Linear Pro Access FM144 Bulldog Automatic Gate Lock
The FM144 Bulldog automatic gate lock is used on swing gate systems that need positive locking in the closed position. A swing gate operator arm is designed to move the gate, but wind load, animals, slope pressure, or people pushing on the gate can place extra stress on the actuator and brackets. A properly installed automatic lock helps hold the gate closed so the opener is not the only component resisting that force. This lock is commonly used with GTO / Linear Pro / Mighty Mule low-voltage swing gate systems that support an automatic lock output. It is especially important to verify compatibility and sequencing on dual gates, because the locked leaf, primary leaf, and secondary leaf must move in the correct order to prevent binding or board damage. The FM144 is not a pedestrian access lock and should be matched to vehicular swing gate hardware and the correct controller wiring.
Compatible With
- Linear Pro Access FM144 automatic gate lock applications
- GTO FM144 automatic gate lock applications
- Mighty Mule FM143 related automatic gate lock applications
- Select GTO / Linear Pro / Mighty Mule DC swing gate operators with compatible lock outputs
- Single swing gate systems needing added closed-position security
- Dual swing gate systems when the primary/secondary sequencing is set correctly
- Pull-to-open swing gate installations when lock mounting and receiver alignment are correct
Features and Specifications
| Manufacturer | Linear / GTO |
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| Product Type | Automatic vehicular gate lock |
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| Part Number | FM144 |
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| Application | Locks swing gate in closed position |
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| Compatible Operator Type | Select DC swing gate operators with lock output |
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| Related Lock Type | Mighty Mule FM143 related automatic gate lock |
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| Included Components | Lock components vary by supplier kit |
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| Safety Monitoring | Not an entrapment protection device |
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| Notes | Dual gates require correct primary/secondary sequencing |
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Also Known As / Related Part Numbers
- FM144
- GTO FM144
- Linear FM144
- Bulldog automatic gate lock
- Automatic gate lock for GTO / Linear Pro
- Mighty Mule FM143 related lock reference
- Related service part: PC board for FM144 / FM143 automatic gate lock
- Not the same item as FM145 pedestrian Bulldog lock
Technician Note
Dual gate sequencing matters. The gate leaf with the lock must be timed so the lock releases before movement and the correct leaf closes last. Incorrect sequencing can damage the lock, brackets, or control board.
Before Ordering
- Confirm the opener has a compatible automatic lock output.
- Confirm the gate is a swing gate and has room for the lock and receiver.
- Check whether the system is single or dual and how the primary leaf is assigned.
- Inspect gate sag, stop position, and latch alignment before installation.
- Do not confuse FM144 automatic gate lock with FM145 pedestrian gate lock.
Professional Advisory
Automatic locks are part of a moving gate system. A qualified gate technician should verify wiring, lock timing, gate stops, and safety devices, especially on dual gate installations.
Product Questions and Answers
What does the FM144 do?
The FM144 locks a compatible swing gate in the closed position so the operator arm is not the only component resisting wind, pressure, or forced movement.
Is FM144 the same as FM145?
No. FM144 is an automatic lock for vehicular swing gates. FM145 is the Bulldog pedestrian gate lock for walk-through gates.
Can FM144 be used on a slide gate?
It is generally associated with swing gate lock applications. Slide gate locking should be matched to slide gate hardware and the operator design.
Why is dual gate sequencing important?
The lock must release before the locked leaf moves and the primary/secondary leaves must close in the correct order to avoid binding or damage.
What should I check if the lock chatters or will not release?
Check battery voltage, lock wiring, gate alignment, receiver position, control-board lock output, and whether the gate is pushing against the lock under load.
