M/T vs A/T: Maintenance and Other Differences Explained
Cars with internal combustion engines have a very limited torque band, so it needs a transmission system to have varying speeds.
When purchasing a car, one of the dilemmas that most drivers face is whether to go for manual transmission (MT) or an automatic transmission (AT). Some people would say you can never go wrong with automatic, while some old timers would say it is best to select a manual one.
To those without working knowledge of car mechanics, the difference would only seem to be in the physical make-up. When a car has a clutch pedal and a gear shift stick between the driver's seat and the front passenger seat, it definitely runs on a manual transmission. It's different in an automatic transmission as you will only see a gearbox with 4 settings for Park (P), Reverse (R), Neutral (N) and Drive (D).
It is important to have a good idea on how the transmission types function so that you can select which one suits you best.
- The Gearbox
- Types of Transmission
- Repair and Maintenance for Manual-Transmission versus Automatic-Transmission Cars
- Fuel Economy and Mileage of Manual and Automatic Vehicles
- Control and Security of Manual and Automatic Vehicles
- Ease and Convenience of Driving Manual and Automatic Vehicles
To understand transmission, you need to familiarize yourself with the gearbox and how it works.
In a car, there are usually three main things that buyers consider: horsepower, torque and transmission. When starting the engine or going uphill, a high torque is required even if at low speed. On a level road, however, even if you are going at top speed, you do not really require a high torque. Changing the speed and torque of your engine is made possible by means of the transmission box, or what is commonly referred to as the "gearbox". The gearbox, in a straightforward definition, is basically a box that houses gears.
These gears all work together to allow you to start your car, change speeds and torque levels, move in reverse and come to a full stop.
The gearbox must be properly lubricated; hence it is oil-filled. If the gear teeth grinds with other moving metal parts, it can cause damage to your vehicle and affect your transmission.
Specific Functions of a Gearbox
A vehicle must switch speeds and torques depending on the load it carries, road conditions and driving conditions. The gearbox ensures this change in torque and speed.
In particular, the gearbox is responsible for the following:
- It provides the torque required to move a vehicle, by changing the gear ratio between the engine crankshaft (the rotating shaft commonly used in internal combustion engines) and the vehicle's drive wheels (if the car's a rear-wheel drive, then this refers to the rear wheels; if a front-wheel drive, then the front rollers). That's why the term "changing gears" is used when you shift your stick.
- It increases or decreases speed. It converts the engine's high speed, low torque to low-speed high-torque and vice versa.
- The gearbox enables the vehicle to change directions. It moves the vehicle backward by reversing the gears and turning back the wheels.
- It shifts the engine to neutral. In an automatic transmission, shifting to neutral readies you to push or tow the vehicle. Pushing or towing is not possible when in Park mode because the gears would be locked, and doing the same when the car is on gear will bring damage to the car.
Types of Transmission
There are two common types of transmissions: manual and automatic. These are two different technologies that apply different configurations and principles. Manual transmission is based on a simple gear pair and utilizes a clutch pack, while automatic transmission is based on a planetary gear set and uses a torque convertor.
Simply put, manual-transmission vehicles require you to operate the clutch and decide when to shift gears, while in an automatic-transmission system, gear shifting is managed electronically with no pressure on the driver.
Manual Transmission Explained
If you have heard of the term "stick shift", that actually refers to manual transmission because you change gears by means of moving the stick.
To change gears manually, you need to release the clutch disc situated between the engine and the transmission. This can be done by pressing the clutch pedal – a third pedal on the left side of the brake pedal. There are three steps required every time you need to change gears. First, you must release the clutch, then choose your desired gear via the stick, and then re-engage the clutch pedal.
As you disengage the clutch, there will always be a power drop, that's why manual transmission driving is not always smooth.
Manual transmission started with 3 speeds dating 40 to 50 years ago. As there rose a need for faster and more efficient vehicles, a 4-speed transmission was developed and became the norm for a long time in the market. Nowadays, cars come with 5-, 6- and for top-ranging vehicles, especially sportscars, 7- and 8-speed manual gearboxes.
In a effort to avoid the power discontinuity or stall experienced in a manual transmission, car manufacturers came up with automatic transmission. Instead of gear pairs, an automatic transmission system makes use of planetary gears or epicyclic gears. This gear system is called as such because it consists of one or more gears or pinions, that like planets, revolve about a central "sun" gear. The planet gears are mounted on a movable carrier which itself may also rotate relative to the sun gear.
A pair of clutch packs supports the motion of the gears. In this setup, when the first clutch pack is released, the second clutch pack is engaged at the same time, therefore there's no discontinuation of power. Four outputs are possible with the two sets of planetary gears arrangement. Adding a third planetary gear set will allow six speeds plus one reverse.
Automatic transmissions can either be traditional or dual-clutch, in which transmission happens by means of a hydraulic torque converter for the former, or through a couple of clutch packs for the latter. Current speed, revolution of the engine and the position of the throttle pedal are monitored automatically. All you need to do is move the shift lever to Drive, Park, Reverse or Neutral and the automatic transmission system will do the rest.
Continuously Variable Transmission
There's a third type of transmission currently available in the market today. You've probably heard about a continuously variable transmission (CVT), also referred to as a shiftless transmission. This transmission type makes use of a belt-and-pulley system that provides an unlimited number of ratios.
Repair and Maintenance for Manual-Transmission versus Automatic-Transmission Cars
A manual transmission has a simple mechanism compared with an automatic. There are no electronic or advanced computers that run it. It has fewer parts. The manual transmission system is generally less complex and it is safe to assume that few things could go wrong compared with the more complex automatic transmission system. In a manual setup, it is often the clutch that gets worn out, but if you drive with care you won't need to change it until after you've reached hundred thousand kilometers. Even if some parts of the system, or even the whole system, fail, the gearbox can be fixed easily by mechanics or those with sufficient technical know-how. Parts too can be easily replaced.
Automatic gearboxes, on the contrary, is composed of more components that could break down. Sensors and computers are expensive to replace if they fail. Depending on the brand of your vehicle, repairs to the gearbox could cost you much. CVTs and dual-clutch transmission systems are usually harder to fix and their parts are difficult often difficult, or expensive, to find such that some repair centers would suggest replacing the entire gearbox which would surely make a big dent in your pocket.
Manual-transmission vehicles utilize engine oil whereas an automatic system uses automatic transmission fluid (ATF). The former doesn't regular change of oil; only when there's a leak or after a repair.
The torque converter in an automatic vehicle consumes more ATF than the amount of oil that a manual gearbox requires. Thus for every transmission fluid change, the cost for an automatic car will be more than that for a manual car.
While we've established that manual-transmission gearboxes are cheaper to repair, it is important to note that abusive driving affects manual transmissions more than the automatic. The automatic's advanced systems protect the parts from being mistreated. More than that, automatic gearboxes are built to be durable even when driven hard.
With abusive driving, you'll end up burning through your clutches faster than desired, and you will end up spending more for repairing and replacing your clutch or the entire manual gearbox more often than you need to. Additionally, if your foot and hand aren't well coordinated when you drive, you could grind gears which will damage your car.
Cost of Maintenance
While generally manual transmission maintenance will cost way less than maintaining an automatic, repairs and replacements, there are still many manual cars out there whose clutch repairs would cost way more than an automatic repair. This applies to European performance cars and luxury cars, and others. In fact, the cost may even exceed the value of the entire vehicle.
Four-wheel drive clutches are also more expensive to fix and replace.
It is also important to note that insurance policies for automatic cars are much higher than those for manual vehicles.
Another cost disadvantage of an AT car is when the engine breaks down. You cannot push or pull it like a manual vehicle. You need to have your car towed, and towing service doesn't come cheap.
With proper care and maintenance, MT vehicles tend to last longer than AT ones.
Fuel Economy and Mileage of Manual and Automatic Vehicles
Since the stick shift system is much simpler, without hydraulics or electronics to weigh down the vehicle, plus it has more gears, it is but logical that it can run more kilometers with the fuel being pumped by the engine. It is said that 5% to 15%, depending on driving conditions and driving style, fuel cost savings can be achieved with a manual gearbox.
On the other hand, a small percentage of power loss is experienced with an automatic transmission as a result of the workings of the torque converter and hydraulic pump when you shift gears. This of course reduces fuel efficiency.
In terms of gas mileage, obviously, a manual transmission allows you to control your engine's revolution per minute (rpm), so you consume less fuel and cover more mileage. An automatic vehicle, on the contrary, covers fewer mileage than a manual car, because it requires a torque converter to shift in between gears.
Control and Security of Manual and Automatic Vehicles
Although it is tough to learn how to drive manual car, with lots of stalls, bucks and jerks, driving it gives you a better sense of control. Brakes are easier to control, and for many manual transmission fans, the challenge of traversing narrow and curvy roads can be thrilling.
An automatic car is best when you are stuck in traffic, especially if you are stuck on a steep road incline. This kind of situation will be extremely difficult to handle if you are driving a manual vehicle. An automatic transmission makes your driving life better when faced with steep inclines or when driving uphill.
Driving a stick shift can also be tiring in cars with heavy clutch pedal feedback as it puts a strain on your joints over time.
Security-wise, automatic cars are seen as more advanced than stick shifts, and are more attractive to car thieves. The complexity of driving manual vehicles make them less appealing to robbers.
The new-generation automatic vehicles, meanwhile, come with loads of security and anti-theft system so they aren't easy to steal.
Ease and Convenience of Driving Manual and Automatic Vehicles
Obviously, automatic-transmission vehicles are easier and more convenient to drive as you have everything cut out for you by the computerized gearbox system. You can easily learn how to drive an automatic vehicle, maybe even in less than 24 hours if you're determined.
On the road, you won't have to sweat it out shifting gears and working on the clutch, which makes wiggling your way through traffic way convenient than when you're driving a manual car. Stop-start situations favor automatic cars better than manual ones. In addition, since you do not have to focus on the clutch and gears, you can focus more on the road reducing risks of being distracted.
You should bear in mind two essential factors when deciding on the type of transmission for your next vehicle purchase: your driving objectives and your driving style.
If you are buying a car for daily commute on heavily congested roads, if you love driving on the hilly countryside, prioritize ease and convenience over a thrilling ride, have money for expensive repairs and insurance, among other considerations, then go for automatic.
If you don't mind sweating and love full control of your gears and clutch, then get a shift stick.
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