Author Topic: Project Roid  (Read 12492 times)

2Ton46

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Re: Project Roid
« Reply #30 on: February 09, 2018, 01:36:37 AM »
No hydraulics here, all pneumatic. That cylinder does look a lot like a hydraulic cylinder though. The system operates by two air sources. The first source is direct from the tank and is plumbed into the filter / regulator / lubricator then through a control valve and ultimately to the cylinder. The control valve is an air operated spring return affair that simply switches one side of the cylinder to the air source and the other to exhaust, and flips the sides when activated. The weight of the arm is such that it will provide enough tension on the belts to allow starting the compressor with no air in the system. As air builds in the tank the cylinder is defaulted to pull down on the arm. It only takes about 5 to 10 psi in the cylinder to move the arm to is lowest position. The idler is spring loaded to provide even tension and a small range of over travel for the arm. This side of the system is set at 30 psi, partly to control noise and to ensure enough force is available. Once the tank pressure rises above 30 psi the regulator keeps the cylinder pressure at 30 regardless of the tank pressure. Cylinder speed is controlled by a combination of exhaust flow control - mufflers, and this particular cylinder also has an end cushion on the downward stroke that further slows the last inch or so of the downstroke. Without these the arm movement is pretty much instant - pretty scary in my opinion.

The 2nd air source is the control. It is piped from the pilot unloader valve through a small regulator and into the control port on the air/spring control valve. If this compressor had an engine mounted on it, this is the same signal line that usually works the engine throttle to idle the engine when the pump unloads. The regulator in this line is dual purpose, as it can be used to disable the arm function to provide continuous pump run operation by turning the output pressure down to 0, and knocks the tank pressure signal down from 170 to something in the valves control port rated operating range of 45-150 psi when in clutch mode. I usually use 60 psi.

Clutch operation is as follows: when the tank pressure reaches 170 psi, the pilot unloader valve trips, supplying tank pressure air to the compressor unloaders and also to the control pipe. The control valve is flipped by the presence of air pressure on its port, and reverses the supply and exhaust to the opposite sides of the cylinder causing it to extend, and the belts get loose and the pump stops. Once the tank pressure drops down below 140 psi the pilot unloader valve resets, the control air pressure drops to 0, and the compressor unloaders are set to load (except on this compressor they won't load without lube oil pressure present in the pump as well), and the spring returns the control valve to its normal state, retracting the cylinder and tightening the belts and starting the pump.

The clutch can be manually actuated by the flip tab on the pilot unloader valve for starting with air already in the tank or to prevent the compressor from starting automatically while leaving the engine running. When starting with little or no air in the tank, the clutch remains engaged, even with the flip tab set on the pilot unloader. This is because the control valve will not overcome the spring pressure in the control valve until the tank reaches about 20 psi. This hasn't been an issue for starting as the compressor isn't pumping against any tank pressure, and the unloaders will start to work when air begins building.

BruceM

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Re: Project Roid
« Reply #31 on: February 09, 2018, 10:15:16 PM »
Thanks for the good details on your pneumatics, 2ton46.  Using the pilot valve for controlling the cylinder is a nice straightforward all pneumatic design.   Sometimes I need a break from electronics and making a version of your clutch would be a good mechanical & pneumatic project.

I didin't recognize that big cylinder as pneumatic, since all my actuators are little round stainless Bimba types.


2Ton46

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Re: Project Roid
« Reply #32 on: February 22, 2018, 02:57:24 AM »
Glort, I've tried to not be a total goon in getting it setup, but I'm probably there anyhow.  At least in the case of the compressor, remounting an engine would only be 4 bolts and two air lines...

BruceM, No problem, hopefully they prove useful for someone's project. Semi-functional yard art anyhow.

I found a few different springs to use up on the pumps to take the slack from the linkage but are about half as strong as the ones I had on there before.  This has helped the sluggish governor quite a bit.  Its not yet perfect, but it is what I would consider reasonable now.  Might not yet be great if I was operating a generator though, I have got about a 75 rpm drop that recovers to about a 45 rpm drop at the engine within a few seconds when the compressor cycles. I do believe there would be a better combination of springs than what I have, might even be able to stretch out the ones I have to reduce their force a bit but still accomplish the goal of taking out the linkage slop. Never figured finding springs would be as difficult as it has turned out to be (at least ones I can handle before purchase).

Weather and other business hasn't been ideal for messing with the projects lately, but I'll include a photo of a short test run with the compressor, the yard fan and the shop fan for your amusement.


2Ton46

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Re: Project Roid
« Reply #33 on: March 11, 2018, 10:45:57 PM »
Finally had some decent weather over a few days when I had time, so I did some painting.  Everything is looking much better. Went with a low gloss black for the frame and some accents, and then decided to use some paint I had around. Settled on metallic blue for the belt pulley and driveshaft, and '40's chevrolet engine gray for the v belt pulleys, and the exposed areas of the engine shaft that aren't used for the crank handle. No paint on the area for the crank handle so it continues to function.  Then added some yellow to some fan blades (the metallic blue on the others, kinda tricks the eyes to make a green to match the engine when in operation lol) and put a spiral around the driveshaft with it. Looking pretty sharp.  Also painted the Compressor frame and clutch assembly, mostly low gloss black. Also in keeping with the theme, put some red and silver together for a spiral on the unpainted driveline I had.

The lighting wasn't that great today, but it looks good in action.


Yesterday with driveline drying for the red coat.  Forgot to get one after the red went on but the lighting is a bit better for the rest. Just a few touchups and I'll consider it successfully painted.


Here is a closeup of the compressor nearly done with the painting after re assembly.

dieselgman

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Re: Project Roid
« Reply #34 on: March 12, 2018, 12:49:52 AM »
That is one purdy machine!  ;)

dieselgman
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2Ton46

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Re: Project Roid
« Reply #35 on: April 03, 2018, 03:49:12 AM »
Had a small event at the Farm here over the weekend, and figured it would be an ideal time to get out the 'Roid and put it to some use, even if it was solely entertainment. Ended up with it powering quite a Rube Goldberg setup, but it was a hit. Had it connected to a small fan for a wacky wavy inflatable tube man near the gate, and then the yard and shop fans for a breeze near the tables, and the air compressor to power a small pneumatic engine. The little Hatz power unit was used as an idler for the belting. It could also double as a starter for the 'Roid, but it complains about the mass that it has to accelerate to accomplish the task mainly due to the light construction of the unit not the engine itself. It also could be used to power part of the display, but not all of it, as it makes about half of the power of the 'Roid. As a side note, that little Hatz seems like it could be made into a neat little generator set, especially if setup to operate around its peak efficiency rpm ~2300. It would probably still be able to handle about a 3KW load at that speed.

I'm thinking that pneumatic engine will be great for an ice cream / frozen adult beverage maker. It doesn't turn too fast but makes a lot of torque. I made it out of some spare parts and scrap metal along with a cylinder. Somehow I managed to get the cam pretty close only with an angle grinder and a hacksaw. Here is a short video and a photo for your enjoyment.

https://youtu.be/Np8qGj_jTTI


BruceM

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Re: Project Roid
« Reply #36 on: April 03, 2018, 04:20:57 AM »
A marvelous display setup.  Loved the pnematic cylinder driven wheel.  Thanks for sharing your video!

2Ton46

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Re: Project Roid
« Reply #37 on: April 07, 2018, 03:56:43 AM »
You're welcome. That little pneumatic engine has provided way more fun than the 3 hours it took to make. In fact, I think I'm going to paint it so it looks pretty. I might even consider making another one. The C-channel steel used to make it is so rusty you can see through it in places, hopefully it doesn't fall apart too soon.  It garnered a lot of comments last weekend at the party. It might not be a very efficient use of power, but its quite interesting to watch and will chuff happily along at about 65 rpm with a very pleasing rhythm. The wacky wavy arm-flailing inflatable tube man and his fan was a gift from a friend and is very much appreciated and is also pretty fun to watch.

2Ton46

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Re: Project Roid
« Reply #38 on: May 05, 2018, 02:11:39 PM »
Made the whole mess a little easier to get in and out of the barn. It now doubles as a train!? This way I only have to make one trip to get it all in. Also built a rack on the back of the engine cart for the driveshafts. Takes about 5 minutes to setup for operation.



My brother hosted a party at his place just down the road last weekend with a bunch of folks he works with, and it was a warm and wind still day. Perfect for the yard fan I said. Pulled the train down the road, set everything up and fenced it off to keep em out of the moving bits. The setup was a hit, everyone loved the fan and the noise level still allows for conversations.

2Ton46

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Re: Project Roid
« Reply #39 on: July 04, 2018, 09:11:02 PM »
Figured I'd share a clip of the setup I had in the yard this past weekend for our annual barbecue. Finally remembered to grab a clip just before I took it all down and headed for the barn after the event was over and cleanup was nearly complete. We have a string of 105 lights around most of the yard that it was powering during the event, as well as working the yard fan in front of a mister and animating the tube man and the air engine. On the day of the event she cranked up at 4:55 am, ran the whole works until noon when we stopped it to address the crowd for a minute and top up the fuel tank. She then ran until a little after 10:00 pm when the last of us decided to move indoors.

https://youtu.be/GxIs-YR-e2E 

2Ton46

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Re: Project Roid
« Reply #40 on: August 13, 2018, 04:24:49 AM »
With all the recent governor spring activity on the forum, I thought I would give a sneak peek at my latest part of the project that is now in the needs to be cleaned up and painted phase. Since I have found a spring solution that gave me a much better speed regulation I decided to tackle something I had planned from the initial start of the project, but never did implement because with the original spring the regulation was all over the place. I have found over the past 6 months that depending on the loads I have connected and even the ground I have the unit parked on (sometimes it still likes to vibrate excessively at certain speeds/loads/ground hardness) I need to tweak the speed set point to suit the conditions for the day. So I decided to fab up a variable speed control for the engine.  This way I can fine tune the speed set point without needing to get out some tools to move the spring hook.  I have also returned to one spring, instead of the two in series as I had been experimenting with.  The response is just slightly less aggressive, but its still a huge improvement over what I had with the old spring and perfectly acceptable for the uses I have. I used some parts I had around and so its a little over built in some areas, but its functional.  The mechanism is calibrated to give a speed range of about 475-675 rpm on the engine, over about 30 turns of the crank handle to give a fine tuning control, but keep it from being able to be carelessly taken far out of the safe operating range.