Using a RuggedMade Cylinder in a Cal Poly Project
See how agricultural students at Cal Poly used a RuggedMade cylinder on a project to build a 3-point hitch hydraulic crane.
Welcome! This has been a long time coming. We've been looking forward to having a call with you from the beginning. It sounded like you had an interesting project and as it's evolved, we've seen more about it; pictures and diagrams and then video, so it's very interesting and I'm looking forward to hearing more about this process that you guys have been going through.
So, this started in the fall as the bioresource and agricultural engineering majors' senior project. There were six teams that were assigned. Each of them was supposed to create a tractor-mounted crane. It needed to mount to the three-point hitch of a tractor or to a quick hitch that's coupled to the tractor already and it needed to be powered by the remote hydraulic system of the tractor.
Maybe back up a little bit and give us a sense of what the purpose of the apparatus is and what is, you know, what its core function or application is supposed to be.
So, the main purpose, it's a tractor-mounted crane. So, really, the main thing is, as a crane, you're going to want to be able to lift heavy stuff up that you normally can't and this is, you know, being able to do that with it on the back of a tractor. So, I know I come from a dairy [background] and, you know, the tractors are used all the time, implements on the back are used all the time so to be able to pick up and use this crane off of the back of a tractor. Like, say you need just some things in the way over there, you know, you can use your crane to pick it up, kind of rotate it out of the way, lift it over obstacles, or pick it up and have the tractor move with it connected onto it. Just to provide some more mobility and then being able to pick up excessive amounts of weight.
Part of our design process was determining which design criterias our group valued over others because, obviously, it's hard to have it perfect in all senses of what it can do. So, our group decided that we really valued it moving side to side as well as up and down. So, we don't necessarily have a telescopic feature, but it does raise and lower and then we also valued that we wanted it to pick up more of like, a mid-range amount of load, so for us that was about 1,700 pounds and we were successfully able to pick up that load. But, those were probably the top three, correct me from wrong, design criteria that we had in mind while making our crane.
What were some of the examples that Mr. Forbes and Dr. Sans gave you when you were designing and what sort of things that they have in mind for ideas of practical situations in which they'd use it?
They said something [about] being able to pick up a load, like over a fence or an object, and put it up on a truck bed was a big thing. You want to move stuff around on the farm. They also talked a lot about not only uses but how the crane they would like it to function; that needed to be really easy to operate and smooth and that they could use it on not only just flat ground, but a little bit of a rough terrain. That's the purpose of having it being an implement to a tractor instead of just driving a crane out.
We also talked about precision and where you want it to be precise. So we used a valve block and we wanted to be able to control it from standing outside the tractor. And so, we wanted to be able to park the tractor and be able to have precision, like being able to move at least inch by inch, I’d say.
Yeah, I saw there was a bit of a learning curve to manipulate the valves. I saw the video. It started out a little bit swinging quite a bit and then, whoever was operating at that time, mastered it quickly and [was] able to move that bucket full of water around without spilling any.
Anton was our, kind of like, hydraulic councilman for our group and so he definitely had a lot of trial and error with getting the hydraulics to work.
Yeah, I think the video you're referring to is, we had a previous video where we had a very small cylinder moving our crane side to side and so if you would barely hit it, it would just fully extend the cylinder and just throw the bucket. And then, we switched that out to just a cylinder with a bigger bore and then the video you saw was with the bigger bore and it still goes pretty fast and then if you just slow it down a little bit, it'll be very precise and smooth.
We had that experience in the past as we developed one of our log splitters that has a hydraulic log lift. The most important cylinder on a log splitter is the one that does the splitting, so that's got a big 22-gallon-per-minute pump, which is a good match for a big 5” inner diameter cylinder, but people wanted the log lift feature and that requires a much smaller cylinder and if you had the orifice in the port, sort of the normal maximum size that it could be, we called it the “pumpkin chucker” because it would launch a log or a pumpkin across the parking lot. So, we had to build in a restriction so that you would lift the load up under control. So, interesting how the pump flow to the cylinder diameter is very important to get balanced.
Definitely. Did you end up needing a flow-control valve of some sort? No, putting in the bigger bore cylinder was enough. If that didn't help enough, we were going to restrict the flow to it. So many teams ran into similar issues and some teams used flow-control valves of different sorts, simple orifice, some that split the flow, etc.
I was curious if there were numerous iterations that you maybe went through because you mentioned a couple different functions. You also mentioned a compressed timeline. There's a limited budget, so did you get it? Did you nail it in the first go or did you have to keep revising?
Yeah, it was definitely at the end of fall quarter, so before Christmas, we had one design that, it wasn't going to be completely feasible by how we designed it. So then when we came back in the winter, we made one that was, for sure, that was the mixture of the 4 x 4.5” tubing and then the 1/2" steel to connect as well. So, it was definitely a lot of iterations. As I said previously, we met every week with Dr. Haberlin and Mr. Forbes and every week, we had mostly, sometimes mostly, similar but still there were several improvements and changes made to the design each time. And, as well to the design of the calculations.
I think one of our biggest adjustments was after winter break. We decided that in our original design, we were going to use a winch and we just did not have a great way of powering it and our calculations weren't really adding up with it, so we decided to completely discard that and we went with a pulley and a cylinder attached to the pulley, and we got exactly what we needed after doing that change. A lot of the cranes the teams designed would have a hook at the very at the end of an arm and so the end of the arm would literally have to grab the load, wherever it was, but theirs has a cable that comes down and the cable is retracted by a hydraulic cylinder which the motion of which is amplified by a factor of two with a pulley system, so it allows a little bit extra travel. So, they can, you know, have the tip of the arm up here, the cables dropping down and they can lift a load directly upwards as opposed to a lot of the arms, you know, rotating or something, so there's a coordinated outwards motion as they lift. But, theirs, they can just lift directly straight up.
Yeah. I’ve seen the video. And that, I was certainly going to ask about that, but I'm glad you brought it up. From an outsider standpoint, that's the most unique thing about the design. And, I'm glad you covered, because I wanted to ask how you came to that conclusion. I was curious if you looked at winches or hydraulically actuated motors and, I think, it does look like a great an attempt to sort of have the advantages of both, as you're saying, to not have the arc of the boom as it lifts changing your lift point. What would you consider one of the most unique features on your design?
I think that, it being used as a winch instead of an actual winch, and then also, a lot of groups separated their arm into two components, while ours we just kept one long, eight-foot-long arm instead and went with that. When we were designing it, a lot of our initial ideas we changed them because they were either too difficult to fabricate or too expensive. Like, the winches were really expensive and the pulley system was really easy to fabricate much cheaper, as well as having our arm split or even having it like telescoping would have just been a lot more work to fabricate and also would have cost more tubing to have a telescoping tube than rather just one rigid tube.
So, some of your early concepts had other degrees of freedom that you didn't end up employing? Yeah, one of our original designs, it was more like a boom but it had a joint in the middle so we thought that we'd be able to move the whole thing up and down but as low as I thought. Yeah. Like a shoulder? Yeah, like a knee joint. Well, we just also couldn't get to where we needed to be with that. So, in the end, it's totally straight, right? Yeah, but then there's that, yes, the pulley with the rope.
Well, it sounds like you guys have faced a lot of challenges and learned skills. I'm hearing about 3D design software, hydraulics, sourcing the components, there's probably some some welding and fabrication involved. Are there any other areas of new knowledge or new skills that you feel you've picked up over the course of this project? Definitely team building. I mean, it's cliche. I feel like we've had group projects throughout college, high school, but this is definitely the largest scale and biggest group project we've had. We've been working with each other for the past year. All of us, I think, are very different people and so it's been an experience. Just being able to understand how each other works and see what we each can bring to the table since this project was also demanding in many different skills. And so, it was cool seeing each other rise up to each of our skills for certain areas of the whole project. We also learned a lot about fabrication and shop work. A lot of us have taken shop classes and done small projects here and there, but nothing this big. And, there was a lot of equipment that we didn't know how to use and we learned from the shop techs and learned some cool new stuff and how to do it. Oh, that's great because I feel like that's going to have great application in your futures.
Back to the project. Now, was this a competition among the different teams? It was. All right, so dare I ask, how did you guys do? I'm not completely sure. I don't know if we've gotten all of our results back, but I know nothing broke and we completed all of the tests. Your cylinder worked amazingly! Glad to hear that. I think all the teams did pretty well. No one's cranes didn't work or failed or anything, so it's just going to be a matter of whose crane did better. There was a placement and the competition did find a winner but it did not name second, third, fourth, fifth. But their team did well. It was not first place but we were up there. We were very happy with our results. Yeah. Did you get some first or second place finishes on any of the tests that you remember? I don't think we ever saw the scores. Yeah. Are there different criteria like cost? I'll tell you that, they tied for first in one of the events. There were six different events. Each event was created by, as Josh was saying, by a different team and the one that you created was the precision test. This gives you the smoothness test, so they were seeing whether you could move the end effector of the crane without jerking it around and losing a bunch of water. Yeah, and did you do pretty well. Our crane’s test was holding a bucket of water and lifting it over a trash can and trying to… Okay, that's the video I saw. Yeah.
So, team, do you have a clip that you can play for us? I do. This is us, now actually, doing the test on the day that everyone tested everything. You can kind of see we're lifting up the bucket. You can see how the top cylinder was used to provide that free range of motion first and now Grace is going to pick up the whole crane arm using your cylinder over the bucket. And then, use the small one that gave us issues at first to move it over to the next target. Great. Well, I know Josh doesn't want to spill any of that milk that he just worked hard to get from the cow.
This was the precision test when we're trying to land the bucket on the dots. This was definitely the test that we were the least adequately designed for. The other cranes that had the extra degree of freedom in the main boom or could telescope could… You're supposed to hit every dot. Since we just have a rigid arm, we definitely struggled with this particular test. Well, it sounds like you got a real lot of first-hand experience with the fact that everything is a compromise and you have to prioritize.
Right now, this is the ease-of-use test. So, yeah. There was one test that was ease of use, which was this last one that was just shown. And, it was, so, we know how to operate our crane and the tractor, and what this test was, is just to have someone else operate it that was not within the team to see how easy it was for them to use it and get adequate work with it. So, you can see me walking around and I'm telling him how you operate it, but I can't actually touch the crane and do it. I just have to…I can only give instructions.
This test, right here, was the max load test that we were able to reach that max load or that just over our rated load of 1750. And, if you have the actual video, and the one that I'm filming, you can probably hear me saying in it, this is 1600 or, I think we did like three lifts. I think we did a 1400, a 1600, and then a 1700? Maybe. Something like that? I think we started…we might have done a 1000 first just to make sure it works and then we went up to 1400 and 1600 and then we said, well, we might as well do 1750 just to see if it will work for sure or not. So, go big or go home. I commend you and your whole team for executing this. It's a lot easier said than done to go from concept to execution and then test it and have it work.
I also want to say it's impressive that Cal Poly has projects like this where it goes beyond the abstract, “Oh, here's how you calculate some math and, and if you were to make one, what would you do?” but to actually carry it out to fruition like this is really great. Because, out in the real world, ideas don't count for much unless you can turn them into something like this.
One last question, does this beast have a name? Pretty much, no, we did not name it because we are not keeping their cranes. Some of them are going to auction, and the rest will be taken apart because we do run senior project every year. Regardless, if they probably will most likely involve hydraulics as well as the steel use so the RuggedMade cylinder, for example, will most definitely be used next year for next year senior projects, which is pretty cool. So, in a sense, our our little project will be passed along. That's great. I'm happy to hear that it served you well and that it's going to continue to live many lives with future teams. Yeah, we loved using your product. It worked great for our purposes and it would be really cool for the future years to be able to also work with your company. Yeah, we look forward to that. Again, when we saw the name, we thought, we have people here [that] have good instincts and that's probably more interesting than some of our typical replace-a-couple-cylinders-on-a-Bobcat story, so I'm really glad we reached out and got to got to meet you all and let us know there's anything else we can help out with in the future. Sounds good, we'll be in touch. All right. Thank you! Thank you, guys. All right. You're welcome. All right. Talk to you guys later. Bye.