ROPS Testing - Structural Safety Test on Tractor Cabin

Introduction

With more than 160 years of experience, Massey Ferguson is one of the world’s leading tractor brands and a force in the global harvesting business. Massey Ferguson has developed a wide range of agricultural vehicles and has a large share of the market across the world, especially in Europe.
 
In 1847, Daniel Massey established a foundry and machine factory making some of the world's first mechanical threshers. In 1953, the company merged with the Ferguson Company to become Massey-Harris-Ferguson and in 1958, the name was shortened to Massey Ferguson, which for more than 60 years, has been the World’s dominant tractor brand.

The AGCO massey Ferguson centre

Massey Ferguson was acquired by AGCO in 1997 and is today one of these companies worldwide brands. AGCO is the world's largest manufacturer of machinery and equipment focused solely on the agricultural industry. The company was founded in 1990 and is headquartered in Duluth, Georgia, USA. Today, it has an annual turnover of around 9,3 billion $ and 20 000 employees worldwide.
 
The AGCO Massey Ferguson Centre of Engineering and Manufacturing Excellence is located in Beauvais to the North of Paris, France. With two sites covering an area of more than 30 ha, it is home to the biggest AGCO-owned tractor manufacturing site in Europe where more than 3000 employees and suppliers work.

The Beauvais plant is a modern tractor production center. Over 915.000 tractors have been built here and nearly 80% of production is exported to over 60 different countries worldwide. Boosted by massive investments in build technologies, tooling, design, and efficiency staff numbers and expertise have grown to generate an output of up to 20,000 tractors a year.

The AGCO Massey Ferguson R&D test laboratory is able to measure & validate every tractor component - engine, transmission, cabin, tools, and whole tractor performances on test benches, or in real drive. The testing facilities include: 

●       Semi-anechoic chamber
●       Vibration test rig
●       Structural test rig
●       Bump Track test
●       PTO Tests Cells
●       Cold Chamber
●       Hydraulic system & component
●       ROPS Bench

Dynamic and static ROPS testing 

A ROPS (Rollover Protection Structure) is a structure - safety cab or frame, roll bars or roll cages - on the tractor to avoid or limit the risks of injuries in the event of a tractor overturn. The structure of the cabin is tested and validated according to ROPS test standards (e.g. ISO 27850) which are mandatory for tractor homologation.

The test consists of simulating the rollover of the cabin during an accident/crash. The structure of the cabin and cab mounts should resist tearing out without interfering with the driver’s security area.

The EU-directive, Directive REG167/2013, establishes that tractors over 800 kg weight can be homologated by using the OECD standard code for the official testing of protective structures on agricultural and forestry tractors (Static 15 test), named CODE 4. Code 4, also describes the function of the protective structure:

“The roll-over protective structure is characterized by the provision of space for a clearance zone large enough to protect the driver when seated either inside the envelope of the structure or within a space bounded by a series of straight lines from the outer edges of the structure to any part of the tractor that might come into contact with flat ground and that is capable of supporting the tractor in that position if the tractor overturns.” – OECD, Code 4, February 2020.

Contrary to the car crash test, the ROPS test is not a “dynamic” test by sending a car into the wall. We use a hydraulic cylinder to push slowly cabin beams in four directions (rear push, side push, rear flattening, and front flattening). By regulating manually the pressure inside the hydraulic cylinder through the piloting system (third-party manufacturer), and knowing its section area, the test operator is able to control the force/displacement and energy injected into the cabin to follow the homologation standard.
 
The Code 4 ROPS test is done in 4 successive phases - a series of 4 loadings with a certain force or energy that the ROPS must be able to withstand. The force or energy applied is depending on the reference mass of the tractor. The test also has to ensure the clearance zone around the driver's position, the seat index point (SIP).

Hardware configuration

• 8 channels data acquisition system DEWE-43A

• 2 analog hydraulic pressures in hydraulic actuators

• 3 analog cabin displacements

• 1 analog inclinometer

• 2 videos web cameras

DEWE-43A is a versatile 8-channel USB data acquisition system with 8 universal analog inputs, 8 digital/counter/encoder inputs, and two high-speed CAN bus inputs, and runs by Dewesoft X software for data acquisition, data recording, and data analysis.

Measurement setup

The test procedure complies with the OECD Code 4 standard. With help of the easy-to-use math formula configuration in the DewesoftX software, we were able to implement directly the different test criteria requested in the official standard. 72 math functions in total are calculated in real-time during the test.

After a series of validations with the official homologation authority, the test procedure and measurement setup of AGCO Massey Ferguson has been now recognized and approved to be used for official cab tests.

The key objectives of applying the Dewesoft solution are to synchronize data from different types of sensors, test bench (force, displacement, pressure), video, and math calculation to see the results directly during the test and validate them quickly.

Future steps should be to pilot the hydraulic power unit and pushing cylinder to automate the test by using the Dewesoft sequencer, IOLITE, and EtherCAT third-party communication…

Conclusion

10 years ago, only 4 parameters were measured - 2 pressures, 2 displacements, 1 calculation - and after the test, engineers should calculate manually the results to know if they fully comply with the standard criteria.

With help of Dewesoft DAQ solutions (DEWE-43A or SIRIUS and DewesoftX software) the customer is now able to record data from more sensors fully synchronized. For example, inclinometers, webcam videos, pressures, and many more. 

With the ability to add unlimited math calculation channels, the customer calculated more than 72 math formulas in real time during the test. A final validation criteria status “Test OK or Not OK” indication is displayed immediately when the test is completed. All data are then used by mechanical/design engineers to improve or validate the simulation models.

The AGCO test configuration and the calculation with Dewesoft are officially recognized by the homologation test authority.

The power of the DewesoftX data acquisition software represents a huge improvement in the ROPS test for AGCO. It saves a lot of time for the cabin development & validation process. AGCO is now considering exchanging the third-party piloting system - or maybe using IOLTE data acquisition systems with EtherCAT communication or analog outputs. This will allow them to have a fully integrated test bench and use the Dewesoft sequencer to automate test steps.

References

• Directive 2003/37/EC of the European Parliament and of the Council of 26 May 2003 on type-approval of agricultural or forestry tractors, their trailers, and interchangeable towed machinery, together with their systems, components, and separate technical units.

• Code 4 OECD Standard Code for the Official Testing of Protective Structures on Agricultural and Forestry Tractors (Static Test), OECD, February 2020.