![]() Peak friction coefficient or PFC means the ratio of the maximum value of braking test wheel longitudinal force to the simultaneous vertical force occurring prior to wheel lockup, as the braking torque is progressively increased. Parking mechanism means a component or subsystem of the drive train that locks the drive train when the transmission control is placed in a parking or other gear position and the ignition key is removed. Maximum drive-through speed means the highest possible constant speed at which the vehicle can be driven through 200 feet of a 500-foot radius curve arc without leaving the 12-foot lane. (b ) For vehicles with a GVWR greater than 10,000 lbs., unloaded vehicle weight plus 500 lbs. or less, unloaded vehicle weight plus 400 lbs. (a ) For vehicles with a GVWR of 10,000 lbs. Initial brake temperature means the average temperature of the service brakes on the hottest axle of the vehicle 0.2 mi before any brake application. Indirectly Controlled Wheel means a wheel at which the degree of rotational wheel slip is not sensed, but at which the modulator of an antilock braking system adjusts its brake actuating forces in response to signals from one or more sensed wheels. Hydraulic brake system means a system that uses hydraulic fluid as a medium for transmitting force from a service brake control to the service brake, and that may incorporate a brake power assist unit, or a brake power unit. Each modulator may also adjust the brake actuating forces at other wheels that are on the same axle or in the same axle set in response to the same signal or signals.Įlectric vehicle or EV means a motor vehicle that is powered by an electric motor drawing current from rechargeable storage batteries, fuel cells, or other portable sources of electrical current, and which may include a non-electrical source of power designed to charge batteries and components thereof.Įlectrically-actuated service brakes means service brakes that utilize electrical energy to actuate the foundation brakes.įull brake application means a brake application in which the force on the brake pedal reaches 150 pounds within 0.3 seconds from the point of application of force to the brake control. (3 ) Transmitting those controlling signals to one or more modulators which adjust brake actuating forces in response to those signals.īackup system means a portion of a service brake system, such as a pump, that automatically supplies energy, in the event of a primary brake power source failure.īrake power assist unit means a device installed in a hydraulic brake system that reduces the operator effort required to actuate the system, and that if inoperative does not prevent the operator from braking the vehicle by a continued application of muscular force on the service brake control.īrake power unit means a device installed in a brake system that provides the energy required to actuate the brakes, either directly or indirectly through an auxiliary device, with the operator action consisting only of modulating the energy application level.ĭirectly Controlled Wheel means a wheel for which the degree of rotational wheel slip is sensed, either at that wheel or on the axle shaft for that wheel and corresponding signals are transmitted to one or more modulators that adjust the brake actuating forces at that wheel. (2 ) Transmitting signals regarding the rate of wheel angular rotation to one or more controlling devices which interpret those signals and generate responsive controlling output signals and (1 ) Sensing the rate of angular rotation of the wheels ![]() This standard applies to multi-purpose passenger vehicles, trucks, and buses with a GVWR greater than 3,500 kilograms (7,716 pounds) that are equipped with hydraulic or electric brake systems.Īntilock brake system or ABS means a portion of a service brake system that automatically controls the degree of rotational wheel slip during braking by: The purpose of this standard is to insure safe braking performance under normal and emergency conditions. This standard specifies requirements for hydraulic and electric service brake systems, and associated parking brake systems. 105 Hydraulic and electric brake systems. ![]()
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