Looking for design ideas on tapered front jack leveling blocks

[jbeletti]

Hello community!

My concrete driveway has about a 6 degree slope and I'm unable to level my coach (front to back) when in the driveway. I want to make some tapered blocks that can be placed under the front jack pads to give me (and my RVing guests) the ability to level out.

Below is a crude drawing of what I'm thinking of. Note, IT IS NOT drawn to scale. Just a quick and dirty sketch to get the conversation rolling.

Things I need to determine:

1. What is the tallest I should make the blocks? I'm using 12" as a discussion starter, but I'm thinking that may be too high. I guess I'd need to know, when hitched and with front jacks all the way up, on most Heartland 5th wheel coaches, what is the distance from the bottom of the jack pad to the ground. Then maybe use the shortest distance as my number for block height at the front edge.
2. What is an ideal width of the blocks? I'm thinking twice the with of the largest jack foot used on our coaches.
3. What is the ideal length (flat across the top) of the blocks? I'm thinking 18" to 24". I want to make sure it is very stable as there will be great pressure on the coach to roll forward. Don't want to roll a block! Of course, wheels need to be chocked before unhitching and remain chocked in this driveway.
4. What material should I use for block construction? I called a Heartland friend and he suggests that I alternate treated plywood and treated lumber, all stood on edge. Then connect them with all-thread, thereby ending up with a laminated sandwich of treated lumber being used at its strongest orientation. What would you do? Bear in mind, I'm trying to support up to 2500 pounds on each block (about 50 pounds per square inch of contacted surface area) in a worse case loading scenario.
5. At the back (left end of drawing) of the block, I don't really want it tapered to zero in a point sort of fashion, so I'd likely square that point (tip) off at some point. Am I "on track" with squaring the back end off?

 

[recumbent615]

Jim,

Few Clarifying questions for you.

1) What is the Finish on the Driveway?
2) is the slope a constant?

If it is a constant - and it is actually a 6 deg slope This would result in a overall grade change of nearly a 52 inch change in elevation over the length of a 40 ft span. Now understanding that we often have 10+ feet behind the axles we could safely drop the run by 10 ft resulting in an elevation change of just under 40 inches.

The Chart I am using is not showing up but I will summarize:

6 Deg Slop
10.5 % Grad
1.3 inches per foot

30 ft X 1.3 in = 39 inches rise over a 30 foot Run.

 

[pegmikef]

What is going to keep the block itself from creeping from the sheer weight on it? You might want to use a rotary hammer to put a couple of holes in the concrete in front of the block location so you can drop some pins in them when you're storing the rig to keep the blocks from sliding. (something like short pieces of stout (5/8") rebar).

 

[Bob&Patty]

I'm not sure but I think JB's driveway is asphalt. If it is, I hope it's fairly thick for warm summers.

 

[brianharrison]

I believe the travel on the hydraulic landing gear is 18" max. Using Kevin's numbers of 39" rise over 30 feet (landing gear to rear wheels), the block dimensions would have to be 21" on the "front" and 23.5" on the "back" (at 24" length across the top). This would have to fit under the jacks while they are in the full up position and the unit is still attached to the truck.

I have the opposite scenario - my driveway drops 5 degrees front to back. It is a bit of a PITA - (Pain In The A**).

Take care,
Brian

 

[TedS]

I would just stack 2x's or build a block tall enough to raise the trailer to level and let the landing leg pad swivel to match the slope on top of the block. If you need to feel more secure, attach a piece to create a lip on top of the block to butt against the leg pad edge. Make sure there is no gravel between the blocks and driveway. At least 18" x 18" width by length.

And 2500lbs on a 18"x18" pad gets you to nearly 8 lb/sq in pressure.

 

[santafesoul]

I do believe you indicated that it is a concrete drive and if so, lining the bottom surface of the block with securely attached rubber like from a discarded tire should provide sufficient grip on the driveway to keep it from sliding. By my calculations, the 12 in block would do quite well. More block means less jack extension resulting in a more stable coach.

The easy way to mark the cut on your block is to lay the block on the driveway oriented the way you will be placing it, use a level with the pivot point on the upper edge of the lowest edge, level and mark.

 

[jbeletti]

Wow - great input guys - thank you!

Some feedback from me:

• Kevin - driveway is concrete with a broomed finish and the slope is constant
  .
• SanteFeSoul - I too had thought about using sections of a discarded tire for the bottom and using screws between the treads to attach it. Then I wondered, with all the pressure on the block, would the tire be more non-skid than the edge grain of wood? Dunno
  .
• pegmikef - I too wonder about block creep. But as stated above, maybe the static load wil be enough to keep things stable
  .
• Ted - On the PSI, I was figuring an 8" diameter jack pad and the pressure of where it contacts the wood block top, not the PSI of the wood block on the concrete. But thanks for helping me think this through as to the pressure on the concrete
  .
• Brian - Not sure I follow your measurements, but for sure, I can't have the leveled height of the front edge of the block be higher than the distance from a fully retracted jack pad to the ground, when hooked up to the truck, otherwise, I'll never get the block slid under the jack pads. Sorry if I am misunderstanding your figures

Question for the group:

• What about containment/capture of of the jack pads on the block with front and side edges on the blocks? I'm thinking on the top, come back from the front edge, some distance and screw on a 2x2 cleat from side to side to ensure the jack pad remains behind that cleat help prevent the block from rolling forward.

 

[2psnapod2]

• What about containment/capture of of the jack pads on the block with front and side edges on the blocks? I'm thinking on the top, come back from the front edge, some distance and screw on a 2x2 cleat from side to side to ensure the jack pad remains behind that cleat help prevent the block from rolling forward.

Jim what about using a router to make a insert into the surface of the blocks?

 

[recumbent615]

I think the Cleat or Router ideal is good, if deep enough to over come the up turn on the feet. Originally I was thinking of a steel bar that would be bolted to the sides of the block ( using the bolts that hold the laminate together and go over the top of the block to act as a capture bar and handle. I would also suggest that X-chocks between all wheels and standard wedge wheel chokes be used to insure there is no forward movement when unhitching... What ever design you come up with you will need to be sure that any initial trailer movement when unhitching is matched by the blocks and I don't know if I would not be comfortable with just the routed or cleat solution knowing what damage could result in the legs slipping off such a high perch.

 

[danemayer]

Jim, before you get too far down this road, you might check out the leveling operation (assume you have auto-leveling) using some scrap wood or other easy to acquire blocks.

When my rig is on very uneven ground (like the curb drop-off in front of the house) some of the leveling operations are disabled. Sometimes this occurs when extending; sometimes when retracting.

I was changing oil on the genny last week and extended the doorside jacks to level the coach left-to-right. I also had about 8" of blocks under each of the door side jacks to minimize the extension. I think I got it pretty close to level left-to-right but had to stop because I was still hitched up.

A few minutes later, the computer would not let me extend or retract the jacks with the RIGHT button. There was an error message indicating the angle was too severe to allow operation. I've had this happen before and had previously learned that the computer will allow operation of one jack at a time. So I retracted FRONT-RIGHT and then REAR-RIGHT. Since I was nearly level, I think this suggests that the computer is programmed to prevent you from having the jacks extended way out on one side and not on the other. I'd guess this might be additional safety programming in case the internal level is screwed up.

Anyway, my thought is that the programming might prohibit any situation where there's a great disparity in how far the jacks are extended. Or maybe it's specific to left-right since that would be the more dangerous situation.

You might want to do a test run to see if front-to-rear is a problem.

 

[FARMER45]

Rember the rear bumper if you raise the front too much, you may put it on the ground

 

[recumbent615]

Rember the rear bumper if you raise the front too much, you may put it on the ground

Based on my Calculations - with 10ft behind the axles there will only be a drop of 13 inches at the bumper... I think we are slightly over 18 inches when level ( so there may be a very small buffer)

 

[jbeletti]

Rember the rear bumper if you raise the front too much, you may put it on the ground

I have a receiver hitch below the rear cap - so that's the lowest item at the tail. That said, I also have 8k axles/springs, so the coach sits a couple inches higher than normal.

So I think I'll be fine at perfect front to back level. Tomorrow, I'll go outside and use the method santefesoul mentioned to measure the horizontal length it will take to have a 1 foot vertical rise at the front.

Maybe I'll even feel moved enough to head to Lowes for lumber and a new table saw blade

I'm thinking of going making the blocks about 1 foot wide. Still thinking of alternating layers of treated lumber and treated plywood with lumber on the outsides. Comments?

Thanks,

Jim

 

[TXBobcat]

Jim.. I am not as smart as those that are posting but what I would do is take a good 6" or better 2x about 2 foot long. Put it about in the area where your jacks are going to sit. Put a level on the board and raise it up until the level shows a level bubble. Then measure the distance from the bottom of the board to the drive way. That would give you the dimensions you would have to make your cleat. (an inverse ramp). Put something on the bottom of it to keep it from sliding. What I would do is take a number of 2x6's Glue them together to get the height you want and then cut at the required angle. You will have 2 solid blockd of wood that should hold the weight one for each of the legs of the jacks.

Just a country boys way but it might work.

BC

 

[hriker]

I made a set of "cribbing" to put under the landing gear and leveling legs. I have a picture of what I made attached. Our level legs have 9" round feet so I made my cribbing 18" wide. I cut 4 pressure treated 4x4s 18" long and screwed 5/4" pressured treated decking to each of the other sides of the 4x4s to completely cover them. And then used wire staple to attach a piece of nylon rope for a handle. Its a nice solid base for the landing gear and level legs to come down on. I have not done this part yet but found a place to get material like a plastic cutting board to attach on one side (I'm going to make it the side the legs sit on) because when the wood gets wet it's no longer an insulator. They are a little heavy but it's a very solid stable base. We started out with 2 4x4s next to each other but it never really seemed too great to me. We used them in Lake George and they worked out well. In my pictures the cribbing is sitting on top of concrete blocks to assist getting to level without over extending the landing gear.

 

[TravelTiger]

Our feet are from the Steadyfast system, a sort of T shaped foot. We use two 12x6x4 pressure treated lumber blocks, side by side, under our feet. I don't think you'll have a problem with the weight on them. Even when our coach was hit with straight-line winds that moved it about two feet the block that took the brunt of the force had gouges in it, but not damaged enough to stop using it! After using these blocks a year in all weather, they haven't deteriorated in any way.

 

[porthole]

4 pieces of 4x4, (or 5 pieces if you feel you really need it) 5/4 decking or 3/4" pressure treated plywood (pricey)

4 - 4x4's, plywood or decking nailed on both sides. 2 or 3 of these as needed for height.

Making thinner stack-able pieces makes for easier storage and handling. If you really feed the need they could be drilled near the corners and pinned with pieces of Rebar.

As to cleats screwed on to the top, if the RV were to actually move, those screwed on cleats are not going to stop it.
Proper chocking should minimize movement. Truck size chocks H-1591

http://www.uline.com/BL_3854/Wheel-Chocks?pricode=WO372&gclid=CMrD6KjM264CFUIRNAodnV9RVw

 

[jbeletti]

Duane,

Thanks for the wheel chock link. I do need a much better pair for this driveway. Rather than getting a pair from U-Line, I got a similar pair via Amazon.com. Saved $22 on shipping

Here's what I got.

 

[jbeletti]

Duane,

You and another person suggested using 4x4 and even 6x6 treated posts and then 5/4 decking on top/bottom to tie that sandwich together.

I get all that, but, what to do about the slope. It's significant. I don't feel there's enough flex in the jack pad to tilt as much as needed. I really want a flat top.

I suppose I could have the bottom course of posts cut to the angle required to match the driveway slope. Then make a second set with no slope and stack them.

Maybe 18"x18" by the height of material used. If I used 4x4s and 5/4 decking top and bottom, I come close to 6" thick. Two of those get me a foot or close to it. I don't have a good enough or big enough table saw to rip 4x4s at an angle for the length needed. My flimsy miter would laugh at that on my $100 table saw. But I'll bet there are several guys here in the Gardens with full wood shops