Hum/vibration in J&S 540 hydraulic system
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    Default Hum/vibration in J&S 540 hydraulic system

    I've noticed a strong "hum" or vibration in the hydraulic system of my 1986 Jones and Shipman surface grinder. When the system is not under a lot of load (traversing slowly) this is almost imperceptible. But when it is fully loaded -- running the table back and forth at full travel and max speed -- I can hear it and even feel it on the table. It's very strong in the hose coming from the pump.

    Can anyone tell me what's responsible and how to fix it? I'd guess that the vibration is at 300 or 400 Hz.

    (As anyone who has followed an earlier thread of mine already has seen, I don't know anything about hydraulics. So what's wrong may be basic/obvious.)

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    Got a video with the sound present?

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    I found this, have you seen it? Jones & Shipman 540 Surface Grinder

    It looks like the tank is inside the base of the machine. I could see the motor bearings going out, the spring in the relief valve broken or stuck, dirt in valves, cushions under tank or motor on pump loose or worn. Can you look at the hydraulic oil in the tank? If it is white the pump is sucking air, either because the tank is low of oil, or the tank filter / strainer is dirty and it is cavitating (no oil sucking) or the shaft seal is leaking. Take a look at that and see if it makes sense.

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    I saw this old thread...post 7 mentions elastic mounts. It also looks like Tyrone knows a lot about them too:
    https://www.practicalmachinist.com/v...nd-inspection/

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    Hi Richard,

    Yes, I've seen the lathes.uk page!

    Quote Originally Posted by Richard King View Post
    I could see the motor bearings going out
    Nope, motor is smooth and quiet with or without load.

    The spring in the relief valve broken or stuck
    The relief valve is my first suspicion, because the vibration seems to be coming from the pump, and apart from the relief valve there isn't much there.

    dirt in valves
    They all seem to be working properly (throttle valve, reversing valve)

    cushions under tank
    Tank sits directly on the base

    motor on pump loose or worn
    Motor and drive chain/gears are fine, as are the motor mounts.

    Can you look at the hydraulic oil in the tank? If it is white the pump is sucking air, either because the tank is low of oil, or the tank filter / strainer is dirty and it is cavitating (no oil sucking) or the shaft seal is leaking. Take a look at that and see if it makes sense.
    Oil is at correct level. Inlet filter is clean and submerged and not sucking air. There is no cavitation/foam (I know what that looks like because I had it once in my other grinder). Shaft seal is dry (or at least as dry as parts around the sump can be).

    It's also not the elastic motor mounts mentioned in post 7 of the old thread, they are fine.

    Since the relief valve is suspect #1, should I take it apart and clean it? Or something else?

    Cheers,
    Bruce

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    Go ahead, that's usually pretty easy and quick. Does your machine have a pressure gauge? Watching the needle might give some indication of something awry also.

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    No pressure gauge, but it looks like there is a port on the pump so I can add a gauge. Here's a drawing the pump:


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    You might be able to add one somewhere else if it's easier to see - on my grinder there's a gauge port for both the high and low side pressures right up front on one of the valve blocks. If at the motor is inconvenient, might be able to find a good location by following the piping.

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    I have a vague memory that, if the pressure reliief valve is set for too much pressure, the pump will howl. But I don't think that is your problem. I'll have a play tomorrow when I'm doing some grinding and see if I can produce the same symptom...

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    I pulled out the pump and tank to have a look



    Oil looks clean, level is good (slightly too high), all the mechanical mounts and drive are good.



    Doesn't look like the pump has the advertised extra port for measuring pressure. In fact it also doesn't look like the one in the parts book!

    I think I'd like to add a gauge that's visible externally like on my Studer



    Is it OK for me to do this with a T-junction from the small black line coming out on the left of the pump? Or should I take it from one of the unused ports on the distribution block? See first photo above.

    I do see some bubbles in the oil and remember that the last time I had this out a few years ago, I wasn't so happy with the appearance of the input filter. So I ordered a new one and now seems like a good time to install it:



    So the plan is:

    - Lift motor and pump out of the sump
    - Replace inlet filter
    - Remove and clean bypass valve/pressure regulator
    - Add a pressure gauge

    Since the pump does not resemble the one in the parts list, any advice about the third step above would be appreciated.

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    It looks an awfully lot like the diagram to me. The black cap on the right side of the last photo needs to come off - the relief valve should be under it. I think that's the third step your talking about?

    20200802_043004.jpg

    If you mean the pressure gauge, you should be fine tapping in anywhere on the output.

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    Are the hoses the original size??
    Perhaps replaced in its lifetime with one with a smaller ID
    Had a bad noise once on a hydraulic system which was fixed with a bigger hose

    Peter

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    Peter, I did replace the hoses, using the old fittings and new tubing and hose clamps. It is the same ID, but perhaps not the exact same material. So something to try is I don’t find another solution. Cheers, Bruce


    Sent from my iPhone using Tapatalk

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    Quote Originally Posted by eKretz View Post
    It looks an awfully lot like the diagram to me.
    On the drawing, the pump has part N (a 1/4" plug for measuring the pump pressure). Not present on my pump. On my pump there is a second small outlet below the relief valve. It's not on the drawing.

    The black cap on the right side of the last photo needs to come off - the relief valve should be under it. I think that's the third step your talking about?
    Yes, that's what I mean by the third step.

    I suppose it is straightforward, but the relief valve in the drawing does not look like the relief valve on my pump. For example on the drawing part Z is a small slotted stem, and sits in parts X and Y which are visible from outside. On my pump the stem is very large diameter, and just sits in a single part visible from outside.

    I'll take it apart tomorrow and see if I can figure out what's wrong.
    Last edited by ballen; 08-03-2020 at 12:45 AM.

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    Is this a machine that runs regularly and just started making noise? Or has it sat for some time and now that you need it, it is making noise? My WVN surface grinder would make a noise after sitting unused for extended time, I forget who suggested it but the idea was that the hydraulic fluid absorbed moisture from air ( it was still clear), letting it run for an hour or two would heat up the oil, and the noise went away. YMMV

    Before that suggestion was made I had pulled and inspected relief valve and replaced the (not working) gauge.

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    Quote Originally Posted by dalmatiangirl61 View Post
    Is this a machine that runs regularly and just started making noise? Or has it sat for some time and now that you need it, it is making noise?
    Good questions. I'm not sure if it has been there forever or just recently started, because it's only obvious when running the machine at maximum feed and travels. That's not something I have done in the past, but only more recently, after doing some work on the main cylinder and understanding how the cushioning works.

    I use the machine sporadically, probably once or twice a month on average, and sometimes just for a 20 or 30 minutes. But sometimes I use it for extended periods, such as an entire day, which does heat up the oil for an extended period. I did that just a week or two ago.

    FWIW the oil is four years old and looks and feels very good.

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    I don't know your problem but I'm amazed that the pump drive is a chain! No idea what's going on but a chain drive would be worth looking at, for sure.

    Stuart

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    i wish my grinder had a pull out sump like that.

    heating the oil is easy with a light bulb under the grinder (you might also put it in the oil directly)to see if it makes any difference. but hydraulic oil absorbing moisture? i wouldnt think so.

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    Replace the seal in the pulley side of the pump and while it's apart install new bearings. The electric motor looks new, could it have been changed I wonder....take off the chain and run it and use a mechanics stethoscope and listen to it. I have also never seen a chain drive on a pump. Check the chain and pulley for wear. On a recent repair of a hydraulic system (Springfield Grinder) I used a stethoscope to track down a bad 2 way valve. I use them on trouble shooting electric motors, valves, etc. A simple way to check pressure on a grinder is try to keep the table from pushing you while standing next to the table. An old timer showed me that once. He lowered the pressure and pushed against the table and had me increase the pressure until he could not keep it from moving. He weighted about 250 and said that was the approx. pressure.

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    Hi Richard,

    Quote Originally Posted by Richard King View Post
    The electric motor looks new, could it have been changed I wonder.
    The motor is original, but you are right that it looks new. That's because it effectively IS new, as is the machine.

    When I bought this machine 4 years ago, it came with the original documentation and order/delivery paperwork. The machine was delivered new to the original owners in 1986 with 5 grinding wheels and 2 hubs. When I got it, all five wheels were still there. Three had never been mounted. The other two had about 1cm used up from the 20cm diameter.

    When I bought it, they told me that the chuck controller did not release properly. As far as I can make out, the chuck controller failed a few weeks or months after delivery, and the machine was then just shoved in a corner for the next 30 years and not used. (It was not hard to fix the controller, some capacitors had fried because they were mounted too close to some power resistors.)

    That's why the ways and other parts of the machine look like new.

    Cheers,
    Bruce


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