Written by Carsten Frederiksen

Abstract

This application note shows how Dewesoft products provide an effective solution for quick validation of braking parameters in the field. The mobile measurement instruments and the easy to setup software are used for checking braking parameters according to regulations. At the same time, a similar solution is providing the testing tool in case of future troubles.

Man on a red tractor ready to do brake test

Introduction

The client, a huge tractor manufacturer in Austria, is developing and producing farming machinery including tractors for the worldwide market. With increasing performance of the tractors (higher velocity) and new regulations, every tractor has to pass brake test in order to pass the homologation test.

The regulation at the moment is quite basic, in comparison to automotive regulations, because the tractor has to drive either with 40 km/h or 50 km/h (depends on the HP of the engine) and brake to 0 km/h, within a certain distance and achieving certain MFDD factor. At the same time also braking force is a key factor in successfully passing the brake test. It does not include the measurement of the temperature of brake lines and several cycles of braking.

Measurement setup

DATA ACQUISITION SYSTEM

• DEWE-43A Data Acquisition System (8 analog, 8 digital channels, and 2 high-speed CAN bus inputs)

• DS-VGPS-HS GPS Receiver (100 Hz GNSS receiver with the support of GPS/GLONASS)

SENSORS

• Entron force transducer with a range of 2500 N

• Dewesoft brake pedal trigger

SOFTWARE

• Dewesoft X with brake test plugin

display of brake test setup on a car

Brake test setup

In the brake test plugin, we have to choose a proper start/stop condition. In our case, it was the signal coming from the brake pedal trigger and stop of the movement with a threshold value of 1 km/h. Since the tractor was “only” 140 HP, the brake test was performed at 40 km/h. So MFDD, brake distance, stopping time and brake deceleration were calculated for these conditions.

brake test setup in software

Analysis 

The display was created for the easier online indication to the driver if the test is valid or not. Therefore all the parameters (MFDD, Brake distance, Start speed, ... ) were compared to regulation conditions with the help of math channels.

analysis of brake test

Analysis screen

Testing engineers were interested in more details, therefore curves like dynamic braking force and velocity are very important for them.

Graph of analysis of brake test

Conclusion

The measurement of this particular model of the tractor has been successful and the tractor has passed the internal check of regulation. The most interesting parameter for the customer was velocity, where they were able to see the swinging of the cabin, which goes up to 5 km/h and will help them at the future development of stiffness of the suspension. The whole measurement including setup of the tractor took 3 h (including soldering the connectors of special sensors provided by customer and comparison tests).