Curiosity about chain "final drive"

I'd love to shed some light on it, but that would render it inoperative, unless maybe I use a small camera and light assembly throught the fill cap.

Seriously,

Chains rarely break, its the timing belts we all have to worry about. As an aside, the ICE uses a timing chain.

Just took a peek at New Car Features, doesn't say much as to the reason for the chain, just that it exists.
Someone did post a theory as to why Toyota chose to put a chain there, rather than gear drive. Possibly to reduce noise and still be able to have a gear ratio.

 

Do these help? 8)

I'd like to know more, as the Mechanical Engineer in me is absolutely amazed at the PSD!

 

the chain is connected to the intermediate shaft in the diffy side of the THSD/PSD unit. That shaft has a gear on it the engages a gear on another shaft that engages the gear on the differential case ( one that holds the spider gears ) this also corrects the rotation of the PSD to Diffy. These shaft/gears sets the ratio of the reduction. Vancouver Yellow Cab15 put about 250,000 miles on it with no problem so I doubt that the average owner has any thing to worry about. As an aside lots of automotive FWD cars use a chain to get the power from the ICE to the transmission. Hi-Vol chains have been used in automotive/pickup truck and even forklift applications for years. In their early incarnations they weren't all that reliable, thinking back to the early NP 4x4 transfer cases on the 4X4 GM's.We changed quite a few in the early years for stretching. The Olds Toronado and the Caddy Eldorados from the 70's used them as well with BIG ICE's and few problems.

 

Saab used chain drives for years in their 99's and 900's. My 1991 900 logged nearly 300,000 miles without any trouble.

 

There is another good document that can be found at the File Library section:

Oak Ridge National Lab Prius Evaluation

You can have a look from another angle of the cutaway with the gears arrangement and the number of gear teeth on them. It also shows the relationship between the generator and motor and how the final drive ratio is derive.

Happy reading

Vincent

 

This is my favorite picture "so far" illustrating the PSD & drive train.

Note, it doesn't display well in the forum frames, so if you want you can access it directly here:

PSD Image

 

<div class='quotetop'>QUOTE(PhilCase\";p=\"97719)</div>

Here's the Internet compatible link translated from "Microsoft" corruption.

PSD Image

 

These pictures are from the Oak Ridge National Laboratory evaluation of the Prius:

 

<div class='quotetop'>QUOTE(jeromep\";p=\"93017)</div>

Single-link chain or double roller? On motors, typically V8's, with the factory chain, it's prudent to replace it early. On my 1984 Ford F-150 with 302 V8, I replaced the factory unit in 1985 when I put in the Crane RV camshaft.

First of all, to control noise, the "teeth" are nylon, so they wear quickly, and the cheap chain will stretch. In the worst case scenario the chain will jump teeth and your timing will be odd to say the least. No harm done, you just sputter to a stop.

Second of all, the aftermarket has a wide variety of replacement timing chains for V8's, some with adjustable timing indexing and some without. The better double roller chains may be considered lifetime units.

Some folks invest in a straight gear drive, which is what you'll find in something like a Ford 300 six. Pete Jackson makes a line of camshaft gear drives. They have a very noticeable gear whine to them, some folks like that sound but it drives me nuts.

 

<div class='quotetop'>QUOTE(jeromep\";p=\"93017)</div>

In "The Prius that shook the World" (Page 103) it states that the chain was used specifically to allow for making the overall engine/motor/psd housing shorter as a purely linear train was too long to fit into the engine compartment. The chain gave them a method to configure the power train in a non-aligned manner creating a shorter, but wider, engine assembly.

It was, therefore, an engineering compromise to solve a problem.

Phil