Thursday, February 17, 2011

Getting Level


Discussion

If you're lucky when you arrive at your campsite, it will be reasonably level. But you sure can't count on that, so it pays to have some capability to get your rig level. This is especially important for your refrigerator, which can be permanently damaged if operated when the motorhome is not "comfortably" level.

There are two approaches to leveling - using leveling blocks under the tires to get the rig level, or to have leveling jacks installed on the vehicle. Use of leveling blocks is definitely much cheaper, but jacks are certainly very convenient. There are also manually-operated stabilizing jacks that can be be installed, but they serve only to keep the RV from rocking; they are not intended to be able to lift the rig to a level position.

One of the benefits of jacks as compared to leveling blocks. And that is with jacks deployed the RV becomes a stable platform. Rocking due to wind or moving about the vehicle is eliminated, contributing to comfort. In storage, jacks unload the suspension, helping prevent suspension sag.
Jacks take away 100 to 200 lbs. from CCC, more of a concern on 30/31 foot models.
It should be mentioned that jacks should be raised and shore power disconnected to help prevent lightning damage from an approaching electrical storm.

Caveat: Hydraulic leveling systems can malfunction and extend on their own and will not retract. At two different LD Caravans, over the past few years, I have had to crawl under someone’s LD and manually retract an inactive ram. One required removing a hydraulic line (very messy) and the other required removal of the ram. In both cases, this was after trying the procedures in the owner's manual. If they stop working and you are not capable of crawling under your LD, you are stuck until a RV repairman can be summoned. Try that in the middle of nowhere.

The failure mode for the HWH kick down jack is different in that it will stay up due to spring pressure in case of a leak. The failure mode that might strand one with a jack stuck down would be electrical. i.e. the electric UP solenoid valve fails and the jack fails to retract with spring pressure. There is a simple fix for this with 4 manual emergency release valves located on the hydraulic power pack unit. Open the valve to the offending jack and it will retract. Of course one would have to either know about this or read the manual!

How to tell if you're level

Most RV'ers have mounted a pair of small RV levels in the cab, visible from the driver's seat. One should be mounted on the dashboard to indicate side-to-side levelness, while the second one should go on the driver's door to reflect front-to-back levelness. To mount the two levels, of course, the rig should be perfectly level - use a bubble level or carpenter's level on the floor. Some of the levels are graduated so that by looking at them you can tell which corners need to be raised and how much (in inches). The bath door on a mid-bath is a great leveler.

Leveling Blocks

You can buy sets of plastic leveling blocks or you can use pieces of wood. There are two brands of plastic blocks available: Lynx blocks which are orange, and Ramble, sold by Camping World, which are yellow. The general consensus is that the orange ones are much more durable. The plastic blocks are interlocking so you can stack them up several high to get the height boost you need. Tina Pratt recommends buying three sets of the Lynx blocks (there are 10 in a set); that way you'll always have enough for just about any situation.

Although heavier to carry around, wooden blocks or ramps are more durable. Use 2" thick boards that are at least 8" wide that will support the full width of the tires. You can use a short length of wood and block up one end as necessary to make a ramp. You can also make a two or three step ramp using boards with tapered end cuts and nailed together. You position the ramps and drive up as many steps as needed.

When I need to get up high, I use two 2x12x21 boards that are bolted together one on top of the other. The length is enough for both rear wheels. The edges are routed so the tires can climb up. If I need more height, I put a lag screw through the middle of one or even two Lynx levelers into the board. This keeps the Lynx from being spun out by the tires.

Caution: With any use of ramps you should always use chocks at one or two tires that are on the ground to ensure the vehicle doesn't roll off the blocks.

Caution: If using blocks under the rear tires you should always have blocks under both tires of a pair. Do not put blocks under just one of the rear tires. Even in a static load condition, the weight concentrated on one tire can cause damage to it, possibly resulting in a blow-out when driving.

Leveling Jacks

A system of leveling jacks has four "feet" that come down from under the RV and raise up each corner to the needed height to be level. They are usually powered by hydraulics. Some models are fully automatic - all you do is push one button and the four feet deploy and level the rig. Other models are manual - you have to push a separate button for each foot and adjust their heights yourself until level. These systems can cost from two to four thousand dollars.
The major brands are HWH, Kwikee and Big Foot.

HWH

Pros: Rams are hinged or “kick down” so vehicle clearance with rams up is not impaired. Lift height is excellent, with the ability to lift vehicle front wheels complete off the ground by several inches, no blocks required on most inclines at typical campgrounds etc. Rear wheels can both be lifted off the ground as well, but in order to do so, front wheels would need to be chocked, for as soon as parking braked wheels all leave the ground, vehicle can “rock” forward causing rams to articulate at knee. Since rams have high lift capability, they may be used to lift any wheels for maintenance (suitable safety blocks or jack stands should be used before venturing under vehicle).

Cons: Due to parking brake or chock limitation, steep inclines are typically dealt with by facing vehicle down hill. HWH jacks are not easy for a 3rd party to repair, and the company doesn't sell seal kits or anything else to independent hydraulic shops. Your only option is to try and determine which jacks need repair and ship them to HWH.

HWH also has available a coaxial high lift straight down ram that work like Bigfoot, but retracts higher and extends down more.

Though not recommended by HWH, the jacks can raise an LD off the ground to allow a tire to be changed.

The HWH “kick down” jacks will not drop down due to a hydraulic leak, as they are extend via hydraulic pressure and retract via spring power - - so if a hydraulic leak type failure were to occur, the jack would fail retracted. That said, if a “retract solenoid” were to fail so as to prevent normal spring retraction, then there is a manual over-ride valve on the power pack. Opening that valve by hand will retract the jack.

Bigfoot

Pros: Rigid ram, when ram is down vehicle is not dependent on parking brake or chock to remain in position. Note this is only a factor if all rear wheels are lifted off ground.

Cons: Limited lift height will not level vehicle without additional blocks on more than gentle slopes. When retracted, rams will still project low enough to limit vehicle clearance and are thus subject to damage.

One adverse comment about the Bigfoot. On a level surface, my MB coach sits with the nose down about 2"(MBs are heavy on the nose). To get the recommended 8" of clearance between the retracted jack and the ground, the front jacks are limited to their 17" units. These have a total travel of 11". The rears are 21" units with a greater travel. The upshot is that on a level surface, the front jacks can just barely bring the coach to level (i.e. 8" of extension to reach the ground, 2" to get level and 1" because the auto system over lifts the coach a bit for stability = 11"). Therefore, I carry a set of those plastic modular leveling blocks. When I set up camp, if the coach's nose is not actually too high to start with, I put 4 or 5 of those blocks under the front jacks. The coach autolevels without problems after that. I almost never have to add blocks under the rear jacks. I do like the stability the levelers bring.

Kwikee

Similar to HWH with a hinged or kick-down foot.

General: Like all equipment, regular maintenance upkeep and checks prevent problems. Monitor the level of the ATF in the pump reservoir in the, coat the rams with silicone and grease the pivot points of the kick-down feet.

Stabilizing Jacks

These are crank-down jacks such as you see on the corners of most trailers. They can be bolted or welded to the frame and you use a crank to wind them down to the ground. They can help eliminate rocking of the RV from movement inside, but they are not strong enough to lift the RV.

Contributors: WxToad, Tina Pratt, bumper, Larry W, KoKo. Linley Gumm

Return to FAQ Index

No comments:

Post a Comment

Note: Only a member of this blog may post a comment.