what does happen when we change gears in car manual transmission

@sarath49 (762)
India
June 22, 2010 7:51am CST
i was told to lower my gear when ever i reach a turn before slow down. well while driving i found that it is also necessary to lower your gear when you want to overtake someones vehical fast. actually when i lower my gear i find that my car speed increases when i press accelerator at higher rate than at higher gear. but my friend said so that we are gaining pickup and not speed that is when we lower gear and we need not change it when we want to overtake. what does it mean. is it really that i am gaining pickup or that is speed i am ganing.
1 response
@urbandekay (18312)
22 Jun 10
When you lower a you alter the engine speed to road speed ratio; so if the engine is spinning at a constant speed the car will go slower in a lower gear. However, being in a lower gear give you greater mechanical advantage so you can accelerate faster but if you keep accelerating without changing up the engine will reach its maximum revs and you will not be able to go any faster and the engine will be screaming. So, you are confusing speed with acceleration. Speed is a distance travelled per unit of time, acceleration is the increase in speed. By 'pick up' your friend probably means acceleration. Changing down my put your engine revs into the band at which the engine is most efficient and produces more power, this we call the power-band all the best urban