YODAONE

LS400 serpentine belt, idler pulleys, belt driven accessories (alternator, power steering pump, air conditioner compressor, fan clutch pulley) and tensioner react to torsional vibration imparted by the crankshaft, especially at idle.

The alternator spins at several times crankshaft speed thus is more prone to amplifying torsional vibration through its considerable rotating mass.

Our LS400's use an idle air control vacuum valve to prevent idle speed from dropping too low while turning steering wheel - torsional vibration is especially pronounced under 550 - 600 RPM.

The serpentine belt and tensioner are hard-pressed to manage the spinning mass of the alternator during sudden engine deceleration.

During transmission upshifts, especially at wide open throttle, the engine decelerate rapidly, however the alternator wants to keep spinning.(possibly affecting shift quality - upon engine shut down, the alternator wants to continue rotating.)

The can produce belt squeal and wear.

It also imparts vibration into other engine components and is felt in the chassis.

It is more pronounced in smaller displacement engines trending to larger alternators.

But what is the solution?

Alternator clutch pulleys...

There are two distinct types of clutch
pulleys, the one-way clutch and the iso-
lating decoupling pulley.

Type 1–The one-way clutch. First, it’s transferring torque from the engine to the alternator via the serpentine belt.
In addition, it is providing an over-
running function during engine deceler-
ations.
Several names associated with
this style of pulley include, overrunning
alternator pulley (OAP), clutch pulley,
freewheeling pulley, decoupler pulley, and the one-way clutch. It is simply an alternator pulley with a one-way clutch mechanism inside.

The pulley will rotate freely in one direc-
tion and immediately lock in the other.
This type of clutch pulley allows the
alternator rotor to coast to a stop when
shutting down the engine or any other
time the engine rpm decelerates quickly
(transmission shifting). (Engine shut down)

Type 2–The isolating decoupler pulley (IDP). This pulley provides three functions.
Its primary function is transferring torque from
the engine to the alternator via the serpentine belt. It further provides an overrunning function
during engine decelerations. And finally,
it absorbs base engine torsional vibrations (firing pulses).
Litens manufactures the IDP, or
Litens overrunning alternator decoupler
(OAD) The IDP not only provides a one-way clutch, it further incorporates a tuned torsion spring to absorb energy. The IDP rotates freely in one direction and have a “spring feel”
in the other direction. The effects of the
internal clutch are the exact same as mentioned above with the Type 1 style puley, however, Litens internal torsion spring is key to how the IDP performs
It's third and most demanding job.
The internal spring is tuned to absorb base engine vibrations (cylinder firing pulses) before they reach the alternator rotor and negatively affect the belt drive system. The IDP significantly reduces belt and tensioner motion, reduces NVH, and offers more durable belt drive system.
OEM's such as Toyota/Lexus are incorporating IDPs in their accessory belt drives. The lower system tension means the alternator, water pump, A/C compressor, power steering pump and all other accessories’bearings will last much longer. Litens is the only manufacturer
of this style of pulley.

Several images of the concept.



LS400 fixed alternator pulley on left and Litens OAD style on right.

Backside view.


Exploded parts diagram of Litens OAD pulley.

Measurements of 1999 LS400 alternator pulley and Litens OAD pulley There is a .6mm difference in the (back) face to center of first groove This should not present an issue, or if so, can mill the face of the alternator mounting ears...


1999 LS400 alternator with pulley removed. An alternator shop offers correct tools.

oldskewel

iTrader: (1)

Yes, very cool new technology. I have a Litens OAD pulley on my wife's 2011 Honda Odyssey.

For those who like videos, here's a scary one:

I learned about the OAD pulley when it failed and started rattling on our Odyssey. Tough to find a problem when you don't even know the pulley is not solid. Now I know.

I believe one of the other benefits of this is that since the spring provides compliance, the belt can operate at a lower overall tension without slipping. Lower belt tension means lower energy loss. But to take advantage of that aspect, you'd need to run with a different belt tensioner.

So this, and the ability for the alternator to over-run, both contribute to slightly better fuel economy, which is what I believe was the driving factor in the development. More power too for the same reason.

YODAONE

Located CFL Starter & Alternators, Inc. On 4929 W. Grand Avenue in Chicago.

Did an excellent job servicing alternator.

Can also retrofit your alternator to high output for audio use.

Yamae

It's a very cool new technology if made well. The problems is that many those pulleys don't last long and there are many market failures. Many of them don't work long enough. They often fail faster than the belt and the alternator. Some people are even doing this type of conversions.

YODAONE

Litens is an OEM supplier to Toyota/Lexus.
Their OAD incorporates a damping spring which presents an improvement over one-way clutch pulley scheme.

As with any other replacement part, there is a lot of crap aftermarket.

The parts department at Lexus confirmed several models incorporate OAD's, but that he has not seen a replacement order.....

As for the video, I am so happy you present this, because this is a perfect example of what NOT to do with an alternator originally equipped with an OAD...!

Vehicles equipped with factory clutch pulleys typically use lighter spring tension in serpentine belt tensioner assembly, or a longer belt perhaps, and sometimes narrower serpentine belt to reduce friction...

Reverting to a regular alternator pulley may damage other system components that were designed to work with an OAD.

Litens discusses this in its promotional materials.

OAD's also make possible use of plastic tensioner and idler pulleys in place of metal ones due to lower belt tension.

No, OAD's do not last as long as standard alternator pulleys....and they give OEM's a way to further cheapen other serpentine system components, but I present it as a way to improve our vehicles as described above.

YODAONE

Located this post online:

https://www.eurekamagazine.co.uk/des...-engine/39568/

The Author writes:

An overrunning alternator pulley (OAP) can play an important part in the smooth running of the modern internal combustion (IC) engine. But it often gets overlooked by design engineers despite the positive effects it can have on energy efficiency.

The function of the OAP is to decouple the alternator from rotational irregularities. This function is critical, particularly as rotational irregularities that occur in IC engines, including those with turbochargers, can be significantly higher than indicated to a driver by a tachometer needle.

In a vehicle's accessory drive, the alternator is the component with the greatest moment of inertia and highest speed. This means that acceleration and deceleration forces acting on the alternator resulting from rotational irregularities have the greatest effect on the belt.
Using an OAP therefore ensures that only the accelerating proportion of the crankshaft forces that are transferred to the belt drive are used to drive the alternator.

The advantage of the OAP with a one way clutch is reduction in the force level in the belt drive. This extends the life typically by a factor of 10 of individual components, while ensuring an increase in the generator speed and a reduction in noise. In addition, the engine runs more smoothly. The OAP also contributes towards the reduction of fuel consumption and therefore CO2 emissions.

In urban traffic conditions, where a large proportion of time is spent idling and accelerating, the belt drive with the OAP is subject to significantly lower loads than a belt drive without an overrunning pulley. Use of the OAP also enables more cost effective design of other components in the overall belt drive system.

Volker Ploetz, senior manager of transmission components at Schaeffler Automotive, says: "The overrunning alternator pulley works in a similar way to the freewheeling of a bicycle pedal, whereby only the acceleration proportion of the crankshafts rotational irregularities is used to drive the alternator. The advantages from this include more effective damping of belt oscillations, which means you no longer need idler pulleys or damping pulleys. You also get a reduction of tensioning forces and lengths, as well as improved noise behaviour, reduced belt width and increased system life. The use of alternators with high inertia is also possible. In terms of assembly, the overrunning alternator pulley is easy to fit as no separate fasteners are required."

This important contribution towards improving energy efficiency also explains why the OAP is being so successfully integrated into both diesel and petrol engines. The component was regarded early on as key for eliminating the rotational irregularities from the belt drive of the new generation of high torque, direct-injection diesel engines. It is also now included in an extensive list of measures for optimising the fuel consumption of internal combustion engines.

Schaeffler recently showcased the CO2ncept-10% vehicle to presents a range of optimisation options for internal combustion engines that can be implemented in a short space of time to yield significant fuel saving. Here, the OAP contributed to a reduction of almost 1% in fuel consumption.

Dr. Robert Plank, vice president of corporate engineering at Schaeffler, says: "CO2ncept-10% is impressive proof of additional potential for optimisation in a system close to volume production standards. CO2ncept-10% is the sum of the individual components."

A comprehensive modular OAP system has been developed that offers many different custom designs for both diesel and petrol engines in passenger cars, commercial vehicles and motorcycles. These also include an OAP manufactured partly to aircraft specifications, which is used in the Schaeffler Audi A4 DTM competing in the German touring car championship.

The Schaeffler Group currently manufactures more than 400 different types of belt pulley with OAP and it hopes that its positive effect to engine design gets fair consideration by engineers in the future.

Structural design
The overrunning alternator pulley consists of a pulley with an outside diameter suitable for using a poly-V belt, a one-way clutch unit with bearing supports, an inner ring and two seals. Following installation, an end cover is snapped onto the front of the alternator shaft to protect it from ambient media such as penetration of contamination like salt water deposits.

A modular system has been developed for overrunning alternator pulleys to provide an economical and flexible solution for customer enquiries. The one-way clutch unit and the seal components are standard parts. Unlike spring decouplers, an overrunning alternator pulley does not have its own resonant frequency and does not have to be adjusted to varying alternator sizes.

Decoupling function
The function of the overrunning alternator pulley is to decouple the generator from the rotational irregularity of the crankshaft of an internal combustion engine. The large mass of the generator cannot follow the high irregularities of the crankshaft at engine start and drive resonances. Therefore it comes to differences of rotation angle speeds of crankshaft to alternator. Contrary to a rigid wheel the overrunning alternator pulley opens in overhauling direction. The alternator mass and their influences are decoupled from the accessory drive. In addition, the overrunning alternator pulley decouples the alternator's inertial torque during a significant engine speed deceleration such as changing gears.

YODAONE

"But to take advantage of that aspect, you'd need to run with a different belt tensioner."

Possible alternative to lower tension tensioner is to use slightly longer serpentine belt from an LS430:

See:
https://www.clublexus.com/forums/ls-...rformance.html

YODAONE

Litens Automotive Group OAD Alternator pulley 920060A.