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Doall D8 surface grinder hydraulics

jwatts

Hot Rolled
Joined
Apr 19, 2006
Location
Missouri, USA
I have an old Doall D8 surface grinder that seems to have a hydraulic issue. The hydraulic pump starts and runs fine, but when I start to turn up the table speed selector it becomes stiff to turn and the pump sounds like it's under quite a bit of load. The table doesn't actually start to move until the speed selector is turned to maximum. Once the speed selector is maxed out and the table starts moving the pump quiets back down until I turn the speed selector back down at which point the pump loads up again. I pulled the table off to make sure the ways were getting lubricated and while the flow rate seemed low, all the sliding surfaces were getting oil and had no dry spots. Any ideas where the problem might be?
 
How long has it been since someone looked at the pickup strainer. While your description of the sounds does not match that well with a clogged strainer, it is a symptomatic of a inlet restriction. A oil filter is on the return line (if it has one) side of things and if the bypass valve is not working, its another place to check. Next look fort any kinked or pinched lines.

There is restriction somewhere.
 
Thinking about what Tom said above, my D1030 sump was packed with crud when it arrived.

If you have not cleaned out the hydraulic system in a few years, it is probably the first thing to do.
Astounding that a machine designed to avoid/shed/segregate grinding grit still manages to load up the far recesses of the hydraulic sump over a period of use.

It is also "interesting" how a certain amount of water can gradually intrude just through condensation, if not some stray coolant. This does none of the hydraulic controls devices any good.

Take the end off the sump, clean everything religiously, run a batch of hydraulic through for a bit, gradually add a shot of alcohol (say a cup or so) to dry everything, purge, run a bit more clean hydraulic through it and drain again, them fill and see what you have.

Basically, if you do any repairs to the system, you are going to have to do the above anyway. Why not start there, and see if it solves the problem?

smt
 
I saw one of those once that the speed lever set screw got loose on the shaft so it wasn't locating in the right position. It's been a while but I seem to recall I had to remove the little crank and move the shaft until it was off and re-install the handle. Be sure the upright handles are in the right position too. How does the in and out feed work or rapid in and out? That caries the table and saddle weight so if it is a whole system issue both would be bad. Have you check the Hyd. Pressure? Rich
 
Jeremy,
Can't add much, but the pressure should be around 250# ± 50#. Have you checked the hyd. cyl. and rod when in free play (not connected to table) to rule out a bent rod and such. What Richard King says is plausible too, if your's is not pinned like mine. All the above will be a good start.
 
I have not yet pulled the end off the hydraulic sump which will be the next step. The speed selector on mine is pinned so I'm pretty sure it is correctly oriented. The right hand lever options are "wheel dresser", "automatic", and "manual". With that lever in automatic or manual position the in/out feed lever doesn't do anything. If I put the right hand lever in the wheel dresser position the pump loads up until I move the left lever to either in or out. Once the saddle starts moving either in or out the pump quiets down. All of the behaviors are the same with and without the table installed. I don't think I have a gauge to measure the pressure, but I can probably hunt one up at work. I may have to order some hydraulic fluid before I can change it unless one of the agricultural varieties will work.
 
Jeremy,
The book states: 5 gal. Valvoline Oil S. A. E. #10 or equivalent. I use the "equivalent".
By the way, if you have the "Cool Grind" feature, I have the correct blotters for it.
 
Looks like ISO32 should cover it. Ray, the machine has the cool grind feature, but I currently only have one wheel adapter which has no provision for it.

Thanks for that link Richard. I have what appears to be the same manual that Doall sent after I contacted them, but it isn't for quite the same machine. I'm not sure what differences there are, but the manual shows a separate way lubrication system whereas on my machine it is lubricated by the hydraulic pump.
 
I got the hydraulic sump cleaned out pretty well and changed the pickup filter. The filter I pulled out was a Purolator 13626 which of course doesn't exist anymore, but Killer Filter makes a direct replacement. There was a little sludge in the bottom of the sump, but really not much considering that once I cleaned off the end plate someone had written on it "oil changed 8/87". I cleaned out the sediment bulb on the return filter from the way lubrication which was good since it and the tube dropping back in to the sump were completely plugged. That's probably where some of the gallons of oil sitting around in the base came from. However, none of that changed the symptoms at all. Suggestions on the next place to look? If it's the bypass valve is that mounted up under the saddle?
 
Can't specifically diagnose for you, but the next thing I did was take the control unit out, disassemble it, clean out the rust, and replace seals and O rings. Mine was blowing a lot of the hydraulic fluid out, and filling the base of the machine. It's been 10 yrs or so, so not much clear memory of the process. I got generic seals and O-rings from the local bearing place. Replaced at least one collapsed hydraulic hose.

smt
 
Hi, what company still supports DoAll surface grinders? I have one that just says model MD1,serial number 157..
Thanks, Rich
 
DoAll still exists, but they don't sell grinders anymore. They were able to send me a manual and I think they provide some parts support, but I really can't say for sure.

I haven't been able to get a lot done lately, but I was able to pull the saddle off so I could get a look underneath. No obviously kinked or otherwise smashed lines.

Stephen, is the control unit you mention the whole valve assembly in the picture?

 
This has been on the back burner for a while, but got back to removing and disassembling the hydraulic valve assembly today. The unit is in three main sections, what would be the bottom section in the above picture came lose pretty easily. The joint between the top and middle sections separated fairly easily, but the rods that pass through are captured in the center section. They move easily over their range of travel, but there seems to be a pretty solid stop at either end. In looking it over this evening I haven't been able to see how they are held. Any suggestions would be much appreciated.
 
It turns out that the seals themselves are what keep the rods captive inside the valve body. At this point I have had the valve assembly completely disassembled, cleaned the whole thing in an ultrasonic bath using kerosene and replaced all the seals and gaskets. Unfortunately, the behavior remains the same. Any thoughts on where else the problem could lie?
 
Finally got back to this project. I put a pressure gauge on the pump output. Before trying to run anything the pressure was quite low, less than 50 psi or so. When I try to run the table it jumps up to ~490 psi and stays there until the speed dial is turned about half way up (that's about where the table starts to move) then gradually drops back down as I increase the table speed to max. According to what Ray said that pressure is too high, but even if the pressure was lower should it change so much during operation?
 
Make sure the cylinder shafts are aligned correctly as well. Move the table all the way to one side. Loosen the connection of the cylinder shaft to the table and retighten it. Then repeat with the table moved all the way to the other side. It could be a binding issue.
 
Sorry, I should have been more clear. I said moving the table, but what I should have said was moving the table cylinder. The table is currently removed.
 
DoAll grinder issues

Sorry, I should have been more clear. I said moving the table, but what I should have said was moving the table cylinder. The table is currently removed.

I am facing saddle issues on a D618-7. I am wondering if you ever got your problem resolved.
My issue is the table works but nothing on the saddle works. Nor will the manual table feed crank work. It is hydraulicly activated as well.
Tony
 
DOALL G10 Hydraulics Issues Repaired.....The table would move a little if I messed with the pilot valve and the manual in/out only worked when dressing the wheel. The problem was fixed by tightening the small set screw the locks the pilot valve shaft to the handle/knob. The table dog would hit the pilot valve but the valve wouldn't actuate to reverse the cylinder. Everything works great now.
 








 
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