# Help solving garden gate statics problem

• ckerr83
In summary: Simply wind the rope around a post or other sturdy object a few times, then tie an overhand knot at one end. Now, hold on to the other end and slowly pull it tight. It's a lot easier to do this than it looks!In summary, a wheel gate requires a weight be carried equally on both sides to ensure it is level. The problem is the gate's diagonal brace, which easily deforms together with the gate. To solve the issue, a wire rope is used to hold the gate up.
ckerr83
TL;DR Summary
how to calculate the force required to counteract the sag in a garden gate due to deformation of joints etc.
I am installing a garden gate at the back of my house.

The length (L) of the gate is 1.7m and the mass is 62.6kg, there are 2 hinges positioned 1.3m apart.

The gate has an inherent sag, such that, the bottom corner on the unhinged side is 5cm lower than the corner on the hinged side.

What upward force(to be provided by a spring loaded wheel) is required at the unhinged side to ensure the gate is horizontal?

#### Attachments

• Gate diagram.pdf
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Welcome to PF.
The simple answer is 62.6 / 2 = 31.3 kg.
That assumes the weight is carried equally on both sides of the gate.
But the compressive diagonal on the gate is there to transfer that force to the hinge post.
Is the hinge post leaning, or is the gate sagging due to poor joints?
Poor joints will fail sooner with a wheel under the gate as it will encourage vibration when the gate is moved.

the post is not leaning, we can assume this is vertical, the sag will be due to joint strength etc.

Would the weight be carried equally on both sides? I was thinking that since the hinged side is fixed, this would then become a question of torque and the resultant vertical component?

I would remove the deformation of the gate by installing a wire-rope with a turnbuckle, running it between anywhere close to the point of anchoring to the top hinge and the opposite bottom corner of the gate.

You will basically have a triangle shape which weight will be pulling from the top hinge (anchorage to gate and post needs to be robust) and pushing against the bottom one.

The main problem with wheels are a non-flat=level surface along its trajectory, as well as a twisting effect on the gate each time it is pushed by hand to open or close.

If you still install the wheel, you could loose the anchors of the bottom hinge some and see by the formed gap how much height you can use for wheel with spring before it starts overstressing the bottom hinge (pulling it out from the post).

Last edited:
Rive
As @Lnewqban already pointed out, the problem is the misplaced diagonal brace of the gate. This way that brace has compression and it will easily deform together with the gate. It's better to have tension/strain. Preferably with adjustable length. The wire rope (or a thin metal bar) across the other diagonal is actually a very good idea. You can add a turnbuckle strainer.

256bits and Lnewqban
There also could be some slack in the hinges which should be checked.
The bottom hinge will push in, and the top will stretch out.

First, check if the gate is square by measuring both diagonals. If these are equal then its not a problem with the gate per se.
Then see how much wiggle there is in the hinges by just lifting up the far end.
If that is the cause of the problem, then perhaps a shim added to the bottom hinge to extend it out, and subsequently raise the far end. That could solve the whole problem.

We had a wheel gate, 20 feet or so in length, and it was no problem opening or closing, except for the annoying twisting that was mentioned. With time, gates do tend to sag.

Lnewqban
Place a car jack (or blocks) under the sagging end to make it just above level.
Then run a heavy-gauge double strand, twisted wire from the upper hinge location diagonally across the gate down to the bottom of the drooping end. Fasten very tightly and securely. This should hold it up.

Often, a picture is worth a thousand words.

berkeman, Lnewqban and Rive
AZFIREBALL said:
Place a car jack (or blocks) under the sagging end to make it just above level.
Then run a heavy-gauge double strand, twisted wire from the upper hinge location diagonally across the gate down to the bottom of the drooping end. Fasten very tightly and securely. This should hold it up.
anorlunda said:
Often, a picture is worth a thousand words.
Yes! I was just about to suggest adding a turnbuckle to the suggestion by @AZFIREBALL

One more tip for DIY. This video shows a simple way to eye splice wire rope, that is much better than clamps. On thin wire ropes, it's easy.

hutchphd

## 1. What is a garden gate statics problem?

A garden gate statics problem is a physics problem that involves calculating the forces acting on a garden gate in order to determine its stability and potential for tipping over.

## 2. How do I approach solving a garden gate statics problem?

The first step in solving a garden gate statics problem is to draw a free body diagram, which shows all the forces acting on the gate. Then, you can use Newton's laws of motion and the principles of equilibrium to calculate the net force and torque on the gate.

## 3. What information do I need to solve a garden gate statics problem?

In order to solve a garden gate statics problem, you will need to know the dimensions and weight of the gate, as well as the location and magnitude of any external forces acting on the gate (such as wind or a person pushing on it).

## 4. What are the common mistakes to avoid when solving a garden gate statics problem?

One common mistake is to overlook or forget to include all the forces acting on the gate, which can lead to an incorrect solution. It is also important to use consistent units and to pay attention to the direction of forces and torques.

## 5. Can I use a calculator or computer program to solve a garden gate statics problem?

Yes, you can use a calculator or computer program to solve a garden gate statics problem. However, it is important to understand the underlying principles and equations in order to properly interpret and use the results.

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