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kelleybe View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kelleybe Quote  Post ReplyReply Direct Link To This Post Topic: Custom Gearbox
    Posted: Jun/14/2017 at 12:00pm
Hello,

Our team is now 4 years strong, and we are looking to design a custom gearbox.  We want to know where to start.

We have access to Shigley's Mechanical Design, 10th Ed., and we will be working with Timken bearing company.

We have been finding different reports from 2012-13 Michigan baja, Akron, and some others, but we are having a hard time with what initial assumptions to make, like output torque to the wheels we want/need, CVT final drive ratio on low and top ends, shift points, efficiencies, losses, etc.

We had a senior design project last year that designed a gearbox, but their knowledge was not passed on, and I am the drivetrain leader this year.

Please help!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Adam_Clark Quote  Post ReplyReply Direct Link To This Post Posted: Jun/14/2017 at 2:14pm
If you search through the forums you will be able to find almost all the answers to your questions. Specific numbers are up to you and how you would like your car to perform. Apply what your schooling has taught you.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brad SXT Quote  Post ReplyReply Direct Link To This Post Posted: Jun/14/2017 at 10:16pm
You've already got the first part right. Start early.

You've got the second part right as well. You know the topics of some of the major assumptions you need to get started. We won't spoon feed you numbers.

What exactly are you looking for from us? You'll need to develop your own models for vehicle acceleration and gear/case/shaft loading.

Sounds like you're on the right track but there really is no way to short circuit the design work on this one.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kelleybe Quote  Post ReplyReply Direct Link To This Post Posted: Jun/15/2017 at 8:53am
What's your opinion on investment casting vs. straight machining?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote RLM Quote  Post ReplyReply Direct Link To This Post Posted: Jun/15/2017 at 12:06pm
unless your school has a professor working on casting processes or can get a sponsorship for it, your best bet will likely be straight machining. 

With straight machining, it is easy to get raw material and CNC time from a school lab or local machine shop, especially for something simple and easy like a gearbox half. run times are generally low, programming is easy, and usually they do not require 5 axis. the other advantage is that all the features get machined at the same time ( bearing bores, gear clearances, centering pin holes, etc) so is is much easier to locate the material as you just need to ensure the part fits inside the stock. 

With casting, you will need to construct a mold cast the part, then mount and locate the part on a machining center to machine your bearing bores and other necessary features. this is not very cost effective for a one off part. this being said, if you can get the casting process sponsored, I would go that way as from a design and cost look for high volume production (remember goal of competition is to design something you can make 5000 units of per year), casting will be a major advantage. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brad SXT Quote  Post ReplyReply Direct Link To This Post Posted: Jun/15/2017 at 1:03pm
Originally posted by RLM RLM wrote:

this being said, if you can get the casting process sponsored, I would go that way as from a design and cost look for high volume production (remember goal of competition is to design something you can make 5000 units of per year), casting will be a major advantage. 


Casting offers no additional design points over machined. Design points are awarded for showing the engineering cycle for a component. This can be done for any material and manufacturing method. 

We CNC'd our gear case so we could spend our time engineering other components rather than trying to figure out casting from a logistic standpoint.


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Originally posted by Brad SXT Brad SXT wrote:

Design points are awarded for showing the engineering cycle for a component. 
This part I do agree with you. A good engineering design cycle is crucial to doing well in design at this competition, but part of that cycle should also include manufacturing cost analysis as the design goal of this competition is to "Each team's goal is to design and build a single-seat, all-terrain, sporting vehicle whose structure contains the driver. The vehicle is to be a prototype for a reliable, maintainable, ergonomic, and economic production vehicle which serves a recreational user market, sized at approximately 4000 units per year. The vehicle should aspire to market leading performance in terms of speed, handling, ride, and ruggedness over rough terrain and off-road conditions. Performance will be measured by success in the dynamic events which are described in the Baja SAEĀ® Rules, and are subject to event-site weather and course conditions." - Baja SAE Rules 2017 Section A1.2

That's why I disagree with you on this:

Originally posted by Brad SXT Brad SXT wrote:

Casting offers no additional design points over machined. 

In good product development you need to look at both the component performance, but also the marketability of the product. Seeing as this vehicle is supposed to be a prototype of a production vehicle, if the team can design in such a was as to reduce cost of manufacture and increase ease of manufacture, all while not impeding performance of the part or overall vehicle, does this not deserve additional design points? reducing the cost of a product will help with the marketability of the product and thus drive sales up. this is something that should always be looked at in the engineering cycle. as a starting point, getting something working is the first step, then comes, making it work better, then how can we make it work just as well, while reducing the overhead cost to make it. this is why casting ( especially in this application) if designed well, should command more points over an equally well performing fully machined gearbox. if you disagree with this, then please explain to me why no-one in mass production of atv's, or automobiles, uses a fully machined from billet transmission housing? 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BlueDevil08 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/15/2017 at 2:03pm
Originally posted by RLM RLM wrote:

this being said, if you can get the casting process sponsored, I would go that way as from a design and cost look for high volume production (remember goal of competition is to design something you can make 5000 units of per year), casting will be a major advantage.

There needs to be some follow up to Brad's comments.  I think the way that both Brad and I read your initial comment was that by casting your gearcase it automatically equates to more design points.  

Originally posted by Brad SXT Brad SXT wrote:

Design points are awarded for showing the engineering cycle for a component...Casting offers no additional design points over machined. 

This should have been phrased that casting offers no additional design points over a machined case inherently.  It is up to the designer and ultimately the presenter to explain why casting was selected over machining from and engineering standpoint and have the necessary data, analysis, and testing to support the decision.  The same can be said for a team that chose machining over casting; it works both ways.  

Originally posted by RLM RLM wrote:

 Seeing as this vehicle is supposed to be a prototype of a production vehicle, if the team can design in such a was as to reduce cost of manufacture and increase ease of manufacture, all while not impeding performance of the part or overall vehicle, does this not deserve additional design points?

This is absolutely true and would be awarded design points IF AND ONLY IF the presenter explains this to the judges, has the necessary data, analysis, testing, etc. to support his/her claims.  If you did not see RIT's design finals presentations in Kansas or Illinois they specifically talked about designing to reduce cost without sacrificing performance and gave examples of areas across the entire vehicle of how and why they did it.

Originally posted by RLM RLM wrote:

then please explain to me why no-one in mass production of atv's, or automobiles, uses a fully machined from billet transmission housing?

Keep in mind that, as you stated earlier, these are prototype vehicles.  While you are correct that the production level ATVs, cars, etc. do typically use some form of casting throughout their production parts, at the prototyping stages of development they are not typically made from the same exact manufacturing process as is used for full production.  Producing tooling for a 1 off part or even a very low volume of parts may or may not be more cost effective over a fully machined housing; especially very early on in development as any design change will require a tooling modification or in worst cases a new tool.


Edited by BlueDevil08 - Jun/15/2017 at 2:19pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brad SXT Quote  Post ReplyReply Direct Link To This Post Posted: Jun/15/2017 at 2:45pm
This is turning into one of the best discussions I've seen on the forum for quite a long time. 

Alex did a great job rephrasing what I was trying to say. There are no inherent design points associated with fancy widgets or different manufacturing processes and I don't want teams to get that impression. It's all about the design and engineering that goes into them.

On a side note, thanks for being on these forums RLM. You are one of very few people who still routinely respond to all levels of questions on here. I particularly like the $10 fee for spoonfeeding. Anybody pay up yet?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bracer Quote  Post ReplyReply Direct Link To This Post Posted: Jun/15/2017 at 4:47pm
Designing a new gearbox is an overwhelming task to the unexpecting. Kudos to you for starting early! This should allow you to get most everything mostly figured out with minor tweaks for system integration.

I know in years past our team hasnt set output torque values, we have normally set our wanted too speed within reason and used that for calcs.

Depending on what cvt you're using, you should be able to find realistic values for the ratio ranges. Shift points of the car are all based on your vehicle, it takes a fair amount of time to tune in a cvt system to a car, and the differences it makes are crucial for a well performing system.

A quick and dirty way for getting a total efficiency is to calc out what your theoretical tip speed is, and then using a long stretch of flat land and a GPS or some other speed measuring device, find your actual top speed.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote RLM Quote  Post ReplyReply Direct Link To This Post Posted: Jun/16/2017 at 8:17am
Alex, Thanks for clearing everything up, makes much more sense now and I 100% agree with both you and Brad. I would still love to see some of the more advanced teams with tried and true gearboxes, push their designs further to a more mass manufacture style box. these are the teams which more or less run the same gearbox year after year, with very few tweaks because it works very well. 

I really like seeing that teams are starting to push their prototyping process further and further each year. I love seeing teams 3D print full size or scale models to verify clearances and simulate motion. Each year this competition pushed the limits further and further and I couldn't be happier about it. I just wish I could still compete. 

Brad, In response to your side note, no one has paid yet, but the number of PM's requesting spoonfeeding has seen a decline. Further testing is required. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kelleybe Quote  Post ReplyReply Direct Link To This Post Posted: Jul/28/2017 at 1:21pm
Update:

So I have done calculations based on wheel sizes, gradients, surface condition, acceleration and vehicle weights.  Basically it's a huge excel file that asks you to put in vehicle weight and vomits out a bunch of tables with different scenarios.  I want to take the  theoretical torque values from this and compare them to the physical max tractive torque of our 2016 car to see whether the theoretical MTT is within a reasonable value of physical.

For a MTT or more commonly Total tractive effort (TTE) test, I was thinking about using corner weights to weigh the car, then do a sled pull and just load it up with weights until the car gets stuck and use the horizontal component of force and use that to estimate the physical MTT at the wheels.  I feel like once I get over this road block...Wink...I know most of the other initial things I have to do to get the project...rolling. Cool  Or I could try and build a small dyno...but that would take too much time I think.

Any suggestions?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote RLM Quote  Post ReplyReply Direct Link To This Post Posted: Jul/28/2017 at 3:24pm
seems reasonable to me. 
dont forget to take into account the vertical component of the pulling force that will add (or subtract depending on angle of attachment chain) to the vertical force on the wheels of the vehicle.

Just a side note, having a roller dyno will also make cvt tuning a breeze down the road.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kelleybe Quote  Post ReplyReply Direct Link To This Post Posted: Dec/28/2017 at 12:54pm
Thanks everyone for your thought, and for the great discussion. As I come closer to machining (things are mostly figured out, I will "share my junk" once everything is machined) I wanted to start thinking about competition.

What sort of things should I include from the design process and what makes my design different than others, how can I present it differently etc. I guess what are tips on presenting to the judges that will effective communicate inginuity, and how will this be able to score points if some top team...I won't say names...is using things like titanium and advanced 3D printing processes...
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talk about the design steps taken, initial concepts, the analysis you did, calculations, validation, etc. also be prepared to answer any possible question and have supporting documentation ready to go. etc, if they ask what sort of analysis you did on the input shaft, have fea plots printed to show them
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brad SXT Quote  Post ReplyReply Direct Link To This Post Posted: Jan/03/2018 at 6:09pm
Originally posted by kelleybe kelleybe wrote:

Thanks everyone for your thought, and for the great discussion. As I come closer to machining (things are mostly figured out, I will "share my junk" once everything is machined) I wanted to start thinking about competition.

What sort of things should I include from the design process and what makes my design different than others, how can I present it differently etc. I guess what are tips on presenting to the judges that will effective communicate inginuity, and how will this be able to score points if some top team...I won't say names...is using things like titanium and advanced 3D printing processes...

This is all my opinion about design. Take it or leave it.

Design judges will not inherently care about fancy widgets or titanium this or Advanced 3D plastic contraptions. (I feel like we covered this in the thread already? It was awhile ago and I didn't bother re-reading it.)

They want to see the design process. Something like this:

Image result for the engineering cycle

Start by telling a story of how your design came to be. Explain why you are building a custom gearbox instead of some other solution. Go heavy on the engineering details but don't get bogged down in the minutiae of the design. Explain why it's not going to explode. (Your tractive effort sheet vs real life) Explain why you manufactured it the way you did. (Cost effective?) That kind of thing. No need to try and be "ingenious". You don't get extra points for that unless it's a design the baja world has never seen before.

The top teams score big points in design not because of the materials or processes used, but because of their ability to explain WHY they've used them. They bring parts to design, they bring posterboards to design. They bring videos, spreadsheets, tablets, slideshows and whatever they need to adequately show the engineering work they put in. The top scoring teams can bring binders worth of engineering work and explain every page of it in depth. 

Really it sounds like you'll do quite well in design with the work you've put in. You just need to make sure you can show the design judges that you've done the engineering work. 

Any other questions feel free to ask. 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote kelleybe Quote  Post ReplyReply Direct Link To This Post Posted: Jan/04/2018 at 10:37pm
This is the idea we wanted to mount the brake rotor. I know other teams have welded the bracket onto the CV joint on the back side, but that might put the rotor too far out from out caliper mount on the gearbox, I'll have to check the stub height once I get the half-shafts so see if that would be an option for those specific shafts.

Any idea how they located the bracket, I can't find anything to suggest how it was done. I'm thinking maybe a shoulder and a snap ring...maybe not though, the shaft diameter would be too big for the size of the bearing they used...




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Post Options Post Options   Thanks (0) Thanks(0)   Quote IM31408 Quote  Post ReplyReply Direct Link To This Post Posted: Jan/04/2018 at 10:48pm
It could just float on the spline. There are floating rotors for pretty much everything that uses disc brakes, and while I can't think of any specific ones that float on the spline like that the general concept is still the same. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote spike36 Quote  Post ReplyReply Direct Link To This Post Posted: Jan/06/2018 at 8:34pm
Originally posted by kelleybe kelleybe wrote:

This is the idea we wanted to mount the brake rotor. I know other teams have welded the bracket onto the CV joint on the back side, but that might put the rotor too far out from out caliper mount on the gearbox, I'll have to check the stub height once I get the half-shafts so see if that would be an option for those specific shafts.

Any idea how they located the bracket, I can't find anything to suggest how it was done. I'm thinking maybe a shoulder and a snap ring...maybe not though, the shaft diameter would be too big for the size of the bearing they used...


uploads/4331/18342376_1548893681833617_870012998665018097_n.jpg



Hey that's the gearbox I designed! To answer your question, the rotor floats on the spline and the brake caliper/pads locates the rotor. I don't think it's necessary to have a fixed rotor if you choose to go this route.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kelleybe Quote  Post ReplyReply Direct Link To This Post Posted: Jan/06/2018 at 9:16pm
That's a really nice, simple but good looking gearbox!

I've read that a floating rotor causes uneven pad wear (the brake system is our capstone project), what were your experiences?

Also, I'm struggling with the thicknesses of the housing for the bearing supports, and the flange all the way around the clamping portion.  I've ran some worst case scenarios on the housing, simulating the preloads on the bolts for mounting and clamping, the reaction forces on the bearings, and the braking force, and put in fixtures as best as I could, and it "passes" in SW simulation, but on the off chance that the gearbox sees some unforseen loading, I don't want the worst to happen.

Any tips you can give me would be appreciated, since we don't really have any previous versions to base this off.  I'm about 95% done with the design, just some odds and ends to figure out.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote spike36 Quote  Post ReplyReply Direct Link To This Post Posted: Jan/07/2018 at 1:06pm
That's true, it might cause a bit of uneven pad wear. My experiences with that gearbox is that the rotor favoured the inside or outside side of the caliper, meaning one side's slave cylinder would be much further extended than the other. All within its limits but it was never perfectly centered. Now for pad wear, the float will cause the rotor to scrub away the pads as it spins and bounces between sides but I assumed that it's nothing significant and I've never seen any dramatic differences in pad wear. It's fine for a year (1 competition + testing through the year) for sure and if you're uncomfortable you can always swap new pads in. 

For the housing, you need to design it based on your comfort level. I ran FEA tests under a few worst-case scenarios that I could think of (i.e. CVT at full reduction, maximum breaking, etc.) and when I was satisfied with the safety factors that FEA was giving considering the assumptions used to determine the loads for the different cases, I went with it. Where your comfort level comes in is in determining what is an acceptable safety factor for you, so adjust your thicknesses accordingly. My theory was that it was a race car so I tried pushing the limits a little since our last gearbox iteration was very strong. That being said, if it's your first iteration I'd tend to err on the side of caution, but it's all up to you!
When I ran my casing tests, I set it up with only the two halves of the casing and no other components to the assembly. From there I added the bolted connections along the flange and other constraints and then applied my bearing housing and braking loads and ran the different scenarios. One thing I totally forgot to consider is that the three shafts serve to keep the two casing halves from rotating relative to each other, meaning that the bolted flange connections are under less loading in real life than in the FEA tests. That should at least help with the thicknesses along your flange. 
Make sure you constrain the casing as realistically as possible within Solidworks and apply different scenarios to it to see how it behaves and it sounds like you're on the right track! It's a huge undertaking so I wish you luck and let me know if you have more questions.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kelleybe Quote  Post ReplyReply Direct Link To This Post Posted: Jan/07/2018 at 1:21pm
Thanks so much for the insight. I tried to run fatigue tests, such as repeated braking force for deceleration not(not full stops)like for a realistic amount of cycles (go pro footage from Illinois 2017 helped with this). But it looks like SW doesn't have fatigue life curves for 6061, and I tried it with 7075, but it said something along the lines of "stresses in entire model are lower than something or other, so I'm not sure what to conclude, because static simulations only go so far.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote spike36 Quote  Post ReplyReply Direct Link To This Post Posted: Jan/07/2018 at 1:32pm
I assumed that those deceleration forces you're talking about would not lead to fatigue failure. For the most part, you're just scrubbing speed so it's very light braking and would be well within the material's yield strength. I'm not sure how many cycles you're getting but assuming it's something like 1000 cycles, you use a fatigue strength of something like 90% of your yield strength so I just ran static FEA tests and accepted those results. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kelleybe Quote  Post ReplyReply Direct Link To This Post Posted: Jan/21/2018 at 8:02pm
How did you find to use the 90% of the yield strength? I found a study that approximated the fatigue strength as an equation, and that's around 70ksi, whereas the yield strength is around 40ksi for 6061-T6.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kelleybe Quote  Post ReplyReply Direct Link To This Post Posted: Jan/21/2018 at 8:03pm
70ksi for 2000 cycles (of the rotating beam)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kelleybe Quote  Post ReplyReply Direct Link To This Post Posted: Jan/22/2018 at 3:36pm
The 90% of UTS at 1000 is for steel, but I talked with a few professors, and they said 90% of the YIELD strength (what you did) should suffice for a racing application like this with relatively low cycle testing.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote spike36 Quote  Post ReplyReply Direct Link To This Post Posted: Jan/22/2018 at 8:56pm
Your professors had the same assumption as I did. It's hard to find aluminum fatigue data for free.
Consider too that this isn't true fully-reversed fatigue loading. The reaction force on your case are only really in one direction every time so you don't get the oscillations between max compression to max tension. That is unless you're going to incorporate a reverse gear and plan on doing significant driving backwards.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kelleybe Quote  Post ReplyReply Direct Link To This Post Posted: Apr/23/2018 at 9:28am
Hey everyone, after months of design, headaches, and companies backing out on us, we got a running car 2 days before competition.  Here she is...we had absolutely no testing save for a few runs to break her in.  Got 4 laps at Maryland due to torqued off driveshafts that were ran at too high of operating angle, but the gearbox chugged us up those hills just fine! Car came in at 75 lb more than designed for, but she still cruises at about 35 mph.   Thanks for all your help, I can't wait to see her do well next year when I'm gone.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Adam_Clark Quote  Post ReplyReply Direct Link To This Post Posted: Apr/23/2018 at 1:40pm
To make sure you do not max out your axles in angle or plunge, when you are tacking your rear-end together, place your shocks at full droop and make sure your cv angle isn't too much. then put your suspension through travel and make sure you do not have too much plunge. If something is off, adjust your axle length.

Great job!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kelleybe Quote  Post ReplyReply Direct Link To This Post Posted: Apr/23/2018 at 1:45pm
That's exactly what we did, our rear track is just too small, which forced us to run really high angles. We're going to change it up here soon and see if that helps anything.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bantu Quote  Post ReplyReply Direct Link To This Post Posted: Jun/12/2018 at 6:37pm
Hi
I am a student from South Africa doing BTech in Mechanical Engineering. I am busy designing a Gearbox for Mini Baja. My Gear Box has only two Gear sets and the optimal gear ratio for my single reduction Gearbox is 8.1:1. I am using 10HP Briggs & Stratton engine coupled with 780 Comet CVT clutch. Tire diameter is 22 inches and the total weight of the vehicle with the drive is 288kgs.
My question is, is it appropriate to use a single reduction gearbox when you want to perform better on acceleration, hill climb and endurance race?

I personally feel like I should utilize a double reduction gearbox to minimize high stresses that will be subjected to my single reduction Gearbox.

Amy ideas if I should go for double reduction gearbox or single reduction gearbox?????
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Post Options Post Options   Thanks (1) Thanks(1)   Quote kelleybe Quote  Post ReplyReply Direct Link To This Post Posted: Jun/12/2018 at 10:09pm
First I would focus on reducing the weight of other subsystems of your vehicle, since you can't reduce the weight of the engine and most off the shelf CVTs are going to be about the same weight. However if your drivetrain is the biggest contributor I would consider all your options based on feasibility, budget, and maintainability, etc. That being said, a single reduction gearbox will not be enough alone to achieve performance specifications common in the Baja SAE competition. With only a single reduction, your gears would have to be very large, thick, and/or strong and the ratio would have to be very large resulting in a packaging issue. For example my gearbox was about 12 lb compared to the 45lb gearbox we used to use, but packaging was only reduced marginally, and this was our first custom gearbox it actually worked, so there is a lot of optimization that can be done on this design.

I would focus a lot of your attention on First Learning how the CVT works and how it will play into giving you the performance characteristics you want on each different event and also reducing your weight to under 400 lb, as anywhere from 325 to 375 can be a competitive vehicle as long as you do enough testing and iteration to understand how the vehicle is going to perform for each different part of the competition. You can work wonders with Minor Adjustments to the CVT, but once your gearbox is complete there's not really anything you can do.

Most teams use a double reduction gearbox because he can get away with pretty small ratios which will result in a higher top speed and higher acceleration because of the reduced weight of the drivetrain. You may suffer on things like sled pull and Hillclimb but most teams decide to do that because it will grant them better acceleration out of turns and higher top speed overall for the endurance race. However this isn't saying that you can't have a great car overall if you have enough research and development into the vehicle.

Research the University of Cincinnati drivetrain report from 2012 or 2013, this will give you a very good insight into how they went about designing their drivetrain and how I went about designing our drivetrain this year (2017-18). As a word of caution, a lot way more than enough time for the development and the manufacturing of the drivetrain, because you could run into sponsorship problems along the way that might leave you without a drivetrain weeks before competition.

If you are using agma standards for Gears, only use it as a guide to begin your designoh, because those gears are meant for years and years of service and Industrial and high loading situations. With racing applications you can really push the limits so if you get safety factors per AGMA bending stresses and contact stresses under 1 for your gears, keep reiterating until you reach an acceptable ratio, but then push the limits based on Research you have done. For example agma standards with my inputs calculated that I needed one in face with gears for the ratios diameters that I wanted to use, however these or similar to what would be in a standard commuter vehicle, and in a racing situation that has lots of weight and is unnecessary. For ours we use the face with the .875 and .75 for the second reduction in first reduction respectively.

With all that being said, there's a lot of work that goes into designing a gearbox. And after everything is said and done you will always look back and wish you could have done something different, as you always see better designs at competition from teams who have had more experience. But remember that every team has to start somewhere.

Also remember that performance characteristics and design specifications are up to you and your team and what you want to get out of your vehicle. Blindly following someone else's design just because it works for them does not mean that it will work for youoh, so take your time and doing your research and do a lot of research until you start to settle on what you feel is appropriate for your vehicle and for your competition. Let me or anyone else on this forum know if you have any questions, there should be lots of threads on drivetrains, and there should be lots of reports out there from teams in the United States that should help you along with this process. Have fun designing and good luck in your future competitions!

Edited by kelleybe - Jun/12/2018 at 10:12pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bantu Quote  Post ReplyReply Direct Link To This Post Posted: Jun/12/2018 at 11:55pm
Thank you Mr Kelleybe, I appreciate your assistance.
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