Manual Transmission Kit
This kit displays the mechanism of a Manual Transmission. This consists of an input shaft, an output shaft, a transfer shaft, all of the internal gearing, alignment mechanisms, and selection mechanisms.
Transmissions are mechanisms which allow cars (or other moving systems) to switch between different speed and power settings - they trade off speed for power, or vice versa. While manual transmissions have been heavily phased out in the modern automotive industry, they still leave a strong legacy behind.
This kit teaches the following concepts:
1. Gear Ratios (Torque and Speed Exchange)
2. Synchronizer Mechanisms
3. Power Transfer
Assembly Video
Assembly Instructions
Concept Breakdown
There are a couple major mechanisms that play key driving roles in a manual transmission. These are as follows: gear ratios, power transfer mechanisms, and synchronizer gears.
Gear Ratios
Let's break down what a gear ratio is - simply put, it is the ratio between the number of teeth on two mechanically connected gears. Let's setup a scenario where there is a gear (let's call it "Gear #1") with 100 teeth, and there is another gear (let's call it "Gear #2") also with 100 teeth. In this scenario, Gear #1 will be connected to a motor, and Gear #2 will be connected to a wheel.
Turning on the motor, we will see that the wheel and Gear #2 will turn at the same speed as the motor and Gear #1. This is because Gear #2 and Gear #1 have the same amount of teeth, so for every 1 full revolution that Gear #1 performs, Gear #2 will perform a revolution.
Now let's change it up and say that Gear #1 still has 100 teeth, but Gear #2 has 10 teeth. Turning on the motor, we will see that the wheel and Gear #2 are moving much faster than the motor and Gear #1 (around 10x faster!). This is because of the ratio between the number of teeth on Gear #1 and Gear #2. Now, for every full revolution that Gear #1 completes, Gear #2 will complete 10 full revolutions, because Gear #2 has 10x less teeth than Gear #1.
So did we just magically make Gear #2 go 10x faster? Of course not. While we did increase the speed of Gear #2 by 10x, we have also decreased the amount of 'power' in Gear #2 by 10x. This is why gear ratios are so important. They allow for the exchange of speed for power, or the exchange of power for speed.
Let's examine a situation where gear ratios will be used to exchange power for speed. Say now that Gear #1 has 10 teeth, and Gear #2 has 100 teeth. When we turn on the motor, Gear #1 will have to spin 10 times before Gear #2 spins once. This is because Gear #1 has 10x less teeth than Gear #2. While we have reduced the speed of Gear #2 by 10x, we have also increased the power of Gear #2 by 10x.
Power Transfer Mechanisms
This Manual Transmission kit has two major powered elements: the transfer shaft, and the output shaft. On the transfer shaft, there are many gears that are directly connected to the transfer shaft. This means that they cannot freely rotate around the transfer shaft without the transfer shaft moving the same amount. All of these gears are connected to corresponding gears on the output shaft, and are all varying sizes.
From what we learned about gear ratios, there seems to be one glaring problem: if the gear ratios are different, and the gears on the transfer shaft are all moving at the same speed, aren't all the gears on the output shaft moving at different speeds?
This is where the different power transfer mechanisms come into play. The gears on the output shaft, unlike those on the transfer shaft, are not directly connected, and are free to rotate around the output shaft without the output shaft moving the same amount.
But if they are free to rotate, how can the gears transfer any power to the output shaft? The hub fixtures mounted on the output shaft are directly connected to the output shaft, meaning they are not free to rotate around the output shaft. While the hub fixtures are not directly connected to the gears, there is a hub ring that slides along the hub fixture. This hub ring acts as a sliding mechanism which when in a certain position, connects the hub fixture to a gear mounted on the output shaft. When this gear is connected to the hub fixture, it is then directly connected to the output shaft through the hub ring and hub fixture.
Synchronizer Gears/Rings
In manual transmissions mechanisms the transfer and output shafts are all moving very fast, and sometimes the notches on the attachment rings (hub rings) don't line up with the notches on the gears. In real manual tranmission mechanisms, this poses a great issue.