Troubleshooting Gate Operators

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Warning: Troubleshooting gates should only be done by trained service technicians due to the dangers of injury, death, and property damage from electrocution, and the possibility of crushing, breaking, or severing of limbs from moving parts. All gates should be installed and serviced by trained professionals and meet all local, state, federal, and UL guidelines and safety regulations.

If the gate closes on vehicles or people, immediately open the gate using a manual override, block access to the gate, or leave the gate closed. Once the gate is secured in the position you wish, turn off power to the gate until repairs can be made. DO NOT allow operation of the gate when it's safety devices are not operating to specifications.

Vehicular gate operators are NOT intended for pedestrian traffic. A separate "man gate" should be used for pedestrian traffic in and out of a facility.

Most gate problems occur due to a lack of maintenance or improper maintenance. Gates should be regularly serviced by a trained service technician. A regular routine of service and maintenance should be planned for in the budget and scheduled throughout each year. Typical maintenance tasks that should be performed on gates include:

For all gate types:

  • Oil and grease gates with the recommended lubricants.
  • Clean parts using the proper solvents.
  • Inspect moving parts for wear or damage and replace immediately if necessary.
  • Check travel limit adjustments regularly. Your gate should not open, or close into it's catch (if it has one) with a bang. It should come to a stop just before contacting any catch fork or limit bumpers installed on the fence.
  • Test loops, beams, and sensor edges regularly and immediately replace or repair them if not working correctly.

For chain driven slide gates:

  • Adjust the chain tightness regularly. Do not have the chain adjusted too tight. You should have about 2" to 3" of chain "droop".
  • Lubricate the chain occasionally with a product designed for such. Do not use WD-40.
  • Clear weeds and rocks away from the chain and gate path.
  • Keep track (if one is used) free from debris and in good working order (unbroken and not lifting up or bending).

For Vertical Lift gates:

  • Check the gate balance occasionally by disengaging the clutch and seeing if the gate will settle in a "halfway open" state. If the gate wants to open all the way or close all the way when the clutch is not engaged, then the gate is unbalanced. An unbalanced gate puts more work on the gate motor and other parts which can cause premature wear. If a sign is hung on the gate, this will affect the balance and it should be checked.

For gates that have a battery backup:

  • Check the condition of the battery and follow any maintenance instructions for your particular type.
  • Check that the charging device is putting out the correct voltage to the battery.


Types of Malfunctions

Gate operator problems can be broken down into these situations.

  • It won't open;
  • It won't close;
  • It's stuck partway and won't do anything;
  • Or, it's open and attempts to close, but it stops partway and reopens. (It may repeat this several times).

In situations 1 - 3, the first thing to check is power.

  • Is the breaker tripped? If it is, reset it. If the breaker trips again immediately or soon after resetting it, the operator is pulling too much current. This could be a result of the gate binding or sticking, or an electrical fault in the operator. Do not reset the breaker again until this is fixed.
  • Most operators have a reset switch on the motor itself.[1] This is a thermal overload and will trip if the motor gets too hot. Reset it and see if the gate then functions[2]. If the motor overload is constantly tripping, this is an indication that the gate itself may be damaged or incorrectly balanced[3], or that the operator itself is underpowered for the application.
  • Some operators have a fuse on the control circuit board inside the operator. Check to see if the fuse is blown and replace if it is. Make sure to replace the fuse with one of the correct type and current rating. This should be marked on the board or a label inside the operator. Do not assume that the blown fuse you took out is the correct type. If the fuse blows again after replacement, this is an indication that the control circuit board or one it's accessories (loop detector, edge sensor, radio remote receiver, etc.) is damaged and will need to be replaced. Try disconnecting all accessories and replacing the fuse again. If it does not blow, reconnect the accessories one by one until it does to locate which accessory is causing the problem. If you find that one of the safety devices is causing the fuse to blow, leave the gate powered off until the device can be repaired or replaced. Do Not operate the gate with any of the safety devices disconnected.
  • The "limit switches" for the gate operator may be out of alignment and are cause the gate to "overtravel", either in the fully open or fully closed position. This may cause the gate to jam and as a result the breaker or fuse may trip.
    • When the gate is closing make sure that the gate is not slamming into its catch fork or bumpers. It should be stopping just short of these.
    • When opening, watch that the chain end is not being pulled into the side of the operator cover or enclosure.


If the power seems OK and the overload is not tripped:

  • If the gate does not open, use a short length of wire to short the terminals for the gate open input. This may be labeled "Gate Vend" or the like. If it opens with this then the problem is somewhere back towards the access device. If it does not open then troubleshooting should be directed at the control circuitry for that particular brand of operator.
  • If the gate will not close, disconnect the wires for the gate open input and see if it will close. if it does not, check any safety devices installed on the gate. Loop detectors, beams or reversing edges. The gate control board may or may not have indicator LEDs showing the status of these safety inputs. Common failures for safety devices are:
    • Loop detectors
      • Bad or incorrectly installed[4] loop.
      • Loose or broken connection from the detector to the loop wires.
      • Bad loop detector, or no power to the detector.[5]
    • Safety Beams
      • Obstruction to the beam. (Dirt on lens, vegetation)
      • Misaligned beam.
      • Loss of power to the beam components, or a defective beam.
    • Safety Edge
      • Malfunction or short circuit in edge.
      • Edge being contacted by part of gate / fence.

If you find that a safety device is causing the operator to remain open (through a defect or other problem), leave the gate powered off until the device can be aligned, repaired or replaced. Do Not operate the gate with any of the safety devices disconnected.


  • If the gate is open and attempts to close, but before it reaches the fully closed position it reverses back to the open position again:
    • One of the safety devices for the gate may be false detecting:
      • If the operator uses a safety loop, an incorrect loop installation may cause the detector to sense the metal of the gate or the operator and trigger the detector. Refer to the page Safety Loop Installation for details.
      • If the operator uses a beam, vibrations from the gate moving may cause the beam to shake and briefly go out of alignment.
    • The Overlimit current detection circuitry of the gate may be sensing a high current draw. This is part of the UL-325 specifications for gates, and helps provide entrapment protection. It is designed to detect if the gate has a sudden current "spike" when it is in motion, as this can signal that someone has become trapped between the gate and a solid object (like the fence). In these situations the circuit will cause the gate to reverse direction. Some models of operators will stop, reverse a short distance, and then stop and wait for another input. If your operator is equipped with such a circuit, it will have an adjustment to raise or lower the level of current that it senses. As a gate ages, it may take more current to move it verses when it was first installed, so this adjustment may need tweaking. It should be adjusted so that when the gate is closing, if you obstruct the gate suddenly (example: By pushing against it sharply with your hand), it should stop and reopen. If it does not, the sensitivity should be increased so that it does.


Chain Alignment

A properly set up chain on a gate operator should have the following properties.

  • The chain should have about 3" of slack in it. It should not be too tight, or be so loose that it whips up and down as the gate is moving.
  • When viewed from the top, the chain should pass through the gate operator in a straight line, and not be bowed out towards the operator.
    Gatechaintop.png

  • The chain connection points should not get any closer than 24 inches to the operator in either the fully open or closed positions.
  • When viewed from the side, the chain connection points should be level with the guide pulleys in the gate operator (This will depend on the type of operator used by your site).
    Gatechainside.png


Notes:

  1. Several different brands of gate operators use the same 1/2 HP motor in their products.
  2. This reset switch may be hard to operate with a fingertip. Sometimes it requires a tool to press in sufficiently. If the motor is still hot, this overload may not reset until the motor is allowed to cool off.
  3. A correctly balanced slide gate should be able to be pushed easily open and closed with one hand (with the chain disconnected). If you have to push the gate very hard to get it to move, it's not balanced correctly. A correctly balanced lift gate will, when it's clutch is released, settle into a position halfway between open and closed.
  4. Some examples of a bad installation of a loop can be incorrect placement (too close to metal objects or the gate itself) failure to twist the wires from the corner of the loop back into the gate operator, wrong kind of wire used, etc.
  5. Loop detectors for gates are set up to "Fail Safe" if the detector or loop goes bad or loses power. This will hold the gate open.