For example, if you shift to 2nd to 1st, does the rpm jump not because the engine load has decreased and it can spin faster, but rather because it has to work harder than it would in higher gears?
In: Engineering
In a car the engine rate is proportional to the wheel rate and the ratio of the two is determined by the gearing. If you change gears (thereby changing the ratio of wheel to engine rates), either the engine or the wheels need to change rate. If the wheels have grip, they cannot spin at a different rate without slowing or accelerating the very heavy vehicle and so the engine speed must change.
When operating a manual transmission, you will typically use the throttle to adjust the engine RPM before re-engaging the clutch that links the engine and transmission. If you don’t and quickly engage the clutch, the vehicle will decelerate slightly with a jolt as the vehicle’s momentum brings the engine to the appropriate speed. If you have no grip at all, the engine rate will depend almost entirely on the amount of throttle (though there will be some small change due to the momentum of the wheels themselves and the bits that connect it all together).
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