Lifting structure

Reply

  #1  
Old 07-01-13, 05:22 PM
Member
Thread Starter
Join Date: Jan 2012
Location: USA
Posts: 190
Received 0 Votes on 0 Posts
Lifting structure

Hi, this might seem like a strange request but I think this section of the forum is the best one.

I would like to build a structure, probably made of wood, under which I can drive my car and then use it to lift a weight of about 300lbs and then lower it to ground once I moved the car.

I think at its simplest it would consist of two vertical "beams" (sorry it's probably not the right tecnical term) and a horizontal one, that will have some sort of hoist to lift and lower the cargo.

The structure would need to be about 14 feet high.

I would bury the vertical posts in concrete and use long bolts to secure the horizontal beam to the vertical ones.

Do you think this is a good project? Am I underestimating anything, what size should the wood be? Am I better off using metal pipes?
 
Sponsored Links
  #2  
Old 07-01-13, 06:07 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,597
Received 13 Votes on 11 Posts
You mean something like this:

[ATTACH=CONFIG]14614[/ATTACH]
Image Source: CDR Equipment Rental
 
Attached Images  
  #3  
Old 07-01-13, 06:47 PM
Member
Thread Starter
Join Date: Jan 2012
Location: USA
Posts: 190
Received 0 Votes on 0 Posts
How can I get 14 feet tall with that - and still be able to move the car or the lift away so I can lower the cargo?
 
  #4  
Old 07-01-13, 08:12 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,597
Received 13 Votes on 11 Posts
OOps missed the 14 feet. Read to quickly.
 
  #5  
Old 07-01-13, 11:59 PM
Member
Thread Starter
Join Date: Jan 2012
Location: USA
Posts: 190
Received 0 Votes on 0 Posts
In fact I had a look and I have around several pressure treated 2x4s that are 16' long. I was thinking to buy those metal bases to bolt everything down to the concrete.
 
  #6  
Old 07-02-13, 04:31 AM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,967
Received 3 Votes on 3 Posts
What are you removing from the car that will require a 14' lift. Some information is good, more information is sensational in giving advice.

2x4's won't handle the load. You will need to sink 6x6's on either side and run a double or triple 9 1/4" LVL across the top of the posts, fastened properly, probably with bolts. This is permanent, I assume, as you are building a structure just for this purpose. You would also need a lifting mechanism, either chain hoist, or block and tackle.
 
  #7  
Old 07-02-13, 09:02 AM
Member
Thread Starter
Join Date: Jan 2012
Location: USA
Posts: 190
Received 0 Votes on 0 Posts
I'm lifting the entire roof rack (about 8'x5') that has a roof top tent on it. The truck is already pretty tall at more than 6' at the lifting point and add another couple of feet to reach the top of the cargo.
I am going to use two straps, one for the front and another for the back of the rack; the reason I want the lift point to be quite tall is to not have too much of a load multiplier for the ropes being at an angle.

The structure will be semi-permanent, I'd like to last about a year until the new garage is ready.
I was thinking of "binding together" two 2x4s per side, so a total of 4; this wont' hold 300lbs?
 
  #8  
Old 07-02-13, 03:06 PM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,967
Received 3 Votes on 3 Posts
As you know, we tend to over-engineer things for safety's sake. I have no idea what a "roof rack" is, and certainly don't know what a roof top tent is. A truck that is 6' tall at the lifting point must be a tractor trailer load. I hate to ask, but could you post some pictures of what you are dealing with? The rack, truck, car, garage, etc?

2x4's are not very structural, especially after about 8'. Doubling them for a vertical support is not much stronger. That is why I originally suggested the 6x6's and LVL. You don't want to trust any load over your head to just any lumber.
 
  #9  
Old 07-02-13, 03:14 PM
Member
Join Date: Dec 2005
Location: USA
Posts: 514
Received 10 Votes on 10 Posts
I think I have done something similar to what your proposing, could you post a pic. of what it is exactly your trying to lift?
 
  #10  
Old 07-02-13, 03:28 PM
Member
Thread Starter
Join Date: Jan 2012
Location: USA
Posts: 190
Received 0 Votes on 0 Posts
Yes. The roof rack is a metal structure that is mounted on top of the roof to carry things. In my case the payload is a "roof top tent" like you can see in the picture:

RTT open

In the picture above the tent is open; I do not have a nice picture of when it's closed but it looks like this:

RTT closed
 
  #11  
Old 07-02-13, 03:42 PM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,967
Received 3 Votes on 3 Posts
Much better!!! Picture 36 is about what I was envisioning your need to be (cleaned up, of course). Are you going to try and hoist this using only two points on the side?? Would be much more stable, and you could use 4x4's if you used 4 points and two straps, one on each point. Of course if you are using a winch, or block and tackle, it may take two to move it smoothly. I am thinking about this from a balance point of view, also.
 
  #12  
Old 07-02-13, 04:20 PM
Member
Thread Starter
Join Date: Jan 2012
Location: USA
Posts: 190
Received 0 Votes on 0 Posts
Haha picture 36 is an abandoned mine in the middle of the desert in Nevada

I was wondering if two 4x4 'equivalent' plus steel guy wires could be enough. The whole setup is 220lbs but I said 300 to have some margin. I do not plan to ever be below it so "human" safety is not at risk here, but the RTT costs a lot and for no reason I want it to be at risk. At the same time, I have plenty of long 2x4s at home and I would not mind a solution that uses these.
 
  #13  
Old 07-02-13, 04:37 PM
Member
Join Date: Dec 2005
Location: USA
Posts: 514
Received 10 Votes on 10 Posts
I don't think you need to go 14' high I would say maybe a foot higher than your truck would work to be able to drive from under it. 300lbs isn't all that heavy so 4X4 posts set in concrete with the same used horizontally would be more than enough since each would be supporting about 75lbs. If your not going to be removing it on a constant basis it could be lifted manually and the horizontal posts slid under it and on to the vertical posts, been there done that with a full sized fiberglass camper shell that had the entire roof flip over exposing a full sized tent. It was called a Wildernest camper, if you do a search you will find pictures of what I was storing on 4X4 posts. I used Simpson Strong-Tie Z-Max 4x4 Post Cap/Bases on top of each post. I nailed them but they could also be screwed on. If you look at them you will see what I mean.
 
  #14  
Old 07-02-13, 04:49 PM
Member
Thread Starter
Join Date: Jan 2012
Location: USA
Posts: 190
Received 0 Votes on 0 Posts
The problem being only a foot taller is that the straps would be and a very wide angle, increasing a lot the pull on the straps and part of the rack. But you are right, maybe 12 feet is enough.
 
  #15  
Old 07-02-13, 05:08 PM
Member
Join Date: Dec 2005
Location: USA
Posts: 514
Received 10 Votes on 10 Posts
You wouldn't need to use any straps if you re-read what I suggested. The way I did it was to lift the front and slide the 4x4 across each post then lift the rear and slide in the 4x4 post, then drive out from under it, pretty simple and removes the issue of a strap giving way in time. Again with that small amount of weight that will be on each post I think your are making it more complicated than it really is.
 
  #16  
Old 07-02-13, 05:32 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,597
Received 13 Votes on 11 Posts
How about a post on either side and drive bewteen.

Name:  hoist.jpg
Views: 977
Size:  22.4 KB
 
  #17  
Old 07-02-13, 08:26 PM
Member
Thread Starter
Join Date: Jan 2012
Location: USA
Posts: 190
Received 0 Votes on 0 Posts
Ron53, how will I be able to lower down the rack so I can work on it and then move it indoors? I still need to have straps, unless I totally misunderstood your advice!
 
  #18  
Old 07-03-13, 06:24 AM
Member
Join Date: Dec 2005
Location: USA
Posts: 514
Received 10 Votes on 10 Posts
I only lowered mine down to ground level once and it only took 3 friends to lift and lower on to some sawhorses. I have no idea what moving indoors would be involved in your case since their are so many variables, distance, terrain, ect. that I don't know. I did finally move mine to a small flatbed utility trailer when I was preparing to sell it so that may be an option for you.
 
  #19  
Old 11-27-13, 05:42 PM
Member
Thread Starter
Join Date: Jan 2012
Location: USA
Posts: 190
Received 0 Votes on 0 Posts
So I came back to this thread to "resolve" it; I have built it!

- I cut two 12"x12" holes in the concrete about 8 ft apart, and then I dug three feet in the hard clay
- I put a layer of gravel and I compacted it
- I put in vertically two pressure treated 6x4, 16ft long
- I poured in concrete (I do not remember how many bags, maybe 9 or 10 total?)
- I fastened a 2" diameter galvanized steel pipe on top
- I added a Harbor Freight chain hoist (wonderful)
- I used 4 slings and some steel tubing from a fence I removed earlier to make the "harness" for the roof rack
 
  #20  
Old 11-27-13, 06:18 PM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,967
Received 3 Votes on 3 Posts
Picture would be worth 320 words. I'd like to see the results.
 
  #21  
Old 11-27-13, 07:14 PM
Member
Thread Starter
Join Date: Jan 2012
Location: USA
Posts: 190
Received 0 Votes on 0 Posts
AHahah I meant to link the YouTube video I shot, but I forgot to copy and paste it!!!!

Here it is:

https://www.youtube.com/watch?v=jiRwvZIthyg
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description: