Adding hydraulic functions to a forklift

I purchased this "boom lift" for scrap for $500:
http://goo.gl/kbvFHE
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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Ignoramus8530 wrote:

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.
--
Steve W.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
message

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. (Amazon.com product link shortened)15455760&sr=8-5&keywords=big+game+scale
-jsw
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 08 Nov 2014 06:41:24 -0600, 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.
--
The more you know, the less you need.
-- Aboriginal Saying
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Yes, i will post some pictures if/when I get it done.
i

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 2014-11-08, Lloyd E. Sponenburgh <lloydspinsidemindspring.com> wrote:

Right, exactly.
i
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 08 Nov 2014 15:16:23 -0600, "Lloyd E. Sponenburgh"

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.
--
That's the thing about needs. Sometimes, when you get them met,
you don't need them anymore. -- Michael Patrick King
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

http://www.yesterdaystractors.com/cgi-bin/viewit.cgi?bd rmall&th43934
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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Friday, November 7, 2014 10:46:04 PM UTC-5, Ignoramus8530 wrote:

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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 2014-11-08, Lloyd E. Sponenburgh <lloydspinsidemindspring.com> wrote:

The drive is a regular drive with automatic transmission.
i
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 2014-11-09, Lloyd E. Sponenburgh <lloydspinsidemindspring.com> wrote:

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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.