bajacalifornian
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Pull Spring Post with tire and truck comment
For a Baja Project
Illustration of a working model . . .
I need to order two springs for a door - ramp about 54 inches wide and 80 inches tall.
Will know actual weight in a day or so when built. Steel frame, sheet of plywood etc., maybe 180 pounds and more.
Kindly share your advice, even where to purchase in San Diego County or internet.
Gracias!
[Edited on 7-31-2012 by bajacalifornian]
American by birth, Mexican by choice.
Signature addendum: Danish physicist — Niels Bohr — who said, “The opposite of one profound truth may very well be another profound truth.
Jeff Petersen
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MikeYounghusband
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Jeff, just google pull spring and the first hit on the list has exactly what you need. I think its called Alababa Spring.
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durrelllrobert
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The correct term for the spring shown on "the working model" is Extension Spring. However I don't think that this is the proper (or best) spring to
use when you are trying to make the ramp easier to lift. I would be using a Torsion Spring.
Torsion springs can store and release angular energy or statically hold a mechanism in place by deflecting the legs about the body centerline axis.
They offer resistance to twist or rotationally applied force. A spring of this type will reduce in body diameter and increase slightly in body length
when deflected in the preferred direction of the fabricated wind. Depending on the application, torsion springs can be designed to work in a clockwise
or counter-clockwise rotation, thus determining the direction of the wind. Common torsion springs are those used in a clothes pin or a garage door
In your case the "mandrel" will be the pivot point on the ramp which I assume is 3/4 inch diameter. If that's the case this is the spring(s) you want:
Product Overview
Close Window
View Larger 302 Stainless Steel Anti-Backlash Torsion spring with 0.045" wire diameter and 1"OutsideDiameter
--------------------------------------------------------------------------------
Specifications
Spring Size
I.D. 0.7920 inch
Leg Specifications
Leg Angle 180°
Leg Length Equal Leg Length
End Style Straight Torsion
Construction
Spring Material Stainless Steel
Finish None
Available from SDP/SI in New York 800-819-8900
Bob Durrell
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bajacalifornian
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durrelllrobert . . . you are the guidance I was seeking. I´ve worn out the links to all springs on my computer, but you put it together. The spring
fits neatly below the hinge system on the bottom . . . yet to be built. Thank you
I now know the weight of the door to be 275 pounds.
[Edited on 7-27-2012 by bajacalifornian]
American by birth, Mexican by choice.
Signature addendum: Danish physicist — Niels Bohr — who said, “The opposite of one profound truth may very well be another profound truth.
Jeff Petersen
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durrelllrobert
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| Quote: | Originally posted by bajacalifornian
durrelllrobert . . . you are the guidance I was seeking. I´ve worn out the links to all springs on my computer, but you put it together. The spring
fits neatly below the hinge system on the bottom . . . yet to be built. Thank you
I now know the weight of the door to be 275 pounds.
[Edited on 7-27-2012 by bajacalifornian] |
That's 138 pounds per spring. 2 springs rated at 150 pounds at 180 degrees deflection should do the trick.
Bob Durrell
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Maderita
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Are you accounting for the weight of the door out at the end? Essentially, the door height (approx. 5' or 6') is a long lever. At the end of that
lever is more than 50% of the door's weight, as you start to lift from the dirt.
I don't know the math, but I'm guessing that it would take many times that spring force just to be of some assitance. To do the math, you'd need to
know the height of the door and the distance from the hinged edge that the spring end makes contact (maybe something like 2" to 6" ?).
At the level position, how much force would it take to lift 138 lbs. on the end of a 5' lever? I think the answer will point to the torsion spring
option as being unrealistic.
My horse trailer rear door/ramp is well over 200 lbs. after adding a lot of steel and thick plywood. A hand winch, mounted on the fender, allows for
one-handed easy operation by my less-strong friends. The wire rope runs up and over a pulley which is mounted on the rear vertical support near the
roof line. The end of the wire rope has a clip/carabiner which detaches from the door when not in use.
Winch $22 at Harbor Freight
http://www.harborfreight.com/1000-lb-capacity-hand-winch-656...
Pulley $6
http://www.harborfreight.com/4000-lb-capacity-lifting-block-...
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bajacalifornian
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You both are correct. At this pooint, many torque spring manufactures offer as a free service the calculations. The door will be 2x6 doug fir in a 2
1-2 x 1 1-2 1-4 inch steel frame and support for the ramp. I need to do the layout for them, nnd they will show me the spring.
I wanna pull this together in the baja photo lugar.
American by birth, Mexican by choice.
Signature addendum: Danish physicist — Niels Bohr — who said, “The opposite of one profound truth may very well be another profound truth.
Jeff Petersen
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bajacalifornian
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Location: Loreto/Lopez Mateos/Rosarito
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The truck came with all wrong tires. Had 7.50 16 trailer tires on the back and much too wide on the front. I looked for used while in San Diego and
after 2 days, found J and M used tire shop , 2275 National Ave above the Naval Station area. For a Baja vehicle, J and M has nice tread and tires for
really good prices. Next time around I would call ahead and order what I needed. He gets them out of LA. Here in Mexico, less is more. Crossiing
them other than on your car is another story.
Just a note. With the exchange, the truck was less than 5K U.S. and already imported. Not a creampuff. But, unmolested none the less.
American by birth, Mexican by choice.
Signature addendum: Danish physicist — Niels Bohr — who said, “The opposite of one profound truth may very well be another profound truth.
Jeff Petersen
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