Crown 20MT Walkie forklift (lift-lower valve problem)

[Sodo]

Sodo,
When looking at this manifold could you check a few items.
1) Is plug "D" directly inline with the pressure or pump supply port. If i would suspect there would be a check valve behind this.

Hi oldnslo

I finally had time to open up this manifold again. Yes there is a spring and check valve behind the "D" plug. It is inside, as in my (red) drawing. The 3 places in the manifold, that it could leakdown are here: A, B, C. How I can figure out which one is leaking?

=============

I decided to first inspect the B) Hold valve. It's a spring-loaded check valve. The spring is very light.

Looking at the seat, the contact ring where the ball would seal against the Aluminum manifold has a small lump in the worst place. The black is not corrosion. The black looks like there was galling, which rolled up a small 'burr' at the yellow arrow. This would definitely make it leakdown, but I can't imagine what could lift up a burr (other than a mfg error, at which the Walkie would have leaked down from day1).

I can see the burr with a magnifying glass, and I can feel it with a screwdriver probe, it can't possibly seal tight.

But what to do about it? Can I lightly "peen" the Aluminum seat with the checkvalve's ball, and smash the burr down? By driving the the ball with a light hammer blow. What do you think?

The ball does not appear to be inconsistent in any way, do they wear out? --i.e. should I replace the ball? it's 0.34" dia. The spring appears to be OK.

I don't see anything wrong with valves A) & C) by the naked eye nothing looks out of order. But this ball-seat sure looks like the leak.

 

[wdchyd]

If the ball is bright and shiny then the ball likely is good.....I'd do a light coin or peen with it on a clean seat

The solenoid "C" would be the most likely culprit to give you a creep down.....are the threads on the valve cartridge 5/8-18?.....the dia of the smaller oring area .498"?

If looks like a common normally closed 2-way cartridge (not repairable but easily replaceable)

It may help if you connect a hydraulic hand pump w/guage to the lift cyl port when doing repairs....you'll be able to monitor real time leakdown when adjusting things

 

[Sodo]

If the ball is bright and shiny then the ball likely is good.....I'd do a light coin or peen with it on a clean seat

Can you explain this again, before I go after it with a hammer?? Would I use a brass punch and give the ball a light tap to mash down that burr?

The solenoid "C" would be the most likely culprit to give you a creep down.....are the threads on the valve cartridge 5/8-18?.....the dia of the smaller oring area .498"? If looks like a common normally closed 2-way cartridge (not repairable but easily replaceable)

Another option. The reduced diameter is .50" (don't have .xxx caliper). But the thread seems to be 5/8-16 (same as a 3/8 bolt).

It may help if you connect a hydraulic hand pump w/guage to the lift cyl port when doing repairs....you'll be able to monitor real time leakdown when adjusting things

Yes I think that would help, but I don't have that tool. Just want this walkie to hold its load!

Really hoping for some way to fix that checkvalve seat. The creep rate is about an inch every 5 seconds. If I can reduce that by 75%, or an inch every 20 seconds I will consider it good enough.

I have high confidence that this is it!

But if not….probably can buy a pump for less than the repair bill to take the walkie to a shop. If the peen (coin?) process doesn't solve my creep problem I may be bugging you about how I might find a replacement for this solenoid valve.

 

[Sodo]

Can you explain this again, before I go after it with a hammer?? Would I use a brass punch and give the ball a light tap to mash down that burr?

I gave the ball some taps with a hammer & punch and I think it worked, I can't feel the 'burr' anymore running a screwdriver over it. Also just a little oil holds the ball in its 'seat' against gravity. I am pretty confident that the check-valve seals tight now but have no way to know.

The reduced diameter is .50" (don't have .xxx caliper). But the thread seems to be 5/8-16 (same thd as a 3/8 bolt)?.. I might find a replacement for this solenoid valve.

Well I put it all back together and it still creeps down at one inch in 5 sec, same as before.

Wdchyd, can you suggest where I might get ahold of a new solenoid valve? I searched the web with these numbers below, found nothing. The reduced diameter section (left of the holes) is 0.50" . The thread diameter is about 5/8, and appears to be 16tpi not 18. I don't know if it's metric or imperial.

Parker
Model: VNUP8C-012
Part No.: 765129
12.0 VDC 1.75 AMPS

 

[mikeinwi]

A possible equivalent would be:

Delta- Power MA-S2A-00-SS-12

You can get it from Trausch Dynamics (Hydraulicstore.com - Call toll-free 800-323-5749 Mon-Fri 7:30-5:00 Sat 7:30-11:30 Central Time -)
Their part numbers are:

Valve: 7010003
Coil: 7013524

This is a double spade coil so you will have to ground one of the spades.

 

[Sodo]

Hi Mike, Thanks for the help. I found some info on the solenoid you listed, it's 5/8-18 thread as WDC mentioned. My Parker valve is possibly 5/8-16 thread. I used 3/8-16 bolt as a thread gauge…….its very likely 16tpi (I used a 5/16-18 bolt to confirm that it's definitely not 18tpi).

The Parker solenoid is a double spade.

I called Trausch, they are going to have a look at my pics. Thanks very much for the help.

 

[wdchyd]

Sodo.....possibly is that valve thread .750 x 16 tpi

If so I have them in stock

If not I would suggest getting a new solenoid cartridge, coil and valve block and put this setup between the existing control valve and the lift cyl....many of these have a built-in check valve for up and energized coil for down....just wire it with the existing wires for the other valve coil....easy peasy

also here's what we use to ream the seats (verrrry gently)

 

[oldnslo]

SoDo,
Measure the OD of the threads like wdchyd shows. Then also measure the length of the valve from the bottom of the hex below the coil to the nose of the valve. Their are two different valve cavity sizes that I know of and they do not interchange. Delta Power, Hydra-Force, Parker & Eaton all make valves that look very similar and may or may not fit in the same cavity.

My first guess would be that this is 3/4-16 threads since the parker model code includes the 8 which is some what of a standard for the 3/4-16 thread cavity size.

The 5/8 thread cavity was more of a odd ball size started by Delta Power and is far less common in the industry.

If you have a lathe that uses collets Vs 3-jaw chuck you could also try dismantling the Parker valve.

 

[js5020]

Just call your local Crown dealer for the solenoid valve they will have it or the updated valve.

 

[Sodo]

Sodo.....possibly is that valve thread .750 x 16 tpi If so I have them in stock

You guys could be right. The reduced diameter (near the holes) is .50, the O-ring seals to a 0.62 bore, so if those threads are 16 then the thd diam has to be 3/4. Can't measure it now because it's all back together.

Sounds reasonable to replace the solenoid valve block, but what if the manual control valve is the culprit?

wdc what's your company, & how much is that solenoid?