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SimXperience Developers Blog

Racing Simulator Developers Blog

27 Aug 2014

Direct Drive vs Belt Drive vs Gear Drive

Direct Drive vs Belt Drive vs Gear Drive

Author: Berney Villers  /  Categories: AccuForce Wheel, Other  /  Rate this article:
3.7

This article aims to explain the key differences between common servo / belt drive force feedback wheels, servo / gear drive force feedback wheels and newer direct drive force feedback wheels.

It's important to note that the term servo is widely misused in the racing simulation industry, causing the term to essentially mean nothing. It's unfortunate that these clever marketing gimmicks have won out in the minds of the consumer. Nonetheless, for the purpose of this article I will use the term as used in this market to prevent further confusion.

Servo & Belt Drive

Servo and Belt drive systems utilize a belt and pulley system to help a smaller motor generate more torque. The steering wheel is NOT directly coupled to the motor shaft. Some Fanatec and Thrustmaster products fall into the category of Servo and Belt.




Servo & Belt Drive Advantages

  1. Facilitates the use of low cost motors.
  2. Belt dampens detail so smoothness is improved

Servo & Belt Drive Disadvantages

  1. Belt absorbs force feedback detail resulting in less driving information being conveyed 
  2. Belt absorbs high frequency details
  3. Belt wear and stretch result in increased maintenance and product failure
  4. Low cost motor use dictates a pulley ratio that results in a loss of force feedback detail
  5. Belt friction results in lost efficiency
  6. Additional mass of pulleys must be overcome by the motor

 

Direct Drive

In a direct drive system, the steering wheel is directly coupled to the motor shaft. There are no gears or belts. Direct Drive wheels typically use larger motors to compensate for their lack of belts. The upcoming SimXperience AccuForce wheel is an example of a direct drive system.



Direct Drive  Advantages

  1. No loss of detail
  2. No maintenance or belts to wear
  3. True 1:1 performance
  4. Ability to transmit high frequency detail
  5. No additional drive train mass or inefficiency for motor to overcome

Direct Drive Disadvantages 

  1. Larger, more expensive motors are required

 

Servo & Gear Drive

To the best of my knowledge, there are currently no force feedback wheels on offer that purport to be a a servo and gear drive combination. That said, depending on your definition of "servo", the Logitech G25 may qualify. For the purpose of this article we'll be going by manufacturer claims so as to avoid confusion and Logitech does not claim the G25 as a servo system.

A deeper dive

It's no secret that SimXperience has chosen direct drive for the upcoming AccuForce product but the primary reason for our choice may surprise you and while stated above, may have escaped you!  

"Low cost motor use dictates a pulley ratio that results in a loss of force feedback detail"

This is actually a quite troubling aspect of using a belt drive system. For the sake of argument, lets suppose a 20:1 pulley gear ratio for the belt drive system. While this ratio allows for the use of cheap motors, it's also the primary downfall. The belt drive motor would have to spin 20 times faster than the direct drive motor to match the direct drive systems ability to produce detail! 

In a force feedback system, rapid motor direction changes are common. A direct drive system simply makes these changes and it's directly felt in the wheel. 

The belt based system in our 20:1 example would need time to get up to the 20x faster speed it needs to match the direct drive system. However, in most cases, the motor will NOT get up to speed before the next force feedback instruction arrives. This means that it didn't accurately reproduce that data being provided to it by the vehicle simulation! 

While many have commented on the smoothness of belt drive systems, I wonder how many realize that some portion of this smoothness is actually a loss of detail due to  the belt and pulley gear ratio.

The Bottom Line

Belt drive is best suited to budget force feedback steering systems while Direct Drive is better suited to the high end wheel market  where realism and accurate detail reproduction is required.

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42 comments on article "Direct Drive vs Belt Drive vs Gear Drive"

9
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Emmanuel Ballet

8/28/2014 12:31 PM

your wheel seems awesome but what's the date of sale and the price? thx


5
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Berney Villers

8/30/2014 10:24 AM

We're targeting 2014 for the initial AccuForce release. Final pricing is not yet established but we have publically committed to a price of less than $2000 USD


0
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Y K Sim

8/29/2014 8:13 AM

I ask the same question as above :) On top of that, may i know the compatibility with other pedals? It's got its own usb connection to the pc and runs on Sim commander ?


2
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Berney Villers

8/30/2014 10:25 AM

Yes, the AccuForce has it's own USB connection to the PC and also can be controlled by the Sim Commander software.


1
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julien raidelet

8/29/2014 10:43 AM

thanks for that technical article

but what about cogging? If I turn a motor axis I feel something not smooth at all, even if the motor are brushless.

Step motors still have a step by step feeling, each step close to the other.

So, you might also write about that point.


6
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Berney Villers

8/30/2014 10:31 AM

Cogging is interesting subject and I agree, it's definitely worthy of another blog article. Each motor style has it's own cogging related issues. Brushless DC will have a few very large cogs while steppers have many very small cogs.

It's important to note that cogging can be introduced by belt teeth and gears in addition to motors.

There is no wheel on offer that doesn't experience some form of cogging. The key is to minimize it to the point that it's difficult to perceive.

With the AccuForce product we tested dozens of motors and ultimately wound up having the motors customized to get the smoothness and response that we wanted.


1
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julien raidelet

8/30/2014 12:11 PM

can we preorder today to be sure to be one the first men to try our new direct drive technology? ^^


1
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Berney Villers

8/31/2014 4:36 AM

You can reserve your spot on the AccuForce list by contacting us and requesting to be added to the AccuForce sign-up list. We'll notify you when the product is available.

You can use the contact us form here: http://simxperience.com/en-us/contactus.aspx


0
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MATHIS Marc

9/1/2014 1:37 AM

Hello Berney,

What is the diffence between your wheel and the EC Sim Hardware wheel ?

Cheers


1
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Berney Villers

9/2/2014 3:29 AM

Nothing is known about it but I would expect that the main difference will be that the AccuForce is complete wheel while the other is a DIY kit. I would also expect the AccuForce price to be lower despite the fact that it comes with all the goodies. Further, I think the main AccuForce difference is simply attention to detail. The other guys have motion systems too but you never hear about them for good reason.


1
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C3PO

9/1/2014 3:15 PM

The wheel sounds great. A couple of questions.

1. What will be the cost of the unit in the UK?

2. How can the wheel be mounted? Is there a mount available for use on a table for example? Will it fit the rSeat cockpit chassis or the Fanatec chassis?

3. I've used the Leo Bodnar wheel many times elsewhere. How does it compare to that?

Thanks for your answers!


4
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Berney Villers

9/2/2014 3:35 AM

We've not officially released pricing yet, except to say that the AccuForce Pro Momo Edition, which comes with a genuine Momo wheel will be priced at under $2000 USD.

This wheel isn't really well suited to desktop use but desktop mounts will be offered.

I think the Leo Bodnar wheel and AccuForce both very competitive wheels. I expect to see most reviews favor the AccuForce due to the extreme similarities in performance and the fact that the Bodnar is not a complete offering. It's simply a DIY kit. Further, the AccuForce is completely controlled by our Sim Commander software and is a complete, professional force feedback toolset.


0
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James Loucks

9/1/2014 10:28 PM

So excited for this. About the quick release, would it be possible to take the wheel rim and disconnect it and put on a real car? Might sound like a dumb question, but if I had the same feel (stitch,grove etc) in sim and IRL on track that would be great.

If it has electrical or propitiatory then I could see that not working, but if it had the curly wire like Motec has for there buttons, then it would be perfect.

curious...


2
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Berney Villers

9/2/2014 3:38 AM

Yes. The AccuForce system uses real race car parts, not cheapy imitations. Further, we designed it to be an open standard, rather than forcing you into a proprietary format and locking you in. You can install real race car wheels of your choosing.


0
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MATHIS Marc

9/3/2014 1:39 AM

Hello Berney,

Appreciate all the work that goes in to this sort of equipment and i have some more question ...

1 - The accuforce will be compatible with the fanatec steering wheels ?

2 - If you are targeting 2014 for the initial AccuForce release, what about the date of sale of the AccuForce Pro ME ?

Keep up the good work.

Marc


1
0

Berney Villers

9/3/2014 5:08 AM

Hi

I'm not sure about compatibility with the Fanatec wheels or if they would survive on a direct drive system. We support most any real racing car wheel. I thin some of their wheel;s don't meet any real vehicle bolt pattern standard so those one's wouldn't be applicable. If you're concerned about budget you could probably find Fanatec-similar wheels on eBay or some of the Asia direct websites.

The AccuForce Pro Momo Edition will be made available at the same time as the AccuForce Pro.


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MATHIS Marc

9/3/2014 5:25 AM

Thanks for your answers !

I am not concerned about budget but using Fanatec Wheels is just an opportunity.

Have you an idea of the month that the AccuForce will be made available ? I need to manage my wife !!!

Marc


1
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Berney Villers

9/3/2014 8:32 AM

:)

Are you asking for the month, or the time of the month?

I'm going to wait until the public beta test has concluded to say for certain.


0
0

Y K Sim

9/3/2014 7:29 AM

Hi Berney,

Will you make available a version without wheel as I have my own wheel I intend to use?


1
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Berney Villers

9/3/2014 8:33 AM

The DIY version will be wheel optional.


0
0

Y K Sim

9/3/2014 7:39 AM

Is the accuforce pro the version that comes without the wheel? From the increase in chatter. ... Can we forsee a very near release date? :)


1
0

Berney Villers

9/3/2014 8:35 AM

The AccuForce Pro is a complete simulation steering system, with all the bells and whistles.

We won't be publishing a release date until the pubic beta has finished and the feedback analyzed.


0
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MATHIS Marc

9/3/2014 10:09 AM

Hello Berney,

I asking for the month only.

The year is realy 2014 ? :-))

I would be one of your first customer for the accuforce pro ... :-)


0
0

alem bosnjakovic

9/4/2014 5:45 AM

I sent you mail a few days ago asking you to put my name for some kind of pre order. Hope you got it .... cant wait to drive that thing :)


0
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alem bosnjakovic

9/4/2014 2:30 PM

im thrilled that you have momo wheels incorporated with that wheel , but one question why not the momo mod 27 ( buy that mod i think mainly about diameter ) . and that design of momo mod 27 screams GT racing to me.... in any case il probably go with some kind of momo wheel...


1
0

Berney Villers

9/5/2014 1:21 AM

You can use a MOMO Mod 27. If you do I would suggest the 290mm version. As is the case in a real vehicle, you often get more precise vehicle control with larger diameter steering wheels.

We haven't ruled out the Mod 27 as an option but the other options seems to be in higher demand.


1
0

Eric Bergeron

9/6/2014 12:57 PM

Hi,

Like many here, I can not wait to see your masterpiece. What caught my attention right now is the DIY kit.

Does your wheel will have buttons? (because they are DD)

If yes, do the DIY kit will have the purchasing options? (addition of QR, buttons etc ....)


0
0

Berney Villers

9/12/2014 9:53 AM

The AccuForce Pro has buttons.

We'll be offering most parts of the AccuForce Pro to DIY builders, the wheel button box for sure.


0
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Eric Bergeron

9/13/2014 7:21 AM

good! thank you to answer. The hardest part now ... waiting ...


0
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Jed A

9/13/2014 11:44 AM

I'm aware the wheel is not for desktop. But will you offer a desk clamp for the wheel when it's already out on market? I do not like having permanent holes on desk and rigs.


1
0

Berney Villers

9/13/2014 5:25 PM

A desktop mount will be offered but a rig is suggested.


0
0

Y K Sim

9/13/2014 9:29 PM

Berney, how's the public beta and analysis coming along? :)


0
0

Berney Villers

9/14/2014 11:49 AM

We're just waiting on some parts to come back from manufacturing.


0
0

Y K Sim

9/15/2014 10:30 AM

Are we almost there yet? :)


0
0

Jed A

9/14/2014 7:51 AM

Will the desktop mount be a clamp? is it sturdy? or you still have to drill a whole on the desk to mount it.


1
0

Berney Villers

9/14/2014 11:48 AM

The desktop mount is sturdy. There is no need to drill holes in your desk. However, your desk will need to be able to handle the stresses of the AccuForce. Again, a robust rig is suggested as I have some concerns about particle board desks, etc. being able to handle the stresses.


0
0

Jed A

9/14/2014 4:36 PM

Don't worry about that, I have hard wood table. Cannot wait for the wheel to be available.


0
0

Ron Lewis

9/18/2014 7:33 PM

I am so ready for this wheel... Can't wait!


0
0

Brian Phillips

10/13/2014 5:33 PM

Hi Berney.

I have a Human Racing GT chassis. I don't know if you have any experience with this rig, but if you do, do you think it will be robust enough for your wheel?

Thanks


0
0

Mark Blayney

10/23/2014 12:34 AM

Hey Berney, I am in Brisbane, Australia and late to the party but just filled in a contact form to request opportunity to purchase the AccuForce Wheel as soon as available... sounds incredible :)

One Question : I have 2 sets of Fanatec Clubsports Pedals and wondered if they will remain compatible with (my new :-D ) AccuForce or will I need different pedal set ?

cheers mate & hope beta is progressing nicely !


0
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Mark Blayney

10/25/2014 9:17 AM

I got an answer for anyone else interested that the AccuForce is compatable with Clubsport Pedals.

Is an Obutto Ozone Cockpit strong / sturdy enough to withstand the strong forces of the AccuForce (I think I read somewhere 15nm ?).


0
0

Mark Blayney

12/4/2014 2:44 AM

Any updates on the Accuforce wheel ? So is not coming to market this year by the looks of things, no info anywhere on the web since long time now.

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