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450A Bang Bang functions not working

Donold

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Apr 17, 2018
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I have an early 450A (Ford dual fuel) with several functions not working. It will not swing, the basket level or pivot and the extension in and out do not respond when selected. The unit will drive, steer and it will go up as well as back down. The non working functions will work if I select a working function in concert with a non working function. I changed the dump cartridge and swapped with a coil that works another function properly even though I could see movement in the shuttle with the valve removed. I checked the power and ground. I did the same thing with the proportional flow control coil and put in a new cartridge. I switched the coil with the lift valve and then I switched around the sequence valves (Bang bang and Proportional) as hey had the same part number. These changes did not help my situation. When I energize pin 14 I get 3K psi at G2. The manual tells me this should be 230 – 325psi. It has me pulling out my last two hairs. Any ideas about what I have failed to check?

Donold, Today at 2:33 PM
 

92U 3406

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I had a newer 450AJ do something similar. Would randomly lose all bang functions. Ended up finding a floating piece of o-ring intermittently jamming up a check valve in the main valve body. This was a long time ago so I'm pretty hazy on the specifics unfortunately.
 

Donold

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Pittsburg
I have been looking for the check valve. I see it on the schematic but I have not been able to locate it on the manifold. I think it may be in a plug that is on the back side where it is flat against the bulkhead.
 

Donold

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Okay I will check it out. Hopefully I will not need to remove all the lines. Thanks!
 

Donold

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I removed the check valve and it looks fine. I took it apart and inspected the plunger and spring. All looks good. I peeked in and did not see any contamination.
 

Donold

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Looking closer at the schematic I see two check valves in the block one for each pump. (between the swing and the upper lift) I only found one pilot to open check valve)
 

willie59

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That's not a check valve, it's a shuttle valve the sends a pilot signal to the sequence valve that maintains a 230 PSI standby pressure on the circuit, it's a load sensing circuit. The one you mentioned, between swing and upper lift, is the shuttle valve for the P1 pump circuit, load sensing shuttle upper lift and swing. The sequence valve for the proportional controls is on the opposite side of the manifold at the very bottom of the manifold. The other load sensing shuttle is for bang functions that sends a pilot signal to the sequence valve for bang functions located next to the bang functions dump valve coil and the proportional flow control coil. To just forget about the bang functions not working for a moment, the thing that has me scratching my head is the swing not working from both platform and ground controls. Both those functions work on the P1 pump circuit, and you stated the upper boom controls work. Then how does not the swing work from both platform and ground controls, it's the same circuit that works the upper boom. I'm thinking you have two different problems, swing not working and bang functions not working, that mimic each other because they're two different pump circuits, P1 pump (upper lift and swing) and P2 pump (bang functions), but what the heck is up with the swing since the upper boom works???
 

Donold

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Willie59 I am confident you are right I have multiple issues. I was beginning to think the hydraulic schematic was wrong as I have one function on each side that works as well as items on each side that don't work. The unit came in with hydraulic leaks and a tech changed lines on the drive and steering. He noticed the swing was not working and checked to see if the gear rotated. It was good. Today I looked at the parts book to locate the check valves. I found orifices behind plugs but no check valves. The orifices next to the rotate coils and the one next to port B2 looked god and not blocked. I have a 600S and started looking at what was different. I noticed that when I hit a function like telescope the unit would idle up. The 450A does not idle up when a function is selected. I put power to terminal 11 to get the idle up and I still lacked response on my non functioning switches. I will continue to search for the check valves.
 

Donold

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Here is the latest. In looking close at the swing it moves. It just moves as slow as I do. That said everything electrical on the swing is good. I have a motor or flow issue to resolve. Still working through the bang bang issue.
 

Donold

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I have the analyzer but I guess this was built before they started including that feature.
 

willie59

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I will continue to search for the check valves.

Please don't bother looking for check valves because you won't find any. What you will find is two shuttle valves, that's a very specific type function valve that performs a specific purpose, it is not a check valve, that's a different type valve entirely. If we're going to discuss troubleshooting it behooves to use correct terms to communicate to prevent confusion or misunderstanding.

With that said, you reported that steer works (which can only be operated from platform controls). That indicates that the dump valve for bang functions, the .045 orifice, the shuttle valve that controls the sequence valve as well as the sequence valve itself are all working properly. What seems to not be working, from both platform and ground controls, are the bang functions that have to power up the flow control valve for the bang functions. The steer circuit is unique in the bang circuit as it doesn't power up the flow control, it utilizes the .045 orifice to control flow from P2 pump to control steer cylinder speed, all the other bang functions power up the flow control valve, that's one of the things I'd check next. I'd start by selecting any of the bang functions at the lower controls and see if you get a voltage signal at terminal 44. If you do get a voltage signal, find the flow control solenoid for bang functions and see if your getting a voltage signal there when you select a bang function from ground controls.
 
Last edited:

willie59

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Old JLG terminology joe--h, you either have proportional functions where valves meter the amount of hydraulic flow, or you have bang functions where valves are either off or full on, as in, function is off, then you flip a switch, bang, function is full on. It's just a JLG term that describes control valves that are not proportional.
 

Donold

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Willie59 you are correct again the valve I pulled out is a pilot operated shuttle controlling flow. I see (on the schematic) both sides have the same 230 psi but I don't get why I can only find one pilot to open valve. (PC08-30 is what I pulled out) Moving back to the flow control side, I have power at pin 44 when selecting a function and I get a flash on 23 when a function is selected. Pin 13 is hot because we are level my main dump gets power on pin 14 pin 42 gets power as well as the function that I select like pin 38 lift down that works fine and I get my bang bang signal like pin 18 when I hit rotate right. I have power at the flow control coil on the terminal closest to the ground control box and the pin farthest away is a good ground. I put in a new cartridge even though I could see the old one shuttle. I switched out the coil with the one off the main lift as I know the main lift works. Nothing changed. I was at a loss at this point and started to look for a cross connection or something else man made. I did notice the Hydraforce 3 way spool valve next to the pump mounted below the 10 micron filter has a magnetized cartridge. I believe it to be a bypass to tank for the filter.
 

JPV

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I hate to interupt as this is interesting and I am trying to follow along but inquiring minds want to know what the heck a bang bang function is?
 

Donold

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JPV Bang bang is the way the JLG pioneers describe the functions that are switched on or off. Some controls are proportional like the boom while others are either on or off like swing right. The latter is just on or off and called bang bang.
 

joe--h

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That must be exciting, full left, BANG!
Sounds good for taking the corners off buildings or the like.
Joe H
 
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