Engineering

In addition to testing and measuring services, developing transmissions, as well as distributing relevant test stands, robots and measuring systems, ATESTEO offers support for the functional development of transmissions as well. The functions of a transmission are defined as those characteristics that facilitate the desired transmission use in the vehicle, according to customers’ expectations. ATESTEO offers support in the following four areas:

  • Specifications / function objectives
  • Reviews concepts/designs
  • Verification / benchmarking
  • Analyses of function deviations

The benefits we can build on are ATESTEO’s exceptional test benches availability options, their in-house measuring technology and the tools for developing test benches. This will help to expand our knowledge base and tools for the deduction, definition and calculation of gear and transmission functions.

Specifications for Gearboxes/Systems

Producing targets/specifications for gearboxes/systems in terms of the definition of functions/properties

An effective development of gearboxes requires that the properties or functions are defined that the gearboxes under development will subsequently achieve.

  • Basic functions, for example, gear ratios, switching capability, accessibility, management and adjustment capability
  • Service life and robustness
  • Secondary functions, for example, rigidity/play, efficiency ratio, vibrations, noise, cooling

Variables have to be defined based on criteria and basic conditions that can be tested objectively. It is therefore possible to check in the subsequent development phase to what extent these targets have been achieved. These targets are derived from the designated purpose of the vehicle or vehicle family, for which the gearboxes are intended. Generally, several scenarios are run through, as a vehicle’s targets are often achieved in a variety of ways.

The resulting targets are often contradictory at the start and therefore have to be agreed with the assumptions for the design concept in terms of their compatibility. Benchmarking of comparable gearboxes is often very helpful, so that no illusory targets are set during planning. As soon as agreement is reached between the vehicle’s goals, the design concept for the gearbox and between each other with respect to compatibility, these are documented and defined in the specification for the gearbox.

Typical work in this area:

  • Calculation of the gear ratios and power train targets etc. in terms of drive performance and consumption.
  • Investigation of the influencing parameters of the gearbox and the drive train to achieve targets in terms of switching capability and driveability.
  • Definition und agreement of criteria and basic conditions to ensure that the gearbox can be reliably managed through the intended control modules and strategies (controllability, adjustability under all the relevant operating conditions as well as wear and tear).
  • Production and adaptation of load collectives and test specifications to guarantee that evidence can be provided of the reliable and robust function of the gearbox over the service life at the subsequent customer through suitable tests during and at the end of the development.
  • Production and documentation of interface functions between gearbox and mounted parts to safely achieve and test the overall functions of the drive train.

Evaluations

Supporting drive developments to guarantee functional targets

  • Break down the targets of the overall gearbox into the targets for the individual gearbox systems
  • Evaluate the gearbox designs in terms of achieving the overall gearbox targets
  • Studies comparing design concepts with respect to achieving the targets of the overall gearbox
  • Benchmark comparable gearboxes in terms of design concepts and function of the overall gearbox

While the gearbox is being developed, design engineers conceive and design the individual components of the gearbox in the typical phases. The functional development supports these phases to ensure that the overall targets agreed for the gearbox are met. To achieve this, the necessary interaction of the individual components of the gearbox are adapted for the overall targets and checked. The requisite design targets are then agreed and documented with the design engineers for the relevant individual components.

Special functional tests are defined to complement or replace existing ones (in case a calculation with the required accuracy is not possible), in order to make a reliable statement available about achievement of the targets for all the development phases. The typical tools that are usual in design are used for the work processes described (FMEA, DVP, 8D, approval documentation etc.).

Typcial work in this area:

  • Development of computer models or special test benches for simulating or testing agreed functional targets.
  • Application of the usual working materials and processes as part of development specially geared towards achieving and checking functional targets.
  • Risk assessment of design alternatives with the aim of ensuring the attainment of agreed targets.
  • Reassessment of the agreed targets for individual components, if incompatibilities arise, putting achievement of the functional targets at risk.
  • Production of approval documents for each agreed development phase.
  • Plan/support/implement functional tests for each development phase with subsequent analysis and evaluation of the test results.

Verification

Benchmarking and verification of the gearbox functions

  • Production of measurement and test specifications for testing/comparison (specification)
  • Production of special test facilities for functional tests
  • Carry out functional tests (vehicle, gearbox and system)

The successful achievement of functional targets for the gearbox depends upon it being possible to test achievement of targets objectively and technically. In many cases, test equipment is required for this purpose, in which the gearbox can be activated or subject to stress, detached from the drive train under laboratory-type conditions. This enables the gearbox’s relevant functions to be tested in isolation. On this basis, targets can be tested with the necessary accuracy and repetitions or design alternatives compared to enable reliable decisions to be made during development.

Alongside knowledge of the function of the gearbox under investigation, experience of the specification, development and operation of test benches and measurement systems is required. Only in this way is it possible to ensure that the necessary accuracy is achieved in the measurements and tests with the requisite efficiency. Implementing benchmark studies also requires that alongside the objective measurement of the relevant gearbox functions, further analyses can be made to be able to work out how the function was achieved.

Typical work in this area:

  • Development of specifications to measure and test gearbox functions, so that the various gearboxes or design concepts may be reliably compared with one another and with the selected targets.
  • These specifications must be compatible with the available resources to apply stress, activate and measure gearboxes, to enable high quality and affordable results with the given technologies for the test benches and vehicle tests.
  • Planning, development and commissioning of special testing equipment, as well as adaption of existing test benches to carry out tests and measurements based on the relevant test specifications.
  • Preparation/support/implementation and analysis of such tests and measurements for benchmark studies or as part of development projects.
  • Especially for benchmarking: analysis of the gearbox under investigation to make a statement about how the gearbox’s measured or tested function has been achieved.

Analyses

Analysing problems in the event of functional deficiencies in gearboxes

  • Use of special measurement and analysis techniques
  • Use of special test benches and test specifications (conditioning)
  • Simultaneous, complementary use of calculation tools and tests

The tools and processes of the functional development enable problems to be analysed effectively, in the event of functional deficits, which only become apparent during application at the customer. In the first instance, the vehicle’s functional deficit is transferred to a gearbox test to define and make it possible to test a functional deficit or a new functional target for the gearbox. The development of a suitable test and measurement specification and test equipment may be required. The intention is to verify the necessary function to the required accuracy.

Influencing parameters for the functional targets concerned are devised and investigated for the functional target with the help of special measurement techniques and/or computer models. Design alternatives can be run through based on an understanding of causal relationships involved in the gearbox’s functional deficit, which are implemented with the help of simulations and tests. The calculations and tests should be used in addition, so that the benefits can be used to positive effect.

Based on the definition of the solution concept for the gearbox, a critical investigation of all previously achieved gear targets is generally required, as the necessary changes may also have a bearing on these.

Typical work in this area

  • Carrying out tests and measurements on the vehicle to be able to determine relevant operational conditions with the gearbox in terms of the functional deficit.
  • Development and adaption of test equipment and measurement technology for the gearbox to be able to record the functions under the operating conditions.
  • Use of special calculations and measurements to explain the causal relationships of the malfunction – development of the relevant properties of the components.
  • Development of alternative design concepts that promise/allow the malfunction to be rectified. Verification of the function achieved by modifying the test item.
  • Evaluation of alternative design concepts in terms of the risks to the functional targets already achieved and with respect to verifying the necessary expenditure.
  • Development of a decision matrix with the inclusion of the teams responsible for the design and for implementing the necessary verification work for approval, as necessary.