This code is intended for commercial vehicles over 4500 kg (10 000 lb) with brake systems having typical service pressure ranges 0 to 14.1 mPa (0 to 2050 psi) hydraulic or 0 to 830 kPa (0 to 130 psi) air and is not directly applicable to vehicles with other systems. Air over hydraulic systems are to be tested as air systems.

This SAE Recommended Practice is intended to provide a uniform means of identification which may be used to classify the friction coefficient of brake linings, based on data obtained from tests conducted in accordance with SAE J661 Brake Lining Quality Test Procedure and SAE J2975 Measurement of Copper and other elements in Brake Friction Materials.

NOTE: It is emphasized that this document does not establish friction requirements for brake linings, nor does it designate significant characteristics of brake linings which must be considered in overall brake performance. Due to other factors that include brake system design and operating environment, the friction codes obtained from this document cannot reliably be used to predict brake system performance.

This SAE Recommended Practice establishes a uniform procedure for the level road test of the brake systems of new light-duty trucks and new multipurpose passenger vehicles¹ up to and including 2700 kg (6000 lb) GVW and all classes of new passenger cars.

This SAE Standard applies only to new winches which are primarily designed for intermittent pulls and lifts and whose configuration and condition are the same as when they were shipped by the manufacturer. They are not intended to be used in any manner for the movement of personnel. They may be driven by any power source recommended by the manufacturer and will be capable of being powered in either direction. They will be equipped with an automatic safety brake system to control a load when lowering under power and positively hold a load when power is not being delivered to the winch. A hydraulic flow control valve or similar device may be used in the brake system to control a load when lowering under power. A clutch to release the drum for “free-spooling” may be provided and will be designed not to disengage itself under load. A drag brake may be provided to control “free-spooling,” but will not be relied on to control or hold a load. Power sources, such as hydraulic motors, even though they may be supplied or recommended by the winch manufacturer, are not considered a part of the winch so far as this document is concerned, except to whatever extent they are a part of the brake system.

This recommended practice shall apply to all on-highway trucks and truck-tractors equipped with air brake systems and having a GVW rating of 26 000 lb or more.

The vehicle dynamics terminology presented herein pertains to passenger cars and light trucks with two axles and to those vehicles pulling single-axle trailers. The terminology presents symbols and definitions covering the following subjects: axis systems, vehicle bodies, suspension and steering systems, brakes, tires and wheels, operating states and modes, control and disturbance inputs, vehicle responses, and vehicle characterizing descriptors. The scope does not include terms relating to the human perception of vehicle response.