Gen III CVT v.s. conventional auto transmission

Prius does not have a conventional CVT. You will not hurt it by stepping on the gas. You also have a warranty. This link will provide details regarding the transmission

This has more detail

Graham's Toyota Prius

 

My concern is:

1) How sturdy and reliable is the Gen III CVT compared to the conventional auto transmission?

Very. Nothing shifts, nothing relies on friction, the only 'weak point' would not be changing the WS ATF as often as needed, here on PriusChat we tend to recommend 60,000 mile change intervals, less than Toyota recommends. The ATF cools the two electric motors, and if not changed, dissolved metals can short them out.

2) Am I tend to break/wear out the CVT when I stomp the gas?

Not unless you enable about 200 more HP out of the Prius engine.

3) How expensive is it to replace the CVT?

About $5000, as you are replacing the Power Split Device, two electric motors and the differential.

Toyota Prius - Power Split Device

 

What Jimbo said.

+There are no clutches or belts so no wearing parts in the normal sense. Prii transmission failures are rare with no problems at 200k being common. In the unlikely chance you do have a transmission go out sometime in the far future, there are lots of good used ones in the wrecking yards. Prices I have seen quoted for used Prii tranmissions are low. I think that's because there is little demand for them.

 

CVTs have a long history. The first production CVT was the 1908 Carter, then it took around 90 years for materials, engineering and lubricants to get to the point that friction type CVTs were good enough for mainstream cars.

 

The CVT on a Prius isn't really a mechanical CVT. It is a set of fixed gears with a variable electrical path around the gearing. In other words (simplifying), the gearing is fixed, but the electricity varies. This makes it very sturdy.

Tom

 

i'm at 176k miles. for the last 100k miles i've been towing friends broken cars, and several small trailers. my recent trailer is 6 x 8. wheels on the outside of the box. no problems so far.

 

It is not a regular CVT. It is an eCVT, electric transmission.

You are looking at Gen2 (left) and Gen3 (right) eCVT with two electric motors and reduction gear. That's how simple it is.

 

In the Prius eCVT, the gas engine's power output is split

A portion of the torque always goes directly to the wheels. The rest of the torque is fed to a generator (MG1) which generates electricity. This electricity is fed to a high torque motor (MG2) which is directly powers the wheels by a fixed gear ratio.

It is MG2 that varies its rotation (RPM) to match the vehicle's speed (wheel RPM). MG2 is designed to have enough torque across its entire RPM range so that it does not need to have additional gearing. This is why it can be conected to the wheels by a fixed gear ratio.

MG2, the gas engine, and MG1 are arranged in a planetary gear set. Basically this means the engine does not have to spin at the same rate as the wheels. This allows the engine to spin at its most efficient RPM and still have a semi-direct path to power the vehicle.

The design of this is called a series-parallel or power-split hybrid.

In a series hybrid, the gas engine is not directly connected to the wheels -- it instead powers an electric generator which then powers an electric motor, and only the electric motor provides propulsion.

In a parallel hybrid, both the gas engine and electric motor power the wheels simultaneously or alternately, and both elements must match the vehicle speed whether they provide power or not -- an example is the Honda Insight or Honda Civic Hybrid. Due to this limitation, the Honda Insight or Civic Hybrid uses a mechanical CVT, so that the ICE can be spun at its optimum RPM.

There are some times when the Prius ICE directly powers the wheels and the electric motors provide almost no torque. You can think of this of being in 3rd or 4th gear in a conventional transmission when the transmission is in a 1:1 ratio. In this case the ICE generates torque, MG2 turns into a generator which powers MG1 to provide a counter-torque to the ICE. In effect MG1 and MG2 cancel each other out.

But basically there actually are no gears or mechanical CVT. Through shifting the amount of power in and out of the electric motor/generators it provides virtual gearing to be compatible with the vehicle's speed and current power requirements.

Physically things can only rotate. There are no clutches, friction plates, actuator, rods, pulleys, etc.

 

Read about Subaru CVT reverse issue - where it can not back out over a 4X4 lumber on a flat surface without momentum. Is the Prius CVT has this issue?

 

No. There's nothing to slip. In reverse, it's being driven only by the electric motors (since the engine can't spin backwards). They have tons of torque, so should have zero issues going over any reasonable obstacle.

 

Unlike the gas engine, electric motor can spin forward and also backward. Prius uses it for the reverse gear. When you put it in R "gear", you dont get the feeling of the car jerking. In fact, nothing happens. Your only clue is by looking at the dash for the gear you are in. So Toyota added a continous beep to indicate that you are in reverse gear. Some people find it annoying and turns it off.

 

My generation 2 Prius has a much weaker reverse than any car I've ever owned. When I have to reverse up a steep driveway sometimes I think it won't have the power. it tries its hardest and then I have to push the pedal nearly all the way down and the gas engine starts in order to create a little electricity and it helps but I don't recommend going up steep hills backwards. I think some steep driveways were too steep so I always reverse down into them so that I can drive for words Up them because I'm afraid of being stuck.
Keep in mind though that 90% of steep driveways will be okay. Now if it's a gravel driveway you can forget about it. Because not enough power in reverse and when going forward every time a wheel rolls over a piece of rock and The Rock slips a tiny bit and I mean the tiniest little bit the traction control kicks in and removes all throttle for over one complete second. During that time the car stops and begins to roll backward. The only way to get up that hill is to get some speed first which is impossible if it's a bit bumpy for this car that has low ground clearance.
this also becomes a problem when you try and pull out into traffic if you push the throttle down a little too far as soon as a wheel starts to slip your left dead in the road with people coming at you T-Bone style wondering why you're just sitting in their way.

 

That feeling might be correct. The issue with the Prius HSD is that while the electric motor can run "backward" and supply the same power, the ICE can not, so reverse will be limited to the power of the MG1. On top of that: when the ICE runs, it will generate opposite torque, so the power going into reverse will be even less.

About the HSD: you can compare it to the rear axle differential on a conventional car: a bunch of gears always in mesh. It will never fail unless you put crazy power on it, way more than it is designed for. And that will never happen in a Prius.
Or you run out of oil in the HSD.

 

I am living in top of the hill . Any time when I am getting back home from work . My prius is not very good on cvt as its slipped and you must push accelerator to the end . Is something wrong ?

 

sounds like it, but it depends on the length, grade and battery state of charge.

are you in eco mode?

 

No , always in normal mode . In the level surface there is not any problem and the engine and gearbox so powerful and act as normal but when I start to climbing uphill its so poor and I need to change to power mode to climb .