How much does the Galley Lid weigh?

[MikeM]

I realize this is a tough one to answer.

But, I'm hoping somone weighed theirs before assembly.

The reason for my madness, is I want to use window lift motors to raise my galley lid, with just a push of the button.

My other hair-brain scheme is to use compressed air. Since I will be using boxed tubing, I could it for the reservoir. Then plumb accordingly with a small compressor on the truck or in the trailer.

Anyone wanting to weigh in on this question is appreciated.

Mike

[Shrug53]

I am just guessing here, but I do not imagine it would weigh that much more than the trunk lid of a car. Several guys at the local car shows have big heavy cars like mine (one of them with several lcd screens mounted on the trunk lid) and they use power window motors to open their trunks.
Take a look at: http://www.springfieldstreetrod.com/POWERTRUNKLIFT.htm

That units has a 60lb lift capacity. I have seen bigger ones too. Plus you could always couple that with a simple shock. Like under the hood of a lot of cars. This would aid the lift.

[Dave Nathanson]

My galley lid was SO HEAVY that it hurt my back to open it. Of course, that's lifting it up pretty high over my head at least, and at an awkward angle. So, I'm guessing it's something like 40-75 pounds. Once we added hefty gas shocks it became easy to open, and it stays open ok. (gas shocks are the same as a full size pickup truck uses for those fiberglass bed covers which are pretty heavy too!)

According to Mike Spicer, plywood weighs:
1/8" is .375# per sq foot.
1/4" is .75# per sq foot.
3/8" is 1.125# per sq foot.
1/2" is 1.5# per sq foot.
5/8" is 1.875# per sq foot.
3/4" is 2.25# per sq foot.

[R Keller]

My Road Toad hatch (before aluminum skin, but with hinge, wiring, and running lights): 36 lbs. It is 60" wide and 50" long. 1/8" Baltic Birch for inner and outer skin sandwiching 1.5" Styrofoam and minimal 1x2 poplar framing. Because of this construction, the hatch is relatively light for its size.

After aluminum skin and trim, estimated weight: 48 lbs.

I'm using twin 150 lbs. gas support lifts. They are mounted such that they support the hatch approximately 6" from the hinge. With that hatch weight,length, and support distance, I calculated that I'd need at least a pair of 100 lb. hatch supports: 48 lbs. acting 25" from hinge (half of hatch length) = 1,200 inch-lbs; divided by 6" support from hinge = 200 lbs.; divided by 2 supports = 100 lbs. each support.

Conclusion: A 60 lb. lift capacity motor would not come even close to working on most full-height teardrop hatches.

Hope this helps.

Rik

[MikeM]

Thanks for the info Rik.

That helps alot. I was hoping that I could use a couple of window lift motors to raise and lower the galley lid.

Mike

[D. Tillery]

Rik,
It has been awhile since my last physics class. Can you give me that leverage formula for determining "hatch force" at a certain point to aid in selecting hatch supports/lifters? Thanks

[Dave Nathanson]

Ok, so I guess that a better guess would be that my hatch weighs 75 pounds or so. Maybe more. All I know is that it was difficult to lift over my head before the gas shocks went in.

[R Keller]

D. Tillery:

OK, here goes: In my example, the hatch weighs 48 lbs. and is 50" long. Assuming the weight is distributed evenly across the hatch, you would need a force of 1,200 inch-lbs. (48 lbs. x 25") acting at half of the hatch length from the hinge to support the hatch in horizontal position. My hatch supports that are located only 6" from the hinge would need to generate the same force. Divide the 1,200 inch-lbs. by 6" and you get 200 lbs. total (100 lbs. for each support).

That's it.

As a formula, it can be expressed as: Force = (W*Y)/(Z*N); where W = weight of hatch, Y = distance from hinge to center of object, Z = distance from hinge to mounting point of support, and N = number of supports

Or go to page 1060 of the McMaster Carr on-line catalog http://www.mcmaster.com for a diagram showing the same thing.

Rik

[JamesW]

Here is a quick and easy way to have the push button feature. Use a linear actuator. It is run off of 12VDC and is fairly easy to find. If you do not know what one is, watch MONSTER GARAGE. They use them all the time.

[JamesW]

Here is a quick link to a website that has them. I have not researched the best one for you, price or otherwise but this is a good place to start for information.

http://firgelli.com/

[D. Tillery]

Thanks for explaining that Rik. And that McMaster catalog is AWESOME! What a great source.

[R Keller]

No problem. Glad to help. And yes, you can spend hours looking at the McMaster catalog.

Rik