Tag Archives: Transmission Basics

Transmission Types and History of Development

From starting with manual transmissions, to the introduction of automatic transmissions in 1939 – learn about the evolution of the modern transmission.

The transmission in automobiles is a system of parts usually contained within a housing, connecting the engine to the wheels. Suitable torque, or turning force, is generated by the engine only within a narrow range of engine speeds, i.e., rates at which the crankshaft is turning. However, the wheels must turn with suitable torque over a wide range of speeds. While its speed is held roughly constant, the engine turns an input shaft on the transmission whose output shaft can be adjusted to turn the wheels at an appropriate speed.

Manual Transmission

The manual transmission is the simplest (and earliest) of transmissions, and consist of a system of interlocking gearwheels. These wheels are arranged so that by operating a lever the driver can choose one of several ratios of speed between the input shaft and the output shaft. These ratios are called gears, first gear being the arrangement that gives the lowest output speed, second gear the next lowest, and so forth. To allow smooth shifting from one gear to another, a clutch is provided to disengage the engine from the transmission. The commonly used dry single disk clutch has a steel disk with a friction lining that is sandwiched between a flywheel on the engine shaft and a pressure plate on the transmission input shaft. When the driver takes his foot off the clutch pedal, springs squeeze the friction disk into the space between the flywheel and the pressure plate, enabling the engine shaft to turn the transmission.

For many cars and for normal driving conditions a transmission with three forward gears and one reverse gear is sufficient. In cars having small engines transmissions with four or five forward speeds are used; racing cars often have as many as six forward speeds.

Synchromesh Transmission

A synchromesh transmission is a manual transmission in which all forward gear wheels are held in mesh at all times. Used on most American cars with a manual transmission, it allows the driver to shift gears more smoothly and makes the car run more quietly.

Automatic Transmission

The automatic transmission, introduced in 1939, switches to the optimum gear without driver intervention except for starting and going into reverse. The type of automatic transmission used on current American cars usually consists of a fluid device called a torque converter and a set of planetary gears. The torque converter transmits the engine’s power to the transmission using hydraulic fluid to make the connection. For more efficient operation at high speeds, a clutch plate is applied to create a direct mechanical connection between the transmission and the engine.

The introduction of microprocessor-controlled electronic sensors has enhanced the performance of automatic transmissions still more. Data about engine speed, exhaust pressure, and other performance characteristics are sent to a processor that controls the changing of gears and the clutch plate in the torque converter via electrical switches, or solenoids. New approaches to transmission design combine the best features of manual and automatic transmissions to provide more efficient ways of channeling engine power to the wheels.

Manumatic Transmission

A manumatic transmission is an automatic transmission with an added manual-shift mode; typically, a floor-mounted shifter offers an alternative selector path supplemented by buttons mounted on the steering wheel.

Continuously Variable Transmission

A continuously variable transmission (CVT) uses a belt that connects two variable-diameter pulleys to provide an unlimited number of ratio changes and uninterrupted power to the wheels; CVT transmissions offer better fuel efficiency than conventional automatic transmissions, which change the transmission ratio by shifting gears.

Sequential Manual Gearbox

A sequential manual gearbox (SMG), developed for Formula One cars, uses computer-controlled actuators to operate the clutch and change gears when prompted by the driver; both manual and automatic modes are possible, and there is no clutch pedal.

Dual Clutch Transmission

The dual clutch transmission (DCT), also called the direct shift gearbox (DSG), substitutes dual clutches for the conventional single-sided clutch to transfer power from the engine through two parallel paths; the gearbox features two sets of gears, identical to those in conventional manual transmissions—one set being the odd gears (1st, 3rd, 5th) and the other the even gears (2nd, 4th, 6th)—the gears must be shifted in sequence, and power to the wheels is never interrupted.

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How Car Transmission Lines Work

Automatic transmissions generate a lot of heat. Transmission cooling lines keep things cool but they’re susceptible to being damaged

Car transmission lines connect your vehicle’s transmission to the vehicle’s radiator. Also known as transmission cooling lines, they are typically made of metal or composite aluminium and rubber hoses because they can handle the flow of hot transmission fluid.

Your car’s transmission lines are essential to preventing the transmission from overheating by carrying hot fluid away from the transmission until it is cooled and subsequently pumped back into the transmission.

If your car’s transmission lines are damaged, they will leak, and that can lead to serious trouble if you don’t notice your car bleeding transmission fluid. But here’s the problem: most automotive transmission lines are particularly susceptible to damage or rupture owing to the fact they are exposed on the underside of your car to the weather, and to debris on the road.

How to Spot Car Transmission Line Problems
If your car’s transmission cooling lines are leaking, it’s not difficult to detect. The most obvious sign is if there’s red fluid pooling beneath your engine where you park your vehicle.

Other noteworthy warning signs that your transmission cooling lines may be leaking include:

  • You’re having trouble shifting into gear; the gears are slipping, or are shifting slowly
  • Your transmission is overheating, or you notice an unpleasant burning smell
  • You hear grinding or whining noises when gears change or the vehicle rattles or jerks when you drive
  • The “service engine soon” indicator on your dashboard lights up

If you suspect your vehicle’s transmission cooling lines are leaking, or if you have questions about preventative transmission maintenance, contact us. Take advantage of our free 21-point multi-check inspection and avoid the cost and aggravation associated with a failing transmission.

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How Transmission Gear Ratios Work

Most mechanical devices with spinning parts need gears. How interlocking gears work together can directly impact your car’s performance

You don’t need to have a degree in mechanical engineering to understand how transmission gear ratios work. Simply, a gear ratio is the relationship between two or more interlocking gears and their rotational speeds. The gear train is the system that mounts and interlocks the teeth of the gears.

Without getting too technical, the pinion gear receives rotational force directly from the engine, and when it spins, it causes the spur gear to turn. Together, these gears transfer power to your car’s drive axle. Why should that matter to the average motorist? Because the gears and your vehicle’s transmission ratio is what affects how your vehicle performs.

If you’re experiencing delayed engagement with your transmission when you drive, it’s possible your transmission gear ratio needs to be adjusted, or dirt and grit could be negatively impacting your gears.

Monitoring the Health of Your Transmission

Identifying potential transmission problems before they erupt into a full-blown malfunction can help you keep your vehicle performing optimally, and save you money.

Whether there’s water in your transmission or one of several other possible problems, regular preventative maintenance and following recommended best practices for the upkeep of your vehicle is your best defence.

If you have a question about your transmission or want to book a service appointment, contact the Mister Transmission service centre nearest to you.

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Transmission Diagram Cut-Away

What are the components of a transmission system? Where is the drive sprocket or differential assembly or torque converter? See the diagram below that can help you identify the working parts of a transmission system.

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How to Save Your Transmission

As any car owner will agree, saving a transmission and avoiding major transmission service or car repair costs are very worthwhile goals. Indeed, some transmission shops and dealerships are quite expensive and lack experience with today’s complex transmissions, so it’s not just a about saving money.

A faulty transmission is a serious safety hazard that can put drivers and other motorists at risk.

Getting more of out of your transmission

In light of this, it makes sense to ask: how does one get more out of a transmission and prolong its life? Those expecting a complicated answer with all kinds of technical car repair tips may be a little taken aback with our advice – because it’s really so simple. What’s our advice? Regular transmission maintenance!

The wisdom of regular transmission maintenance

It’s simple but true. Regular transmission maintenance is a car owner’s best friend when it comes to getting the most of out a transmission, and avoiding a great deal of unnecessary, and potentially costly, transmission service or transmission repair down the road.

Regular transmission maintenance involves replacing the fluid and the filter (if it’s possible to drop the pan and replace the filter, that is).  By replacing the fluid, car owners help keep their transmission cool and well lubricated, which are two critical keys to long transmission life, and to avoiding the need to fix or rebuild a transmission later.

Transmission 101 and towing

Drivers who are going to be towing any kind of vehicle should also install an external oil cooler if they want to keep their transmission running optimally, and avoid transmission repair and transmission service surprises. It doesn’t matter if the tow is for a boat on the weekends, a motor home for the summer, or anything else – it just makes sense to install an auxiliary transmission fluid cooler.

Questions about transmission repair?

At Mister Transmission, our trained experts are here to answer any and all transmission-related questions that our customers have. Unlike some transmission shops, we actually love it when our customers pick our brains for advice. When it comes to transmissions, “there’s no such thing as a bad question”!

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