Do you own a Mercedes-Benz Zetros? Are you experiencing issues with the rear axle? Well, you’re not alone. The problem seems to be a compound one, requiring some dissection. Let’s take a closer look.
The Steering Lock Issue
According to the designer’s video, the steering lock on the Zetros is limited to about 30 degrees to protect the CV joints. However, there seems to be some disagreement on this matter. While the designer claims that this is the best point for the CV joints, others have found that the maximum working angle for these joints is actually around 40 degrees or more. Many applications have been built with this angle, and no problems have been encountered.
The Failure of Ackermann Geometry
In the same video, the ackermann geometry is mentioned as a solution to improve the steering lock. Unfortunately, it does not do the job effectively. Here’s why:
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The angles are not correct for the current distance between the axles. If the wheelbase was half of what it is, the designed angles would be more accurate. However, with the given distance, the angles are too high. In fact, having excessive ackermann geometry is even worse for the steering lock than having no ackermann geometry at all.
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With ackermann steering, the maximum angle is given for the CV joints, meaning that the inner wheel takes that maximum angle. The outer wheel’s angle is lower by definition. As a result, when the angles don’t line up with the wheelbase, one of the front wheels will skid sideways during cornering. Usually, it is the inside wheel with the higher angle that skids. Therefore, the practical steering angle is reduced to what is represented by the outside wheel.
Additional Issue with the Code
Apart from the design issues, the code also presents a problem. When using the PU profile for the first time, there is a calibration process that the motor goes through, taking both endpoints and settling at the middle point. However, during actual use, the maximum angle is lower, presumably to protect the components. Unfortunately, this also decreases the steering angle.
The Solution: Modifications and App Control
Now, for the good news. By making some modifications, you can improve the Zetros’ turning circle. By removing the ackermann design and connecting the steering rods one stud closer to the hub pivots (where they are supposed to be by default), you can achieve a decrease of about 20-30 cm in the diameter of the turning circle.
Additionally, using the BrickController2 app made by @imurvai can further enhance the control of your Zetros. This app does not apply safety measures but instead gives you full control over the vehicle. The end result is a reduced turning circle diameter of 90cm between the inside wheels and 130cm between the outside ones.
Check out this humble demonstration: [link to demonstration image]
We will soon provide a stud.io file for you to use as a reference.
FAQs
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What is the maximum steering angle of the Mercedes-Benz Zetros?
The maximum steering angle of the Zetros is about 30 degrees, as stated by the designer. However, some enthusiasts have found that the CV joints can handle angles of around 40 degrees or more. -
How can I improve the steering lock on my Zetros?
To improve the steering lock, you can consider removing the ackermann design and connecting the steering rods one stud closer to the hub pivots. Additionally, using the BrickController2 app can enhance your control over the vehicle.
Conclusion
If you’re experiencing rear axle issues with your Mercedes-Benz Zetros, don’t worry, there are solutions available. By making some modifications to the design and utilizing the BrickController2 app, you can improve the steering lock and reduce the turning circle diameter. Give it a try and enjoy a smoother driving experience in your Zetros.