"Glenn Ashmore" wrote in message
news:wDxHd.21318$EG1.15830@lakeread04...
| I am working on the refrigerator box for the boat. It is top loading and
| the lid is to light to press the weather stripping down good. At the same
| time I don't want the d*#$ed thing dropping on my head when I am digging
in
| the bottom of the box to find a lemon for my tequila. So I figured a gas
| spring would be a good idea. The problem is how to figure out the closing
| force that the spring will give.
|
| The distance between the pivots is 8.5" and the lid pivot will be 1.5"
below
| the fixed pivot resulting in a downward force when the lid is closed. The
| force of the spring is 40 pounds. I vaguely remember that the downward
| component of the force is equal to the total force* vertical
| distance/horizontal distance) or 40*(1.5/8.5) = 7.058 pounds. Does that
| sound correct?
|
| Now the next question is, for the galley slave's sake, how much force will
| it take to start opening the lid? The spring will be pushing down 11"
from
| the hinge and the lift ring is 18" from the hinge. The lid weighs about 2
| pounds and is 20" long.
|
| --
| Glenn Ashmore

Regular fridges have magnetic tape inside the seal to ensure no leakage.
I was thinking that you might work with an overcenter idea on the lid.
Cabinet shops and other woodworking sources will have nice hardware just for
this. If you locate the pivots in the right spot, it will overcenter in the
closed position to hold closed and again in the open and full up position.
I think that if you had the pivot of the spring to the side of the box, at
about a 45 degree angle relative to the centerline of the hinge it'll
overcenter at both ends, assuming you also mount the other end on the side
of the lid. Lower pressure spring, too.