Automatic Sliding Driveway Gates on Uneven Ground
Ideally Sliding Driveway Gates should have a nice straight track for the gate to roll on but this isn't always possible or economic, so how can sliding gates be made to work on uneven driveways?
Dips and Humps Across a Driveway
No driveways are absolutely dead straight, they always have some sort of dips and humps in them, which is okay so long as no part of the gate strikes the ground at any point along its travel, otherwise the gate could stop working.
Packing the wheels
To get more clearance under the bottom of the gate the wheels can be packed out, although this does increase the height of the gate from the ground, so it's best to keep the top of the gate lower than the fence in first place just in case.
For smaller packers flat washers will do. Thicker packers can be made from metal flat bar with holes drilled into it for the screws. For larger packers a length of metal box section fitted to the bottom of the gate can be used with holes cut into it for the wheels and mitred ends so it looks nice.
Positioning of the Wheels
The position of the wheels from the each end of the gate effects how well it works on uneven ground, it is a common mistake to place the wheels 25% of the gate width from each end, which in theory is the best spot for handling uneven ground but in reality this makes the gate rock like a rocking chair when it starts and stops regardless of the weight of the gate, causing issues with the automation. The wheels should be around 10% of the gate width from the ends, so a 3m (10') wide gate would have the wheels at around 300mm (1') from the ends for the most stable rock free operation.
Cutting and Filling the Driveway
If a driveway has curbing with drains or similar certain parts may be cut or filled to make the track straight, although if the track is too high off the driveway the bottom of a low slug vehicle may impact it, cuts mustn't be so large a vehicle's wheel drops into it and how it effects drainage must be considered.
Multi-panel Sliding Gates
Sliding gates with two or more panels that stack one in front of the other are better for uneven driveways because the bottom of each panel can have different rakes. Also because each panel is narrower and moves separately they're less likely to strike the ground than a single panel sliding gate.
These gates are commonly known as Telescopic Gates and have the added benefit of requiring less space to open.
Cantilevered Sliding Gates with No Track
If the driveway isn't suitable for a sliding gate with a track but has plenty of room to open then a sliding gate that is cantilevered across a driveway is an option. These have a special rail fitted to the bottom of the gate that must be extended by at least a third of the gate width past the motor and braced as it supports the entire weight of the gate when closed.
This rail runs on two roller carriages, one is installed just off the driveway and the other at end of the extension. These carriages need to be fitted well to the ground with deep concrete footings that won't pull up. A normal sliding gate motor can be used with Cantilevered Gates.
Hanging Sliding Gates
If the driveway isn't suitable for a sliding gate with a track on the ground, doesn't have room for a cantilevered sliding gate to open but head room isn't an issue then a hanging gate is another option. Hanging gates have an overhead track that the gate hangs from with a roller guide system and keeper at the bottom of the gate.
Special rollers are fitted to the top of the gate that run inside the overhead track that must have suitable support. Hanging gates are quite often used for basement car parks. A normal sliding gate motor can be used with the hinging gate.