Combining a new hydraulic brake actuation system with its proven disk brake design, ArvinMeritor has released a “premium hydraulic braking system” for medium-duty truck and bus applications. Available immediately to North American manufacturers for vehicles with GVW ratings between 18-33,000 lb., the new package is said to shorten stopping distances, improve lining life and provide better pedal feel for drivers.
The actuation portion of the system is the Meritor WABCO Hydraulic Power Brake (HPB), which uses electronic controls and internal pumps to provide faster reaction times and shorter stopping distances. The HPB simplifies installation by integrating a number of components in a single, compact unit, including the electronic controls, two pumps and pressure accumulators, four pairs of ABS solenoids, and the parking brake solenoid.
HPB also provides ABS functions without any additional hardware and can serve as the “platform” for other advanced braking features, including automatic traction control and electronic brake force distribution. In addition, the system supports an auto-apply function for its mechanical parking brake, engaging the parking brake when an automatic transmission is placed in park or when the ignition key is switched off. A powered park option is also offered, replacing a hand-operated lever with a dash-mounted parking brake switch.
Future additions to HPB advanced features could include roll and electronic stability controls, according to ArvinMeritor.
The Meritor Quadraulic hydraulic disc brake portion of the new package is a fixed-caliper design with four opposed pistons offered in two sizes. Designed to accommodate 19.5- and 22.5-in. wheels, it features simplified maintenance, allowing brake pads to be changed without removing the caliper. It also features common replacement and wear parts for both sizes.