Old swivel log / pulp grapple GPM requirenments

racingjoe66 · April 07, 2018, 09:09:45 AM

Thanks Mike, that explains it on the switch and controll for both grapple and rotor!

That is deff simple enough. Only thing I see then, with the extreme flow my excavator pushes out 39 gpm and looks to be 3,250 psi to the bucket cylinder. Is there a reducer to reduce the flow before the valve or will the valve be able to do a good enough job of that? Also will the rotor flow be okay that high?

Thanks for the input Skeans1!

I think I am just going to simply hang it from the bucket pin. Simple and easy enough

racingjoe66 · April 07, 2018, 09:17:08 AM

I see the valve says 13.2 gpm max.

Don P · April 07, 2018, 10:42:43 AM

I'm not a hydraulic guru, feel free to correct this. The valve doesn't care that you have 39gpm available, it can only pass 13.2gpm of that. That might be an issue if you were running an auger or something constant. The rest of the time it is off and passing 0 gpm. You will always be feathering that control to swivel in fine increments, more like passing pints per minute. I have an old I'd guess '70's prentice similar to that, it has 1/2" lines and I believe the relief is set at 1500psi.

racingjoe66 · April 07, 2018, 10:48:34 AM

Thanks Don I'm not a hydraulic guru either lol. I guess I was thinking the valve had to match the size of the pump...? Guess just need some clarification on that

mike_belben · April 07, 2018, 12:15:23 PM

I routinely govern down cylinder travel speed with hose size. If its jerky with a -6 i will put on a -4 for instance.

The pressure is a more complicated matter and a bit more of a frontier for me. If you were to let your grandkids go play then yeah theyll hold the valve full open way past sufficient clamping until the hose swells and pops or a seal pukes. Are you going to do that? If its only you and youll be taking your time at half throttle and a light touch, then just using small hoses is probably sufficient. It doesnt RELIEVE pressure like a relief valve, but a restrictor orifice like that will create a pressure drop and it will slow the RATE of pressure rise which means youll be less likely to hold the valve open until the explode point. This is also the 'do nothing extra' option.

To do it "right" enough for the liability insurance agent to sign off on your manufacturing these things, would require a relief valve or atleast an adjustment. Your spool bank may have an adjustable cartridge in it that could lower the force only on that circuit and would be an excellent stroke of luck. Look hard for this, itll be under a cap or plug inline with that spool section. Probably with a spring. Pulling shims or reducing that spring will lower the pressure in that circuit.

If not youd have to plumb in a relief valve that only effects that circuit, which is made up of an A and B hoses so itd actually take 2 reliefs to be sure. That means a return line needs to be plumbed. You dont really need to worry about grapple open or rotate, neither of these will build a lot of pressure, but grapple close will.

I mean i wouldnt go through all this unless i have employee operators who cant be trained. Id start with small hoses and redesign after i prove i cant stop it from blowing up.

Speaking of blowing up, you cant double stack differential poppet relief valves on a series circuit and then use both at same time. So a pair of 2500psi valves that are looking at differential pressure across the two sides. Well that puts 2500 psi on the low side of one valve so it wont relieve until 5000 psi total and stuff 'splodes. Its not related to your project, just a general safety warning for everyone.

racingjoe66 · April 07, 2018, 12:28:27 PM

Thanks Mike. I am just planing on me doing it or the old man. I know the kids would love to try it out, but I don't think that will happen. Maybe just let them dig up a scoop of clay or dirt while digging the pond to keep em happy

But yes would deff be going slow and taking the time unload and move the rocks into place.

As for the spool bank on the excavator I am about 95% sure there are adjustable cartridges. As I recall seeing the on schematic some that were and also ranging from 1500 all the way up to 3250 psi. I will double check but I think there are some

To plumb in a return line with a relief valve just on the grapple close, that could be done on the boom and just T that return into the main return line there? instead of running it along the whole boom?

racingjoe66 · April 07, 2018, 12:32:05 PM

I just looked, there are 2 relief valves on the control valve for the bucket set at 3,250 psi.

racingjoe66 · April 07, 2018, 12:33:37 PM

Says they are a "cartridge type service port reliefs used in the valves are of the pilot poppet style with external adjustment"

mike_belben · April 07, 2018, 03:24:24 PM

Work with the relief valves youve got. Otherwise youd be adding one all the way out on the stick and then plumbing a return. You shouldnt really treat either of the A/B ports as a return to tank. I mean one is pressure and one is exhaust but they switch when you change direction. Pressure working against the wrong side of a relief exhaust line then. Check valves maybe?

I dunno, It gets muddy from there and isnt an elegant solution. Working with the oem relief is.

racingjoe66 · April 07, 2018, 03:38:19 PM

Thanks Mike! I will pull apart one of the relief valves that are currently set at 1500 psi and compare the shims count it has to the bucket ones at 3250 psi. Then change the 3250 to match that and should be set to go

If I can keep from running hoses all the way out, that would be great for sure.

Glad I found this site and posted on here!!!!! Wasn't expecting super fast replies and such great help, and I deffinatly appreciate it more than you know!!!

I am also working on an old Bobcat 642B with the auxiliary hydraulics, could use some help on that too if you wouldn't mind....?

mike_belben · April 07, 2018, 03:41:53 PM

Youre welcome joe. Im here to help.

Does your bobcat have the big hose into the charge pump inlet, or does it have the big aluminum block with tubes and hoses and sensors?

Whats it doing wrong?

racingjoe66 · April 07, 2018, 03:51:31 PM

Glad to hear!

It has the auxiliary hydraulics plumbed off the pump into the engine compartment and then capped off from the factory. From there to the end of the boom was never installed. I have recently bought a set of the steel boom lines and connectors to put on it. Where the 2 rubber lines would be installed to connect the 2 steel lines I have bought a Daman manifold block to put 2 D03 12vdc directional valves on to control the auxiliary hydraulics. The reason for 2 valves is I have a toyota 3 stage forklift mast with side shift onto it. The side shift is dual acting cylinders and the mast is a single acting cylinder. So I need 2 lines for the side shift or normal auxiliary attachments and then 1 line only for the mast.

The manifold I have already bought is Daman # AD03S022S/C which has a relief cavity for a relief valve. Needing some help to figure out what valves would be a good choice. My pump is 10.8 gpm @ 1800-1950 psi. Also needing some help on the plumbing. Me and my dad were thinking to run the 1 valve for the mast would just need to plumb the 1 line back to the return line behind the manifold?

mike_belben · April 07, 2018, 04:11:19 PM

So your main loader valve under the right elbow only has 2 spools, not 3?

A 642 is not heavy enough to run a full forklift mast with side shuttle and actually pick anything up. I actually built my first fork rack with side shuttle from a raymond electric truck i cut up, and never used the stupid function. Plus, because of it, you cant see a thing through the forks. I was smashing and knocking things over all the time. I still have the fork base, id like to sell it. My machine is a 742 with filled tires and a 1" plate bolted through the back door.

Im all for the aux hydraulics, wish i had 2 aux spools instead of one.. But the fork mast probably wont be as great as you think. Unless you are frequently loading pallet racks offroad i guess.

mike_belben · April 07, 2018, 04:15:00 PM

Just fyi, bobcat changed the hydraulics on these older machines a bunch so i kinda need to see a pic of yours tocl be sure but its a complicated system and parts are becoming obsolete.

the gear pump is also the charge pump for your hydrostatic drives. Flow comes out of the gear pump and into the loader valve. The return pressure from the loader valve is the charge inlet pressure for the drive pumps. Its critical they have 100ish psi at all times.

racingjoe66 · April 07, 2018, 04:20:42 PM

It has 3. The auxiliarys come right out of it and already plumbed and capped off from the factory. I am putting wheeled outriggers on each side of the mast for stability. I already have 250 lbs of counterweight onto the back of the machine and my roof is removeable to be able to view what I am lifting. I plan on using it to only lift 500 lbs snowmobiles on a pallet to stack them 3-4 sleds high in my storage shed. Eventually I would like to get a bigger machine and make it more versatile to use. Hence the reason for putting a quick attach plate on it.

I know a forklift itself would be easier to use for what I am doing, but I already got the machine and figured why not. Plus if I need to borrow a larger skid steer for it for other jobs that isn't a problem. Just they wouldn't be plumbed for the side shift which isn't an issue. I just need that side shift when fine manuevering the sleds into there spots on the pallet racking.

racingjoe66 · April 07, 2018, 04:29:43 PM

I have the service manual, so I can get you pictures. I can scan and post them here real quick, what would you like to see?

racingjoe66 · April 07, 2018, 04:31:02 PM

Skeans1 · April 07, 2018, 04:44:08 PM

What machine is this? Make and model?

mike_belben · April 07, 2018, 05:07:28 PM

Bobcat 642b

Yeah thats the big port block diagram. There are two variants. One with bronze return filter and one without. Its under the large NPT fitting in the center of the three, they face passenger side. You ever clean this? It may not have one but ill await your response.

So if you have the aux valve and your RH steer lever is double jointed then you just need to finish the lines, right? Whats with the DC parts?

racingjoe66 · April 07, 2018, 05:22:59 PM

Nope never had any of the hydraulics apart as never had any issues with it as of yet.

Yes have the aux valve and RH steer with the bolt keeping it from pivoting.

The 1 directional control valve was going to control the side shift with a toggle switch on the one hand control and the other DC would control the mast going up or down. Was told by someone, would need ones like these in this link.

Shopping

racingjoe66 · April 07, 2018, 05:25:31 PM

If there is a filter there or not, I am unsure and don't recall. sorry

mike_belben · April 07, 2018, 05:49:34 PM

Its called "the hidden filter"

Most people dont find it until the machine is whining and way down on drive power then they post on skidsteer forum and firat question is 'did you clean the hidden filter?'

Do your mast have a single hose or two for raising it? Single acting or double acting cylinder more specifically.

racingjoe66 · April 07, 2018, 06:05:33 PM

I will have to find this hidden filter and get her cleaned before hand

The mast is a single acting cylinder, side shift is a dual acting.

mike_belben · April 07, 2018, 10:49:59 PM

Sigh* alright this is getting complicated.

Im pretty certain that your machine has load checks on the boom and curl spools but im not certain about the aux spool. If it does you may need to defeat it in order to lower the mast.

What youre trying to do is turn a two way spool into a one way spool, which requires connecting the B port to tank and letting the A port be a two way street. Fluid pumps up the ram and then weight collapses it. But with load checks, pressure on the B port is required to unseat the load check on port A in order to let fluid back down and lower the mast/boom. Basically this prevents your loader from drifting down. It hydraulically locks until you actually press the down pedal, then the lock comes off. Very common in telehandlers and manlifts etc. But again i dont know if the aux spool has a check.

Anyways i think this is about the right way to diagram the aux spool on your machine. It will do double acting right off the bat, just hook up the two couplers to your side shuttle.

A/B are your work ports to and from a DA cylinder or hyd motor. P is from pump and T is to tank. The top row is labeling your stick position. Left/spring center/right/detent to far right for motor continuous on.

To make your DA spool into a SA spool you need a way to connect it to tank. The simplest, most dependable way is a manual 3way valve. It will be on the machine with you. Not out on the attachment. It must be after the loader valve but before the lines that go up the boom. And it requires plumbing an extra tank return. I dont suggest T-ing in with the main line as that is the charge pump pressure line and it has 100 or so PSI in it.

Anyway all this does is convert your aux spool from DA to SA so it can work the forklift mast cylinder. It either connects port B to your coupler, or blocks the coupler and connects port B to the tank.

Okay. Then to select between mast and side shuttle you also need a 2 way selector valve out on the attachment so that your A/B ports are connected either to the mast or the shuttle. It is exactly what we discussed doing on the excavator. A huge project that will do nothing for you that a regular old fork setup cant. Personally I would build another sled shed or buy an old clark/hyster/etc before i went through all this effort on the bobcat.

racingjoe66 · April 08, 2018, 12:25:07 AM

I will do some checking on the load checks or not as I am not certain either.

So pretty much could use the same valve as you linked for the excavator for the skid loader? Just need to run the mast positions B line back to the tank?

Or would using the manifold I listed with 2 seperate DA valves be better?