Car Gear Indicator

In one of my project I need to display the current gear in which my vehicle is running at that moment and also need to suggest a best preferable gear for that particular vehicle speed to get the best of my motor efficiency. I am finding difficulty in doing so.. need help...Thanks.

by dmcabhi
November 22, 2017

1 Answer

Answer by mikerogerswsm

Assumptions: 1. It is an ordinary petrol-engined car. 2. It is manual shift. 3. You only need to consider running on a level surface. 4. You know the gearing. 5. This is an academic problem with no safety considerations. Put a set of switches on the gearbox to indicate on leds which gear you are in. Monitor the speed with an electronic device. Decide an efficient speed range for each gear. This is usually with the engine running at 2000-3000 rpm. Indicate which gear gives this engine speed.

+1 vote
by mikerogerswsm
November 22, 2017

PS - My speed range of 2000-3000 rpm is for old long-stroke car engines. Modern cars with short-stroke engines tend to be most efficient at 2500-3500 rpm. See: But it doesn't really matter, your prof will accept any reasonable numbers.

by mikerogerswsm
November 22, 2017

PPS - It is reasonable to assume first=0-15mph, second=15-25mph, third=25-40mph and top=40+mph as efficient, but your prof may require you to work these speeds out from gear ratios and wheel diameter. Typically the gear ratios might be first=3.3:1, second=2.5:1, third=1.5:1 and top=1:1. Final drive=4:1 and wheel circumference = pi x d Hence you can translate engine efficient running to road speed in each gear.

by mikerogerswsm
November 23, 2017

Your Answer

You must log in or create an account (free!) to answer a question.

Log in Create an account

Go Ad-Free. Activate your CircuitLab membership. No more ads. Save unlimited circuits. Run unlimited simulations.

Search Questions & Answers

Ask a Question

Anyone can ask a question.

Did you already search (see above) to see if a similar question has already been answered? If you can't find the answer, you may ask a question.

About This Site

CircuitLab's Q&A site is a FREE questions and answers forum for electronics and electrical engineering students, hobbyists, and professionals.

We encourage you to use our built-in schematic & simulation software to add more detail to your questions and answers.

Acceptable Questions:

  • Concept or theory questions
  • Practical engineering questions
  • “Homework” questions
  • Software/hardware intersection
  • Best practices
  • Design choices & component selection
  • Troubleshooting

Unacceptable Questions:

  • Non-English language content
  • Non-question discussion
  • Non-electronics questions
  • Vendor-specific topics
  • Pure software questions
  • CircuitLab software support

Please respect that there are both seasoned experts and total newbies here: please be nice, be constructive, and be specific!

About CircuitLab

CircuitLab is an in-browser schematic capture and circuit simulation software tool to help you rapidly design and analyze analog and digital electronics systems.