A car comprises several parts, all of which are extremely important to ensure proper functioning and safety. As important as a car’s engine is, the transmission is also one of the most critical components of a vehicle. While the engine is responsible for generating the power a car needs, the transmission is what transfers that power to the wheels. Transmissions are either automatic or manual. Manual transmissions require the driver to change the gears with the help of a stick shift and the clutch. Automatic transmissions do not require the clutch as the transmission changes gears according to the speed. Transmissions are typically mounted on the front of the vehicle’s chassis. Let us answer some of the most common questions people have regarding automatic and manual transmissions.
How Does a Manual Transmission Work?
Manual transmissions include a shifter and a clutch pedal, both of which are used by the driver for changing gears. A manual transmission consists of a gear set and a pair of shafts known as the output and input shafts. As the driver disengages or engages, so does the transmission, using a clutch, pressure plate, and flywheel. The pressure plate and the flywheel are connected to the engine, while the clutch lies between the two. It is also splined to the input shaft. Every time you change gear, you have to use the clutch first.
In a Dual clutch transmission, there are two clutches, which can be dry or wet. In a dual system, one of the clutches is responsible for operating the even gears. At the same time, the other is responsible for operating odd gears. These transmissions can still be found in modern racing cars but were usually a feature of older cars. They are also known as twin-clutch or double-clutch transmissions. Modern ones include a computer system that controls the gear shifting and clutch engagement.
The original manual transmissions were “Non-synchro”, i.e. unsynchronized. Also known as rock crushers as drivers would try to mesh the gears together by grinding them. It was primarily used in trucks as they were very strong and reliable.
Constant Mesh or Synchronized Transmissions
Constant mesh/Synchronized transmissions enable a constantly moving drive gear, main shaft gear, and cluster gear. Pads are installed to slow down the gears. The system eliminates the need for double-clutching action.
An automated or automatic transmission or AMT is a combination of computerized controls and manual transmission. The computer controls the clutch and the shifting. It is common in heavy trucks.
Single-clutch transmission is a manual transmission with a computer that controls the clutch and the shifting. The clutch and the shifting can be electrohydraulic, hydraulic, or electric. They became less popular with the development of dual-clutch transmissions as the latter can handle high torque.
Mainly used from the 1930s to the 1950s, preselector transmissions were manual with a hydraulic or vacuum shift control. Some even used planetary gears and bands.
How do Automatic Transmissions Operate?
The primary difference between automatic and manual transmissions difference is that in the former, the entire power transfer process is internal in an automatic transmission. Instead of relying on the clutch, automatic transmissions rely on torque converters for changing gears. When the automatic transmission was first introduced, it came with a clutch known as a semi-automatic transmission. However, in 1939, Earl Avery Thompson introduced the first complete automatic transmission, which was used in the 1940 Oldsmobile.
CVT stands for “Continuously variable transmissions”. A CVT transmission is a pulley-based transmission primarily used in small engines. They have been around for years and are also found in ATVs and snow. They have also become a primary feature of hybrid cars. In a CVT setup, a large driven clutch and a small drive are connected with a chain or a belt. The chain or the belt sits low in the primary drive while it sits high in the secondary drive when the car is stopped. During acceleration, the primary drive contracts, causing the chain or the belt to walk up/ This is followed by a simultaneous expansion of the secondary, causing the chain or the belt to walk down.
What is Transmission Servicing?
Transmission servicing is an essential part of car maintenance. It is similar to getting your engine oil changed. The primary purpose is to flush out the old transmission fluid and replace it with a new fluid. A complete servicing would include the following:
- An Inspection of Your Sump Pump
- Cleaning or Replacing the Filter
- Pan Cleaning
- Installing a New Gasket
What is a Transmission Fluid?
As the different parts of the transmission move constantly, they create friction which will wear out all parts without a lubricant. That is what the fluid does. It lubricates all moving parts so that your transmission can live longer. The fluid also acts as a coolant because it reduces the heat produced by friction.
Which Transmission Fluid Do You Need?
The purpose of the transmission fluid is lubrication; however, there are different types of fluids for different transmissions. ATF or automatic transmission fluid is used for automatic transmissions, while manual transmissions can use gear and motor oil.
How Often Should You Get Transmission Service?
Your car’s owner manual mentions the time interval you should carry out a transmission service, but a visit to your local mechanic should be enough to see if your transmission needs servicing. The frequency would vary depending on the type of transmission and your usage.
Manual Transmission Servicing
Transmission fluids in a manual transmission will get contaminated easily. As your transmission parts, such as gears and bearings, wear out, your transmission fluid will need to be replaced more frequently. Tiny metal shards and particles will affect the lubrication ability of the fluid. These metal particles can also damage your transmission, so it is best to replace the fluid quickly. Many manufacturers recommend servicing to be performed after every 30,000 to 60,000 miles.
Automatic Transmission Servicing
Automatic transmissions generate more heat, which is why the automatic transmission fluid needs to be replaced earlier than in a manual transmission. Similar to manual transmissions, particles of worn-out parts will contaminate the fluid, reducing its efficiency and affecting the life of your transmission. It is recommended that when your vehicle has covered a mileage of 60,000 to 100,000 miles, transmission servicing should be carried out.
What Regular Checks Should Be Carried Out?
Even if you think it’s not time for your transmission fluid to be replaced, you should keep a check on it. The first thing to be watchful about is the transmission fluid level. A low or no transmission fluid can cause irreparable damage to your vehicle. Some warning signs of low or no transmission fluid include unusual noises when changing gears, leakage, etc.
What if You Never Replace Your Transmission Fluid?
This is highly unlikely because if you never replace your transmission fluid, your transmission will let you know about it. Worst comes to worst, it can collapse, and you will have to replace your transmission. Regular servicing ensures that your transmission fluid does not stay loading with metal shavings and particles. Therefore, it protects your transmission and vehicle from expensive repairs and replacements.
Tips for Taking Care of Your Transmission
- Transmission fluid has to deal with contaminants constantly, and it is best to set a fixed frequency for replacement.
- You do not have to reach the mileage recommended by the manufacturer to replace your fluid.
- Grinding sounds when you drive your car, especially when a gear changes, are clear evidence of dirty or low-volume transmission fluid.
- Stiff gears are also a sign that your transmission fluid is contaminated.