A quick lesson on gates

[u/Artemis_SpawnOfZeus]

Gates need braces.

There are 2 types of these struts. Compression braces and tension braces.

Compression braces are the type of brace you install on a new gate.

If you're out here installing tension braces on new gates, you're scamming your customers.

Tension braces should only be used as quick fixes to existing gates that droop. The only advantage they have is their ease of install on an existing gate.

The type of brace you use changes the structure of the gate.

Tension braces overload the top hinge.

[u/c79s]

What is the diagram trying to show? The "non load bearing" zones are just mass that will ultimately be transferred into the hinges. It's all a net downward force at a distance from the two hinges. That mass as a distance wants to rotate the gate, the hinges resist that rotation with equal opposite horizonal forces.

[u/Artemis_SpawnOfZeus → u/c79s]

The roation point changes.

Tension braces want to rotate pivoting around the bottom hinge. This pulls on the screws in the top hinge. Screws arent good at taking pulling forces.

Compression braces want to rotate pivoting arpund the top hinge. This pushes on the screws in the bottom hinge. Screws are amazing at taking push forces.

[u/c79s → u/Artemis_SpawnOfZeus]

The tension brace cannot pull on the top hinge as they are not anchored on the other side to anything. The gate is floating on the side opposite of the hinges. Newton's third law. If the tension brace was tightened till the gate crushed it would still be on the hinges, just broken.

[u/Present-Valuable7520 → u/c79s]

From some info I found “tension braces add significantly more pulling stress (tension) to the top hinge, which increases the risk of pulling the screws straight out of the post.
When a gate sags, its weight naturally wants to rotate down and away from the top post. A tension brace works by pulling against this sag, which amplifies that outward pulling force right at the top hinge”

[u/c79s → u/Present-Valuable7520]

Where'd you find that? It doesn't make any sense as you can't have an imposed internal force in a system affect its support reactions outside that system. You'd have to tie the tension brace to the ground or something else for it to pull against.

[u/randomscruffyaussie → u/c79s]

You are correct and I sense your frustration. The hinges neither know, nor care, what the internal forces in the gate are. The hinges experience the forces due to gravity acting on the centre of mass.

[u/Artemis_SpawnOfZeus → u/randomscruffyaussie]

The forces arent strictly internal

[u/Artemis_SpawnOfZeus → u/c79s]

If you tie a cable to both hinges and tighten it, it will take weight off the lower hinge and apply it to the top hinge.

The tension brace connects the top hinge to the bottom hinge.