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RVing message boards => Motorhomes => Topic started by: RedandSilver on September 18, 2017, 12:07:02 PM

Title: Hydraulic Jack questions
Post by: RedandSilver on September 18, 2017, 12:07:02 PM
I have a situation where 2 of my jacks (rears) will drift downward at times.  Not all the time or on every trip.

Recently I put the jacks up and then drove a couple hundred miles - looked under the coach (at a Rest Stop) and noticed the 2 rear jacks
were down about 1 - 1".  I went inside and pushed the "store" button and they did go up.  I was surprised that the buzzer
hadn't gone off - I don't know how far they have to extend before the buzzer goes off.

I have been driving and the jacks down buzzer has gone off too.  Luckily I knew what to do (after the first time this happened)
and corrected the problem by storing them and the buzzer goes off.

My questions are:

What is making them come down?
Do they have to be powered down?
Could the springs be getting weak?
Are the springs the only things holding them up?
Is there only one hydraulic line going to jacks in most cases?

Has anyone experienced this?
What was done to fix it?

Thanks for any help.
 
Title: Re: Hydraulic Jack questions
Post by: TonyDtorch on September 18, 2017, 01:22:33 PM
On a Rexhall the jacks should be HWH,   they have return springs on them that should prevent them from 'drifting' down.

Take a look at the springs,  if the springs are weak they would be rather slow to return.
Title: Re: Hydraulic Jack questions
Post by: taoshum on September 18, 2017, 01:28:20 PM
I have a situation where 2 of my jacks (rears) will drift downward at times.  Not all the time or on every trip.

Recently I put the jacks up and then drove a couple hundred miles - looked under the coach (at a Rest Stop) and noticed the 2 rear jacks
were down about 1 - 1".  I went inside and pushed the "store" button and they did go up.  I was surprised that the buzzer
hadn't gone off - I don't know how far they have to extend before the buzzer goes off.

I have been driving and the jacks down buzzer has gone off too.  Luckily I knew what to do (after the first time this happened)
and corrected the problem by storing them and the buzzer goes off.

My questions are:

What is making them come down?
Do they have to be powered down?
Could the springs be getting weak?
Are the springs the only things holding them up?
Is there only one hydraulic line going to jacks in most cases?

Has anyone experienced this?
What was done to fix it?

Thanks for any help.


We get a little bit of that from time to time... the only explanation I can conjure is that the fluid in the line to a jack gets warm... especially if you raise them early in the morning and then drive for a while.
Title: Re: Hydraulic Jack questions
Post by: Kevin Means on September 18, 2017, 01:53:22 PM
The "Jacks Down" alarm for our HWH jacks will sound if any of our jacks drop by as little as 1/4 inch. Both of our HWH jack-equipped motorhomes were like that. The only time we ever had a problem with our jacks creeping down was with our previous MH. If I turned the power to the jacks off immediately after the jacks retracted (right after the warning horn shut off) they'd sometimes creep down over time as we were driving, but the warning horn always sounded immediately.

I finally figured out that I had to leave power to the system on for a few minutes, even after the warning horn had shut off, and even though the jacks appeared to be fully retracted. I don't know if that's the cause of your issue or not, but in any case, I think your Jacks Down alarm should be sounding before your jacks deploy more than an inch.

Kev
Title: Re: Hydraulic Jack questions
Post by: Gary RV_Wizard on September 19, 2017, 09:47:37 AM
If the jacks have springs, then yes, the springs are what brings them up and holds them up. The hydraulics push them down by overcoming the spring tension when the hydraulic pump runs.  The vale to each jack closes when at the desired extension, maintaining pressure so the jack stays down.  To retract, the controller merely opens the valve in the hydraulic line and lets the spring push the jack up, forcing the hydraulic fluid back into the reservoir.  That "single action"  type of jack will have only one hydraulic line to each jack.
Title: Re: Hydraulic Jack questions
Post by: RedandSilver on September 20, 2017, 09:02:01 AM
Thanks for the replies everyone.

I will keep the power to the system on longer and see if that helps.

One more question is - when I have used the store button and all the jack lights go out,
Is the store light supposed to go out too?  I have waited awhile and it never goes out, so I just shut the system off.

If anyone can confirm that the HWH store light does go out, then that may be my problem that I didn't wait long enough.

Just so you know my system is manual and not auto.
Title: Re: Hydraulic Jack questions
Post by: tugboat on September 20, 2017, 01:30:11 PM
The Power light should shut off after a while and the jacks are stored.
Title: Re: Hydraulic Jack questions
Post by: RedandSilver on October 03, 2017, 09:39:11 AM
I finally put up my jack as I had been working under the MH for awhile.

After I hit the store button I went out to move some wood that the jacks pressed against.
When I returned to the dash area all the power to the HWH system was off.  Don't know if the
store light went out first or it just timed out - but in the past if I forgot to shut the system off
after extending a slide and noticed 10 minutes later the system was still on.

Oh well from here on out I plan on leaving the system on until it shuts itself off - at least the jack part of the system.  ;D