Pump from Bottle Jack

[yrralguthrie]

I need a small hand operated hydraulic pump. I realize the bottle jack is a pump, but I need to separate the cylinder from the pump.

If I drill and tap a fitting into the inner cylinder for the pressure side, drill and tap a fitting into the outer cylinder(jack body). Drill a clearance hole in the outer cylinder for the inner cylinder fitting. Put the jack back together, screw the inner fitting into it's cylinder through the clearance hole, I have a pump, correct?

If I allow the ram to bottom up, or take it out and weld the hole up, it should operate a cylinder?

Then to operate the remote double acting cylinder I will need a valve?


Have I overlooked anything? A little work, but much cheaper than the new hydraulic hand pumps I've been able to find. This project needs to go together cheap.

ljg

 

[DonnieP]

We called the hand hydraulic pumps 'porta-power', guess it's a brand name.

Porta-Power Hydraulic Ram Systems - JCWhitney

 

[kennyd]

Horrible Fright has them also: Search results for: 'portapower'

Enerpack has them also.


I think the main problem with the jack idea in reservoir capacity, plus they are not designed to operate DA cylinders.

What are you making?

 

[oldnslo]

I need a small hand operated hydraulic pump. I realize the bottle jack is a pump, but I need to separate the cylinder from the pump.

If I drill and tap a fitting into the inner cylinder for the pressure side, drill and tap a fitting into the outer cylinder(jack body). Drill a clearance hole in the outer cylinder for the inner cylinder fitting. Put the jack back together, screw the inner fitting into it's cylinder through the clearance hole, I have a pump, correct?

If I allow the ram to bottom up, or take it out and weld the hole up, it should operate a cylinder?

Then to operate the remote double acting cylinder I will need a valve?


Have I overlooked anything? A little work, but much cheaper than the new hydraulic hand pumps I've been able to find. This project needs to go together cheap.

ljg

How much oil volume are you trying to move? Bottle jack reservois are not very large.

Roy

 

[yrralguthrie]

I don't think any pump by itself will operate a double action cylinder. The flow has to be reversed and I've not seen a pump that reverses. All I've seen use a 5 way switch to reverse the flow to the cylinder. I intend to try to use a 5 way pneumatic switch. (cheaper)

I've seen all the hand pumps on Harbor Freight and others, for this project they are too big and way too much money. I need to move a ram about 3 inches with 500-700 lbs of force within about 1 second no faster. I have an operating model using an air cylinder, but the fingers have to be in the vicinity of the ram and an air cylinder operated way too fast with that kind of force. Also I need to be able to instantly stop the piston, which I can do with a hydraulic hand operated pump.

Oh...I forgot. The cylinder only has to operate the 3 inches with 700 lbs force so the volume of the double action cylinder can be quite low. The diameter of the cylinder less than 1/2 inch perhaps. That would require a hydraulic force of about 200-300 lbs. Within the capacity of a 2 ton bottle jack, which would be 2000 lb. per square inch.






ljg

 

[Iplayfarmer]

I don't think any pump by itself will operate a double action cylinder. The flow has to be reversed and I've not seen a pump that reverses. All I've seen use a 5 way switch to reverse the flow to the cylinder. I intend to try to use a 5 way pneumatic switch. (cheaper)

I've seen all the hand pumps on Harbor Freight and others, for this project they are too big and way too much money. I need to move a ram about 3 inches with 500-700 lbs of force within about 1 second no faster. I have an operating model using an air cylinder, but the fingers have to be in the vicinity of the ram and an air cylinder operated way too fast with that kind of force. Also I need to be able to instantly stop the piston, which I can do with a hydraulic hand operated pump.

Oh...I forgot. The cylinder only has to operate the 3 inches with 700 lbs force so the volume of the double action cylinder can be quite low. The diameter of the cylinder less than 1/2 inch perhaps. That would require a hydraulic force of about 200-300 lbs. Within the capacity of a 2 ton bottle jack, which would be 2000 lb. per square inch.






ljg

You lost me early on in the description of how to convert a bottle jack to a pump, but I can agree with you 100% that you'll need a valve. The only exception I've seen is a hydraulic pump for a convertible car. I have a pump from mustang convertible that is double acting.

 

[Mace Canute]

I need to move a ram about 3 inches with 500-700 lbs of force within about 1 second no faster.

I doubt a pump made from a hydraulic jack would have that amount of volume at that pressure even with a lot of modification.

Your math is wrong, btw.

Just a quick look at a hydraulic jack shows the piston is about or a shade smaller than the size your cylinder would be. For your application, lets say for simplicity's sake that they are the same size and we forget about efficiency. That means the piston will have to move the same distance as the cylinder and you will have to input the same force on the piston as you want to have the cylinder develop. That can be done with mechanical advantage. Lets say you have a 20:1 MA so you only have to input 35 lbs of force at the handle end. That means you have to move the end of your lever 60"...5 feet...because piston travel equals cylinder travel. 50 lbs at the handle would mean moving it 42"...3 1/2 feet. You would have to do this in the time frame of around 1 second and with a piston travel of 3". Even at 500 lbs at the cylinder and 50 lbs at the handle, the handle would still have to travel 30". Making the piston smaller would lessen the required input force but it would have to travel farther to make up the volume. A 3/8" piston would have to travel a third more to have the same volume.

 

[Iplayfarmer]

I doubt a pump made from a hydraulic jack would have that amount of volume at that pressure even with a lot of modification.

Your math is wrong, btw.

Just a quick look at a hydraulic jack shows the piston is about or a shade smaller than the size your cylinder would be. For your application, lets say for simplicity's sake that they are the same size and we forget about efficiency. That means the piston will have to move the same distance as the cylinder and you will have to input the same force on the piston as you want to have the cylinder develop. That can be done with mechanical advantage. Lets say you have a 20:1 MA so you only have to input 35 lbs of force at the handle end. That means you have to move the end of your lever 60"...5 feet...because piston travel equals cylinder travel. 50 lbs at the handle would mean moving it 42"...3 1/2 feet. You would have to do this in the time frame of around 1 second and with a piston travel of 3". Even at 500 lbs at the cylinder and 50 lbs at the handle, the handle would still have to travel 30". Making the piston smaller would lessen the required input force but it would have to travel farther to make up the volume. A 3/8" piston would have to travel a third more to have the same volume.

For that matter, no hand pump anything is going to move 700 pounds 3 inches in one second. That work is equivalent to 4 horsepower not counting any losses due to energy transfer. Assuming an average guy can curl 80 pounds, that's 9 pumps in a second if all of the pump ratios are perfect.

10 seconds is possible. 20-30 seconds is likely.

 

[evo803]

Look for a used pump that is used to operate the trim cylinders on a mercruiser sterndrive. They are very small , 8"x8"x10", electric ( 12v ), have a 2 pint reservoir, DA with rocker switch and certainly would be strong enough for your application.

 

[jbooth]

Common grease guns held in the vertical position will pump hydraulic oil just fine. Don't need the spring to force the oil as required with the grease. Some grease guns are advertised to pump as much as 10,000 PSI. I would think the higher volume guns which develop 2500-3000 pounds would be adequate.