What rating gas strut for loft hatch?

[perky416]

Hi guys.

Im about to make a custom size loft hatch with folding ladders from scratch. The only thing im having trouble with is the gas strut to lower the hatch gently rather than it swing down fast under its own weight.

How do i work out what Newton strut to go for? Is there a type range or something?

Thanks

 

[Harry Bloomfield]

Im about to make a custom size loft hatch with folding ladders from scratch. The only thing im having trouble with is the gas strut to lower the hatch gently rather than it swing down fast under its own weight.

It read as if you need a damper, rather than a gas strut.

 

[perky416]

If thats what it is, they are listed as downward gas springs on iron mongery direct.

 

[Harry Bloomfield]

If thats what it is, they are listed as downward gas springs on iron mongery direct.

A gas strut uses a compressed gas, to act as a powerful spring to provide assistance in lifting things like heavy boot and bonnet lids. I think what you are asking for is just something to slow the hatch down, make it more controlled - a damper will do that, rather than a gas strut.

 

[Why Not Indeed]

How do i work out what Newton strut to go for? Is there a type range or something?

You need to know the weight of the thing you're trying to slow down, to answer that.

 

[perky416]

A gas strut uses a compressed gas, to act as a powerful spring to provide assistance in lifting things like heavy boot and bonnet lids. I think what you are asking for is just something to slow the hatch down, make it more controlled - a damper will do that, rather than a gas strut.

Yeah thats what im after, ive googled loft hatch damper and nothing seems to come up. Everything is described as a loft hatch strut or spring.

You need to know the weight of the thing you're trying to slow down, to answer that.

Is it literally just a case of converting the kg to N?

 

[Harry Bloomfield]

Is it literally just a case of converting the kg to N?

You would also need to take into account the distance from the pivot point, to where a strut is mounted, plus the desired reach of the strut (difference between closed and fully stretched).

 

[perky416]

If i know the weight and the reach how would i know what NM strut/damper to pick?

 

[Harry Bloomfield]

I am inclined to suggest a simple friction damper - Three metal disks, with some friction material between them, clamped together with a bolt with a strong-ish spring on it. Middle disc is bracketed to movable hatch, both outer disks to fixed hatch surround. Tensioning the bolt, increases spring pressure, which in turn increases the damping effect on the hatch.

 

[foxhole]

Hi guys.

Im about to make a custom size loft hatch with folding ladders from scratch. The only thing im having trouble with is the gas strut to lower the hatch gently rather than it swing down fast under its own weight.

How do i work out what Newton strut to go for? Is there a type range or something?

Thanks

Do you have weak wrists? Loft hatch weight should be minimal.

 

[Harry Bloomfield]

Do you have weak wrists? Loft hatch weight should be minimal.

I can understand him not wanting it to come flying down, like mine does, but I learned to duck after the first couple of contacts

 

[perky416]

Do you have weak wrists? Loft hatch weight should be minimal.

Lol and the ladders attached to the hatch? They arent made from polystyrene lol. Nearly ever loft hatch available with ladders attached has some form of soft open system.

 

[perky416]

I am inclined to suggest a simple friction damper - Three metal disks, with some friction material between them, clamped together with a bolt with a strong-ish spring on it. Middle disc is bracketed to movable hatch, both outer disks to fixed hatch surround. Tensioning the bolt, increases spring pressure, which in turn increases the damping effect on the hatch.

Do you have any links to something similar to illustrate please? I cant quite picture what yoj mean.
My current hatch uses a spring either side of the ladders but i wanted to get away from the springs. A lot of websites offer downward struts i just dont know what force rating to buy.

 

[Harry Bloomfield]

Do you have any links to something similar to illustrate please?

No, it would probably have to be something DIY. I had in mind what they used to use as a caravan friction stabiliser. One arm attaches to rear of car, other arm to the caravan hitch, with the adjustable friction plates forming the hinge. The friction damps the caravan from swaying.

Early cars used a similar friction damper system, before they began using hydraulic dampers, to damp out vertical movement.

If I understand you correctly, all you are trying do is slow the hatches progress down, once you unlatch it.

Another idea - Could you adapt an hydraulic door closer to the task. They provide both a bit of spring assistance, but include a damper to limit the speed of closing of a door - which is what you want. The damping level is adjustable with a screw.

 

[foxhole]

Lol and the ladders attached to the hatch? They arent made from polystyrene lol. Nearly ever loft hatch available with ladders attached has some form of soft open system.

Never seen one . Hatch is lowered using a pole .