Question

Discuss a technical problem you have experienced with a device, equipment or vehicle in form of a story (one paragraph).

Note: you have to follow the problem solving checklist as follows:

1. User's observations

- nature of fault

- circumstances of faults

external factors

2. Process of elimination

3 - Identify the failure

4 - Determine action and urgency

Please Solve As soon as
Solve quickly I get you two UPVOTE directly
Thank's
Abdul-Rahim Taysir

Answer 1

An All Terrain Vehicle was being manufactured by our college to participate in SAE BAJA. In the competition, there was a rule that the buggy shouldn't crawl (crawling is the buggy moving immediately after turning on the engine without pressing the accelerator pedal). The drive train of the buggy is as follows. The engine is equipped with a CVT (Continuosly Variable Transmission) which is connected to a reduction gearbox. The gearbox is connected to axles, through which, the power is transmitted to wheels. There will be a spring in CVT, the tension in which we should adjust to tune the CVT with max torque characteristics of the engine. On the day of testing, suddenly the buggy started to crawl. The entire crew panicked. So, we decided to resolve. By normal inspection, we were convinced that there was no issue at axles and reduction gearbox. So, there has to be an issue at CVT. We immediately disassembled the powertrain and removed the belt that connects the two pulleys of CVT. Then we started the engine again. We noticed that the CVT was engaging to engine at lower rpms. With the help of tacometer, we realised that the CVT was engaging to the engine at 1300rpm. But engine without any acceleration runs at 1500rpm. So, the CVT should engage to the engine at rpms higher than 1500, preferably 1800 rpm. So, that CVT engages to engine only when accelerated. After some discussion, we came to a conclusion that the tension in the spring of CVT might be altered because of an unknown reason and this is causing the CVT to engage at lower rpms. We immediately removed the CVT from the engine and opened the CVT. We noticed that the additional washers that were kept along with the spring to keep it in tension were missing. We enquired about it and came to know that juniors who were asked to clean the buggy, the day before the testing as the area was full of dust and our buggy got dusted as well. The juniors removed each and every part of the buggy and cleaned it. Apparently they didn't knew the importance of the tension in the spring. So they thought that the washers werent that important and removed them completely. We immediately kept new washers in the spring slot and assembled the buggy. The buggys wasn't crawling after that. We tested the buggy successfully.

1)Users Observations : The buggy started moving immediately the engine was turned on which is called crawling. It would be difficult for the mechanics working on the track and on the wheels if this happened. So, the authority considered crawling critical. Our Buggy was crawling

2) Process of elimination : We started analysing the core of the problem. We knew that the problem is in drive train. So, we started checking the wheels, axles, reduction gearbox. After concluding that they are all fine, we realised that the problem is in CVT.

3) Identify the failure : We realised that CVT is enaging to engine at lower rpms. We concluded that there could be a problem with the spring. We opened the CVT and the washers were missing.

4)Action and Urgency : We immediately replaced the washers and reassembled the buggy. If the buggy crawls, it would be very difficult for the people working on it in the manufacturing stage. There was also a rule in the competition that the buggy shouldnt crawl.