Building another chassis dynamometer. Need absorber ideas.
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    Default Building another chassis dynamometer. Need absorber ideas.

    We built a water brake years ago but want to build an electro-magnetic (eddy current) design that is more mobile and compact. Most all designs out there are using either the Klam or Telma power absorbers for truck drive lines. We have been shopping for a year trying to snag some used ones. VERY hard to find because they are made outside the US.

    Obviously we would rather buy used as the new price of these is HIGH! We can build a water brake for peanuts compared to the eddy current designs but want one non the less. So, anyone know where we can either find Klam or Telma brakes or know of any other mfgs in the states that we can shop for? We will want to buy a few brakes for our different requirements but for now, 500ft/lbs and 2000rpm would work fine. Could even use a smaller 200ft/lb unit too.

    I am also going to post in the electrical forums to see if anyone has any ideas.

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    We imported and installed Telmas on some of our heavy truck test vehicles when I was at Michelin. That was close to 30 yrs ago. At that time, retarders were required equipment on most all passenger buses in Europe, and were used on a lot of trucks over there as well. I'm wondering if imported buses common in the US from mfgrs such as MAN and Setra might be equipped with retarders as std equipment. Other than that, I don't know of any sorts of vehicles in the US that might have E/M retarders, so I'd think the supply of used ones would be slim indeed.

    I had a conversation recently with a guy who worked in engineering with Dyno Jet for several years, and he mentioned they imported their retarders from Spain, although I don't remember the brand specifically. He did say Spain is sort of the manufacturing center for retarders in Europe though, and that there are several brands made there.

    Most of the pics I've seen of the Chinese ones appear to be dead copies of Telmas. Any idea of how the Chinese ones hold up?

    IMO, we ought to be able to go to any truck junk yard anywhere in the US and buy all the retarders we could haul off. Were it not for the trucking industry's absolute mindset against anything new or different, that would be the case. Rockwell had heavy truck air disc brake systems fully developed and ready for the market 30 years ago. 20 years later, they were still non-existent for the most part on heavy trucks. That oughta give you some idea of when they'll adopt retarders.... maybe by 2090?

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    Default Dyno

    There used to be several companies that made electric dynos. I have used the old Midwest and Eaton electric dynos and the DC motor style made by General Electric. A popular Midwest unit was the model 1014 rated at 175 hp and the 1519 which was 600 hp. I worked on design and installation of Chassis Dynos that used the 1014 Midwest unit and large diameter rolls (300 revolutions per mile)
    JRW

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    I remember Telma and Klam being VERy close to each other in Europe and I asked how that could be. That is when I was informed they were standard equipment. That just blew my mind that there was only two mfgs that I could find.

    I would sure think a China unit would hold up fine for our application since this will not be in service daily and only for seconds at a time. OK, maybe minutes if we start writing run-in programs for it.


    Any ideas where to find them in China?

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    Quote Originally Posted by J.R. Williams View Post
    There used to be several companies that made electric dynos. I have used the old Midwest and Eaton electric dynos and the DC motor style made by General Electric. A popular Midwest unit was the model 1014 rated at 175 hp and the 1519 which was 600 hp. I worked on design and installation of Chassis Dynos that used the 1014 Midwest unit and large diameter rolls (300 revolutions per mile)
    JRW
    5.6ft diameter rollers!!! That might have a little inertia to it!


    The rollers are going to be the hardest part of the design. Our previous ones are not balanced and causes bearing issues. Any ideas on how to "economically" make some rollers with traction grooves?

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    Quote Originally Posted by viper View Post
    5.6ft diameter rollers!!! That might have a little inertia to it!


    The rollers are going to be the hardest part of the design. Our previous ones are not balanced and causes bearing issues. Any ideas on how to "economically" make some rollers with traction grooves?
    Over here our MOT ( vehicle roadworthy test) brake testing rollers are coated with a coarse abrasive bonded on.

    Traction grooves ;- parallel to axis or spiral?

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    Why not look into using an appropriately sized alternator or DC machine running into a water resistance/electrode boiler and active control of the excitation to give the load control.

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    Default Dyno Rolls

    We had five units with steel rolls and one made of Aluminum. The rolls were belted to the Dyno shaft and on that shaft was a set of plate flywheels (each one was an additional 100 pounds equivalent of vehicle weight) and this shaft was belted to a large centrifugal fan to blow air onto the vehicle and provide 'windage" loading.. The rolls were not coated and we had no slipping problems.

    JRW

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    tecalamit make them over here [uk]http://www.tecalemit.co.uk/00723.html
    mark

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    Default

    I know some vehicle inspection shops have some type of chassis dyno for checking emissions. I don't know much about them but I think the car spins a roller that can simulate hills and create varying loads on the test vehicle. Can something like that be used to make a dyno?

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    I am not familiar with emissions equipment but if it is able to simulate load, it would have to operate under the same principals. I am not sure if they have enough load to stall a car or not. We will have to bring motors near stall to test peak torque.

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    Quote Originally Posted by Joe T. View Post
    I know some vehicle inspection shops have some type of chassis dyno for checking emissions. I don't know much about them but I think the car spins a roller that can simulate hills and create varying loads on the test vehicle. Can something like that be used to make a dyno?
    Our shop has exactly that. The roller is about 1.5 ft diameter and is attached to a water brake of some sort. It hasn't been used for years for actual emission testing but we did spin it up last year for an initial drivetrain shakedown of one of the vehicles we produce. Compared to the other chassis dynos I've seen, it's rollers are much smaller and lighter.

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    Quote Originally Posted by Mark Rand View Post
    Why not look into using an appropriately sized alternator or DC machine running into a water resistance/electrode boiler and active control of the excitation to give the load control.

    Or better yet a regenerative dc drive. Here is a link to a guy who has some Telma brakes for sale for $550

    http://cgi.ebay.com/ebaymotors/ws/eB...%3D%26_fvi%3D1

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    Yeah, I have chatted with him before but no dice as of yet. I have to have the model number of the brake and he could no produce it. Gotta know what it can do before we buy it.


    I figure the DC input should be peanuts afterward. DC drive, or even just see if I can get the DC driver for the brake I buy. They gotta have one on the truck to use it! That being said, a DC motor drive will have some nice electronics to program in for ramp, decel, and such. Probably a better route.

    I know those damn brakes are floating around somewhere need a new home! Problem is we need a few. hard to test a an 50HP motor with a 400HP brake and vise versa.

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    Have you considered using a gearbox to step up the rpm so you can use a smaller brake for different sized motors?

    Roger

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    Our main design goals are simplicity and to minimize inertia for the smaller loads. We have not directly looked at gear reductions yet and hopefully can do it by simply engaging different absorbers for different loads. We are looking hard at Al rollers to reduce inertial problems.

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    Hey Viper,

    Any updates on this? I'm currently in the process of designing my dynamometer, which will be used for testing small 30hp and below engines. I've found quite a bit of useful information in the threads you started on the subject, but I'm interested in final results.

    I apologize to dig up a thread that's years old, but it peaks my interest enough to do so.

    I bought an old conveyor belt roller thinking I could use it, but it's 20" diameter with 1/4" wall leaves me a little wary of spinning it at 85 MPH (whatever RPM that would be) and it's going to cost to have it dynamically balanced. I wasn't sure if a roller that was only 16" long really had to go through the multi-plane dynamic balancing that land-and-sea boasts.

    I've pretty much settled on DataMite by Performance Trends for DAQ, but after reading this thread I'm going to read up on other systems and see what I come up with from omega.com and ni.com. If nothing else, I can get the base DataMite Mini USB and then purchase the thermocouples and leads from one or the other suppliers.

    My primary concern is being able to apply a load and read exhaust gas temps (EGT), cylinder head temps (CHT), and air fuel ratio. I'm not sure what other functionality I should be looking for, as I have never run a dynamometer before. I do know that shelling out the $13,000 for a new unit from one of the US manufacturers is not an option yet. I'd rather save the money and work on some of the other projects that are in the bag of tricks. :P

    All the best,

    ~Josh

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    At one time Caterpillar made a retarder for use behind it's 600 hp truck engines and I believe it was also used in their large quarry trucks, many years ago some truck builders tried an electo magnetic retard system that was part of the drive shaft, It seemed to do it's job but was hard on drive shafts and u joints.

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    In February of this year a friend received some (unsolicited) info on Chinese eddy current units in his email. Contact info for the company (Zhejiang Rebang Machinery Co., Ltd) is in the PDF and it has some technical info on the different absorbers.

    http://www.eurospares.com/graphics/engine/rebang.pdf

    cheers,
    Michael

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    Quote Originally Posted by Michael Moore View Post
    In February of this year a friend received some (unsolicited) info on Chinese eddy current units in his email. Contact info for the company (Zhejiang Rebang Machinery Co., Ltd) is in the PDF and it has some technical info on the different absorbers.

    http://www.eurospares.com/graphics/engine/rebang.pdf

    cheers,
    Michael
    I wonder if they have any that are smaller? I may e-mail and find out.

    Here's one used by DynoJet, though I think it is the larger variety:


    I'm looking for something smaller:



    I assume the torque rating of the eddy current brake needs to be higher than the maximum expected torque of the engine.

    Air-Cooled Eddy-Current Absorber - Load Charts Looking at this chart, it looks like the DynoMite #20 Eddy Current Absorber will work for small engines on a chassis dyne.

    Say, am I getting terminology mixed up? Is an eddy current brake different from a current absorber? :/

    Load cells look common enough, and inexpensive enough as well:
    Load Cells

    ~Josh


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