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Converting aux hydraulics to proportional control

materthegreater

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On my Bobcat E60 I have an aftermarket two spool solenoid valve for the auxiliary hydraulic circuits. Currently there are simple push buttons on the joysticks for control. Obviously this makes for very jerky movement of the attachment since it's either off or full flow.

I'd like to convert it to proportional control but I'm not sure how to do that. I know I will need joysticks with slide or rocker style switches (not sure of the proper term). And I assume I'll need a pulse width controller. But I'm not sure if I'll need different solenoids on the spools.

Any ideas of where to source the parts I'll need to do this?
Thanks
 

1693TA

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You could do what you suggest but it's going to take quite a bit of engineering to make things both fit, and be ergonomically useful. Yes, the solenoid coils must be matched in resistance value to the output of the square wave generator circuitry. The main control unit for a proportional controller is a center null rheostat which is shifted one of two ways from the null to a maximum value from zero and this increases, or decreased the on/off times of the desired output of the square wave generator.

I don't know your application but I wouldn't rule out "soft star" hydraulic valves for your application. These are dampened in spool shift and many times eliminate the "all or nothing" engagement and lesses shock loading. They seemingly would work very well in slowing the engagement of an auxiliary attachment I'd think.
 

materthegreater

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Thanks for the advice.

I hadn't heard of soft start valves. From what I gathered in a preliminary search is that they replace the relief valve. Is that correct?

Uffex, that's some good info on adding a circuit.

I tried calling Hydraulic Circuit Technologies in Georgia yesterday hoping they would be able to sell me a kit, or even just some parts. But they said they don't have any technical info for my machine and can't help me out (even though I mentioned that the two spool auxiliary valve is a generic add on valve).

It seems like dealers must have a source for things like this when they have to add auxiliary circuits to a machine that didn't come with them from the factory.
 

uffex

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Good day Glen
I suggest you make a decision on how you would like to operate the thumb. If you go to the website excatech.org look at the alternatives you will find a document "Thumb questions & answers" it may well help you figure out the best way to go. Once you decide you can give us a line a bucketsense@gmail.com we can steer you through the install using of the shelf parts.
I would recommend that you avoid proportional control unless you are electronically minded. There are easier ways to achieve the same goal.
Kind regards
Uffex
 

1693TA

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"Soft Start" hydraulic valves tend to incorporate a small "RC" network, (timer) to designate the time delay to full opening and/or closing so the action is "ramped". This lessens the harshness of the application, or engagement. Some are adjustable, some fixed in delay. They act much like a manual valve that you slowly stroke/engage full on, or full off in position.

Usually have nothing to do with a relief section which is either a cartridge assembly, or a shim adjustable affair incorporated into the system.

I used two soft start valves with D03 mounting pattern on a matching manifold to power drive motors on my shop gantry. Also a manually actuated pressure compensated speed controller to make this crane traverse the shop floor fast, and then very slow such as when placing a cab or hanging engine assembly into a chassis when "finesse" is required. With these valve incorporated, the application of hydraulic engagement is very easy.
 

materthegreater

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Thanks Uffex,
The machine already has two sets of lines/hoses installed, and a two spool solenoid valve controlled by push buttons on the joysticks. I use it with a tilting cleanup bucket and a rotating grapple. It works quite well for both of these, except being quite jerky when the machine is at normal operating RPM. I am looking for a way to have better control of these auxiliary circuits to allow for finer movements of the attachments.

PXL_20230310_135415676.jpg
 

The Peej

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Connecticut
If your only trying to slow down a thumb and make it less jerky I would try installing a restrictor valve. They make them adjustable so you can dial it in to where you like it
 

materthegreater

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Messages
642
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VT
"Soft Start" hydraulic valves tend to incorporate a small "RC" network, (timer) to designate the time delay to full opening and/or closing so the action is "ramped". This lessens the harshness of the application, or engagement. Some are adjustable, some fixed in delay. They act much like a manual valve that you slowly stroke/engage full on, or full off in position.

Usually have nothing to do with a relief section which is either a cartridge assembly, or a shim adjustable affair incorporated into the system.

I used two soft start valves with D03 mounting pattern on a matching manifold to power drive motors on my shop gantry. Also a manually actuated pressure compensated speed controller to make this crane traverse the shop floor fast, and then very slow such as when placing a cab or hanging engine assembly into a chassis when "finesse" is required. With these valve incorporated, the application of hydraulic engagement is very easy.

Thanks for the explanation, I think I understand better now. Sounds like this would replace the valves that I am currently using? As opposed to being an add on to the circuit
 

1693TA

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Sometimes, but not always. Many times it is just the solenoid package that shifts the spool you would replace. I like either "Yuken", or "Eaton" valves myself as very well supported.
 

John C.

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Years ago we softened the thumb action by installing a pressure control cartridge in the pilot circuit that controlled the thumb actions. It took a special sub plate but used the standard solenoid valve setup.
 

materthegreater

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Sometimes, but not always. Many times it is just the solenoid package that shifts the spool you would replace. I like either "Yuken", or "Eaton" valves myself as very well supported.

This is exactly what I was hoping. But, I will need to find out where to buy them.
 

materthegreater

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Years ago we softened the thumb action by installing a pressure control cartridge in the pilot circuit that controlled the thumb actions. It took a special sub plate but used the standard solenoid valve setup.

I may have to look into this as a secondary option. Thanks
 

uffex

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Good day
It is possible to improve some solenoid valves installing a one way restriction, may be worth a thought.
Kind regards
Uffex
 

1693TA

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If you could attach a photo of the solenoids package itself and some identifiers, I can do some research also. Some things can be rather inexpensive to incorporate, some quite expensive, but need to know what is being worked with to start.
 

uffex

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Good day
Consult your nearest Rexwroth - Bosch dealer or catalogue for more details.
Kind regards
Uffex
 

Attachments

  • Sol with throttle.jpeg
    Sol with throttle.jpeg
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materthegreater

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If you could attach a photo of the solenoids package itself and some identifiers, I can do some research also. Some things can be rather inexpensive to incorporate, some quite expensive, but need to know what is being worked with to start.

I will definitely post some pictures. I thought I had taken some pictures when I installed the valve block and solenoids about a year ago but I looked through my phone and computer and can't find them. I need to tip up the cab and remove some panels to get access for pictures so it won't be tomorrow but I'll try to get them soon. Thanks
 

materthegreater

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PXL_20230328_210950524.jpg

Well maybe I'll have some downtime now to check out that solenoid valve while I'm waiting for welding/line boring.
 
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