Power Transmission Overview

What Are Power Transmissions?

Many different types of machines have power transmissions, in addition to a power source. The transmission helps to give a bit more control over the machine to the operator. The term transmission can refer to different things. Most often, it refers to the gearbox that provides the speed and torque conversions from one power source to another.

Other times, people use the term transmission to refer to the gears, propeller shafts, and more. In Britain, the term generally includes every aspect of the drivetrain, including the gearbox, clutch, drive shaft, and prop shaft. The most common use of a power transmission is in motor vehicles, but some other types of equipment have used transmissions as well. In the past, they were used for steam engines, windmills, and even devices powered by actual horses.

Transmissions are highly complex pieces of equipment, and they have a host of different parts that all need to work together in order to provide the movement of power. One can learn about the basics of the various elements of the transmission here, and learn to put them into action.


How Does a Power Transmission Work?

The transmission is one of the most important parts of a vehicle. An automatic transmission is different from a manual transmission, although both are used for providing power to the vehicle. With a manual transmission, you would need to use a clutch and a gearshift to change gears in a vehicle. With an automatic transmission, you will only need to put the transmission into drive. After doing that, the vehicle will take care of all of the necessary gear changes without you needing to worry about it.

To understand more about transmissions, it is important to have a basic understanding of some of the most common terms used to define them. In a transmission, a gear is a set of wheels with teeth on them that work to help change the speed of the engine and wheels. The gearshift is a mechanism that is in a manual transmission and lets the user actually shift between the gears.


What Type of Power Transmissions Exist?

The two basic types of power transmissions, mentioned earlier, are automatic and manual. Automatic transmissions are the most popular option today simply because they are so much easier to use. Manual transmissions have a simpler, although very similar, mechanism to help them work.

In a manual transmission, there is a set of gears along with the input and output shafts. Drivers will move the shifting lever in order to choose the gear he or she wants to use. A car could have four, five, or six speeds. They also need to press the clutch pedal when they are shifting gears. They choose the gear, and put the shifter in place.

Automatic transmissions operate in much the same way, only they do not need to have the same level of input from the user. The vehicle will automatically cycle to the appropriate gears when driving. The driver only needs to put the vehicle into drive, reverse, park, etc.

The automatic transmission is easily the most popular option today when people are buying new vehicles. People want their vehicles to be easy to drive, and they do not want to have to think about using the clutch and shifting while driving. While manual transmissions might be able to provide more control and power for the vehicle, those things are less important for people today. Still, manual transmissions do have a number of benefits.

One of the benefits that cause some people to stick with manual transmission vehicles is the fact that they are generally cheaper, which lowers the purchase price of the vehicle. They do give better control, and they are generally going to provide better fuel economy as well. Many feel that they are easier to maintain as well since they are so much simpler than automatic transmissions.


What Are Power Transmissions Used For?

Power transmissions are in use in all sorts of vehicles today, from large diesel trucks to small compact cars. Recreational vehicles and ATVs have transmissions as well. Even boats have transmissions, albeit it much simpler than those found in other vehicles. Owners should have at least some basic knowledge of the type of transmission they have within their vehicle no matter what that vehicle might be. They may learn the skills to rebuild or repair a transmission, or they may only want to learn enough to diagnose their transmission issues.

Whenever there needs to be a transfer of power, chances are good that there is a transmission working behind the scenes. With most of the large pieces of equipment and vehicles using transmissions, the action will not require manual input, except when changing the gears in vehicles. With some of the other types of transmissions though, such as simple roller chain systems, manual power is necessary for the transfer of power. Bicycles are a very good example of this in action. They are much simpler than a motor vehicle’s transmission, but the basic concept behind them is the same.


Parts and Accessories for Power Transmissions

Transmissions have a large number of parts that go into them, and it is important to understand at least the basics of these different items. In addition to the parts featured here that might need replacement at some point, there are some tools as well, and these can make working on and repairing a transmission far easier.


  • Linear Bearings, Housings & Blocks – The linear bearings are a rolling element bearing that features a cylindrical shape. Linear motion systems make use of linear ball bearings. The bearings are generally high quality steel. The housings and blocks, also made of metal, are the devices that will hold and keep the bearings inside of the transmission.


  • Bearing Tools – Many different types of bearing tools are available for those who are working on repairing and building transmissions, and they cover a range of different purposes. Some of the tools can heat up the bearings evenly to help mount them onto the shaft. Portable bearing heaters are available as well.


  • Belts – Power transmission belts come in a number of types and styles. They offer polyurethane belts, wedge and vee friction belts, twist link belts, and timing belts. These belts fit into the transmission and help to drive the transmission by providing the motion it needs. The belt drive system includes a belt and at least two pulleys that will transmit the motion. Vee belts are popular. They have tapered sides and a flat bottom. Most of the time, the belt system will actually feature at least two of these belts, which can help to increase the carrying power.


  • Bushes & Collars – Collars and bushes will go right onto the shaft without marking it. They come in a variety of different types and styles based on the transmission and the intended usage. The collar and bushes are cylindrical and metal. The bushes are available as locking bushes, keyless bushes, plain bushes, taper bushes, and reducing bushes.


  • Clutches & Brakes – The clutch is a type of mechanical device that will gradually start or stop the transmission of power, torque, or speed in the transmission. A variety of different types of clutches is available, including electromagnetic clutches and adjustable friction clutches. Brakes are a type of clutch that will slow and eventually stop the transfer of energy from the shaft to a load. Anyone who has driven a vehicle before knows that applying the brake will slow the vehicle by stopping the transfer of power from the transmission to the wheels.


  • Couplings – A coupling is a device that connects two shafts in the system as a means of transferring motion. It literally “couples” the two shafts. They will not usually disconnect once engaged. However, it is sometimes possible for them to slip in the event the torque limit is exceeded.


  • Gaskets, Seals & Packings – The gaskets, seals, and packings are all elements to make the seal between the transmission housing and the pan. This ensures there is no oil leakage out of the pan when it cycles through the housing. Some of the most common types of materials for gaskets, seals, and packings include rubber, fiber, cork, and even metal. Packing material can be graphite, fiber, fluolion, and more.


  • Gears – The gears are the round, or cylindrical in some cases, components that have teeth that engage one another. The turning of the gears transmits the power. The gears are able to change the torque, direction, and even the speed of the mechanical energy.


  • Linear Shafts, Rails, Ball Screws & Lead Screws – The linear shafts, rails, ball screws and lead screws help to translate the rotational motion to linear motion. Ball screws and lead screws help to reduce the friction. The lead screws are generally less bulky than the ball screws, but both have the potential to work very well in transmissions. When repairing or building a transmission, it is important to find the shafts, rails and screws that will work best with the rest of the transmission. The parts must work together seamlessly.


  • Linear Slides, Guides & Positioning Tables – The right assemblies for transmissions to work properly and seamlessly are very important. Linear slides, guides, and positioning tables help to ensure that the transmission works properly.


  • Pulleys – Different belts – timing belts and the wedge and vee belts – require specific types of pulleys to make them work properly. The belts slip onto the pulleys. The attached belts can then drive the pulleys in one direction, or the belt may be crossed so the direction of the shaft is reversed.


  • Rod Ends & Spherical Bearings – Other terms for rod end bearings are heim joints and rose joints. They are on the end of the control rods or tie rods. At the end of the metal rod, they will have a round hole, to which bolts and other hardware can attach. The threaded parts of the rod end could be male or female. A spherical bearing will support rotating shafts in the inner ring. The bearings will generally have inner and outer rings, as well as rollers and cages.


  • Roller Chains & Accessories – A roller chain is a type of drive train. They are common on many types of machines that use mechanical power, such as conveyor belts, motor vehicles, and motorcycles. These are the most common types of chains in use, and one of the benefits they offer is that they can be used at high speeds.


  • Rotary Bearings – Rotary bearings are available in a number of different styles including cylindrical rollers, spherical rollers, tapered rollers, needle rollers, and balls. They have cages around them that help to reduce friction, which can prolong the life of the bearing. Different bearings have different capacities, so it is important to check the capacity of any bearing before purchasing.


  • Sprockets – A sprocket is a gear or a wheel that has metal teeth that will work with and attach to the roller changes. The teeth of the sprocket will go right into the chain drive. When the sprocket turns, the chain moves, and the power is transferred. One of the simplest ways to see this in action is to look at a bicycle. The toothed sprocket on the bike turns when someone turns the pedal. This engages the chain, which then transfers that power to the wheels and provides movement.


When working on a transmission, whether building one from the ground up or repairing one, it is important to know about every different piece and element that goes into it and how to choose the right ones when working on the transmission. To have a transmission that works properly and that lasts, proper care and maintenance is vital. It is also important to choose only the very best when it comes to the parts of the transmission.