B670 BackHoe swing speed

[Lil Foot]

My B670 Hoe swing speed is WAY too fast- like 1 second from center to 90 degrees, if you just shove the lever over.
This requires VERY careful, slow feathering when swinging side to side. I would like to ad restrictors to slow this way down, and was looking at the hose/valve/cylinder layout to decide where to put the restrictors in. The swing cylinders are single acting, so I thought the best location for a restrictor would be where the line connects to the cylinder.
Looking at the diagram, it appears there are supposed to be restrictors at that location.
Drawing shows swing cylinders (#126) with ports 4A & 4B.
The inset shows restrictor assemblies in ports 4A & 4B, and they appear to be some kind of o-ring sealed fittings.
When I rebuilt this hoe, there were no special fittings, o-rings, or any restrictions in the existing fittings.
The pics below appear to show just standard hose connection fittings.

My questions are these:
Do these fittings appear to be anything besides a standard hose/cylinder connection?
Is it likely that there were washer style restrictors in these fittings at one time that fell out when the hoses where changed or cylinders serviced?
Is it likely that someone removed the restrictors?
Can I just buy a restrictor that will connect between the hose & cylinder?
Thanks in advance!

 

[Lil Foot]

I pulled off one of the hoses and removed the fitting from 4A.
As I suspected, it is just a standard 1/4 NPT to 1/4 JIC swivel, with a .230 bore through.
There is no provision for a washer-type restrictor.
I will head for my local hydraulic shop tomorrow to see if they have anything that will replace this with a some kind of a restrictor.

It is possible to drill & tap this fitting for a set screw with a hole drilled through it, but there isn't much "meat" to work with. I have done this before, but on larger, chunkier fittings.

 

[torch]

Different model, but my backhoe has the restrictor plates in the fittings right at the spool valve set.

 

[Lil Foot]

Yeah, I checked there too.
Kinda weird that the swing is the only place I have the "overspeed" problem.

 

[North Idaho Wolfman]

Those are one way free flow and one way restricted so you need restrictors that act that way.
Otherwise you could suck the seals out of the cylinder.

 

[North Idaho Wolfman]

Here is one example:

EF20S DELTROL. HYDRAULIC VALVE, INLINE FLOW CONTROL, 1/4" FEMALE PIPE PORTS, UP TO 6 GPM, CONTROLS FLOW IN ONE DIRECTION ONLY, FLOW IS UNRESTRICTED IN OPPOSITE DIRECTION. 5000 PSI MAXIMUM. MADE OF STEEL. DELTROL #EF20S, DELTROL PART # 10120-44 | Trausch Dynamics

6500103 - EF20S - EF20S DELTROL. HYDRAULIC VALVE, INLINE FLOW CONTROL, 1/4" FEMALE PIPE PORTS, UP TO 6 GPM, CONTROLS FLOW IN ONE DIRECTION ONLY, FLOW IS UNRESTRICTED IN OPPOSITE DIRECTION. 5000 PSI MAXIMUM. MADE OF STEEL. DELTROL #EF20S, DELTROL...

www.hydraulicstore.com

 

[Lil Foot]

Finally got back to this project, and I have to thank torch for his post above.
I looked again, and you were right, the restrictors are on the underside of the valve body.
(I traced the wrong lines back earlier )
Didn't help that the restrictors are supposed to be in ports 4A & 4B, and there are two of each of those.

Sorry for the long dissertation, but you might find it helpful, or at least interesting.

Back to the problem.
I removed & disassembled the restrictors, and, as shown in the 2nd drawing above, there is a small hex shaped hardened disc with a .060 hole through it, off center. The upper side has a flat circular "seat" that sits against a similar seat in the upper half of the restrictor. The other side of the disc has a slot cut across it, with no sealing provision against the lower half of the restrictor.

After hitting every major hydraulic shop in the area, we all came to three conclusions.

1) No vaguely similar fitting is available today, must have been custom from AeroQuip.

2) As shown in the inset cross section, the free flow mode sends fluid from the spool valve both through the hole and around the hex into the slot and on to the cylinder, with no restriction.
When the flow is reversed, the disc is lifted against the upper half, and the two surfaces seal, allowing fluid to only pass through to .060 hole, restricting flow. Great.

3) It can't possibly work as configured. Crap.

Everyone agreed that basically there was nothing to lift/hold the disc in the upper position, fluid would just go around the disc, unrestricted.

That night, I was pondering all of this, and realized there is stepped bore in the lower half of the fitting.
(see modified drawing below, red outline)

I put in a light spring, .250 dia x .900 fl x .015 wire, and reassembled and installed them.

IT WORKED!

Testing reveals swing speed cut by 60-70%. I haven't dug anything yet, but it has to be a great improvement.

I have no idea why there were no springs in there, but it is obvious there should have been.

 

[Lil Foot]

Just noticed that in the 4th, 5th, & 6th pic the upper half of the restrictor is reversed. Sorry.

 

[torch]

Congratulations! Glad you were able to figure it out, even if the process was a bit frustrating.

 

[Vigo]

So I'm fixing up a B670 for a buddy and it seemed to me to have 'unrestricted' swing speed. I recently ordered every single hose on the thing from Surplus Center and in the process of replacing them I noticed these restrictor sections and remembered reading this thread a couple of months ago during my prep/research.

So, my experience with the restrictors was a little different. When I opened mine, both of them had the hex-shaped restrictor plate rotated and with its sharp edges wedged into the circular 'seat' area above it.. both were stuck sitting diagonally instead of flat. Banging them upside down on the bench didn't dislodge them, so i got a proper size punch/dowel and popped them out.

To me it seemed that the main issue causing this failure mode was that the hex disc has too much vertical clearance between its seat and the ORB fitting screwed in above it, which allowed them to rotate. However, it didn't look like anything was missing, either.. I think this was a home-brew by some Aeroquip guy which, while clever, was slightly flawed.

To shrink the vertical clearance i simply found a stainless washer which was very close to the thread ID of the fitting and installed it between the hex disc and its 'seat'. The washer is essentially a wider seat which doesn't allow enough slack between the hex and the housing for the hex disc to rotate out of plane and jam one of its machined edges into something and get stuck. I didn't measure the thickness of the washer or how much clearance was left, just verified that it let the ORB fitting fully seat without trying to 'compress' the disc/washer assembly. The ID hole in the washer is probably almost as big as the ID of the 1/4" hoses it leads to, so i don't believe it actually restricts flow meaningfully on its own, just helps the hex disc do its job.

When i reassembled it, it does work and the swing is at an easy, safe speed now. I can't see how the current setup could ever fail so i believe it should be a permanent fix and very easy for anyone like me with a vast washer collection.. to replicate.

Here you can see the seat damage from the wedged in hex disc.

Washer and hex disc with restrictor orifice.

Washer installed over damaged seat, taking up excess clearance to prevent rotation of hex disc.

I'll be starting a thread on the whole rehab of this tractor/loader/backhoe.. i'm 2 months in and have plenty to show already. This thread was very useful to me in fixing this issue!

 

[Lil Foot]

This thread was very useful to me in fixing this issue!

Glad to hear it!