And now for something a bit different.

[hydriv]

I am putting together a stationary lift platform that will allow me to store garden tractors at ground level, a mid-point level and also at an upper level.

To do this, I bought a mast and forks from a forklift truck that had been sold to the metal recycling yard and after welding some feet on the mast, it is now securely fastened in place. I made some fork pockets from 1/4 wall rectangular tubing and then welded up a 4 X 8 platform to those pockets. Essentially, this is a hydraulic elevator and I want to power it as follows.


I have a C-face - 56C Frame Baldor single phase electric motor that is 1 1/2 HP and spins at 1750 RPM that will allow me to bolt a pump adapter to it and then add a Type AA gear pump that is .61 cubic inches using a Lovejoy style of coupler. This should give me around 4 1/2 GPM or so to feed the 4" diameter single-acting hydraulic cylinder that raises the forks. I am assuming it to be a 4" cylinder since the circumference is about 12 inches.

I have a brand new 5 gallon reservoir that has a 1 1/2" FIP outlet that will be bushed down to supply the oil to the inlet opening of the pump. It also has a 3/4" FIP inlet that I intend to add a 3/4 X 1/2 X 1/2 tee fitting to. My intent is to have the output of the pump feed the INLET of the control valve I have. The OUTLET of that control valve will hook to the Tee fitting and that will allow the oil to constantly circulate through this open-center system. The reservoir will be mounted above the motor/pump combo so as to provide a flooded-inlet situation.

As it happens, I have had a Gresen control valve kicking around on my shelf for the past 30 years and now I think that it will work just fine for this application BUT... I cannot seem to find any specs for it. Here is what I can tell you. It is a Type 2701 single spool valve that is spring loaded for center return and no float feature. The work ports are 1/2" FIP. It appears to have a Power Beyond port in it, which I will plug up, since it is not needed. I intend to connect ONE work port to the bottom inlet of the single-acting lift cylinder of the forklift mast and the other work port will be plumbed to the Tee fitting on the reservoir. The valve appears to have a cartridge style relief but I have no clue as to what spring is in that cartridge..... and that is of some concern to me because I want to protect the pump.


This is a two-stage mast and I cannot visualize me ever raising the mast to full height and topping out the cylinder travel. I am guessing but I think that this fork truck was rated to lift at least 6 tons and I cannot visualize me ever asking it to lift more than 3/4 ton. I am including the weight of the forks, movable mast section, platform and garden tractor in that estimated figure. However, the cylinder rod pushes on a pair of rollers that have two chains around them. One end of the chains is fastened to the fork carriage and the other end is anchored to the mast and this set up essentially doubles the lifting height of the cylinder but also doubles the load it must lift.


Lift speed is not important compared to having a nice smooth, controllable lift to the 4 foot level and then the 9 foot level. The same applies to the descent and if need be.... I have an adjustable flow control that I could add to either or both of the work ports.


Here are my questions:

1. Will I be OK with using the 1 1/2 HP motor?

2. Am I on the right track with the plumbing?

3. Do you see anything that I have overlooked?

 

[Redneck in training]

Every hydraulic valve has leakage so if you lift somethind up it will slowly come down. In other words you can't rely on hydraulics to keep it where you put it. You will need some kind of mechanical means to secure the platform when lifted in example ratchet. I would install electrical switch similar to circular saws.
Object moved
Good luck with the lift.

 

[hydriv]

The valve being used is brand new even though I have had it for 30 plus years..... it has never been put in service. While you do make a valid point, the fact is that the platform will only stay in an elevated position for a matter of minutes....... just long enough to either move a GT onto it or off of it. When not in use, it will remain in the fully-down position. Thanks for your input.

 

[pmsmechanic]

The valve being used is brand new even though I have had it for 30 plus years..... it has never been put in service. While you do make a valid point, the fact is that the platform will only stay in an elevated position for a matter of minutes....... just long enough to either move a GT onto it or off of it. When not in use, it will remain in the fully-down position. Thanks for your input.

I hear you loud and clear but I would still put a mechanical safety latch on the mast to hold it at the levels you are working at. It only has to fall once. Someone only has to bump the lever once.

 

[J_J]

Your pump turning 1750, and with a displacement of .61, the pump GPM will be 4.5.

At 1500 psi and 4.5 GPM, you need 5 HP .

If the pump psi is rated at 3000, you will need 9 HP.

Your 1 1/2 HP motor pumping 4.5 at 750 psi requires about 2 HP

If you can split the flow and use 2 GPM, and regulate the pressure to 1500 2 GPM = 2 HP

A 4 in cyl bore, and 2 in rod, 1500 psi force = 18,850 lbs

 

[jenkinsph]

If anything I think you may want the lift to move slower. I would not be concerned about the strength of the fork lift mast while picking up a garden tractor, this should be an easy load for any of them to handle. Even a small pump package with enough reservoir will work in this case similar to the truck lift gates and dump trailers. These are available in applications for ac and dc power too. Point being that your set up is plenty big enough for your purposes.

Many years ago I bought a three section fork lift mast and set it up to work on a Case 1370 tractor with duals and cat 3 hitch, worked pretty good but if doing it today I would build a frame hitch for it. That thing was really handy to have while building a large shop and home, forks could raise over 24' above the ground. Being fastened to a 150 hp field tractor made it manageable for hanging red iron.

 

[jenkinsph]

JJ's calculations are accurate imo but I doubt you will need to be anywhere near the 1500 psi to make this lift work for your use. 300 psi would be a more likely pressure without doing the math.

A safety lock of some sort is a good idea as others mention.

 

[J_J]

It's the load that will determine the pressure.

So what is the max load you expect to lift.

 

[LD1]

Deleted

 

[LD1]

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?