The issue of installing automatic sliding gates on slopes has come up over the years and has been the subject of much debate. These are doors mounted on two wheels that run on a rail fixed to the ground that open and close by means of a sliding door motor.
Many years ago, manufacturers of gate automation equipment told installers that up to a 4% slope was acceptable for sliding gates. That gives a height change of 4 cm for each meter of track. With a typical track length of 6m, that means a total height change of 24cm.
Anyone who has ever done basic physics or ridden a bicycle will know that things with wheels are pulled down slopes by gravity. And on a slope, a sliding gate is exactly the same, it requires power from the gate motor simply to stay in one position. Once it is moving downhill, it will require a lot more force from the gate motor to stop it. And rolling a stationary gate uphill requires considerably more force than it would on a level track.
Sliding gate motors are designed to move an automatic gate back and forth and stop it on level ground. They are not built to cope with the different forces involved when automatic gates are driven uphill or controlled as they descend.
The different forces involved in operating a slide gate motor on a slope will also affect its operation and there are likely to be difficulties even setting it up. Furthermore, without intelligent electronics, this type of use is likely to cause rapid problems with mechanical elements, such as gearboxes, that withstand forces greater than those specified in their original design.
The suggestion that sliding gates could be automated on sloped terrain was made before the most recent tragedies caused by automatic gates. These have illustrated how a poorly designed and installed automatic sliding door produces incredible shear forces and consequently acts like a horizontal guillotine.
Today, we have additional safety devices such as safety edges and obstacle detection that are integrated into the gate motor or control panel electronics. However, the safety features of the gate are only as good as the engineer who designs and installs a safe automatic gate system.
Now it’s hard to find gate automation manufacturers who recommend their equipment for use with gates on slopes of any kind. Even with safety edges, it would probably be impossible to ensure that such an installation meets today’s requirements for door automation safety.
Today, safety is rightly placed as the number one consideration when designing and installing automatic door systems. So if you have a slope and need a sliding door, the best answer is to level the ground or use a cantilever door.