Grit dog
Black Diamond, WA
Senior Member
Joined: 05/06/2013
View Profile
 Offline
|
He meant rotated 45deg, not 45 deg out of plumb….
2016 Ram 2500, MotorOps.ca EFIlive tuned, 5” turbo back, 6" lift on 37s
2017 Heartland Torque T29 - Sold.
Couple of Arctic Fox TCs - Sold
|
SJ-Chris
San Jose, Ca
Senior Member
Joined: 09/24/2017
View Profile
Good Sam RV Club Member
Offline
|
Something I haven't been able to figure out... Is there something inherently bad about scissor jacks that make them not good for lifting an RV for leveling it?
Disclaimer: If I am ever going underneath my RV I always have multiple jacks and jack stands just in case for safety, and I suggest you do so also. This discussion is only as it pertains to leveling/lifting an RV with scissor jacks when at a campsite.
Many many many people will be quick to say, "scissor jacks are for stabilizing and not for jacking up your RV", but can you explain WHY?? People read that on the internet somewhere and then they are quick to regurgitate it without a real reason why.
Think about it for a minute....MOST regular cars (not RVs) come with a scissor jack for what?? For jacking up your regular car to replace a flat tire if needed. The scissor jack lifts up your regular car. Lifting is what a scissor jack is designed to do.
I would argue that your RV doesn't know WHAT KIND of jack you are using....scissor jack, bottle jack, floor jack, etc. Seems like the two main considerations would be 1)What weight limit is the jack rated at, and 2)Where are you jacking it up? For example, I routinely use a 12-ton bottle jack on my axle to jack up one rear side of my 30' Class C RV if I need to remove a tire. I'm pretty sure the RV would not care one bit if I used a properly weight rated scissor jack and lifted it from the same exact spot. Right? (Side note: This assumes you have proper contact and things don't slip while jacked up. Using the flat top of a scissor jack probably wouldn't be a good idea on a round axle jack location, but if the scissor jack were used on the flat portion of the frame AND bolted to the frame slipping would not be a worry.) My point is that a scissor jack that is rated to lift 9000lbs can lift the weight of half of the rear of my RV which is ~4500lbs.
AS LONG AS you are using a scissor jack that is weight rated to lift a side of your RV, can anyone explain what is wrong with using a scissor jack?? For example, my rear axle weight is about 9000lbs (total). Let's assume it is evenly distributed so that means 4500lbs on each side. If I use a scissor jack on one side and that scissor jack is weight rated for 9000lbs (double the weight of one side of my RV) what is the problem?
I *DO* see a potential problem with using a jack (ANY type of jack) to level your RV by lifting it AT THE WRONG LOCATION, where maybe you could bend the frame for example. BUT that seems like it would have nothing to do with using a scissor jack per se as you would have the same problem if you used a bottle jack or floor jack in an improper jacking location. Right??
One last example to prove my point.... A Class C RV DOES have 4 100% proper jack locations that we know about. Let's assume those 4 locations are on the front and rear axles right near the respective tires. Would you agree that it would be okay and do no damage to use 4 properly weight rated bottle jacks (or jack stands), one on each of those jack points to level your RV at a camping site? (Note: I wouldn't actually do this, but I'm trying to prove a point.) If you agree that no damage would happen in this scenario, then how about if the jacks were replaced with floor jacks that were properly weight rated. Any issue? I think not. Well what if those jacks were replaced with properly weight rated scissor jacks. Any issue? I think not.
If this thinking is correct, then would it be right to say that using scissor jacks to level your RV is ok as long as you use scissor jacks that are weight rated properly (I like to use 2x the actual load it is lifting) AND you are using a proper jack location? If so, it gets back to my previous question above regarding Where on the frame is it okay to jack up the RV (from an "I don't want to bend the frame or do any damage because of improper jack location" perspective)?
Ah.....I just thought of one other issue, and maybe this is the reason people say not to use jacks to level your RV, but I don't think I've read it anywhere before... I will wait for a bit to post the issue as I am curious to hear feedback on the above.
-Chris
PS: Have you ever seen an RV being worked on at a repair shop with a jack stand underneath the 4 jack points by each tire? I have. Doesn't seem to bother them.
San Jose, CA
Own two 2015 Thor Majestic 28a Class C RVs
|
ScottG
Bothell Wa.
Senior Member
Joined: 02/25/2005
View Profile
|
Chris, the co's that make them always include a CYA statement that says they're only for stabilizing and not lifting. That being said, from my 40 yrs experience there's nothing wrong with using them up to their rating and maybe even a little beyond. After all, they are first and foremost "Jacks".
I can tell you that when they are very substantially overloaded, nothing dramatic happens. It simply bends the "jack" screw and thereafter causes the jack to wobble when extending or retracting.
I learned this when I forced mine to lift the whole side of my RV so I could change out a tire in some sand on the side of the road (thank you Carlisle).
Since then I'm sure I've overloaded them many times when leveling my rig and I was close but just needed a few extra turns. When I see the screw start to deflect, I stop (or at least soon after..).
* This post was
edited 10/19/23 08:52pm by ScottG *
|
valhalla360
No paticular place.
Senior Member
Joined: 08/19/2009
View Profile
Good Sam RV Club Member
|
One thing to consider is the leveling systems I'm familiar with run 2 jacks at the same time (both front, both side or both rear). This causes the whole rig to rotate with the frame not twisting.
If you are doing it manually, one jack at a time, that can introduce a lot of twisting in the frame. Not a big deal for the frame as it's unlikely to fail but the house is bolted to the frame and not very strong...you might be opening up the seams in the roof as it all twists or loosening the screws holding the cabinets.
Tammy & Mike
Ford F250 V10
2021 Gray Wolf
Gemini Catamaran 34'
Full Time spliting time between boat and RV
|
SJ-Chris
San Jose, Ca
Senior Member
Joined: 09/24/2017
View Profile
Good Sam RV Club Member
Offline
|
ScottG wrote:Chris, the co's that make them always include a CYA statement that says they're only for stabilizing and not lifting. That being said, from my 40 yrs experience there's nothing wrong with using them up to their rating and maybe even a little beyond. After all, they are first and foremost "Jacks".
I can tell you that when they are very substantially overloaded, nothing dramatic happens. It simply bends the "jack" screw and thereafter causes the jack to wobble when extending or retracting.
I learned this when I forced mine to lift the whole side of my RV so I could change out a tire in some sand on the side of the road (thank you Carlisle).
Since then I'm sure I've overloaded them many times when leveling my rig and I was close but just needed a few extra turns. When I see the screw start to deflect, I stop (or at least soon after..).
Thanks for sharing your experience/feedback.
If anyone is using any type of jack (scissor included), I would suggest using one that is rated for well over the amount you are lifting. I like to shoot for 2-3 times more weight rating than what I am lifting as then I know the jack itself shouldn't be getting stressed.
-Chris
|
|
|
valhalla360
No paticular place.
Senior Member
Joined: 08/19/2009
View Profile
Good Sam RV Club Member
|
SJ-Chris wrote:Thanks for sharing your experience/feedback.
If anyone is using any type of jack (scissor included), I would suggest using one that is rated for well over the amount you are lifting. I like to shoot for 2-3 times more weight rating than what I am lifting as then I know the jack itself shouldn't be getting stressed.
-Chris
Any borderline competent engineer is already including a 2-3 time factor of safety when setting the load limits.
The typical "stabilizing" jacks are only intended to support a few hundred pounds to take some of the bounce out of the rig. If lifting, they should be much stronger.
|
eHoefler
ozark mountains
Senior Member
Joined: 10/22/2011
View Profile
Offline
|
Found this at the end of the description;
Specs:
Capacity: 5,000 lbs per jack
Extended height: 24"
Retracted (collapsed) height: 4"
1-Year limited warranty
Note: These jacks are designed to stabilize a portion of your trailer's weight, not to support the full GVWR of your trailer. Do not use these jacks to lift your trailer or RV. Doing so will exceed the capacity of the jacks.
Not intended to level, just stabilize.
2021 Ram Limited, 3500, Crew Cab, 1075FTPD of Torque!, Max Tow, Long bed, 4 x 4, Dually,
2006 40' Landmark Mt. Rushmore
|
ScottG
Bothell Wa.
Senior Member
Joined: 02/25/2005
View Profile
|
valhalla360 wrote:SJ-Chris wrote:Thanks for sharing your experience/feedback.
If anyone is using any type of jack (scissor included), I would suggest using one that is rated for well over the amount you are lifting. I like to shoot for 2-3 times more weight rating than what I am lifting as then I know the jack itself shouldn't be getting stressed.
-Chris
Any borderline competent engineer is already including a 2-3 time factor of safety when setting the load limits.
The typical "stabilizing" jacks are only intended to support a few hundred pounds to take some of the bounce out of the rig. If lifting, they should be much stronger.
LOL
|
SJ-Chris
San Jose, Ca
Senior Member
Joined: 09/24/2017
View Profile
Good Sam RV Club Member
Offline
|
valhalla360 wrote:One thing to consider is the leveling systems I'm familiar with run 2 jacks at the same time (both front, both side or both rear). This causes the whole rig to rotate with the frame not twisting.
If you are doing it manually, one jack at a time, that can introduce a lot of twisting in the frame. Not a big deal for the frame as it's unlikely to fail but the house is bolted to the frame and not very strong...you might be opening up the seams in the roof as it all twists or loosening the screws holding the cabinets.
It is actually kind of amazing that RVs stay together at all when you consider they are twisting and flexing and turning and bouncing for 1000s and 1000s of miles as you drive down the road, over bumps and potholes, etc.
When leveling an RV, I believe you will either need to adjust 0, 1, 2, or 3 tires ("corners") to make them higher in order to get your RV level. I would contend that leveling your RV from a correct jack point (or like most people, just putting blocks under their tires) does absolutely zero damage and adds zero stress to the structural integrity of your RV. In fact, it ALLEVIATES stress/twisting/etc. The fact that your RV is unlevel implies it is being stressed or twisted as long as it is unlevel. Here is an exaggerated example to illustrate my point... Imagine you pull into a campsite and your front 2 tires and your rear driver side tire are all perfectly level but your passenger side rear tire is 12 inches too low. You are parked there. The rear passenger side of your RV is causing your entire RV to be wildly unlevel. If you try walking in your RV it is sloping a tremendous amount. At that moment, the frame and everything attached to the frame is under much stress BECAUSE it is unlevel. It is designed to handle it, but it is under stress. If you now raise that passenger side rear corner (from a proper jack point and/or by putting something under that tire) you will NOT be stressing/twisting the frame but rather you will be de-stressing/un-twisting the frame and putting the RV back to level (...I suppose you could call it the RV's happy place...being level). Right?
Or, another example...Assume you are parked perfectly level. I think we can all agree that when level and parked the RV and its frame and everything attached to it are in their happy place and they are not experiencing extra structural stress. Now imagine if you start putting blocks under just one tire (or jacking up just one corner from a proper jack location). You raise that tire/corner 3 inches, then 6 inches, then 9 inches, then 12 inches. As you are doing this, it is ADDING stress to the overall frame/structure/integrity of your RV. Right? Well, as you start removing this added height and you are dropping it back down to being level once again it is removing all that added stress. Making the RV level puts it in a state of the least amount of structural stress.
If the above is true, then any time you are leveling your RV, and you are doing so with items designed to support the load (either blocks under the tires, or jacks of any kind designed to hold the proper amount of weight) from a location designed for that purpose (ie. under the tire, or at a proper jack point), then you are actually REMOVING stress/twisting to the structural foundation of your RV.
-Chris
* This post was
edited 10/21/23 04:32pm by SJ-Chris *
|
SJ-Chris
San Jose, Ca
Senior Member
Joined: 09/24/2017
View Profile
Good Sam RV Club Member
Offline
|
valhalla360 wrote:
Any borderline competent engineer is already including a 2-3 time factor of safety when setting the load limits.
I agree that a responsible company who produces a jack with an advertised weight rating of 5000lbs (for example) probably designs it such that it can safely handle quite a bit more load just so that there is some buffer of protection for the company's liability (and the end user).
As a consumer/user, If I am looking for a jack to lift 5000lbs I want to be extra safe so I will add in my own buffer of 2-3x (or more) just so that I know whatever jack I am using is more than capable of performing the task. I usually use a 12-ton bottle jack (24,000lbs) when jacking up one rear side (~4500lbs) of one of my 30' RVs. (And if I'm going under my RV or removing tires, I will also put some 3-ton jack stands under the frame as backup)
I would never use (or recommend) a jack to lift a load that is more than what the jack is rated to lift.
valhalla360 wrote:
The typical "stabilizing" jacks are only intended to support a few hundred pounds to take some of the bounce out of the rig. If lifting, they should be much stronger.
I haven't seen any stabilizing jacks (usually scissor type) rated for less than 1-ton (2000lbs). But I agree that even those would be only to provide some minor stabilizing to take some of the bounce out of the rig as you mention. They do have scissor jacks rated at 9000lbs+ though and I believe those could lift up to their weight rating if used safely, and thus could under the right circumstances be used for leveling an RV.
-Chris
|
|
|
|
