The condition of the brakes on commercial vehicles must be perfect, that´s why it´s extremely important to perform a complete maintenance of the brakes. To conduct an exhaustive check is necessary to disassemble and assemble the braking system. In this edition, we are going to explain the most important steps on the disassembly stage:
- Verify that the all shoes have an even wear. If not, it is possible that some components are failing or adjusted incorrectly.
- Examine the pushrod stroke at 90 to 100 psi reservoir pressure. Pay special attention for extremely short or long strokes, possible signs of problem.
- Inspect if there is an oil seal leakage before taking off the wheels, which would be a signal of bearing wear and/or adjustment or seal problems.
- Check the heat on the lining surface. Excessive heat could mean that an improper lining is being used, it is overloading, all wheels are not braking uniformly, or a mix of these factors.
- Inspect the lining wear through every shoe, as disproportionate grooves and irregular pattern could mean that is necessary to replace the drums.
- Examine the drum surface for heat checking, glazing and/or even wear. Signs of cracks, blue spots and heat checks mean excessive heat. It is recommended to not reutilize a drum if there are hard spots, various heat checks are lined up across the braking surface, or the wear is up to .080.
- Check if there is oil or grease on the lining surface. Do not reutilize an oil-soaked or grease brake shoe, because the presence of oil or grease on the friction material may produce the lining to glaze and compromise its role in the braking.
- Inspect s-cam for wear at the interior and outside of the bushing surfaces and spline areas. The wear of those can assist to longer than usual pushrod stroke.
- Verify that the brake adjuster have the correct settings and operation. Inspect anchor brackets and clevis pins for wear. Do not mix manual brakes adjusters with automatic ones, operate with worn components or utilize, on the same axle, various brands of brake adjusters.
- Inspect if the front and rear axle shoes have different wear, which could indicate different rated friction materials and air timing imbalance.
Don´t miss the next edition with the brake assembly recommendation.