Some Volvo Brake Parts

Anthony Fontanelle
October 16, 2007

Volvo brake parts include a host of components that are each essential in providing and supplying the brake system with everything it needs to accomplish its role. Car service brakes that typify a number of Volvo brakes basically work by friction. This is often happens when brake shoes or pad components are rubbed or abraded against brake drums or rotors on the rotating wheel, generating friction. One of the many Volvo brake parts in existence in a number of automotive models is the master cylinder. It is a container that serves as a fluid reservoir as well as a pump responsible for producing hydraulic pressure. The cylinder is operated by a pushrod that is attached to the brake pedal or to the power brake booster. A single chamber master cylinder was used on most passenger cars. At least, on the models built before the year 1968. A dual chamber, on the other hand, was decreed by the law to be installed on 1968 models as well as later ones. A single chamber master cylinder has only one fluid reservoir and one piston. This set-up, though, does not provide sufficient protection as that of a dual chamber cylinder, in the event of a total hydraulic system failure. A dual chamber master cylinder has two fluid reservoirs and two pistons to supply the two separate halves of the dual or split, the hydraulic system. One half of the system operates the brakes for two wheels. Most hydraulic systems are split front and rear so that one half of the master cylinder operates the front brakes and the other half operates the rear brakes. Some systems are split diagonally, however, particularly on compact cars. In a diagonally split system, one half of the master cylinder operates one front and one rear brake on opposite sides of the car. The other half of the master cylinder operates the other to front and rear brakes.

In addition, Volvo brake pads also include drum brake wheel cylinders on some car models. The wheel cylinders change hydraulic system pressure into mechanical force at the brake shoes. A typical cylinder consists of housing, pistons, cups and in some cases, an internal spring along with cup expanders. The double-piston, straight-bore cylinder is the type most commonly used on drum brakes on late US-built and imported cars. Some older US models employed a double-piston, step-bore cylinder. Step-bore cylinders contain the same parts as straight-bore cylinders except that the pistons are of different diameters. Single piston wheel cylinders are used in pars on center plane, or two leading shoe, brakes. They are used, as a single unit on some non-servo rear brakes and on uni-servo brakes. Wheel cylinders must be securely attached to the backing plates and are usually held by bolts or mounting clips. Used with non-servo rear brakes on some imports, single-piston cylinders slide on the backing plates in order to apply force in both directions to both shoes. The clips that hold these cylinders on the backing plates permit the sliding motion while securely holding the cylinder. If the mounting clips grow rusted however, brake operation can be impaired. Most brake designs use pushrods, or shoe links, to connect the brake shoes to the cylinders. On some brakes, though, the webs of the shoes bear directly against the cylinder piston, and pushrods are not used.

Another Volvo brake component are disc brake caliper pistons. On disc brakes, the wheel cylinders are replaced by pistons that operate in bores within the brake caliper assemblies. The caliper bores are connected to the hydraulic lines, and pressure from the master cylinder is applied to the pistons. The pistons, in turn, apply force to the disc pads. Rubber seals and boots seal the pistons in the bores and prevent fluid leakage and contamination. The seals can also serve to retract the pistons when the brakes are released. Disc brake calipers may have one, tow or four pistons, depending on the design of the brake system. Then, of course, there are the Volvo disc brakes at work. These Volvo brake parts were either standard or optional equipment on most late-model cars. Most disc brake systems are a combination of disc brakes on the front wheel with drum rakes on the rear. Several domestic and imported cars, however, have four-wheel disc brakes. There are many variations in disc brake designs, but all are either one or the other of two basic types: fixed caliper or floating caliper. Regardless of design, each disc brake assembly has a rotor and caliper. The caliper assembly will include the hydraulic cylinders and pistons as well as friction pads while the rotor assembly that rotates with the wheel hub, provides the frictional surface. Disc brakes exert a clamping action on the rotor at right angles to the direction of the rotor.

Source:  Amazines.com