Compared to internal combustion engines, electric drive units (EDUs) enable extremely quiet driving. This makes manufacturers all the more concerned about the noise generated by gears. With the new requirements for “ultra-quiet transmission” and the rigorous reduction in gear tolerances that this entails, it is clear that traditional testing methods do not provide reliable quality control of the end product and, more importantly here, of the noise generated when two gears mesh.

As the world’s leading supplier of end-of-line (EOL) test systems in transmission production, JW Froehlich has developed an innovative production testing system that is capable of identifying defects in individual gears during the manufacturing stage – until recently, such issues could only be detected later, during driving operation (noise development). The customer has requested a test time of less than 35 seconds per test stand, four of which are currently being built for a German OEM. The test part changeover is fully automated – a robot equipped with a double gripper picks up the fully tested gear before immediately inserting a new one into the test stand’s clamping device. This flexible solution facilitates seamless and automatic integration into an existing production line.

A complete measuring system from Discom is also built into the unit – the ideal solution for a rotating gear test stand. This is because, whereas conventional methods can only record the noises made by the test parts indirectly, here the measurement takes place directly while the gear rotates. A torsional acceleration sensor (TAC sensor) is used for this purpose.

The acceleration differences while rolling the test parts against a master wheel are tested under load. A load change makes it possible to examine both flanks (traction and thrust) of the gear. The TAC sensor analysis thereby provides highly accurate information about vibrations, which can indicate possible damage or contact surface defects. The evaluation is performed using software from Discom.

Key requirements for a successful test run on the test stand are an extremely rigid design with highly repeatable geometry in gear contact, good vibration isolation and high-precision mandrels. With its many years of expertise in the field of end-of-line transmission test stands, JW Froehlich offers the expertise required to achieve the best possible results.

Features of the test system

• interchangeable mandrels for test part clamping (mechanical or hydraulic)
• highprecision mandrels with minimal concentricity error (< 5 µm)
• userfriendly master gear change
• uncoupling the measuring sensors from the drive components
• robotic loading
• test part rotation speed 4,000 rpm (or more if necessary)
• drive torque up to 40 Nm (or more if necessary)
• automatic gear centring
• testing space encapsulation, resulting in minimal oil mist carryover
• mechanically rigid design with readily replicable gear contact geometry
  • transmission shaft and main shaft are parallel to each other
  • replicable distance between shafts with identical gear geometry
• special operation (e.g. manual test part insertion)