CCV Medium Height Top

[1der]

Herb/Admin - my request is to have the title of this thread changed to eliminate the Beastie 3 Build part. The thread was taken WAY off what I intended. I will start a separate thread for our build.
Greg- thank you was just getting ready for surgery this morning when I saw your post.

Chris - wow! How surprising to see your "valuable" well informed and thoughtful "contribution" here. Really insightful - again.

Re: facts about the CCV top - I laid out facts about this design. I see MG facts about loads on scissors lifts etc. but not a single FACT supporting his opinion about the CCV lift design, not a one. I am not even sure the CCV design, like REF said, is a scissors lift design. MG has not inspected, based in his posts, a CCV lift first hand, does not even own (or owned?) a pop top?? Seriously, MG is a very sharp guy with lots of experience in his field but seems to suffer engineering NIH syndrome and no taking of the next step of "this might be an improved approach/design". Lots of bashing but no positive input. I have managed engineers and owned manufacturing companies, seen this before.

I did my due diligence around tops. Of what tops are out there right now - yep, shenrie's question is a very good one. Lift, utilization, ergonomics, function, comfort, safety - each of these manufactures/up fitters are one big compromise. And Shenrie - have a look at Derek's design for the full extended SMB failure that you saw. SMB had no more travel available to disengage the clevis hardware. It needed another inch plus which was not designed in to it, so a sawzall was needed. Hope MG has lots of batteries for his saw all since he likes SMB better, IF. he actually had a top. In the scenario, the CCV lift provides three places per side and requires an 1/8 " or less (along a socket, wrench and /or pliers to remove the cotter pin) to reduce pressure on the pins so they can be removed.

REF - you have first hand experienced using both tops for quite a while. Not sure there are too many people out there that have that perspective. That is the most valuable input, real life hands on user experience.

This is a valuable thread, should be left - just modify the title.

[boywonder]

Originally Posted by Scalf77

Maybe we can have a Admin move the deep dive into CCV's tops into it's own thread. That way we can keep the Ray's post clean, and continue on with the worthwhile discussion in it's own thread.

-greg

Good idea!

........anyway, the calcs are done for the top lift, and based on the sketch and the load rating of 1000 lbs push for the actuators, the max load (including the weight of the roof and everything attached to it) appears to be roughly 328 lbs. With each actuator pushing with 1000 lbs when the top is down, the vertical force available for lifting the top is around 164 lbs per side, so 328 lbs total.

This assumes that the actuators reach their rated load before the cross members bend/fail.

I can post the calcs if anyone is interested......basic static free body diagram and some trig....

I imagine the roof weighs less than 300 lbs...probably 150-200 lbs or so.....just a guess based on moving/installing my SMB top.

Also, as 1der mentioned, the high roof geometry will probably result in a higher weight limit if the starting angles of the members are more vertical and the actuators are equivalent.

[BroncoHauler]

Originally Posted by 1der

Herb/Admin - my request is to have the title of this thread changed to eliminate the Beastie 3 Build part. The thread was taken WAY off what I intended. I will start a separate thread for our build...This is a valuable thread, should be left - just modify the title.

Done.

[UJOINT]

Originally Posted by 1der

Chris - wow! How surprising to see your "valuable" well informed and thoughtful "contribution" here. Really insightful - again.

Not sure what you mean.....

[2horsegarage]

https://www.youtube.com/watch?v=1sONfxPCTU0

[mgmetalworks]

I'm a critic of the lift mechanism design. It's not because I have any kind of syndrome and it's not because I've got some personal vendetta to carry out. I'm a critic because it concerns me to see so much reliance on welded joints, bonded joints and hardware in the design. I'd rather see the top load more evenly distributed across all members. Maybe that doesn't concern some of you but it does me. You can calculate loads all day long based off of the geometry and material properties but at the end of the day, the welded joints are only as good as the experience of the fabricator.

I've seen semi-scissor designs before and I think they can work well and provide many benefits including the open design underneath but I don't like what I will call the "opposite" corners in this design. I see what appears to be a 3/8" Grade 5 bolt as the only thing supporting the corners opposite of the actuators. It's a bold move on CCV's part but a risk in the eyes of this engineer (I view it as a risk based on many years of experience with fasteners). Even if this has been changed to a shoulder screw, I still don't get a warm and fuzzy.

After seeing the pictures and reading all of your descriptions, I got curious about the motion of the linkages. I have this wonderful tool called Solidworks. It is a fully featured 3D CAD package with more features than I can make use of. When I start on a design of a mechanism, I typically begin with simple line drawings. I draw lines to represent members, circles to represent joints and then I add in some dimensions and constraints to mimic the design boundaries I want to work within. To make a long story short, I can simulate the motion of linkages very easily and very quickly. It is especially helpful for those moments when you think you have things figured out in your head but once you see how things move together, you might want to make some changes before you get too far in the design. What's the point here? Well, one of the really helpful things about these simplified layouts is that the software won't let you move members that are over-constrained. When you think you have linear motion but in fact one of the linkage ends is moving in an arc, SW won't let you drag the linkage along a straight path if it is actually moving in some other path. Now this could mean that you over-constrained the drawing with too many dimensions but it could also mean that your motion is doing something you don't want it to do. In the case of this design, constraining the linkages like they are shown in the pictures results in a SW layout that won't move because the intended path of actuator/linkage motion does not match the actual path. But I'm not telling you anything you don't already know though, right?

So what? Why does this matter? It might not matter that much at all. The deviation in the motion could be small enough that it is no big deal. It's an unknown though and unknowns are risks in my mind until someone proves them to be tolerable risks or inconsequential. Rather than do a deep dive into what is going on here and dwell on the significance or insignificance of this, I choose to just pass on the CCV top because I've reached my limit of concerns and I don't want to be a paying customer helping out with the engineering of someone else's design. I may as well do it myself and save the money. Some of you obviously feel differently.

For the record, I'm not a fan of the SMB top either. I think their concept is fine. They've obviously proven through many years and many hundreds of units that their design works (for the most part). What I don't like about it is the high tension springs and how the mechanism is constrained. Kinda seams like the cheap route to me. I understand that is totally subjective but build quality is in the eye of the beholder sometimes. I don't see the price/value being where I'd like it.

If you're happy with your tops, great. I hope you have many years of flawless use. I really do. I'm just choosing a different route after seeing the pictures, reading your descriptions and doing my own research (BTW...I've been researching lift mechanisms a lot longer than just the last week of this thread...). My intent was not to start a war, I just think there are two sides to every coin. I have my views, others have their's... We can just agree to disagree and move on.

[boywonder]

Originally Posted by mgmetalworks

In the case of this design, constraining the linkages like they are shown in the pictures results in a SW layout that won't move because the intended path of actuator/linkage motion does not match the actual path.

...help me to understand.......of course the linkage moves in an arc, it pinned at one end. When both sides rotate at the same rate this lifts the top linearly, same as SMB PH .......what linear motion are you hoping for? What's the "intended path"?

I understand that the starting loads are high due to the sinusoidal nature of the links, similar to the SMB PH......

There should be no reason why this setup is over constrained in Solidworks....

[mgmetalworks]

Originally Posted by boywonder

...help me to understand.......of course the linkage moves in an arc, it pinned at one end. When both sides rotate at the same rate this lifts the top linearly, same as SMB PH .......what linear motion are you hoping for? What's the "intended path"?

I understand that the starting loads are high due to the sinusoidal nature of the links, similar to the SMB PH......

There should be no reason why this setup is over constrained in Solidworks....

You're right. I did finally get it to work but it took a few tries to get it right...and even though I did get the motion to work, it doesn't really change my mind about one of my original comments. I think there is a way to get the same amount of upward lift with less actuator travel in the same envelope. That's part of the design process. I won't edit my post because I still think it is important information to consider. You guys can have your fun with my mistake. I can take it.

[boywonder]

Originally Posted by mgmetalworks

I think there is a way to get the same amount of upward lift with less actuator travel in the same envelope. That's part of the design process.

Sure, but less actuator travel means more force required since TINSTAAFL..after all we are doing the same amount of work...the existing actuators are almost pushing at rated load just lifting the top.

That's most likely also going to end up with highly stressed tubing members since you'll need to push closer to the pivot point to lift the top the same distance. Perhaps the best approach is an actuator that starts perpendicular to the lifting element to minimize force required at startup and then ends up at some acute angle at the end of it's travel...just thinking out loud......or a linear rack and pinion setup for lifting.

[boywonder]

Originally Posted by mgmetalworks

You guys can have your fun with my mistake. I can take it.

no worries.......In my booklet, anyone who can reverse engineer canbus protocol and buys a spare frame to figure out how to shoe-horn in a cummings motor is a genius....or needs their head examined, or both.....