Limited Side Room Arm Options for Swing Gates

Articulated swing gate operator – Arm options

Articulated swing gate operators have a ‘primary arm’ which connects to the output shaft of the gearbox and a ‘secondary arm’ which connects to the primary arm and the gate.

As the output shaft of the gearbox turns the primary arm also turns which then also pulls the secondary arm which is connected to the gate – therefore swinging the gate open or closed.

To get the gate to open 90 degrees the primary arm needs to swing back past the hinge point to approximately 500mm off the driveway (depending on the length of the arms)

This may be an issue if there is restricted side room (i.e. a fence or wall in the way) and therefore the arm is unable to swing the gate open to the 90 degree position.

What can be done? There are 2 options

Firstly, depending on the amount of room there is for the arm to swing back, one way is to shorten the secondary arm. By shortening the secondary arm it means the primary arm does not have to swing back as far to get the gate open to the 90 degree position. The amount the arm is shortened is done by ‘trial and error’ ! It is done the following way:

• Firstly close the gate and if the secondary arm is say 500mm long as a standard, mark on the gate where the gate bracket would be fitted if the arm was say 300mm long.
• Now open the gate and measure from the primary arm pivot point to the gate where the mark is and see if it also is 300mm
• If the measurements do not agree then try say 350mm and repeat the process
• What you are trying to achieve is seeing if the smaller secondary arm length can both open the gate to the desired open position as well as being able to do so successfully where the same secondary arm length will work for the full open and closed position.

If there is simply not enough room for a modified secondary arm to work, then what will work is a single arm and channel. This works the following way :

• A single arm (normally longer, approximately the combined length of the secondary and primary arm connected together) is connected to the output shaft of the gearbox. On the end of the single arm is a ‘roller’ (like a roller bearing) this roller is mounted on a shaft and then fits up into a channel which is bolted to the gate.
• As the arm swings open the roller inside the channel moves, because the channel is connected to the gate the gate also then swings open.
• This method means there is no side room required, only the width of the gate operator.

Disadvantage !

The single arm and roller channel solves the issue with the side room problem, but they do have other problems :

Firstly, the articulated arms work in a way whereby as the gate comes to the fully closed position the arms straighten out, this actually slows the gate down (by the geometry of the arms) to the extent where if the arms end up straight, the gate will actually stop !

This then means the limits are able to be adjusted so the articulated arms will slow up the gate as it comes into the full closed position and therefore allow the gate to close ‘softly; onto the closing post or stop. The single arm and roller channel does not have this function, so it can mean the limits are harder to set and also the gate may come onto the stop much harder.

Secondly, it is also then normally recommended to use gate locks (to the ground or fixed post), if the gates are forced the single arm and roller channel system means the load is placed straight back onto the gears of the gearbox, which may well damage the gears or output shaft of the gearbox.