Monitoring Practical Tests
The Hyster-Yale Group (HYG) factory on the industrial estate near the canal harbours in Nijmegen, Netherlands, manufactures Hyster heavy forklift trucks on two production lines. These trucks have been designed for lifting and moving heavy loads weighing from 8 to 52 tonnes. The dynamic in sectors such as industry, transport and logistics makes the continuous development of new models necessary, with improvements in payload, lifting height, lifting speed, energy consumption, maintenance-friendliness and safety being the principal driving factors. Product development and validation occur entirely in house at Hyster. HBM supplies HYG with measuring sensors and data acquisition equipment for monitoring practical and endurance tests.
Product development at Hyster in Nijmegen takes place according to a fixed plan and is carefully recorded. The process is continually adapted in line with clients’ changing preferences, new working methods, new technology and new regulations. Every new model is developed in a full CAD/CAM environment and tested using simulations. The extent to which a new model can differ from existing ones can vary. It can be partly based on an existing model, with improvements to a number of crucial parts, or an almost entirely new model can be developed. The basic assumption in every case is that a new model has to go into series production, whereby the number made can vary. Over 2000 trucks are built in Nijmegen every year, making Hyster the market leader in the heavy forklift truck segment. The company also produces client-specific solutions such as attachments for lifting specific loads.
A first prototype is built once the virtual design of a new model is complete and is 95% ready for production. This prototype is subjected to extensive practical testing on the in-house test site. The forklift undergoes clearly-defined test cycles in order to validate the design, test the construction and the parts and measure its performance. Client input and feedback are included during this phase. More prototypes are built after the test phase and further development, and selected clients test them in practice for a number of months. A model is ready for series production in the Nijmegen factory only after these tests have been successfully completed. Two production lines are set up for assembling the trucks. One line is for the high-volume segment in a range from 8 to 16 tonnes and the other is a low-volume line in which heavy models up to 52 tonnes are assembled. The first models off the line undergo extensive quality testing.
“We aim for zero defects during production. That is why the entire process of product development, engineering and testing is precisely defined. If faults creep into the development process, costs can rise rapidly. That’s all right in the engineering phase, but the cost of correcting design faults we discover in the prototype before the practical tests can increase to a considerable level.”
Mark Janssen, reliability test leader at Hyster
“We set very high requirements for the forklift trucks, because they are used in industrial environments for especially tough work”, explains test engineer Rob van den Brink. “Our latest prototype can lift two stacked sea containers. Aspects such as ride characteristics, turning circles, stability and lifting capacity are studied in simulations during the design phase. The practical tests are of crucial importance in examining the behaviour of the forklifts in the physical working environment. We look there at aspects such as useful life, reliability, i.e. the number of hours a truck can be used problem free, sturdiness and maintenance-friendliness. The number of tests a truck and its components are subjected to is huge. We test axles, exhaust systems and tyre wear. We perform braking tests when laden and hose tests for the hydraulic system. Laden forklifts are placed on tilting platforms in order to determine the longitudinal and lateral stability of the load and the counterweight on sloping surfaces. The mast, including the hydraulic system, undergoes endurance testing in a special test rig on site and, furthermore, trucks are subjected to loads in excess of their actual capacity. Additional safety measures are taken in this instance, of course. We also look at the effect of environmental factors such as dust production and temperature, which can affect engine performance and the viscosity of the oil in the hydraulic system.”
HBM has been one of the suppliers of test and measuring equipment to the Hyster-Yale Group since the nineteen-nineties. Among the items it supplies are strain gauges for measuring the loads on chassis and masts. Hyster also uses various Somat and QuantumX data acquisition systems from HBM, which are used for acquiring and processing a large quantity of data. HBM nCode software is used to process and analyse the measurement data.
Van den Brink: “HBM measurement amplifiers are compatible with virtually all measuring sensors and measurement equipment from other suppliers. We connect not only strain gauges but also laser sensors, load cells for measuring tensile forces, and angle sensors and displacement sensors for measuring the height and position of the mast. We also monitor fuel consumption, the oil pressure in the hydraulic system, operation and the steering system, and we collect GPS data. With the Somat eDAQlite we can collect, process and report on 95% of all the test data during the practical tests. The eDAQlite is IP certified, which means it is extremely sturdy, and furthermore it is a small, handy box that is highly suitable for building into test models. It takes the measurement data from the sensors and communicates with the forklift truck’s CAN bus controller for all forklift truck data. We store the data in a data logger or send them via a wireless modem to a notebook at the test site or directly to a PC in Nijmegen. The data link is very reliable, so we can even send the measuring equipment to clients in the USA for carrying out endurance and practical tests there.”
“We deliberately use all the facilities for testing and measuring. In this way R&D receives enormous amounts of data to validate the design and to monitor performance in practice. If we need information from an R&D point of view, we collect it in any way we can. We even take systems from forklifts apart, including items such as engines and hydraulic and braking systems, to see how they have lasted the tests and how wear has developed. If we wish to develop a new model for a client we can use the client data for developing new applications, and the data help us in simulating the correct test conditions.”