Hydraulic cylinder question

[Georgia Mike]

Getting ready for a trip and was cleaning out some of the bays when I found this hydraulic cylinder in the diesel tank bay not connected to anything. I was confused as to why it was there. After thinking about it I thought could it be an equalizer or bleed off for the pressure in the system? I searched on the site and couldn’t find anything. Probably a dumb question but I just like to know how things work.

 

[Chargerman]

That’s your equalizing cylinder for the slide

[Mike H]

That's the synchronizing cylinder for your slides two hydraulic cylinders.  There are two connections on the side of the cylinder.  it's a 'blind' cylinder and has a rod sticking out of both ends. It makes sure the pressure in both of your slide cylinders is the same, so the slide extends and retracts straight.  From your photo it doesn't appear to be leaking.  If it ain't broke, don't fix it !  😉 

[Tom Cherry]

1 hour ago, Mike H said:

That's the synchronizing cylinder for your slides two hydraulic cylinders.  There are two connections on the side of the cylinder.  it's a 'blind' cylinder and has a rod sticking out of both ends. It makes sure the pressure in both of your slide cylinders is the same, so the slide extends and retracts straight.  From your photo it doesn't appear to be leaking.  If it ain't broke, don't fix it !  😉 

WHILST on the subject....many, as Mike did not, know that SUCH exists.  This morning I commented on an issue or maybe yesterday.  It is IMPORTANT that you do NOT stop immediately when you extend or stop a slide.  You LET THE SWITCH STAY IN...for maybe a few seconds...or until you hear the DEFINITIVE pitch or Noise Change from the MOTOR.  Folks will sometimes STOP for fear of Tearing OUT the WALL and the SLIDE falling.  That cylinder keeps them moving and balanced.  NOW, from a personal experience...if you have a VOLTAGE drop on the motor and a high resistance connection...that will be RATCHETY...but ordinarily the slide will sort of "Crab" or move a smidge on one end...then the other catches up.  NORMAL.

The Balance Cylinder as Mike points out....controls that.  BUT, short cycling or shutting off prematurely can and HAS caused issues.  SO, just keep that in mind.  NOW....the next question IS...DO I HAVE AIR TRAPPED or is mine messed up.  You can easily put to to rest.  With a GOOD charge or on SHORE...  Run the slide out...and hold for a few seconds and hear the change.  Then retract...same deal....learn how long to hold after the motor pitch changes.  THEN repeat that drill for 3 or 4 complete cycles.  You will have BLED OFF any any air and also properly "CHARGED" the system.  

BTW....check the level....SLIDES IN.  The reservoir should be right up to the top surface of the tank.  THAT's IT...  very little free space.  NEVER add Fluid to the extended slide....unless it is so low it DIES...  YES...that is in the manual...or has been in many.,...but with Monaco....you never know.

This is Hydraulic SLIDE 101....

[Chargerman]

Thanks as always Tom for the detailed explanation. One item that I don’t think is accurate, at least for the HWH X Brace slides is that the reservoir should not be full with all slides retracted because the hydraulic rams on the raised floor slides are fully extended in this condition. Therefore when extending one of these slides with a full tank oil will overflow the tank. HWH told me to fill with raised floor slide extended. 

[Mike H]

33 minutes ago, Tom Cherry said:

WHILST on the subject....many, as Mike did not, know that SUCH exists.  This morning I commented on an issue or maybe yesterday.  It is IMPORTANT that you do NOT stop immediately when you extend or stop a slide.  You LET THE SWITCH STAY IN...for maybe a few seconds...or until you hear the DEFINITIVE pitch or Noise Change from the MOTOR.  Folks will sometimes STOP for fear of Tearing OUT the WALL and the SLIDE falling.  That cylinder keeps them moving and balanced.  NOW, from a personal experience...if you have a VOLTAGE drop on the motor and a high resistance connection...that will be RATCHETY...but ordinarily the slide will sort of "Crab" or move a smidge on one end...then the other catches up.  NORMAL.

The Balance Cylinder as Mike points out....controls that.  BUT, short cycling or shutting off prematurely can and HAS caused issues.  SO, just keep that in mind.  NOW....the next question IS...DO I HAVE AIR TRAPPED or is mine messed up.  You can easily put to to rest.  With a GOOD charge or on SHORE...  Run the slide out...and hold for a few seconds and hear the change.  Then retract...same deal....learn how long to hold after the motor pitch changes.  THEN repeat that drill for 3 or 4 complete cycles.  You will have BLED OFF any any air and also properly "CHARGED" the system.  

BTW....check the level....SLIDES IN.  The reservoir should be right up to the top surface of the tank.  THAT's IT...  very little free space.  NEVER add Fluid to the extended slide....unless it is so low it DIES...  YES...that is in the manual...or has been in many.,...but with Monaco....you never know.

This is Hydraulic SLIDE 101....

Yes Tom, lessons can sometimes be very painful 🙂 ...... don't ask me how I know.  Regarding those synchronizing cylinders, they are a little tricky to get all of the air bled out of them.   The main extend/retract cylinders have a sliding 'collar' over the internal rod keeping it from completely bottoming out.  If you pick one up and flip it back and forth you will hear it 'rattling' around inside .... it's supposed to do that, it's not broken.  Holding the retract mode switch down like you say also pressurizes the system to help hold the slide in from creeping back out.  Same goes for the front generator hydraulics.

[Tom Cherry]

3 hours ago, Chargerman said:

Thanks as always Tom for the detailed explanation. One item that I don’t think is accurate, at least for the HWH X Brace slides is that the reservoir should not be full with all slides retracted because the hydraulic rams on the raised floor slides are fully extended in this condition. Therefore when extending one of these slides with a full tank oil will overflow the tank. HWH told me to fill with raised floor slide extended. 

You have the SAME year and the Dynasty and Execs were supposed to have "all the same".  I did a key word search of the 2006 Dynasty manual and there was NO mention or the brand in the manual.  NOW, the illustration LOOKED like an HWH...so that's as much as I can verify.  Lipperts ARE supposed to be checked that way.

If that is what Lippert told you or is in the Manual for your system...then that is probably correct.  @Frank McElroy is my GOTO source.  His manual does NOT, I think, discuss HWH...and has LIPPERT in the key word search...or maybe I goofed.

The ADVICE is always...  Know the Model and Brand of your system.  Download the appropriate manual or consult with the vendor.

SO, my method pertains to Lippert...on that I am SURE.  OTHER searches are futile as MOST say...  Lower the jacks...and then retract and FILL.  We do NOT have those units...

Frank may chime in and correct me....as usual....

[Chargerman]

I’m going to check what my manual says tomorrow. Paul Maddox from HWH was who told me how to assure proper the proper fill level 

[Ivan K]

Why exactly does it need to be filled with cylinders retracted if they are always full from both sides of the piston and the fluid volume in them and in lines is the same? Not talking about spring return cylinders. Just something I always hear and don't understand. 

[Benjamin]

Most cylinders have a rod on only one side, so the base has a larger volume than the rod side.  If you remove the piston entirely, the cylinder will still function as a one way cylinder (spring return) with the displacement of the rod.  So the volume is not the same, which is why you fill with the cylinders retracted to avoid overfilling in this case. 

[Ivan K]

7 hours ago, Benjamin said:

Most cylinders have a rod on only one side, so the base has a larger volume than the rod side.  If you remove the piston entirely, the cylinder will still function as a one way cylinder (spring return) with the displacement of the rod.  So the volume is not the same, which is why you fill with the cylinders retracted to avoid overfilling in this case. 

Ok, that makes sense.

[Mike H]

9 hours ago, Benjamin said:

Most cylinders have a rod on only one side, so the base has a larger volume than the rod side.  If you remove the piston entirely, the cylinder will still function as a one way cylinder (spring return) with the displacement of the rod.  So the volume is not the same, which is why you fill with the cylinders retracted to avoid overfilling in this case. 

If you're referring to the hydraulic cylinders that operate the slides they do not have springs in them.  They are fully hydraulic operated for extend and retract.  As for the leveling jacks they have external springs to assist in retracting the jack cylinders and keeping them retracted

[Tom Cherry]

15 hours ago, Ivan K said:

Why exactly does it need to be filled with cylinders retracted if they are always full from both sides of the piston and the fluid volume in them and in lines is the same? Not talking about spring return cylinders. Just something I always hear and don't understand. 

It was explained.... technically and correctly.  From an end user point of view...  LIPPERT says to always check level when the SLIDES are retracted.  If you EVER do "forget that", I can, as other may...but most are smarter than me, can attest to.  Check extended....Level is down....more if BOTH.  Check retracted... Level is at, as it should be, the TOP of the reservoir. NEVER check or add when one or more slides are extended....OTHERWISE???😡

I'll yield to those who know more...  Like Mike H and Frank McElroy...

[Benjamin]

1 hour ago, Mike H said:

If you're referring to the hydraulic cylinders that operate the slides they do not have springs in them.  They are fully hydraulic operated for extend and retract.  As for the leveling jacks they have external springs to assist in retracting the jack cylinders and keeping them retracted

Sorry, that wasn't clear about a one way cylinder.  I was trying to refer to a two way cylinder with the piston hypothetically removed as operating like a one way cylinder.  And using the "spring return" reference to Ivan's post.  Clear as mud. 

edit: on these you fill with rods retracted, "otherwise" there's no room and the fluid overflows when you retract them. 

Edited May 12, 2024 by Benjamin

[Chargerman]

I looked at my HWH manual today and here is what they recommend.  Looks like what I was told is not accurate for my application. Manual says front slides in and rear slides out. In my case only one of the rear slides is hydraulic 

[Frank McElroy]

Here are a few pages taken out of the HWH Operators manual.  Basically all jacks (if the coach has that option) and all slides except the X slides need to be retracted when checking oil level. 

In practice, having all slides retracted will be close enough unless you are completely filling the tank which you shouldn't do.  Warm oil needs room to expand.

HWH Operators Manual - How to check oil level.pdf