What is the function of the inboard high ridge on older shoe linings?

The inboard high ridge on older shoe linings serves primarily to prevent contamination of the brake assembly. This ridge acts as a barrier to help contain the brake dust and other debris generated during braking within the brake shoe itself, keeping it from spreading to other components of the braking system. By doing so, it helps maintain the overall cleanliness and efficiency of the brake system, preventing potential failures or performance issues that could arise from contamination. This design feature is particularly important in older braking systems where the integrity of the assembly can significantly affect braking performance.

While enhanced braking power, improved shoe flexibility, and increased durability are valuable attributes, they are not the primary functions of the inboard high ridge. Instead, the ridge's main focus is on maintaining the integrity and cleanliness of the brake operational environment.