How to slow the closing of a rolling gate
How to slow the closing of a rolling gate
(OP)
Some folks installed a rolling gate on a 7% grade. To open it, it rolls uphill. To close it, it rolls downhill.
The gate rolls along a 20' track between a brick house and the end-post of a fence along an alleyway. It rests against the fence end-post (6x6 pine) when closed, and against the house when all the way open. The track is anchored to a concrete driveway, and the gate is made of a 10' x 6' steel frame with cedar planks affixed to it. Needless to say; it is VERY heavy (300lbs?), hard to open, and very dangerous if left to close alone. If it were accidentally let go I imagine the impact would topple the end-post it rests against while closed, and end up in the alley.
I would like to minimize the damage done by the closing gate if let go. My idea is to slow the velocity of the gate -- but not sure what the best method is.
Some ideas are;
1. Counter weight - Fix an eye ring to the home, attach a rope to gate, run through ring and attach to some clock weights. Not sure if these will have enough slowing effect... and may allow the gate to be too easily opened? Could change with weather/rain?
2. A tension spring that works similarly to the above. Again, would it slow the gate in time?
3. A hydraulic fixture with a telescoping arm that when pulled on, will only pull out at a fixed, slow rate. This seems ideal but does anyone make them and what are they called?
Any suggestion are welcome!
The gate rolls along a 20' track between a brick house and the end-post of a fence along an alleyway. It rests against the fence end-post (6x6 pine) when closed, and against the house when all the way open. The track is anchored to a concrete driveway, and the gate is made of a 10' x 6' steel frame with cedar planks affixed to it. Needless to say; it is VERY heavy (300lbs?), hard to open, and very dangerous if left to close alone. If it were accidentally let go I imagine the impact would topple the end-post it rests against while closed, and end up in the alley.
I would like to minimize the damage done by the closing gate if let go. My idea is to slow the velocity of the gate -- but not sure what the best method is.
Some ideas are;
1. Counter weight - Fix an eye ring to the home, attach a rope to gate, run through ring and attach to some clock weights. Not sure if these will have enough slowing effect... and may allow the gate to be too easily opened? Could change with weather/rain?
2. A tension spring that works similarly to the above. Again, would it slow the gate in time?
3. A hydraulic fixture with a telescoping arm that when pulled on, will only pull out at a fixed, slow rate. This seems ideal but does anyone make them and what are they called?
Any suggestion are welcome!





RE: How to slow the closing of a rolling gate
Presumably, you're using some sort of chain drive. If that's geared, then the gearing itself can provide so level of slowing, but the wear and tear on the gear teeth might be excessive.
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RE: How to slow the closing of a rolling gate
RE: How to slow the closing of a rolling gate
To minimize effects of the mass of the gate whacking the post, one could attach an industrial damper on either element.
Then, of course, most any of these engineered solutions may be more expensive than redesigning the gate frame out of aluminum or composite material. Just a thought.
TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering
www.bluetechnik.com
RE: How to slow the closing of a rolling gate
How about a gate opener?
RE: How to slow the closing of a rolling gate
Sounds like a fun engineering project if you have some free time on your hands. It's amazing how little energy it can take to operate an extremely heavy system that is well balanced.
Good luck to you.
Terry
RE: How to slow the closing of a rolling gate
The gate is not on a chain drive now -- and the budget won't allow.
It seems that the counterweight system is the way to go, with the addition of a damper for emergencies.
A series of pulleys (compound arrangement) is the way to go -- I'll need to research how to get 10' of cable to travel @ 3' in height. BrianPetersen -> What kind of chain is recommended for this? Does it run through geared pulleys?
I also love the idea of a passive brake -- although this would need to be non-locking so the gate can be operated from both sides.
Thanks again for the inspiration!
RE: How to slow the closing of a rolling gate
At the chosen speed, can you accept the risk that the gate will squish a car or person standing in the way?
RE: How to slow the closing of a rolling gate
There's a safety risk in the gate closing too fast. If someone is in the way or a car driving by at the time it smashes through the end post -- it won't be pretty. Not one for it closing too slowly.
I am having trouble devising a pulley system for the counterweight however. I'd like to get 10' of cable travel to @ 3-6' in height -- are there calculators for this?
Thannks
RE: How to slow the closing of a rolling gate
Read through the attached, after you have grasped the principals involved it will be easy for you to calculate what you need.
B.E.
You are judged not by what you know, but by what you can do.
RE: How to slow the closing of a rolling gate
Thanks for sharing that. Very understandable, fun, and practical -- excellent resource!
I'm still unclear re: mechanical advantage and travel distance. They say if the mechanical distance is 2, you'll need to haul in twice the amount of rope. So with a gun tackle rig (2:1) lifting an object 10' high, you would pull in 20' of rope. They did not say if doubles each time.
If I rig a luff tackle with a 3:1 mechanical advantage, will I need to haul in 30' of rope to lift the object 10'?
Also -- does anyone know of an affordable maker of quality pulleys? I'd like something that lasts outside for years to come... and really like Harken but simply can't afford them for this project && am weary of going with National hardware and others I see on amazon.
RE: How to slow the closing of a rolling gate
Fabricate a 10+ foot long pipe with pulley on top. Sink the pipe into the ground at the end of the rail. Attach a cable to gate, over the pulley, down the hole, and add sufficient lead weights for counterbalance.
(Simplified solution, but you should get the idea. If you have 10+ feet of depth available.)
TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering
www.bluetechnik.com
RE: How to slow the closing of a rolling gate
If it's a 6 feet tall gate why are you constrained to 3 feet of height for your counterweight travel?
RE: How to slow the closing of a rolling gate
It'll be less than 6' due to height of weight, + height of attachment pulley at top of gate. I also imagined I'd be rigging to the center point of the gate rail (midway to the top).
Can you confirm I'll need to haul in 3' of rope to lift an object 1' when rigged with a 3:1 mechanical advantage system?
Thanks!
RE: How to slow the closing of a rolling gate
RE: How to slow the closing of a rolling gate
RE: How to slow the closing of a rolling gate
Mint julep has done the heavy lifting for you in his last post.
So now work backwards. What is the travel of the gate, I think you said 10'-0" How you have the mechanical dis-advantage of getting the short vertical lift. did you say 3'-0" that gives you a ratio of 3.333 so now you say the gate weighs 300 Lbs that would mean your block W in mint julep's sketch would have to weigh 1000Lbs.
Now the thing that you are going to have to play around with is the friction in those blocks.
B.E.
You are judged not by what you know, but by what you can do.
RE: How to slow the closing of a rolling gate
Actually not too sure how it works at the moment, but would seem to be people powered, so can't need that much force to open / close safely unless they are training to be a line backer or a wrestler....
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: How to slow the closing of a rolling gate
I sketched a 1:4 mechanical disadvantage, so you are in the neighborhood of 90 pounds weight needed when rolling resistance and friction are considered, with a lift of 30 inches.
RE: How to slow the closing of a rolling gate
If manual then how about a 'dead man brake' built into the handle?
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: How to slow the closing of a rolling gate
Neglecting friction I get 36 LBs for the 7% grade with 120 LBs on the counterweight.
I used a metric calculator with the force on the gate being 161 Newtons.
B.E.
You are judged not by what you know, but by what you can do.
RE: How to slow the closing of a rolling gate
Regardless of how it is done there is more money and effort involved in making the gate close. Why not do the job right and level the gate?
RE: How to slow the closing of a rolling gate
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: How to slow the closing of a rolling gate
I have seen that system and totally forgot about it. If I remember right, the catenary effect of the chain increases the force on the gate as it gets closer to the closed position.
B.E.
You are judged not by what you know, but by what you can do.
RE: How to slow the closing of a rolling gate
http://www.oldhouseonline.com/build-gate-doesnt-sa...
has a picture of the idea
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: How to slow the closing of a rolling gate
As far as damping the final travel of the gate to prevent banging, you might look at a door check like this:
http://www.dictator.nl/engels/fredo.htm?http://www...
They make the door checks for swinging doors as well as sliding doors.
Kyle
RE: How to slow the closing of a rolling gate
And briceburg, it will do no good to try and blame the posters on this forum for any problems that may occur with your gate system.
RE: How to slow the closing of a rolling gate
http://www.gemplers.com/product/173161/Hand-Crank-...
actuation would be kind of slow, so a call for an electric gate opener would likely follow shortly thereafter.
http://www.chamberlain.com/garage-door-openers/cha...
RE: How to slow the closing of a rolling gate
Mike Halloran
Pembroke Pines, FL, USA
RE: How to slow the closing of a rolling gate
RE: How to slow the closing of a rolling gate
Mike Halloran
Pembroke Pines, FL, USA
RE: How to slow the closing of a rolling gate
RE: How to slow the closing of a rolling gate
If you go that route, and I am not sure the OP will, Then a garage door wind up spring attached vertically to the wall of the house would work.
Put the cables one to the top of the gate and one to the bottom, and let the gate wind up the spring as it closes.
It may be possible to dispense with the top cable if the design of the garage counterbalance spring will allow it.
B.E.
You are judged not by what you know, but by what you can do.
RE: How to slow the closing of a rolling gate
RE: How to slow the closing of a rolling gate
It could definitely be made to work.