And now for something a bit different.

[hydriv]

It's the load that will determine the pressure.

So what is the max load you expect to lift.

Without dismantling the forklift mast and then weighing the 2nd stage mast, the pair of forks and the fork carriage, I am just guessing that these items will not weigh more than 600 LBS. The platform will likely come in at 300 LBS.... so let's assume 1000 LBS total to be on the safe side. The GT's will top out at 800 LBS. Realistically, I was hoping for a 2000 LB lift capacity here.

But since this is a two-stage mast, isn't the cylinder actually seeing 4000 LBS due to the doubling effect?

The choice of pump was dictated by using something I already owned but perhaps I will end up buying something in the .30 CI size.


The cylinder shows no signs of leaking from the top seal but...... I cannot vouch for the piston seals at this point. The overall length of the cylinder is about 80 inches so the total stroke will likely be a few inches less. I am thinking that it would take around 4 gallons of oil to fully extend the cylinder. So at 2 GPM, it would take a full two minutes to reach full height. This seems rather slow but on the plus side, it is a very controllable lift rate that would allow for highly precise stops at any point. The last thing I want is something that is twitchy, jerky or erratic.

jenkinsph.

I have not witnessed this mast in operation so I do not know for sure if the forks and fork carriage lifts first to its maximum height and then causes the 2nd stage to start lifting. I am guessing that this is how it will function. I am all for safety but I think that trying to install some sort of mechanical device to hold the extended mast in two locations would be difficult initially and cumbersome to employ. I am open to all suggestions.

 

[LD1]

But since this is a two-stage mast, isn't the cylinder actually seeing 4000 LBS due to the doubling effect?

YES

The cylinder shows no signs of leaking from the top seal but...... I cannot vouch for the piston seals at this point. The overall length of the cylinder is about 80 inches so the total stroke will likely be a few inches less. I am thinking that it would take around 4 gallons of oil to fully extend the cylinder. So at 2 GPM, it would take a full two minutes to reach full height. This seems rather slow but on the plus side, it is a very controllable lift rate that would allow for highly precise stops at any point. The last thing I want is something that is twitchy, jerky or erratic.

.

Likely a 72" stroke cylinder. With a 3.5" diameter cylinder, it will take 3 gallons to fill. If it were a 4" cylinder, it would indeed take 4. But if you say the outside circumference is ~12", there is no way its a 4" cylinder. A 4" bore cylinder would likely have 3/8" walls. Thats a 4-3/4" overall diameter, which would be lots closer to 15" circumference.

Any way you can get a more accurate measurement?

And yes, it is typical that the entire first stage will lift first, then the second stage will kick in.

Got any pictures of the mast??

 

[hydriv]

Good advise so far. I'll add some input:

I am betting the cylinder is 3.5" though, if the outside circumference is ~12". That will make it faster and less powerful. A 3.5" cylinder is usually found on forklifts rated to lift 4000-4500#. So the mast is still pleanty strong. As long as you have a good solid anchor to the floor.

IF you want/need to lift something in the ~1500# range, I'd shoot for 2000# capacity. That will cover the weight of the forks, and fork carrier plate.

So, to lift 2000#, with a 2:1 ratio the chains give, you need the cylinder to make 4000# force. To get that, you need ~416 psi to do the job. So lets call it 500psi. With only 1.5HP, you can deliver 4.3 gpm max before you overload the motor. (electric motors wont stall, but will continue to draw amperage till they fry). Your 0.61 cu in pump is 4.6GPM @ 1750 rpm. I think if you already have the pump, thats close enough to try.

Might be a tad on the fast side though. Extend speed of the cylinder would be 1.8" per second, with the 2:1, the lift would lift 3.6" per second. Or 10 seconds to lift 3'.

As to the plumbing, on the pressure side, make sure you only use steel hydraulic fittings. No black iron fittings or bushings like you would find at the hardware store. Make sure you go to a hydraulic shop, or order online from a hydraulic supplier. And I also didnt see mention of a filter set-up?

I am betting that you are correct in assuming a piston diameter of 3.5 inches. The OUTLET side of the pump will connect to the control valve by way of high pressure hydraulic hose and no plumbing fittings. However, the Tee fitting at the tank will be a plumbing fitting since the pressure there will be less than 300 PSI. Even so, I will use high pressure hydraulic hose on both return lines......because I have plenty of it and it will never give me any problems.

This is a solution to a problem I have with respect to storage of my GT's. By going this route, I do not have to maintain a proper fork truck or FEL of some kind. I feel that this setup will be at my beck and call 24/7, not consume any gasoline or diesel and not take up any valuable space. It will only be used on an occasional basis in order to either retrieve at GT so it can be restored or to put that GT away once the restoration has been completed. In other words, it is going to sit around and do nothing for most of the year but when I need it....... then it is there for me.

 

[hydriv]

YES




Likely a 72" stroke cylinder. With a 3.5" diameter cylinder, it will take 3 gallons to fill. If it were a 4" cylinder, it would indeed take 4. But if you say the outside circumference is ~12", there is no way its a 4" cylinder. A 4" bore cylinder would likely have 3/8" walls. Thats a 4-3/4" overall diameter, which would be lots closer to 15" circumference.

Any way you can get a more accurate measurement?

And yes, it is typical that the entire first stage will lift first, then the second stage will kick in.

Got any pictures of the mast??

I will take some photos today and then post them. I will also take some measurements of the mast height etc. I do not own a caliper that can measure the true OD of the cylinder. I won't be back on here until after suppertime tonight.

 

[Xfaxman]

I will take some photos today and then post them. I will also take some measurements of the mast height etc. I do not own a caliper that can measure the true OD of the cylinder. I won't be back on here until after suppertime tonight.

Can you get on it with a c-clamp, then measure the opening of the clamp with a ruler?

 

[hydriv]

Here is a photo of the mast from the front.





I welded angle iron to either side of it and then used expanding anchors to bolt it into the concrete. Those nuts are 1 1/2" in size and I used my four foot torque wrench to tighten them.





Currently, it is standing just fine on its own BUT.....to give it some additional support, I welded some 1/2" thick x 6 inch wide flat bar to a length of wide-flange I-beam and then used the same type of anchor bolts to secure that upright to the solid concrete block that the mast sits on. These blocks a 3 ft by 3 ft by 6 ft long and make up my "loading dock" retaining wall for the trailers.




I am going to run two lengths of 1/2" threaded rod between the I-beam flange and the heavy cross support on the rear of the mast. The threaded rod will have nuts on either side of where it is bolted to those two items so that it is "passive" and they do not have any tension on them unless the forklift is in use.





The height of the mast between the concrete block and the top of the channel is 91 inches. The width of the mast assembly is 22 1/4 inches.

The width of the fork carriage is 36 inches and it uses 42 inch forks that are 4 inches wide by 1 5/8 inches thick in the vertical section.


The highest the forklift must rise is 9 feet to reach the top of the trailer roof.


I can use a C-clamp on the cylinder later today to get a more accurate OD and then post it here.

 

[LD1]

With the rear supports, I think you will be fine with what you want to lift.

IF you already have a 0.61 cu in pump and 1.5hp motor, I'd say try it. But put a amp clamp on the motor leads and watch the amp draw and make sure you dont exceed the nameplate amps x S.F.

If you dont already have a pump, I'd downsize a notch to be safe.

And BTW, that is a single stage mast.

 

[J_J]

You could do a simple load test.

One pallet, two 55 gal drum full of water should equal about 1000 lbs, and note the pressure when load is lifted.

If showing about 500 psi, then the 2000 lbs should take about 1000 psi.

Your pump pumping 4.5 GPM and 500 psi requires about 2 HP. Your pump is 1 1/2 HP

I would do some lift test before you get fully engaged in the project.

If you have a tractor, use it for the test or a friends tractor.

 

[hydriv]

Without question, I truly appreciate all of the advice and feedback thus far. Perhaps it is just my own vanity talking here but I think that some members find this thread rather interesting because it pits the theoretical aspect against the actual end result. I have every confidence in J J's input but in order to put it to the test, this is what I will do. I intended to dismantle the mast anyway to clean it up, inspect it thoroughly for any problems and then repaint it before assembling it and putting it back in place.

As it happens, I own a platform scale that is capable of weighing up to 2000 LBS very accurately because it uses no springs, just counterweights. I am going to weigh the pair of forks, the fork carriage and the inner mast stage.... all of which the cylinder is required to lift. No matter what, I need to make the platform to go onto the forks and I will weigh it as well once it is completed. Because I already own the electric motor and gear pump, I will proceed with finishing the power pack using those items and I will add a pressure gauge capable of reading up to 2000 LBS. All of this will be photographed and noted for my future posts. Once the work is completed and the lift is operational, I will do a test run with absolutely nothing on the platform to see how much pressure is being generated. Adding fixed amounts of weight to the platform is not a problem because I can scale those items first and then use my Case skid steer to place them on the platform. The changes in pressure on each test will be recorded.

It is far cheaper for me to purchase a smaller pump for around $100.00 than it is to purchase a 5 HP motor. I just bought a 5 HP motor for the air compressor I am building and it cost me $328.00. I will likely be a couple of weeks before I can get to this but when I am done, I will report on what happened.

 

[LD1]

Sounds like a good plan. Keep us posted.