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Author Topic: hydraulic leveling question  (Read 873 times)
Uglydog56
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« on: February 10, 2012, 11:13:55 PM »

My bus is sprung, so I can't do air leveling.  HWH leveling systems are outside of my budget (too many other things higher on the list right now).

There's a fellow with 4 12pmp jacks from Holloway that he is considering parting with.  In my searches I can't find much on these except that there is no Holloway company anymore.  If they are cheap, can I hook them to a different company's central unit?  I figure cylinders are cylinders, so as long as they arent' bent or pitted, seals could be replaced as needed.  Just wasn't sure about the control unit or if the company went out of business because they are crappy.  All info is appreciated. 
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Rick A. Cone
Silverdale, WA
66 Crowny Crown "The Ark"
Utahclaimjumper
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« Reply #1 on: February 11, 2012, 03:53:31 AM »

 I know nothing about that company,, but you are correct in that cylinders are cylinders,, the difference being that some are rebuildable and some are not. That will be the key.>>>Dan
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Utahclaimjumper 
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« Reply #2 on: February 11, 2012, 06:08:23 AM »

Have you checked out Big Foot leveling system.I have them on my Prevost for 7 years now and they work great.
   Don
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luvrbus
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« Reply #3 on: February 11, 2012, 06:18:51 AM »

Holloway is still in business they moved from Holloway Ohio to some place in SC they made the hydraulic rams for some equipment like Deere
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rv_safetyman
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« Reply #4 on: February 12, 2012, 07:18:07 AM »

You will need to know quite a bit about the cylinders.  The first thing you will need to know is the diameter of the piston.  You will need at least 3 inch - 4 is better (if the Crown was a heavy as an Eagle, you would need 4 inch).  

Next is the rod diameter.  I really would not go with less than 2 inches.  If the rod diameter is too small, the rod will bend when loaded sideways.

Lastly you will need to think about the stroke.  I think anything less that 15 inches is not worth it.  Mine are 24 inches.

There are two kinds of hydraulic cylinders:  single acting and double acting.  With single acting you will need a spring return system.  With double acting the hydraulic pressure will retract the ram.  With double acting you will need twice as many hoses.  Both will work for a jack system.

If the cylinders you have access to, have characteristics that are acceptable, the fun and $$$$ begin.  You will need a pump that is capable of producing at least 2000 PSI.  You will need a control valve system (choice will depend on whether you have single or double acting cylinders).  You will need to plumb the system with tubing or hose.  All of these can add $200-500 to the cost of the system.

There are at least three ways to power the pump:  belt driven, driven off an engine gear (like the PS pump) or 110V.  If you use the power steering pump, you will need to be aware of the consequences of a jack component failure on steering and safety related issue.   Pumps are rated at both pressure and flow.  You will need the pressure (2000 PSI) but flow is not a big issue - low flow will just make the jacks power down slower.

You can mix and match manufacture for the various components.  The only issue is getting all the connections to match up - can be done with adapters.

You will need to fabricate mounts for the cylinders and figure out how to drive the pump.  

I have a bit of detail about the system I built on page 4 of my project pages (signature).

Bottom line, the cylinders will be a small part of the cost of the system.

Jim

« Last Edit: February 12, 2012, 07:26:55 AM by rv_safetyman » Logged

Jim Shepherd
Evergreen, CO
85 Eagle 10/Series 60/Eaton AutoShift 10 speed transmission
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TomC
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« Reply #5 on: February 12, 2012, 08:26:34 AM »

Since you have a Crown with a full truck frame-just get four sets of big rig trailer landing gear and bolt it to the frame in front behind the front axle, and in back in front of the rear axle. You'll be able to crank each of the four corners down independently of each other.  The crank mechanisms are usually two speed so even under the weight of the bus, cranking is easy.  Just not as convenient as electric powered, but will be the cheapest, and the strongest.  Good Luck, TomC
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« Reply #6 on: February 12, 2012, 09:54:28 AM »

Most of the time the pumps and motors hydraulic combo units are not hard to find at old a military surplus store for less than a 100 bucks the draw back they 24 volts but easy to change for 12 volt they are a old Ford type starter without the bendix drive and relays are cheap from Texas Industrial Electric

good luck
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gus
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« Reply #7 on: February 12, 2012, 06:45:34 PM »

Rick,

If you are concerned about leveling because of your refrigerator remember that it only has to be level side to side (Fore and aft for most buses).
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PD4107-152
PD4104-1274
Ash Flat, AR
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