SWEDISH STANDARD SS 3658 Approved 2003-03-14 Edtion 2 Vägfordon Bromsanpassning av tunga fordonskombinationer med pneumatiska bromssystem Provning med rullbromsprovare Road vehicles Braking compatibility of heavy commercial vehicle combinations with pneumatic braking systems Testing with roller brake tester ICS 43.040.40 Language: English Published: April 2003 Copyright SIS. Reproduction in any form without permission is prohibited.
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Page 1 Contents Introduction... 2 1 Scope... 3 2 Normative references... 3 3 Definitions... 3 4 System threshold pressure recommendation... 4 5 Test equipment... 4 6 Test procedure... 4 Annex A (informative) Report form for roller brake test without printouts... 6 Annex B (informative) Measurement of system threshold pressure Examples of roller brake tester printouts... 7 Bibliography... 9 Page
Page 2 Introduction In the EC Directives (71/320/EEC, Annex II and 75/524/EEC), and the ECE Regulation (R.13, Annex 10), the braking performance compatibility between motor vehicles and trailers is governed by the compatibility bands. The purpose of these compatibility bands is to maintain the stability of a vehicle combination during all braking conditions. In practice there exists a compatibility problem between motor vehicles and trailers in the low-pressure range. The compatibility between motor vehicles and trailers has not only a stability aspect, but also a wear balance or rather a wear optimisation aspect. Wear optimisation and low adhesion utilisation requires much closer tolerances in the pressure range up to 0,2 MPa (2 bar). This improvement in accuracy will be achieved by letting all brakes start to develop force at the same pressure, p t. This second edition cancel and replace the first edition (SS 3658 :2000) which has been technically revised in clause 4 and in Annex B.
Page 3 1 Scope This Swedish Standard describes a method for the evaluation of braking compatibility of heavy commercial vehicle combinations with pneumatic braking systems, by means of a roller brake tester. The standard provides a recommended pressure range of the system threshold pressure for motor vehicles and trailers a recommended practice for determining the system threshold pressure. This standard does not cover high-pressure compatibility. The high-pressure compatibility includes the control of the coefficient of adhesion between lining and drum and is beyond the scope of this standard. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 611 SS 3585 SS-EN 837-1 SS-EN 837-2 SS-EN 837-3 Road vehicles Braking of automotive vehicles and their trailers Vocabulary Road vehicles Heavy commercial vehicles Brake compatibility truck-trailer and tractorsemitrailer Pressure gauges Bourdon tube pressure gauge; dimensions metrology, requirements and testing Pressure gauges Selection and installation recommendations for pressure gauges Pressure gauges Diaphragm and capsule pressure gauge; dimensions metrology, requirements and testing 3 Definitions For the purpose of this Swedish Standard the following definitions apply in addition to ISO 611: 3.1 rolling resistance, A resistance force generated by rolling causing a braking force or torque 3.2 trailer pressure, p m pressure at the coupling head of the control line to the trailer 3.3 brake chamber pressure, p c pneumatic pressure in a brake chamber of a braking system 3.4 system threshold pressure, p t pressure when the braking force or torque starts to increase above the rolling resistance measured as p m NOTE The system threshold pressure should be measured with increasing pressure.
Page 4 4 System threshold pressure recommendation The recommended system threshold pressure measured as p m is p t + 10 + 0, 1 ( 70 ) kpa ( 0, ) bar) =. 20 7 0, 2 5 Test equipment The following test equipment with respectively performance requirements is needed: pressure gauges according to SS-EN 837-1, SS-EN 837-2 and SS-EN 837-3, or equivalent, with an accuracy of ± 10 kpa below 500 kpa and ± 2 % of the measured value, above 500 kpa an adapter to measure control line pressure at the truck or trailer. The adapter shall be capable of fully opening the self-sealing valve. a roller brake tester with a braking force resolution of 100 N or better in the range up to 5 000 N and to 500 N or better, above that limit. The accuracy of the braking force measurement shall be within ± 100 N below 5 000 N and ± 2 % of the measured value, above 5 000 N. a compressed air source with a continuous pressure regulator. The system shall be capable of delivering a maximum pressure of 1 MPa (10 bar), and adjusting the pressure within 10 kpa (0,1 bar) in the range up to 0,2 MPa (2 bar). This source may be the motor vehicle. a device for operating the brakes gradually on the truck and/or trailer is recommended. However, a wellbriefed operator who has a clear view of the control line pressure gauge, may achieve comparable results by applying the brake in the normal manner. 6 Test procedure 6.1 Introduction This procedure sets out a method of measuring the brake pressure system threshold, relative to the coupling head pressure, of a vehicle in the simulated laden condition. Whilst the procedure is based on measuring the system threshold pressures of a laden vehicle or a vehicle in the simulated laden condition, the procedure could also be applied to vehicles in the unladen condition. When load sensing valves are used, they shall have such a characteristic that pressure reduction starts at a brake pressure above the level needed to overcome the resistance of return springs etc. 6.2 Vehicle test Truck The instructions for the roller brake tester to be used shall be checked before applying the procedure below. 6.2.1 Charge the air system to cut-out pressure and fully apply and release the brakes five times. 6.2.2 Install adapter and gauge in the trailer control line (yellow). 6.2.3 Charge the air system to cut-out pressure and set any load sensing valve (if applicable) to the laden condition. 6.2.4 Drive the vehicle so that the axle is on the roller brake tester. 6.2.5 Gradually increase the pressure by operating the service brake starting with the foremost axle.