general question, engine bogging

[max29a]

Still very much a newbie here. I bought a book on how combustion engine vehicles tend to work in order to understand more about my car.

I was wondering what exactly is going on in the engine and possible with the tranny when you are in too low of a gear for your speed. When you try to start from a dead stop in 2nd lets say and you feel the engine bogging down and making that characteristic noise/feeling.

Anyone like to explain what is going on that generates that?

Thanks

[AFJuvat]

A transmission has two shafts - an input shaft which is spun by the engine, and the output shaft which is spun by the input shaft and transmits power to the differential and thus the wheels

On the input shaft of the transmission, each gear is larger than the one preceeding it - 1st gear is smallest, 2nd larger, etc.

smaller gears spin faster - closer to actual engine speed (relative)

On the output shaft, the gears go from largest to smallest - 1st is the biggest, 2nd smaller, etc.

2 or 3 gears are locked to one shaft or the other - meaning if 1st gear is locked to the input shaft, the cooresponding 1st gear on the output shaft is floating and is only locked to the shaft when the gear is engaged.

Since smaller gears rotate faster than a larger gear, the smaller gear will complete as an example 4 rotations for every 1 rotation of the big gear. This enables the engine to transmit more power through the transmission. By starting off in a lower gear, the transmission is actually forcing the engine to slow down, reducing power. Go to a high enough gear, the input gear is significantly larger than the output gear - the big gear has to rotate once to spin the small gear 4 times - way too slow and the engine will stall.

That should do for a very simplified explanation.

AFJ