acts to ensure that for normal service conditions the lost motion device acts through the main connection and the bias of this spring is overcome by manual operative device before the secondary connection becomes operable.
Claims7
An internal shoe drum brake assembly including:
- a pair of brake shoes each having a web thereon;
- a strut acting between the shoes and having a variable overall effective length for automatic adjustment of clearance between the brake shoes and the brake drum when the brakes are released;
- a first lost motion connection means whereby one end of the strut is connected to the web of one brake shoe and which provides a minimum clearance between the brake shoes and the drum;
- and a de-adjusting means associated with said first lost motion means and whereby said minimum clearance can be increased,
- and said de-adjusting means comprises a second lost motion connection having a greater clearance than said first connection means;
- and a first spring acting perpendicularly to the web of the one brake shoe to bias the strut towards said web so that for normal service conditions the strut is connected to said one shoe by the first lost motion connection, and the bias of this spring must be overcome by manual operative means insertable through a hole defined in the drum brake assembly, during servicing of the brake, before the strut is connected to said one shoe by the de-adjusting means.
Dependencies are inferred from the claim text.