A manual transmission is a multi-speed motor vehicle transmission system in which the driver must manually select gears by operating a gear stick and a clutch when changing gears. It’s a transmission that allows the driver to choose between different gear ratios to drive the car.
Basically, 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.
Early automobiles used slide-mesh transmissions with up to three forward gear ratios. Constant mesh manual transmissions have become more common since the 1950s, and the number of relay ratios has increased to 5-speed and 6-speed manual transmissions for current vehicles.
In the simplest case, the gearbox consists of three shafts with constantly meshing gears of different sizes. The input shaft is connected to the engine via the clutch. The countershaft constantly meshes with the input shaft and has several gears.
The output shaft connects the countershaft with the drive shaft and possibly the wheels. In vehicles with four-wheel drive and all-wheel drive, the output shaft is first connected to the transfer case. Reverse is usually on a fourth shaft to effect a change in direction.
The gears themselves are not attached to the output shaft, but to the freewheel. Locking collars, on the other hand, rotate with the output shaft and can slide or slide back and forth to engage one of the gears.
That’s why we call it ” shifting ” gears. When idling, the input shaft and the countershaft rotate just like the gear wheels of the output shaft without a gear being selected and the clutch being released. However, the output shaft does not move because none of the locking collars are engaged.
How Does a Manual Transmission Work?
To change gear, the driver presses the clutch, when engaging first gear, for example, and disengages the input shaft. With the gearshift lever, the driver engages first gear and the linkage moves the gearshift fork to move the 1st to 2nd gear. To connect the locking collar with the 1st gear and to lock it with the output shaft. If the clutch is now released and the input shaft engages, the output shaft rotates because 1st gear is locked to the output shaft by the locking collar.
If the driver drives faster, the process only needs to be repeated when selecting 2nd gear, but the gearshift lever is shifted to 2nd gear. The shift shaft moves the shift fork to disengage 1st gear and engage 2nd gear.
By releasing the clutch, the input shaft is re-engaged, this time the power is passed through 2nd gear. When shifting into 3rd gear, a second shift linkage, a shift fork and a locking collar are used between 3rd and 4th gear.
Because the countershaft and the output shaft rotate at different speeds and shift from 1st to 2nd gear. Trying to shift into higher gear while the vehicle is moving slower would be like trying to turn the shaft at two different speeds, which is impossible.
Synchronizer rings are like tiny clutches that use friction to bring the circlip and gear up to the same speed. At this point they will easily interlock and the force can be reapplied.
Manual Transmission vs Automatic Transmission
Modern vehicles come in two different transmission types, automatic or manual. With a manual transmission, the driver is responsible for shifting gears, while with a vehicle with an automatic transmission, the car does the shifting for you.
Vehicles with a manual or standard transmission are typically called stick shifts. The driver uses a gearshift lever to manually change gears when accelerating and braking his vehicle. The gearshift lever is located on the center console and is connected to the transmission via a linkage.
In addition to a gearshift lever, a manual transmission requires the use of a clutch pedal, which is located to the left of the brake pedal. Pressing the clutch pedal releases the clutch mechanism between the engine and the transmission. Pressing the clutch pedal stops the power from the engine to the transmission so you can change gears.
To change gear, the driver presses the clutch pedal, shifts the gear lever to the desired gear, and then releases the clutch pedal to reactivate the power from the engine to the transmission.
Learning to ride a stick requires some practice. Press the clutch pedal too quickly and the engine will stall. Depress the clutch pedal too slowly and premature wear can occur. Practice creates masters.
- Requires extensive driver input driver selects and shifts to the desired gear.
- Less than 3% of the cars sold in the US have a manual transmission.
- Popular in Europe and Asia over 80% of vehicles sold are manual.
Advantages of manual transmission
- Easier to maintain. Since they are less complex than automatics, there is less of a chance for something to go wrong. The clutch is the only item that generally needs repair, but for the most part that isn’t needed for hundreds of thousands of miles.
- Use of gear or engine oil. This fluid deteriorates less quickly and doesn’t require frequent changes.
- Fuel efficient. Automatic vehicles have a torque converter and hydraulic pump, which robs the car of a percentage of its fuel efficiency. Those who drive manual vehicles can increase fuel economy by as much as 15 percent.
- More control. Braking is easier without the torque converter found in automatic vehicles.
- Lower purchase price. In general, brand-new stick shift vehicles are cheaper than their automatic counterparts.
Disadvantages of manual transmission
- Requires practice to learn how to use. Those learning to drive a manual can expect the first few rides to involve jerking and stalling while becoming accustomed to the clutch and shift timing.
- Difficulty on hills. Stopping on a hill and starting again can be inconvenient as well as scary. Since the vehicle rolls back, drivers have rolled into traffic or stalled.
- Pain from the clutch. Your left leg will be in constant use when driving a stick shift car. Over time, it can mess with the joints in the leg.
- Driver must coordinate clutch, gas, and shifting.
- Lower resale value.
- Can be difficult to drive in stop-and-go traffic.
- Not as widely available.
While the driver plays an active role in operating a vehicle with a manual transmission, with an automatic transmission the driver simply selects D on the shifter and the car does all of the hard work. With fluid pressure, the vehicle automatically changes gears its own.
The heart of the automatic transmission is the planetary gear set. This part is responsible for creating the other gear ratios than the gearbox used.
The provision of the pressure required to activate the belts and clutches to determine which gear to be in the vehicle is automatic transmission fluid. This fluid not only cools and lubricates the moving parts of the transmission, but also helps drive the vehicle.
A torque converter, which acts as a clutch on a manual transmission, is attached to the drive train. The fluid is used to lock and unlock planet gears in order to switch between gear rations. This shift takes place automatically; The driver doesn’t have to do anything.
- Requires little driver input put the car in drive and go!
- Popular in the US – 95% of the cars sold have automatic transmissions.
- Relies upon automatic transmission fluid and planetary gear set.
Advantages of Automatic Transmission
- Driving comfort. One of the best advantages of driving an automatic car is the convenience it offers. Thanks to the clutch-pedal-less operation and the fact that you don’t have to shift gears manually.
- Good Fuel Economy. Fuel consumption has always been a major point of concern for people opting for an automatic car.
- Engineered for Versatility and Great Performance. The automatic transmission is quite responsive to driving inputs; it has sufficient power on tap to deliver quick acceleration and solid driving performance. There’s a Hill Hold function as well that prevents the car from rolling backward when driving on inclines.
- Higher resale value.
- Widely available.
- Great in stop and go traffic.
- Good for beginners.
Disadvantages of Automatic Transmission
The disadvantages compared to the manual transmission are the higher space requirement and the higher weight. Compared to the automatic torque converter transmission, the worse starting comfort and the higher wear are the main drawbacks.
- Higher purchase price than manual.
- Higher repair costs.
- Historically less fuel-efficient than manual – but the gap is closing.