Mock Tender
Adventurer
I was wondering if anyone has added lifting jacks on to their campers or on the frames to make removal from an FG, for what ever the reason?
Mark
Mark
Anyone ever put lifting jacks on
- Thread starter Mock Tender
- Start date
gait
Explorer
after a lot of thought and a few suggestions from people who have done it with various vehicles and slide ons.
The acme screw jacks are a tad expensive for very limited use (possibly once or twice in vehicle life). The hi lift 4x4 recovery jacks lack stability.
So. Two steel tubes. One inside other. Outer has angle welded to it. Inner as long as I like, with solid base. Possibly link four corner bases together with a bit of steel. Possibly "wheels". The angles will have a "seat" welded at the bottom for body to sit in. I have webbing and ratchets used to restrain truck in shipping container. It will hold the four legs to the four corners (wrapped horizontally round the whole body and legs like Christmas ribbon). Similar to how I held it together while glueing.
Lift with hi-lift jacks.
The advantage of separating legs and jacking is that height is no longer restricted by the screw inside the legs. And its heaps cheaper.
The corner design means I don't have to pierce the fibreglass skin and create cold paths. My box is frameless foam sandwich.
Here's rough sketch.
The acme screw jacks are a tad expensive for very limited use (possibly once or twice in vehicle life). The hi lift 4x4 recovery jacks lack stability.
So. Two steel tubes. One inside other. Outer has angle welded to it. Inner as long as I like, with solid base. Possibly link four corner bases together with a bit of steel. Possibly "wheels". The angles will have a "seat" welded at the bottom for body to sit in. I have webbing and ratchets used to restrain truck in shipping container. It will hold the four legs to the four corners (wrapped horizontally round the whole body and legs like Christmas ribbon). Similar to how I held it together while glueing.
Lift with hi-lift jacks.
The advantage of separating legs and jacking is that height is no longer restricted by the screw inside the legs. And its heaps cheaper.
The corner design means I don't have to pierce the fibreglass skin and create cold paths. My box is frameless foam sandwich.
Here's rough sketch.
gait
Explorer
ta, and yup,
beat me to the edit ...... first pass says 50x3mm outer tube and 40x3mm inner with 12mm pin. I could be convinced to use 60mm outer and 50mm inner - I haven't checked available steel yet.
SkiFreak
Crazy Person
Personally, I think that a 50mm sliding leg would be safer if you plan on going up higher than 1000mm. I am sure you can appreciate the effect of wind loading on something like this.
I would use 4mm wall on both sections, as this will give less movement in the telescopic portion (only 2mm clearance) and make the sliding pipe stronger. BTW... a 10mm pin would be more than sufficient and it would keep the legs stronger. To be honest, I could not see the weight of your camper body even shearing an 8mm pin. I am guessing that your box is about a tonne, so that's only 250Kg per corner, and it's just a static load.
One other thing I would do is weld on hoops for the webbing to go through, purely as a secondary safety measure. Tension and gravity should secure the legs to the camper body nicely, but as you loosen the straps off it would give you a bit more control of them.
My 2c worth...
I would use 4mm wall on both sections, as this will give less movement in the telescopic portion (only 2mm clearance) and make the sliding pipe stronger. BTW... a 10mm pin would be more than sufficient and it would keep the legs stronger. To be honest, I could not see the weight of your camper body even shearing an 8mm pin. I am guessing that your box is about a tonne, so that's only 250Kg per corner, and it's just a static load.
One other thing I would do is weld on hoops for the webbing to go through, purely as a secondary safety measure. Tension and gravity should secure the legs to the camper body nicely, but as you loosen the straps off it would give you a bit more control of them.
My 2c worth...
gait
Explorer
thanks,
weight with roof off and upper sidewalls removed, fridge and batteries out, but sub-frame still attached, is about 350kg.
More awkward than heavy.
With a bit of trigonometry .... outer wall thickness 4mm gives 2mm play over 700mm which is 5.7mm play at 2000mm (end of fully extended leg). 3mm wall thickness is 4mm play over 700mm which is 11.4mm at 2000mm. Haven't calculated any effect of pin.
Hopefully I'll not bend outer tube while welding.
I'll make sure my webbing is long enough tomorrow!
weight with roof off and upper sidewalls removed, fridge and batteries out, but sub-frame still attached, is about 350kg.
More awkward than heavy.
With a bit of trigonometry .... outer wall thickness 4mm gives 2mm play over 700mm which is 5.7mm play at 2000mm (end of fully extended leg). 3mm wall thickness is 4mm play over 700mm which is 11.4mm at 2000mm. Haven't calculated any effect of pin.
Hopefully I'll not bend outer tube while welding.
I'll make sure my webbing is long enough tomorrow!
Mock Tender
Adventurer
Gait-
I wish I was smart enough to figure out from your drawing how you will raise and lower the homemade jacks?
Considering Ski Freaks comment about windage, you might want to look at the jack stands that they use on monohull boats. the bases are more shaped like a lopsided "A" than the flat base you have. Went the boat carrier is removed from under the boat they attach a chain from one stand to the other. Very strong and yet light.
I am trying to draw up a design where I will put a beefy crossbar attached to the frame at the front of my Bigfoot 17 with welded on plate that could either take my jacks or add an angle braced 4 inch x 4 inch plate that could take any jack when far from home. The rear of the Bigfoot frame can already accommodate two jacks as well.
I wish I was smart enough to figure out from your drawing how you will raise and lower the homemade jacks?
Considering Ski Freaks comment about windage, you might want to look at the jack stands that they use on monohull boats. the bases are more shaped like a lopsided "A" than the flat base you have. Went the boat carrier is removed from under the boat they attach a chain from one stand to the other. Very strong and yet light.
I am trying to draw up a design where I will put a beefy crossbar attached to the frame at the front of my Bigfoot 17 with welded on plate that could either take my jacks or add an angle braced 4 inch x 4 inch plate that could take any jack when far from home. The rear of the Bigfoot frame can already accommodate two jacks as well.
millerfish
Adventurer
Rather than lift the box off the truck. Lift the truck with a floor jack, deploy the stands, Drop the truck and drive away...
gait
Explorer
they aren't jacks. Just "telescopic" legs. One long tube in a sleeve attached to truck body. They provide the lateral stability. Jacking provided by normal hi-lift jacks beside them.
Operation is - take weight on jack, remove pin in leg, raise or lower jack, insert pin in leg, release jack, repeat at other three corners. One corner at a time. Possibly two with care. Never three or four.
The legs only provide stability when there is weight on them. The hi lift jacks are inherently unstable as they have only one point of location to the body.
I've pondered introducing an angle into the legs, so they aren't vertical but inward at the top. The "trapezium" is inherently more stable than a "rectangle". I could do it because while jacking each leg there is no weight on it so the base would realign. It would need a spacer between the bottom of the angle that locates the body corners and the outer tube its welded to.
I've seen a "T" laser cut in a piece of 4mm steel sold as "jacking point" for hi-lift jacks. For my purposes it would only provide limited stability in one direction (left-right).
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gait
Explorer
In my case I need to get the body with sub-frame attached down to ground level so I can roll it over for maintenance.