Popup lift more than 1m?

[dzzz]

I've been somewhat stumped at how to do a hardsided popup more than a meter or so - lets say 48" - to 52". Straight piston, or double pistons, don't seem to be that long. The issue isn't strength, it's the torques that occur in real word use. I can use compound movements, but all of these I've considered are either weak or complicated. How would you do a large 48" popup? How would you do a 2m one side popup (The other end is just a hinge). How would you deal with the side loads caused by wind?

 

[dzzz]

The simplest scissor lift has one edge that moves:

To be fixed at top and bottom requires compound motion:

This could be good for photography

Lots of choices in using electromechanical pistons instead of hydraulic:

http://www.duffnorton.com/products/linear.aspx

 

[ntsqd]

If you move away from linear actuators then your lift distance is only limited by the longest rigid enough for the job lead-screw length. Those could be in the base of a scissor lift, or they could a 4 post lift timed & driven by chain(s).

Some garage door openers are lead-screw designs. Have a look at how those are built.

 

[Metcalf]

Use a lever. Just because you can't find a stroke long enough doesn't mean you just can't move down the arm.

Are you trying to do a triangle hard side pop-up?

If its hard side you can have the inner and outer shell touch each over with some long brush seals. As long as the 3 sides that move have some support and a close fit the only other force you should be seeing is perhaps the entire shell trying to lift off the bottom part. That would put the lifting device in tension...and maybe the weak side of the ram piston.

 

[Prybry]

check out a typical pop up camper...

I would check out a pop up camper at a local dealer...
The top on my Pickupper works well enough that it would support a full hard side shell.
I don't have any good pictures of how the mechanism works... but here are a couple showing the top up.

http://www.expeditionportal.com/forum/showthread.php?t=14615&page=3

Prybry

 

[dzzz]

Thanks for all the suggestions.
I spent all day on design. When I put the criteria and constraints together I come up a triangular, or one sides pop-up. The back if the camper hinged. The front of the camper lifted to a solid wall.
I like the stability of having a hinged end. I could also use two linear accuators to lift the top, but have a solid end wall carry the load. (The wall could be hinged to the roof, and drop down with just gas dampeners.)
That would give we a 7'x6' second story sleeping area, with a ceiling that went from 3' to six feet. I hate coffin cabovers. One of my criteria was not to sleep with a ceiling a foot above my face.
One note I'll mention from my research today. There are waterproof marine actuators. They use these for hatch closing and underwater trim. I don't have a use yet, but these sound promising.

 

[ThomD]

Have you seen this?

http://www1.ttcn.ne.jp/~gyo/English/index.htm

 

[OutbacKamper]

This is something that I spent quite a bit of time thinking about myself;

If I were building a lift top that is hinged on one side (or end) I would go with a very simple and proven gas strut system like this:
http://www.innovan.com.au/video/setup.html

If I were building a horizontal lift system (all four corners lift at the same time) I would use hydraulics (like Alaskan) or a variation of the "tent trailer" style lift system such as:
http://www.goshenstamping.com/content/lift_system.htm
Or a scissor lift system like this topup camper:
http://www.truckaddons.com/Catalog/subpages/topup_campertonneau.htm

Cheers
Mark

 

[vhram]

I was going to suggest the hydraulic Alaskan camper type lift with a pin.My Alaskan camper is 35 years old and still works like a champ. Very simple system.

 

[dzzz]

Use a lever. Just because you can't find a stroke long enough doesn't mean you just can't move down the arm.

Are you trying to do a triangle hard side pop-up?

If its hard side you can have the inner and outer shell touch each over with some long brush seals. As long as the 3 sides that move have some support and a close fit the only other force you should be seeing is perhaps the entire shell trying to lift off the bottom part. That would put the lifting device in tension...and maybe the weak side of the ram piston.

The brushes are a good idea. What size of space would you put between the walls? I'm thinking about 1/2 inch (~1cm) Would you put brushed within the space between walls, or just at the top of the lower wall? I'm thinking of a six inch overlap.

As far as uplift, that condition is why I wouldn't use gas springs. Although perhaps these devices can be made to stop pushing when fully extended. With a hinged roof I will use something like a 30" linear actuator to open the roof six feet. My only concern with this much leverage is damage from localized force where the actuator arm meets the roof beam.

 

[Metcalf]

I planned with the unimog camper I designed ( see my sig line ) to use brush seals on the moving and non-moving edge. That way it is well supported and will be sealed enough to keep dust and breezes to a minimum.

Here was another innovative top idea that I came up with. I think it would work VERY well. It allow almost a doubling of interior space while still maintaining a simple pass through to the cab that stays fixed. It also allows a fixed door on the side of the camper.

How the camper top works.....small video...hope this works...

 

[dzzz]

I've been working on something similiar with a one piece wall that swings down. It's a bit more involved but puts a window at the right height for my design.

In you model, if the roof and upper wall portion is extended I think the weather tightness would improve.

I like the box covering the door if there is internal access.

Positive pressure would be an easy way to keep the dust out. But I expect a deep field of brushed works well, with the air sticking to each brush.

 

[JetMech]

I would recommend a ball screw actuator. Reliable and offer very long lifting lengths.

Here's some tech info:

http://duffnorton.com/products/mech2.aspx

 

[63tlf8]

I would recommend a ball screw actuator. Reliable and offer very long lifting lengths.

My infrequent posts are normally in the MOG section. Now I'm in the build mode I have made some binding decisions and this is one of them.

I went through this process over the last 12 months and to suit my own requirements, finally went with screw jacks. Ball screws here are far too expensive for the weight and duty cycle so I went with acme threaded rod. I purchased 12 Ft of rod, 4 nuts and eight 2 tonne jack bevel gears. I've made 4 bevel gear boxes from some 70mm RHS and used taper roller bearings as the thrust race. The pinions are actually 3/8 socket extensions so I can easily link the two front and two rear jacks with torque tubes. The jacks are encased in sliding sections of square tube, with the inner tube secured to the nut at one end and the upper mount on the other. My normal lift is 800mm but could be more. One benefit is that I can lift the top section clear of the bottom whilst still on the jacks to service the sliding seals. Makes that maintenance very easy.

The threaded rod solution won't be for everyone but as the lift distance increases it remains in the decreasing list of potential options. Finally, as a positive displacement system, it overcomes the synchro problems of linear actuators or the simple hydraulic, pneumatic systems.

Tony

 

[tlbrewer]

My infrequent posts are normally in the MOG section. Now I'm in the build mode I have made some binding decisions and this is one of them.

I went through this process over the last 12 months and to suit my own requirements, finally went with screw jacks. Ball screws here are far too expensive for the weight and duty cycle so I went with acme threaded rod. I purchased 12 Ft of rod, 4 nuts and eight 2 tonne jack bevel gears. I've made 4 bevel gear boxes from some 70mm RHS and used taper roller bearings as the thrust race. The pinions are actually 3/8 socket extensions so I can easily link the two front and two rear jacks with torque tubes. The jacks are encased in sliding sections of square tube, with the inner tube secured to the nut at one end and the upper mount on the other. My normal lift is 800mm but could be more. One benefit is that I can lift the top section clear of the bottom whilst still on the jacks to service the sliding seals. Makes that maintenance very easy.

The threaded rod solution won't be for everyone but as the lift distance increases it remains in the decreasing list of potential options. Finally, as a positive displacement system, it overcomes the synchro problems of linear actuators or the simple hydraulic, pneumatic systems.

Tony

Ok now you've got us all interested in seeing the final product all assembled. HaHa. I've often considered this as a possibility for a lifting mechanism as well. My problem is the only experience I have with them is on aricraft landing gear (C-130's) where they can be very dirty (due to lubrication issues) and require periodic adjustment. A clean, efficient, self contained ball screw assembly with 3-4 feet of travel would be... well let's just say it would solve some design ideas.

Tom