This specification defines the requirements for hydraulic brake (jounce) hose assemblies. This hose assembly is suitable for use at temperatures of -40 °C to 120 °C, and operating pressures up to 20.7 MPa.

Material Description.

Hose Construction.

Inner Tube.

The inner tube of the hose shall consist of a smooth inner rubber tube of Ethylene Propylene Diene Monomer (EPDM), or a blend of Ethylene Propylene Diene Monomer and Isobutene-Isoprene Rubber (EPDM-IIR). There shall be no materials in the tube compound extractable through exposure to either DOT 3 or DOT 4 brake fluids, as evidenced by 0 or positive values for volume change when the hose is tested to the requirements of 3.1.3.4 for each of the two (2) fluids, DOT 3 and DOT 4. No halogenated butyl polymer may be added to the rubber of the inner tube.

Reinforcement.

The reinforcement for the hose shall consist of two (2) layers of Polyvinyl Alcohol (PVA) or rayon. A rubber cushion liner may be placed between the two (2) layers of reinforcement. Alternative reinforcement materials may be considered after review and approval by the GM Materials Engineer issuing the specification approval.

Cover.

The outer cover of the hose shall consist of a layer of EPDM.

Coupling Construction.

Coupling Design.

The coupling shall be designed, inserted, swaged or crimped so that no internal tube abrasions, cuts or flaws shall result under any condition or combination of assembly component dimensioning or tolerancing allowed by supplier production specifications or under any condition of rubber hose compression allowed by supplier production specifications.

Corners.

Sharp corners shall be avoided where the coupling contacts the tube to prevent cutting of the hose when subjected to internal pressure.

Tube Insert.

The tube insert must not extend past the end of the crimp shell after crimping, and the end of the tube insert must be radiused to eliminate burrs or sharp edges which might cause hose damage under conditions of assembly vibration or pressure impulse.

Damage.

Damage to hose rubber or reinforcement generated by the crimping of the hose is not permissible under any possible production manufacturing conditions or supplier production tolerance stack-up, including variations in hose compression concentricity.

Tube Collapse.

Metal tube insert collapse during crimping is not permissible, except when this collapse is limited, predictable, controllable and does not increase the potential for assembly leakage or other malfunction.

Design Restrictions.

Grooves, upsets, or serrations are not permitted on the tube stem Outside Diameter (OD), or on the crimp shell Inside Diameter (ID), except that these grooves, upsets, or serrations do not cause hose cutting or other damage under any condition or combination of assembly component dimensioning or tolerancing allowed by supplier production specifications, or under any condition of rubber hose compression allowed by supplier production specifications.

Skiving, Adhesives.

Skiving of the hose is not permissible. Use of adhesives in the crimped joint is not permissible.

Flow Requirements.

The coupling shall be designed for low flow restriction.

Fluid Compatibility.

All hose assemblies supplied to this specification must be compatible with the following brake fluids. Use of these hose assemblies with other grades or types of brake fluid requires complete retest to this specification with those brake fluid(s), for those test procedures requiring the use of brake fluid.

• DOT 3.

• DOT 4.

Material Identification and Marking.

To properly define the hose, the material specification number (GMW3056) is to be referenced. The hose marking must conform to labeling requirements specifying government regulations, such as United States of America Federal Motor Vehicle Safety Standard (FMVSS) 106.

Symbols.

Not applicable.

Applicability.

Hydraulic brake (jounce) hose assemblies.

Remarks.

None.