If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
|
#1
|
|||
|
|||
Cobra trailer stuck closed
Anyone have any experience with the gas strut failing in the compressed position? My 2002 fiberglass top didn't quite open fully on its own in March, so I ordered replacement struts. Unfortunately, the next time out the top only opened a few feet, then progressively less as I tried to lower and then raise it. Now it is stuck closed and will not open even a crack despite two people hauling on it. Did I mention the glider is still inside? I can't get to the strut from the front door with the fuse and wing in the way.
So, I'm trolling for ideas on how to force the top open without damaging something. Thanks in advance. |
#2
|
|||
|
|||
Cobra trailer stuck closed
With zero pressure in the struts, you've got to lift the whole weight of the top and it's heavier than hell! I used a block and tackle from the shop roof. The rear handles were strong enough to take the load on a Komet..............Should be OK on a Cobra. Have 2X4's ready to prop it open and be carefull ..............its little more than a gilatine! Three man job, one on the hoist and two placing props.
Let us know how it worked out, JJ |
#3
|
|||
|
|||
Cobra trailer stuck closed
With zero pressure in the struts, you've got to lift the whole weight of the top and it's heavier than hell!
It may be worse than that: If the piston seals failed but the rod seals held, all the gas pressure is now on the annulus or ring-side of the gas spring thus keeping the rod from extending swiftly. Applying up-pressure on the lid and then waiting may do the trick. Good luck! Uli 'AS' |
#4
|
|||
|
|||
Cobra trailer stuck closed
Uh-oh, someone doesn't understand how gas springs work:
It may be worse than that: If the piston seals failed but the rod seals held, all the gas pressure is now on the annulus or ring-side of the gas spring thus keeping the rod from extending swiftly. Applying up-pressure on the lid and then waiting may do the trick. Good luck! Uli 'AS' |
#5
|
|||
|
|||
Cobra trailer stuck closed
On Saturday, June 9, 2018 at 9:21:30 PM UTC-4, Steve Koerner wrote:
Uh-oh, someone doesn't understand how gas springs work: I do - I used to design similar devices.... Uli 'AS' |
#6
|
|||
|
|||
Cobra trailer stuck closed
At 03:22 10 June 2018, AS wrote:
On Saturday, June 9, 2018 at 9:21:30 PM UTC-4, Steve Koerner wrote: Uh-oh, someone doesn't understand how gas springs work: I do - I used to design similar devices.... Uli 'AS' It might help to unbolt the hinges and lift the lid evenly with two winches? |
#7
|
|||
|
|||
Cobra trailer stuck closed
On Saturday, June 9, 2018 at 8:22:46 PM UTC-7, AS wrote:
On Saturday, June 9, 2018 at 9:21:30 PM UTC-4, Steve Koerner wrote: Uh-oh, someone doesn't understand how gas springs work: I do - I used to design similar devices.... Uli 'AS' Well Uli let's talk gas springs for a moment... If you actually did understand how gas springs work - the everyday gas springs used for car tailgates and glider canopies and Wing Riggers and Cobra trailers - then you would know what a silly suggestion that was. Gas springs already have a controlled leak across the piston. That is what establishes their wonderful damping property. Once stopped, there is no pressure differential across the piston at all. The nominal force produced by a gas spring does not relate to pressure across the area of it's piston (as is the case for a pneumatic drive cylinder); the gas spring force arises from the pressure exerted across the cross-sectional area of the rod itself. Anyway, don't feel too bad about getting this wrong. I did a google search so that I could provide a link for you. Amazingly, virtually every little story that came up about how gas springs work on the internet was also wrong -- including the wikipedia article on gas springs and a bunch of youtubes on the subject. It wasn't until I downloaded a lengthy manufacturers catalog that I came upon actual sound science that tells the story correctly: http://pdf.directindustry.com/pdf/di...57-175377.html So back to the original poster's issue: You do not need to worry about pressure leaked to the wrong side of the piston and holding the clamshell down.. That is a red herring of the highest order. |
#8
|
|||
|
|||
Cobra trailer stuck closed
Guillotine (https://en.wikipedia.org/wiki/Guillotine)
Agree with JJ. (but not with his spell-checker) Use a hoist to lift by the handles, but only far enough to put a couple of blocks under the lid. Then run a strap all the way around the trailer top so when you are raising it and working under it, you aren't relying solely on the handles and their attachment points. Also, since it is now attached to the roof of your shop, and is at a serious angle, make sure to block the wheels, set the brake and use some method of securing the strap so it cannot try to slide off the end of the trailer top. |
#9
|
|||
|
|||
Cobra trailer stuck closed
On a Cobra trailer for Duo Discus, I used a hoist in a hangar to the handles then ran a sling under the lid (heavy ratchet straps, could be adjusted to take the weight off the handles) while replacing a dead strut. Yes, heavy and above a height you'd want to lift to.
Requires pulling the wing out to easily access the hardware and remove/replace the strut. Initially one strut had failed on this trailer, two were purchased but only one replaced. Suggest that if one strut fails, replace both as soon as you can. This job is easy with the right tools. The rod ends from the original struts may be needed for the new ones. Jim |
#10
|
|||
|
|||
Cobra trailer stuck closed
Uh.. I forgot the glider is still inside, so JJ is correct- raise the lid all the way, prop it up and hope the handles hold while raising it. No way around it as far as I can see.
|
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Wanted to Buy : Ka-6CR Closed trailer | Tango Juliet | Soaring | 0 | January 5th 15 01:31 AM |
2013 Cobra trailer price list needed for TA trailer sale | [email protected] | Soaring | 0 | June 22nd 13 02:42 PM |
Looking for closed trailer for ASK-21 or Grob-103 | kirk.stant | Soaring | 0 | September 23rd 12 06:26 PM |
Cheap Cobra Trailer Lights 1998 Trailer on E-bay USA ONLY! | flyingmr2 | Soaring | 4 | November 16th 10 02:11 AM |
WANTED (USA): Blanik L-23 Trailer (Open or Closed) | CLewis95 | Soaring | 0 | November 14th 08 09:23 PM |