What size post and hinges do you need
Choosing the right size post and hinges for your gate depends on four things:
Gate Weight
Heavy gates need stronger hinges and posts of course. Try to make your gates strong but light by using aluminium over steel and tubular sections over solid ones. Larger thin wall sections also add to rigidity without adding much weight. 65x3mm SHS will be stronger and lighter than 50x5mm SHS for example. For timber gates you also need to consider whether they will take on water. A waterlogged gate is super heavy and can blow out a set of hinges in no time.
Height to Width Ratio
Ever tried holding an extended ladder sideways rather than upright - its a lot harder right? The ratio of height to width makes a big difference to your hinge selection too. Wide gates need higher rated hinges. This simple table will help you to chose the right size hinges. Multiply your gate weight by the factor in the table to get an Effective Gate Weight.
| Height to Width Ratio | 1 : 1 | 1 : 1.5 | 1 : 2 | 1 : 2.5 | 1 : 3 |
| Gate Weight Multiplier | 1x | 1.5x | 2x | 2.5x | 3x |
Is the gate automated
Linear gate operators put a huge amount of sizeways force on the hinges. Consider the Roger Smarty-4 for example. Its max thrust is 4500N or 450kg. Most of that force is being driven back into the hinges in order to get the gate moving. This needs to be added to the existing weight of your gate. Having a hinge design that is designed to take sideways loads in addition to downward ones is strongly recommended. Hinges with a tapered thrust bearing on the bottom such as the Cais and Lynx bearing hinges should be used for heavy automated gates. And super heavy gates should use an articulated gate operator to reduce the force on the hinges.
What is the potential wind load
Wind load is a consideration for gates with a high percentage infill. Heavy steel gates with perforated sheet steel or similar infill should have a little extra strength added to the posts and hinges.
Post Size Selector
Many a nice gate is let down by being swung from too light a post. Use the table below to determine your post size. Use steel over aluminium and use a wall flange where possible. And for concrete in posts make sure your hole size and reinforcing are sufficient for your soil type.
| Weight Per Leaf | 40 kg | 50 kg | 100 kg | 150 kg | 200 kg | 300 kg |
| Post | 65x3mm | 75x3mm | 100x3mm | 125x4mm | 150x5mm | 200x5mm |
For help to choose the right posts and hinges for your gate please give us a call so we can make more detailed engineering calculations for your set up.
