How manual gearboxes work (PDF)

manual gearboxes

what is a manual transmission car?

Basically, a manual transmission is a gear box that enables the driver to choose between different gear ratios to drive the car. Lower gear ratios offer more torque, but less speed, while higher gear ratios offer less torque, but higher speed. Different gear ratios are often referred to as “speeds,” so a “six-speed” manual transmission has six forward gear ratios.

At its simplest, the manual transmission consists of three shafts with constantly-intermeshed gears of different sizes. The input shaft connects to the engine, via the clutch. The countershaft is constantly meshed with the input shaft and has multiple gears. The output shaft connects the countershaft to the driveshaft and eventually the wheels. In four-wheel drive and all-wheel drive vehicles, the output shaft connects to the transfer case first. Reverse gear is usually on a fourth shaft to effect a change in direction.

The gears themselves are not fixed to the output shaft, but freewheel. Locking collars, on the other hand, rotate with the output shaft and can shift or slide back and forth to engage one of the gears. That’s why we call it “shifting” gears. In “neutral,” with no gear selected and the clutch released, the input shaft and countershaft are spinning, as are the output shaft gears, but the output shaft doesn’t move because none of the locking collars are engaged.

Manual transmission, how does it work?

The pdf you will download contain:

  • The constant-mesh gearbox
  • How gear ratios work
  • Synchronising the gears

Download pdf on How manual gearboxes work.

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