SAE J1807 pdf download
SAE J1807 pdf download.Hydraulic Power Assist Brake Booster Test Procedure.
1. This SAE Standard applies to direct acting hydraulic power assist brake boosters only, of the type which provide ‘push through manual braking of the static brake circuit(s) via a separate master cylinder, in event of inoperative power assistance similar to existing vacuum boosters (SAE Ji 808), for passenger cars and light trucks [4500 kg GVW (10 000 Ib)).
1.1 Purpose—This document specifies minimum test standards for direct acting hydraulic power assist brake boosters of current established designs utilizing mineral oil based hydraulic fluids. It is applicable to assemblies from commercial production and after production shipment.
2. References
2.1 ApplIcable Publication—The following publication forms a part of this specification to the extent specified herein. Unless otherwise indicated, the latest version of SAE publications shall apply.
2.1.1 SAE PUBLICATION—Available from SAE, 400 Commonweafth Drive, Warrendale. PA 15096-0001 SAE Ji 808—Vacuum Power Assist Brake Booster Test Procedure
3. DefinItions—In order to establish and maintain a continuity of discussion throughout this document, the following definition of terms will be utilized. See Figure 1 for illustration of terms as applied to a typical inputoutput force curve.
3.1 Released—The unapplied. fully returned state with no force on the input pushrod.
3.2 Poise—The condition of placing the control valve in a steady-state of force equilibrium so that the hydraulic power assist brake booster is neither fully applied, nor fully released.
3.3 Cut-In—The input force required to actuate the valving and produce an output force.
3.4 Power Slope—The ratio of change in output force to change in input force in the area of performance.
35 Hydraulic Runout Line—The line defined by two or more points on the input-output curve beyond the input force at which all available pressure differential exists across the power piston.
3.6 Hydraulic Runout PoInt—The point defined by the intersection of the power slope line and the hydraulic runout line.
3.7 HysteresIs—The difference between apply and release input forces at a given output force during the power slope.
3.8 Return Cut-Out—The input force at which the output force drops to zero or some specified level during release.
3.9 Boost Pressure—The pressure level from the primary power or reseve supply system acting to apply the power p4stOn.
3.10 Pressure Limiter or Relief—The device used to limit the maximum boost pressure.
3.11 Travel Ratio—The ratio of input rod travel to output rod travel.
3.12 Ratio Changer—The device integral with the booster that is used to provide a travel ratio different than one to one,
3.13 Travel Limiter—A device used to reduce input rod travel losses when above the power runout point of the hydraulic power assist unit.
3.14 Reserve System—An alternate power system of a power assist unit that provides assist in the event the primary system is inoperative.
3.15 Flow Switch—A switch used to provide an electrical signal to a warning or motor in the event of loss of fluid flow,
3.16 Pressure SwItch—A switch used to provide an electrical signal to a warning light or motor In the event of loss of pressure.
3.17 Accumulator-A means of stcwing energy for a reserve system.
3.18 Accumulator Unloading Valve—A mechanism for releasing stored energy from an accumulator.
3.19 By-Pass Flow—Hydraulic ftuid flow directed around the primary flow path to the booster outlet or outlet line.
3.20 Power Boost (When Appllcable)—The output force minus the Input force for a given hydraulic level and with the maximum available pressure differential across the power piston(s). and at 80% of the usable output stroke.
3.21 Initial Rise (When Applicable)—The intersection of a vertical line through the cut-in point and the power slope line.
4. Test Apparatus
4.1 General—The basic apparatus shall be that shown and as arranged In Figure 2. or equivalent. The apparatus shall operate per the following description arid as called for in Section 6. It is desirable to have the test apparatus portable to facilitate cold, hot, and room temperature testing.
4.2 Force Absorbing Mechanism—The force absorbing mechanism shall be connected to the hydraulic power assist brake booster front housing. This mechanism shall be capable of absorbing a minimum of 150% of booster hydraulic runout pornt output force or 17600 N (4000 Ib) output force, whichever is greater. In addition, this mechanism shall be capable of restricting the output force — stroke relationship to the shaded area of Figure 3.
