All hydraulic foundation brakes are disc brake type. The Dayton-Walther rail slider type disc brake caliper is used on the 15,000 lb rear axle. All other axles use the Bendix® rail slider type disc brake caliper.

The front and rear disc brake assembly consists of the following components:

The brake rotor is bolted to the front hub or wheel. The rotor turns with the tire and wheel assembly. The brake caliper housing has machined bores and pistons. A seal in a groove of the wall in each bore provides a hydraulic seal and retracts the piston when fluid pressure is relieved. A dust boot keeps the piston bore clean. A metal heat shield protects the dust boot from the heat caused by braking friction. The brake caliper is mounted by a brake caliper retainer and the brake caliper retainer spring to the stationary brake caliper mounting plate. The brake caliper mounting plate and the brake shield is bolted to the steering knuckle.

The brake pad assemblies are held in place on each side of the brake rotor. The outer brake pad moves with the brake caliper housing. Depending on axle size, the inner brake pad is held in place by either the brake caliper mounting plate or the brake caliper housing. All original equipment brake pad linings are asbestos free.

Applying the brake pedal causes hydraulic pressure to move the brake caliper pistons. This causes the brake pads to clamp the brake rotor. The brake caliper adjusts its clamping position by sliding laterally in the support rails on the brake caliper mounting plate.

Releasing the brake pedal relieves the pressure applied to the brake caliper pistons. The pistons are pulled back in the bore by the action of the square cut piston seals returning to their original shape. This allows for a running clearance between the brake pad linings and the brake rotor.

The disc brake rotor is bolted to the hub assembly. The brake rotor turns between the brake pads, basically free-wheeling until you apply the brake pedal. Applying the brake pedal creates hydraulic pressure, which the brake caliper converts to a stopping force. This force acts equally against the pistons and the bottom of the fixed-type brake caliper bore, moving the pistons outward and clamping on the brake rotor. With a rail slider-type brake caliper, the force also acts equally against the pistons and the bottom of the caliper bore sliding the caliper inward, and clamping on the brake rotor. The clamping action of either caliper type forces the brake pads against the rotor, stopping the vehicle.

The front brake caliper is a rail slider type with dual pistons. The rear brake caliper is either a dual-piston rail slider-type, or a fixed-mount-type with four pistons. A piston seal, in a groove of the wall in each machined bore, provides a hydraulic seal. The piston seal also retracts the piston when hydraulic fluid pressure is relieved. A dust boot keeps the caliper bore clean. A metal heat shield protect the dust boot from the heat caused by braking friction. A brake caliper retainer, brake caliper spring, and brake caliper retainer bolt hold the rail slider-type caliper to the brake caliper mounting plate. The fixed-mount-type rear caliper bolts directly to the brake caliper mounting plate.