[Jack Houpe]

I have heard more horror stories about slides than I want, we all have had problems with the HWH slides and its safeguards which in a way make their product unreliable and expensive to repair besides to say obsolete now. HWH has one hydraulic pump which controls slide locks, raises floors, moves slide in and out all controlled by a brain that must have certain criteria met in order to have valves switch open and close to send fluid to each hydraulic ram one at a time. Many limit switches control this process and the brain hopefully can get the right solenoid open to make the magic happen. Why didn't they use a 12vdc double action hydraulic pump for each hydraulic ram? My count is 3 pumps for a 2 slide coach, 1 for main slide, 1 for floor up and down, and 1 for rear slide. These pumps have a single valve that opens to pump and closes to hold so no need for locking pins as hydraulics does not compress. I would bet the DC amps required to operate these hydraulic rams to me minimum, two pumps could be located where the old unit is and 1 under the bed in the back. Use the existing limit switches to control lights for full in or full out, floor up or floor down up and down and when the light comes on or you hear the pump load quit pressing the switch. The electrical part of the system could be simplified by using just relays, and momentary switches for reversal of the hydraulic pump. You would still have to turn a key to activate the system and bleed the air seals.. Gordon and I briefly talked about something different awhile back and my head has been spinning. Looking forward to feedback on this and I may use our coach as a test vehicle. 

https://www.ebay.com/itm/305345588847?_s...BMjJrYk_Rk

[HoosierDaddy]

I am watching this thread with great interest!!!

[cwl1979]

Coming from my experience with auto transport and the massive use of hydraulics, you're going to need more than that.

Hydraulic cylinders are dual flow, one line pushes fluid into the bottom of the "tube" to extend the rod, the other line fills the tube from the top and pushes the rod down to compress the internal rod.  The truck i was using at work was one of 2 ever built, and they had simplified the hydraulic system as much as possible, for user convenience. We still had over 100 gallons of Hydraulic fluid in the system at any given time.

The pump unit your looking at will push the slides out but never pull them in. That's a gravity release unit, while great for a dump trailer or a snow plow that just needs on direction of pressure not useful for horizontal slides.

While i don't have slides on my 96, if i were to fathom a guess, one with slides would have an electric motor driven PTO pump. using sophisticated computerized programming to take human error out of the equation. That said, remaking the system in a manual fashion could be achieved with say, a valve bank in one of the bays, thereby eliminating the "brains" of the operation.

Prepare yourself for some amazing artwork...

   

Hopefully you can make sense of my artistry.

With a valve bank and hydraulic slides this could be achieved but it would have to have the equalizer blocks on the "push" to make sure the slides stay straight. A simple T would work on the return lines.

This would be a start, you would still need a second person to make sure things are level/ plumb, and when to stop since you wouldn't be able to see inside the coach while outside running valves.  
You would also need lock pins as this style of system will eventually "blead down" and cause the floors so sink. You could use some anti fall hydraulic locks to solve that but that gets complicated as well. 
Now that I've covered all of that don't forget to think about the age of the hydraulic lines and be prepared to replace them all. As well as all the added weight from this system.

While i like your thinking Jack bypassing the brain isn't a simple task.

[Jack Houpe]

Carl I'm on the road right now and all I have is my phone to look at which doesn't do me any good. I'll be back in Northwest Arkansas tomorrow and pull this up on my computer screen I'll give you a shout back, your input is very important and after giving it a good look over will give you my best educated guess. As far as the electrical and electronics that part is the least of my worries. To be continued.

Dean get some popcorn this may last a while.

[Jack Houpe]

Carl what about putting a 4 port switching valve connecting the In and Out of the cylinder to the In and Out of the pump, this will be the same for all 3 pumps.

[Gnawrocki1]

Have you thought about getting rid of the hydraulic mess and go completely electronic using linear actuator for your force? I don't know if they make them small enough for the slide lock location....

[cwl1979]

Carl what about putting a 4 port switching valve connecting the In and Out of the cylinder to the In and Out of the pump, this will be the same for all 3 pumps.

If you really wanted the pump and tank say, under the bed, you could use it to accomplish the same thing. You take the pump output and connect it to a 2 pack of spool valves and you could lift the mattress, and push the slide out from inside. The return line from the spool valves would be connected to the return line of the pump unit. In theory this would work. Using a diverter like that instead of the spool valves would actually be more expensive, and prone to leaking. Spool valves will leak as well, but, they are easier to tighten up or replace an O-ring. You would still need the equalizer valves on the slide out. These are adjustable so the push out at the same time. If one side is pushing to fast you can turn a screw and "equalize" it with the other side. This is how auto transporters keep cars "level" when lifting and lowering them.



Like i said i don't have slide outs but ill bet that somewhere under that coach is a block with electric solenoids that control the spool valves. something like this eBay link.

https://www.ebay.com/p/27020436293?iid=276222669136

If you can locate that and count out how may in and out ports it has... you could just replace it with a manual use one... possibly.

The real question Jack, is, would this really be better? The way most equipment and things running on hydraulics is going to electric over hydraulic. These parts are getting much cheaper and easier to find and replace. Look at a classic road grader with that stack of 24 levers in front of the operator and compare it to the newer ones, a steering wheel and 2 joysticks. Looks less daunting but the parts are just electric over hydraulic.