Did You Know

All you need to know about RPM

Introduction

Have a look at a vehicle’s instrument cluster; you will notice some unknown numbers and gauges. Curious about it? Wondered what is that gauge one labelled RPM? Let us find out the answers to the questions.

Definition

RPM stands for Revolutions per minute. It is the measure of the frequency of rotation. The word ‘per’ means division so RPM is also written as R/M or r/min. 1 RPM means an axle or shaft rotates once per every minute.

In the vehicle’s instrument cluster, the gauge that indicates RPM is known as a tachometer.

Mechanism

RPM is a way to measure how many times per minute the crankshaft in the engine rotates. The tachometer actually measures RPM in thousands, so if the needle is pointed at number 3, that would be 3,000 RPM.

RPM helps you determine how fast your engine is running and when to change the gear. Actually many don’t pay much attention to the tachometer. When you see the needle rising into the red coloured portion, it is not good for your vehicle. You need to shift gears before the RPM goes high.

Advantage

By keeping the RPM low, the engine performs with better fuel efficiency or fuel economy.

Disadvantage

In automatic cars, when the car is driven at high RPM, the health of the car deteriorates because you are forcing the car to make more Revolutions per minute.  Obviously, automatic transmission changes the gear automatically but you need to slowly accelerate and keep the RPM is control as you don’t have the option of changing gears manually.

Relation between RPM and Torque

RPM and Torque are interred related. Torque is the twisting or rotating force that the engine generates. Torque causes the crankshaft to rotate.

torque and rpm
Relation Between RPM and Torque

Every engine of a vehicle has a particular RPM at which it delivers the highest torque.

As the RPM Of an engine increases, torque increases up to a certain value of RPM. Later as the RPM goes on increasing, torque starts decreasing. You can experience this while driving.

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Aman Singh

Mechanical Engineer and a Passionate Writer

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