Vehicle Axles Must Withstand High Forces and Have More Torque Capacity
Sisu Axles manufactures heavy-duty planetary axles for vehicle types ranging from trucks and container handling equipment to military vehicles. Such axles are subject to tremendous forces while carrying heavy loads. Increasing competition among vehicle manufacturers has forced them to make their vehicles more economical and efficient. Therefore, the modern axles that go into these vehicles must be more durable and offer greater torque capacity. To ensure their new axles meet the increasing demands of their customers, the product development team at Sisu Axles needs accurate measurement data.
Inaccurate Measurement Data From an Old Test Bench
Sisu Axles had previously used a test bench that simulated and measured how various loads strained the axles. However, the torque data this test bench produced was not reliable or accurate enough for the team’s needs because it had to be collected from the control system by measuring the electrical output to the inverters.
Sisu Axles rebuilt their test bench by installing the T40 torque transducers from HBM to produce more accurate measurements more easily. The test bench, which allows testing one axle or one axle component at a time, consists of a 193 kW electric drive motor plus two 98 kW electric motors, which act as brakes, replacing wheels. The drive motor represents the vehicle’s engine; the braking machines simulate the stresses caused by the loads from tires. The product development team can change test setup as needed, such as by using the braking machines as drive motors and adding any gears needed to generate a suitable ratio.
Reliable Measurement Results
The T40 torque transducers measure torque from the flanges of the electric motors. The MP60 amplifiers from HBM condition all torque signals from the sensors, which are transferred to the system via an analog output. The T40 is the optimal device for torque measurements in a test bench because It provides reliable measurement results, even in the most extreme conditions, such as those caused by surrounding electric disturbances, vibration and temperature. The small size of the T40 makes it easy to integrate into test benches. The sensors also have good resistance for axial and radial loads. The T40 requires no maintenance because its structure includes no wear parts.
"It is essential for the product development that design data can be verified in a test bench. We can make sure that what has been calculated takes place in practice. With the data we receive, we can save in production costs. Accurate and real-time torque data is extremely important to us,” says Jouni Teppo, director of R&D for Sisu Axles Inc.
According to Teppo, the biggest advantage of the HBM T40 torque transducers is that they offer a sufficiently high level of torque and accurate measurement data. With their old test bench, the measuring error could have been several percent; today, they can achieve 0.05 percent accuracy.
Wireless Data Transmission
According to Teppo, one of the benefits of the T40 torque transducers is that torque data can be transmitted wirelessly from the test bench. The digital torque data signal is transferred wirelessly by telemetry from rotor to stator.
The compact size of the T40 allows it takes up little space in the test bench. Together, the size of the T40 and wireless data transmission capability simplify both transducer installation and test bench operations. Sisu Axles’ new system is also easier to integrate with existing measurement systems and electronics by Fieldbus.
"In addition to accurate data and wireless transmission the third important benefit of measurement solution from HBM is, that it is available all the time. Real-time measurement data is displayed on the PC screen and it can also be stored into the measurement database,” Teppo concludes.
"With the data we receive, we can save in production costs. Accurate and real-time torque data is extremely important to us"
Jouni Teppo, Director of R&D for Sisu Axles Inc.
- Reliable results even in the most extreme conditions
- Easy to integrate into test benches and completely maintenance-free
- Accurate and easy measurements