Adding hydraulic functions to a forklift

I purchased this "boom lift" for scrap for $500:
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It is a huge 20,000 lbs capacity boom lift. I do not need it and, I
suspect, neither does anyone else, this is why it was surplused by a
local public agency.
The way this works is that the boom goes up and down with help from
the lift cylinder, and extends and retracts with help of another
cylinder inside the boom.
However, I have an idea: Take off the hydraulically powered boom from
the front, and make it into a forklift attachment and mount on my
30,000 lbs forklift.
Then, I suppose, I could use it to reach higher and handle awkward
loads, and so on. This lift has a capacity of 10,000 lbs extended and
170 inches lift. Adding 120 or so inches lift od the forklift, this
can give you a 290 inches combined lift.
I can sort of visualize what needs to be welded to it to make it
attachable and detachable.
However, what I do not know is how easy it is to add hydraulic
functionality to a forklift with only a two lever spool valve. Can I
add another spool valve to handle these two functions (lift and
extend)? Would that be "in series" with the original spool valve?
Thanks
i
Reply to
Ignoramus8530
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You will lose a LOT of the lifting capacity. Most fork lifts are rated at a set distance from the boom. As you extend out farther the leverage starts working against you.
But- adding spools is easy. You need to determine if it's an open or closed center valve system. Then you buy the correct type of valves and connect the inlet ports to the pressure feed. The outputs go to the new quick disconnect fittings you will need to add.
Reply to
Steve W.
its easy if you got open center (hydraulic pump always runs) not so much if closed center. You have an older truck? Pretty sure it would be open center. If so "T" off your hydraulic line on both pressure side and drain, add in your valves. FWIW, the Farm and Fleet store stock this stuff cheap. Maybe they don't have those inside the windy city.
Ya, you'll loose some lift capacity, but you're starting from 30K
should work well for your needs.
Karl
Reply to
Karl Townsend
Right. I am quite aware of that. Usually, when moving things very close the ground, overloading forklifts is not very dangerous, it just tips a little and that's it. When things are high in the air, losing balance is very dangerous.
At 24 center from face of forks, my 30,000 forklift can lift 30,000, and at 40", only 20,000, etc. Even less with the boom adding to the lifting radius. But in any case I could deal with some substantially heavy stuff like 8,000 lbs items.
OK, thanks, this is good news.
i
Reply to
Ignoramus25323
This forklift is from something like 1960's. It is in a very good shape actually., but yes, it is old. (Towmotor)
On other words, you are saying, add the second spool valve in parallel, right?
Exactly, if I can handle 10k with the boom extended, I will be very happy. I will, obviously, test that and make up a load chart.
I am extremely aware that losing balance with things high up in the air, is a very bad idea.
i
Reply to
Ignoramus25323
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The third option is closed center with a positive displacement pump and a pressure relief valve, as I did on my tractor which was designed around whatever cheap surplus hydraulic components I could scrounge and repair. Though it's inefficient, the parts are much cheaper and simpler and the power dissipated into the oil warmed it, which helped in New England winter.
Open center valves can be added in series, closed center in parallel.
-jsw
Reply to
Jim Wilkins
Yep,
BTW, maybe i have my terminology wrong. i see I'm backward from what Jim says. With a tow motor I'm sure you just have the old system with pump always running and dump to relief valve when a spool valve sin't being used. This system is easy to add spool valves.
Karl
Reply to
Karl Townsend
Karl, this is what I also think, you got it exactly wrong in your first post. If I have open center, I add another apool valve in series. Very easy to do.
i
Reply to
Ignoramus25323
Yes, parallel. (Current throne room material is a '67 Sperry Rand Vickers Mobile Hydraulics Manual)
I'm curious to see your final build for a scrapper forklift crane.
Yeah, life-altering.
Reply to
Larry Jaques
"Ignoramus25323" wrote in message news: snipped-for-privacy@giganews.com...
The easy way to tell is to install a pressure gauge at the valve inlet. I added them to my log splitter, tractor and porta-power clone. The one on the log splitter is of necessity poorly positioned out of my view of the wood, on the pump outlet, but it would be easily broken if located closer to the action. I can watch the other two without taking my eyes too far off the job.
The gauges show how close I am to the safe limit and give an early warning when the system needs repair.
Perhaps my experience as a lab tech makes me comfortable monitoring dials and gauges. The other day I lagged together a retaining wall on sawhorses and then lowered it into position with my shop crane. I hung it from a scale to weigh it, then substituted a chain to position it, and found it was better to put the scale back and support half its weight while nudging it into final position. Without the scale I couldn't tell from the pump end of the crane whether it would be too heavy to tap into line with my toe or too light to stay in place.
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-jsw
Reply to
Jim Wilkins
Yes, i will post some pictures if/when I get it done.
i
Reply to
Ignoramus25323
I am not the right person as I was never involved in any fork lift mods, but as I remember doing something as simple as changing forklift tines required the manufacturers approval. So you might want to figure where you are going to hide this if you get inspected by the state.
It may not be any problem for you. We were handling explosives and that might be the reason for the big deal on safety.
Dan
Reply to
dcaster
Ignoramus8530 fired this volley in news: snipped-for-privacy@giganews.com:
Ig, unless the valves were actually custom-built by/for the forklift company, they are probably "power beyond" valves. That, because some of their lifts probably did come with accessories that needed extra valves beyond the lift control. (BTW, you didn't say anything about the traction drive... does it _get_ power from the lift valves or supply power to them, or is traction on a different circuit with separate traction pump?)
Lloyd
Reply to
Lloyd E. Sponenburgh
Larry Jaques fired this volley in news: snipped-for-privacy@4ax.com:
Fooey! The two spools already on there aren't in parallel! With open- center spools, the 'bypass' (drain, if you will) of one valve feeds the next valve's pressure input.
If you put open-center valves in parallel, nothing moves unless ALL the valves are actuated, and then they all move.
The valves are "physically in parallel", because they're constructed to dump flow to the next valve, and/or accept flow from the prior one.
But schematically, they're in series.
Lloyd
Reply to
Lloyd E. Sponenburgh
Right, exactly.
i
Reply to
Ignoramus25323
The drive is a regular drive with automatic transmission.
i
Reply to
Ignoramus25323
Sosueme. I haven't reached the open/closed-center valves chapter yet.
I thought open center valves all had full pressure to them at all times and they only use it when the spool is moved.
How can you move two things at once (loader beam up, rotate bucket up, or crane up, crane right) if they're in series? Or is it set up so he can only work one function at a time? Still, they'd seem to have to be in parallel for that, too.
My head has a problem grokking that at this time. I'm sure I'll get it by the time I read the rest of the manual, though. I've played with hydraulics for decades (including Lincoln ps/pb with accumulators) but not quite in this context. That's why I bought the book.
Reply to
Larry Jaques
Ignoramus25323 fired this volley in news: snipped-for-privacy@giganews.com:
That didn't tell me much. There are 'automatic' hydraulically driven traction drives, there are directly engine-driven trannies...
Did you mean the traction system is directly engine driven? (and yes, automatic transmissions have hydraulics in them, too, but the pump is inside the case, and part of the assembly).
Lloyd
Reply to
Lloyd E. Sponenburgh
It is engine driven, like a car. The transmission has its own hydraulic pump.
That pump on the transmission is also used for steering. Power Steering was screwed up on this forklift and we threw it out: the steering gearbox, the arms etc, are gone. We replaced it with an Orbitrol all-hydraulic power steering. This was really great. It is no longer hydraulically assisted mechanical steering, it is all-hudraulic.
i
Reply to
Ignoramus25323

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