Hi, new to PCPs here. I just received the GAMO Urban from walmart.com. I had been waiting for the Guantlet to become readily available, but the Urban was on sale for $219; so I grabbed it up! Question: It came with 3000 psi already in it according to the gauge. Is that normal to ship these new fully charged? I was worried I have a defective gauge. And I've read they should be stored with pressure; but full pressure?
That's question 1. Now for question 2. I've seen a DIY HPA pump using a bottle jack and a hydraulic cylinder I have seen that in more detail in other places on the web, but that's all I can find right now. I work with hydraulics and pneumatics and I have designed several small systems; mostly mobile. I can get hydraulics components on the cheap. I have some DC HPU's with 1500psi output pressure that I only pay $60 for. I can get cylinders cheap too. So I roughed out a schematic using two cylinders, one hydraulically driven and the other to move air. My rig had the cylinders pulling on each other; as opposed to the bottle jack contraption I've seen that pushes. Getting the pressure and compression ratio is no issue, but even with my discounts; my costing added up to about $400 after the check valves, purge valve, guage, etc. More than I want to pay. I could get a shoebox max for that almost. Doing it over time helps to spread the cost around, but still, too expensive.
Has anyone ever tried to use those port-a-power foot operated air over hydraulic pumps as pcp pumps? They are 10,000 psi. They probably don't have the compression ratio required to drive air up to 3000 psi, but the valve block can be modified to reduce the volume in it. I'm just curious why I haven't seen any attempts on the web. I've never torn into one, but I think they are reciprocating piston pumps. I've done work with hydraulic breakers, so I've sort of seen the mechanics in action there. A concern is getting ALL of the original oil out. A compressor grade oil could be lightly applied if there is no danger due to the heat. A complete tear down is essential, if only to remove the oil. Its probably necessary to also modify the valve block for a better compression ratio too. And seals or o-rings would need regular replacement too I imagine, so the tear down procedure would be familiar after a while. And I could likely source better seals and o-rings than stock. Another concern is pressurizing the oil reservoir. Not having ever been inside one yet, I don't know how likely it is that I could apply shop air directly to the oil side inlet or if the entire reservoir would need to be pressurized to 100-120psi. That's probably not necessary, but it's possible that would be an issue to come up. My rig would consist of my regular shop compressor driving the air side of the pump. And I have an oil-less compressor for the "oil" side. I would plan my compression ratio (if it needed to be modified) to give me about 3000psi when the oil-less comp. is set to around 60-70 psi. That would give me some room for error and be able to use the compressor's regulator to roughly control the final output psi.
Any thoughs? Anyone try those things for our hobby? I've seen other, more expensive, more complicated approaches.
Here is the hyd. unit from Harbor Freight, they can be had for cheaper. https://www.harborfreight.com/10000-psi-air-hydraulic-pump-98318.html
That's question 1. Now for question 2. I've seen a DIY HPA pump using a bottle jack and a hydraulic cylinder
Has anyone ever tried to use those port-a-power foot operated air over hydraulic pumps as pcp pumps? They are 10,000 psi. They probably don't have the compression ratio required to drive air up to 3000 psi, but the valve block can be modified to reduce the volume in it. I'm just curious why I haven't seen any attempts on the web. I've never torn into one, but I think they are reciprocating piston pumps. I've done work with hydraulic breakers, so I've sort of seen the mechanics in action there. A concern is getting ALL of the original oil out. A compressor grade oil could be lightly applied if there is no danger due to the heat. A complete tear down is essential, if only to remove the oil. Its probably necessary to also modify the valve block for a better compression ratio too. And seals or o-rings would need regular replacement too I imagine, so the tear down procedure would be familiar after a while. And I could likely source better seals and o-rings than stock. Another concern is pressurizing the oil reservoir. Not having ever been inside one yet, I don't know how likely it is that I could apply shop air directly to the oil side inlet or if the entire reservoir would need to be pressurized to 100-120psi. That's probably not necessary, but it's possible that would be an issue to come up. My rig would consist of my regular shop compressor driving the air side of the pump. And I have an oil-less compressor for the "oil" side. I would plan my compression ratio (if it needed to be modified) to give me about 3000psi when the oil-less comp. is set to around 60-70 psi. That would give me some room for error and be able to use the compressor's regulator to roughly control the final output psi.
Any thoughs? Anyone try those things for our hobby? I've seen other, more expensive, more complicated approaches.
Here is the hyd. unit from Harbor Freight, they can be had for cheaper. https://www.harborfreight.com/10000-psi-air-hydraulic-pump-98318.html
