Brake testing South Africa

ECE90 Brake Testing (Pty) Ltd is a company that was established with the objective of providing a test and certification service for replacement brake lining assemblies. This being primarily to the requirements of the Economic Commission for Europe ECE Regulation 90 but also other national, international and industry specifications used in the brake friction industry.

Thursday, August 17, 2006

Dynamometer test design

by W.S. Scholtz
It is logical to conclude that dynamometer tests will be designed using the ECE90 and VC8053 specifications as a guide. These specifications are specific about the required testing and go as far as to supply the pressures, speeds, temperatures and torque’s required to do the testing.

A test report should supply the required results in a format that would be recognised by engineers world-wide. Such a report is supplied by ECE-90 Brake Testing (Pty) Ltd and is discussed in some detail below.
dynamometer test design

Fig. 2 Dynamometer Results Data Sheet

Test Interpretation

Dynamometer Test Overview

A short overview of the Test Sequence will be presented below, followed by a more detailed explanation of each stage supported by presenting actual portions of the complete test sheet that is shown above. This will assist the reader to have a better understanding when interpreting a test.

Brake pad bedding-in procedure.
In order to do a test the friction surface of the pad need to be bedded-in first of all. This is to ensure a proper contact surface between disk and pad. (For the same reason one should drive careful for the 1st 100 km’s when a vehicle was fitted with new pads. Also see article on Burnishing) There are proposed bedding-in procedures in existence but this portion of the test is not regulated as such. It is therefore up to the manufacturer to specify a specific and suitable procedure. For this reason it is common that a full dynamometer test is used for bedding-in.

Test Preparation.
After the bedding-in cycle the pads are removed from the calliper, weighed and measure for thickness. The pads are then replaced when the weight and thickness measurements as well as the other relevant information have been entered into the control program. (See Fig. 2 above, the General Information call-out.)

3 stops at 30 km/h are then done to heat up the brake pad samples but are not reported on the Test Sheet.

3 stops at 40 km/h are done at the predetermined pressure. The average torque is inserted under Test Results Type-O (40 km/h). (VC8053 & ECE90 requirement) – See plot in Speed Sensitivity area

3 stops at 80 km/h are done at the predetermined pressure. The average torque is inserted under Test Results Type-O (80 km/h) (VC8053 & ECE90 requirement) – See plot in Speed Sensitivity area

3 stops at 120 km/h are done at the predetermined pressure. The average torque is inserted under Test Results Type-O (120 km/h) (VC8053 & ECE90 requirement) – See plot in Speed Sensitivity area

3 stops at 160 km/h are done at the predetermined pressure. The average torque is inserted under Test Results Type-O (160 km/h) (VC8053 & ECE90 requirement) – See plot in Speed Sensitivity area

3 stops then done to calculate maximum pressure values for the Cold Performance Equivalence Test as well as the pressures for the residual performance test. These are not reported.

6 stops are then done at 80Km/h but at increasing pressures for the Cold Performance Equivalence Test. – An ECE90 requirement only.

A further 3 stops are done to determine the pressure to be used for both Fade Tests.

1st Fade Test – 15 repeated stops at regular intervals (eg. 45 sec. intervals from 120km/h to 60km/h.)

1-off residual performance stop to determine the hot performance of the brake pads.

2nd Fade Test – 5 more applications done at similar intervals as 1st fade (A Safeline only requirement.)

2nd residual performance stop (a Safeline requirement)

Steps 4 to 7 then repeated – This is done to see the change in performance after the pads were exposed to a high heat cycle (This is done for information purposes only and is not a requirement)