Hinged Lift Bridge Counterweights or Gas Struts?

I used a gas strut.  I have a big/heavy section.  4x3.

I felt it was easier.  I have a stop so it can only go so far when up.

Looks like a good design.  How did you choose a strut?

You may want to consult forum member Susan Deats since she uses a gas strut for a double track main line:

http://www.slsprr.net/features/bridges1.htm

Interesting topic.  I have also wondered how to calculate gas strut size.  The entry to my cellar is through a lift up door in the floor.  My wife has often asked if it could be made easier to lift.  The door is light but if it were to slam down on your toes, you might take notice.  

On the other hand, since I like simple, counter weights on cables and pulleys is a no brainer.  That is it takes no brains to figure it out.

Thanks for the link to Susan Deat's site.  There is a link to the supplier she used for the gas strut.  The supplier has information on picking struts.  I still wonder if there is a way to find detailed specifications on readily available automotive gas struts?  Dan, you are correct about the simplicity of counterweights - I wasn't even planning on having cables or pulleys!

I just went to auto zone and got the strongest one.  My lift up is 4x3 of 1/2 plywood with 1x3 bracing plus the homastoe, pretty heavy.  I felt even the strongest one would not be too strong.  I could always add a second one to make it come down slower.

I use the gas strut too.  I did not do any calculations.  Just bought a big one.  It works just fine.

Ron

  If you want to get slightly fancy, adjustable speed, or lazy, go pnumatic.

Search pnumatic bridge and look for a video post reply by Mike G; a month old tops.

i do not fabricate hinges. Found nice thin ones on Amazon.

Narrow Table Hinge, Brass, 3" L x 1/2" W Hinge, Requires #6 Screws Not Included. i reamed out the holes for #8 screws.

place one on either side of the bridge; raised up so the hinge above the track height,

I ordered a lift strut that fits a Dodge Caravan rear hatch.  I will let you know how it works out.

I like the strut idea. You could also try a storm door closer. They can be adjusted as needed. 

Just an FYI - the pics show what I did to create by opening into the center of my layout. Approx 3' wide x 4' deep opening. You can see the shiny bolt head just above the "faux" crossing gate counterweight. Notice the black paint can hanging down on a cord - this is the actual counterweight to help me open up, and I can adjust the weight by adding more gravel inside the paint can.

Since pics, have also added some LED clusters on the bottom of the arms, created a 555 timer IC based flasher, and a magnetic proximity switch that turns off the flashers when the in the open position.

That's awesome MED.

I could see a balsa/bass bascule bridge done on the idea too 

It could be made more contemporary if you wanted to also.

  I like "piano hinges"; often drilling extra holes along the length for the best grip. Thin, but they need to sit topside with hinge pin down on a lift section leaving a stip to disguise, or need to cut 1/16-ish steps for a flush fit; and to go with hinge pin down, the original holes taper is often reversed so you have to drill all new holes and countersink a taper for scew heads to get a true flush.... And this is provided the hinge you chose will open beyond a 90° so the door can rest with the weight shifted away from the opening... check that.   I like them because there is never hinge to hinge alignment issues and the hinge design keeps things, even dust, from dropping into the gap, into the doorseat area.

Whatever you do, leaving ability to trim and adjust the latch edge or footing as the option for a very last step is a good idea.

A little off topic, and you can delete this if you want.

But, how and what do you use to center the tracks when they come down? I'm having a little difficulty with my homemade version, even though it has worked for the past 8 years. As I said, just asking.

I took an Atlas track joiner and soldered wings on it.  I can slide the joiner over the joint with two fingers and a thumb on the bridge side to line it up.

I painted it red for easy visibility.  

Dude. Gas struts. Make it sound like something from startek. 

Roger Wasson posted:

A little off topic, and you can delete this if you want.

But, how and what do you use to center the tracks when they come down? I'm having a little difficulty with my homemade version, even though it has worked for the past 8 years. As I said, just asking.

I've seen brass dowl and sockets used (cabinet and boating hatch hardware) and also  a blade inserted & soldered to the stationary side and the bridge side has its rail's foot and web spread slightly to accept the blade and the span drops onto the footing.

My update:  I have finished my bridge (except for wiring) and successfully used a gas lift strut.  It took several iterations and two types of lift struts.  The first lift strut was for a minivan hatch.  It was much too strong and I eventually broke the plastic ball joints while trying one of multiple configurations.  I found lift struts than fit 1993-97 Chrysler Concordes for only $9.99 a pair - probably a close out.  These were much shorter and just barely long enough to fit my bridge.   I only needed one lift strut and the force on the mounting brackets wasn't as scary as the minivan lift strut.  The bridge takes a bit over 4lbs to start opening compared to over 10 lbs without the strut.  The bridge stays open and can't fall on anyone.  If I had a completely different setup that accommodated a counterbalance, I might have not used the lift strut.  The difficulty with using a lift strut is finding one that fits the application. The advantages are that it takes almost no room and can work really well.