Are you really trying to comprehend how such things work? That is a great starting point for making any modifications; if you want to get the max performance out of the Torque converter, then you will have to know how it really works.
The torque converter makes use of a Continuously Variable Transmission (CVT) system, like the ones available in scooters. But not precisely like the CVT from the scooter. It has a belt and two pulleys, a driven pulley with the v-shaped belt, and a driver pulley (connected to its engine crankshaft).
Both the driver pulley and the driven pulley are further divided into two parts, one moving part and one fixed part. The belt goes in between these two pulleys, and firstly, the belt in the driven pulley has a larger diameter than the other one.
As the engine’s RPM increases, the movable half of the driver pulley glides inwards (towards its engine), pushing its belt upward, while instantaneously, the movable part of the driven pulley moves outwards (further than the fixed part), and the belt glides down the driven pulley.
If you’ve ever seen the torque converter functioning, you’d have seen how its gear ratio changes; if not, then you can see a video for better comprehension. For this post, we’ll have a glance inside the pulleys to figure out what exactly is happening and how such movable components are moving as their RPM increases.
Let’s first take a glance at all the parts of the comet thirty series from the user manual. (The forty series also function on a similar principle; the main difference is the weights and the spring inside the driver pulley’s clutch).
For our purpose of comprehending how it all functions, we’ll not be concentrating on the bolts and nuts and washers, etc.; just the label numbers four to ten and fifteen to nineteen are significant for us to comprehend the functioning mechanism. Let’s first name all such significant parts:
|Label # in the diagram||Item name and description|
|4||Drum of Driver|
|5||Hub of Driver|
|6||Weight and spring|
|10||The driver’s stationary part|
|15||Cam fixed (the part that’ll hold the spring)|
|16||The driven pulley’s spring|
How Does It Actually Work?
Now with the basic comprehension of what goes on as the throttle opens and with all the components defined, let’s have a look into how it really functions. When you turn its engine on, the crankshaft will begin to rotate; since the crankshaft is actually attached to the driver pulley, the driver pulley’s weight-spring system will rotate with the crankshaft.
The most significant part of the entire driver pulley system is actually the weight-spring system. As the system begins to rotate, the weight will face a centrifugal force in the way opposite to its spring force; as the RPM boosts, the centrifugal force will also boost and push the weights in the outwards way and stretch the spring during the procedure.
The spring will actually retort with an even higher force for resisting such expansion. If you take a glance at part number seven (the driver’s movable part), it’s not flat but rather has a little angle to it. So when it’s expanding against the hub, it’ll begin to come in touch with the movable half (part number seven), pushing the movable half towards its engine.
The belt also has the angle according to the movable part’s angle, so when the movable part is actually pushed outwards, the belt regulates itself, and the belt’s diameter in contact with the driver rises.
While the driver pulley is pushing its belt upwards, the belt will therefore apply some force on the movable part of the driven pulley’s movable half; the driven pulley’s movable half actually has a spring that’ll fight the force from its belt.
Relying on the engine’s RPM, all the forces will even out, and the go-kart will go at some particular gear ratio. The four stages diagram from the user manual does a great job of elucidating the relation between the RPM of an engine and the diverse gear ratios the torque converter attains.
At idle state, there’ll be no engagement. As the engine’s RPM increases, the driver’s active diameter will begin to increase while the driven dia decreases, providing you with the immeasurable gear ratios in between such two extremes.
The torque converter will actually provide you with infinitely diverse gear ratios. The ratio will be greater when you’re just starting off and will drop as the RPM of the engine increases. It denotes that it’ll create more torque for starting with and reduce torque with more speed, making it perfect for the majority of situations.
Calculating The Gear Ratio:
The gear ratio between the two pulleys will alter; in the Comet thirty Series, the ratio actually ranges from 2.7:1 to 0.9:1. For finding the gear ratio, you have to know the number of teeth present in the Torque converter sprocket, the jackshaft sprockets (if any) and the wheel axle sprocket.
For instance, let’s say that we have the wheel axle sprocket with 60T; the torque converter has a 12T sprocket and no jackshaft. In that situation, the ratio between the two sprockets is actually 5:1; for finding the ratio of output and input shaft, we simply multiply all of the ratios, so in this case, the lowest ratio is 4.5:1, and the max ratio is 13.5:1.
If you want to get a better start, then changing the weight and springs is the go-to choice; the harder springs are gonna need higher rotations for engaging; similarly, the lighter weights will also need more rotations for engaging. You can also change the spring of the driven pulley and/or change the hole to which the spring is actually connected.
Torque Converter/CVT actually are well-engineered; the diverse gear ratios it offers provide you with excellent mechanical benefits; no wonder a lot of individuals prefer it over the centrifugal clutch.
A clone engine like the predator 212 with the torque converter is a great way of going if you have the budget and will be driving the kart off-road and aren’t really concerned about the top speed. Such CVTs also last a long time.