Liftmaster BG790 Barrier Gate Parts
LiftMaster BG790 Replacement Parts
Genuine LiftMaster replacement parts for the BG790 barrier gate operator — the long-arm, counterweighted barrier operator for wider lanes, using a two-shaft crank drive with a chain-driven intermediate shaft. Use the exploded diagram above to find the key number for the part you need, then click any part number in the table below.
Order the motor by supply voltage. Ref 35 splits three ways: K20-1050B-2P for 115/230V single phase, K20-3050B-4P for 230/460V three phase, K20-3050M-5 for 575V three phase. Read the motor data plate.
Two shafts, not one. The BG790 has a main shaft (K11-8061) and an intermediate shaft (K11-8062) linked by the sprocket set. The BG770 has only one shaft — check which you are replacing.
Counterweighted arm. The K10-8056M counterweight and 10-8055 clamp balance the long arm. If the arm is slow to lift or slams down, check these before the drive.
Not a BG790? The smaller BG770 uses a different cover, shaft, crank set and belt. The contactor, transformer, relays, terminal blocks, bearings, rod ends and overloads are common to both.
Common BG790 Repairs
| Symptom | Usual cause | Parts to check |
|---|---|---|
| Motor runs but the arm does not move | Drive belt slipping or glazed | K16-8002 belt, K17-2001 and SW008 pulleys |
| Arm lifts slowly or slams down | Counterweight out of adjustment or loose | K10-8056M counterweight, 10-8055 clamp |
| Arm overruns or stops at the wrong angle | Limit switch or limit collar slipping | K23-2017 limit switch, K91-G0122 limit collar |
| Trips the overload repeatedly | Overload sized wrong for the motor | K25-2006, K25-2008, K25-2010 overloads |
| Operator dead, nothing at the panel | Transformer, contactor or on/off switch | K21-3260-1 transformer, K03-8024-K contactor, K23-2761 switch |
| Knocking or lost motion in the linkage | Crank set or rod ends worn | K07-8063 and K07-8064 cranks, K12-8033 / K12-8034 rod ends |
| Chain noise or slack between the shafts | Sprockets worn | K15-5032 and 15-50B12LGH sprockets |
| Play at the shafts | Flanged bearings worn | K12-8032 flanged bearing, K11-8061 / K11-8062 shafts |
Barrier Gate Repair & Service Parts
| Ref | Part # | Description |
|---|---|---|
| 1 | K03-8024-K | Reversing Contactor |
| 2 | K07-8007 | Arm Hub |
| 3 | K07-8058 | Crank Link |
| 4 | K07-8063 | Upper Crank |
| 5 | K07-8064 | Lower Crank |
| 6 | K10-8014 | Switch Bracket |
| 7 | K10-18022 | Top Cover |
| 8 | 10-8017 | Access Panel |
| 9 | K10-8021 | Control Panel |
| 10 | K10-8026 | Bearing Plate |
| 11 | 75-32001 | Cover, BG790 |
| 12 | 10-8055 | Counterweight Clamp |
| 13 | K11-8061 | Main Shaft |
| 14 | K12-8032 | Flanged Bearing, 4 Bolt, 1-1/2" |
| 15 | K12-8033 | Female Rod End, Right-Hand |
| 16 | K12-8034 | Female Rod End, Left-Hand |
| 17 | K15-5032 | Sprocket, 50B32T, 1-1/2" x 1/2" |
| 18 | 15-50B12LGH | Sprocket, 50B12, 1" |
| 19 | K16-8002 | Belt, 4L330 |
| 20 | K17-2001 | Pulley, 8" x 5/8", 4L Belt |
| 21 | SW008 | Reducer Pulley, 2", 5/8" Bore |
| 22 | K21-3260-1 | Transformer, 120/208/230/460, 60VA |
| 23 | K23-2017 | Limit Switch |
| 24 | K23-2761 | On/Off Switch, 125/250V, 16A |
| 25 | K23-8001 | Toggle Switch and Outlet Combination |
| 26 | K24-24-1 | Relay, 24V, 10A |
| 27 | K24-24-6 | Relay, 3PDT, 24V, 10A |
| 28 | K32-8002 | Gear Reducer |
| 29 | K42-110-2 | Terminal Block, 10 Position |
| 30 | K42-3608 | Terminal Block, 8 Position |
| 31 | K10-8056M | Counterweight |
| 32 | K84-DT-06 | Nut, 6-32, Tinner-Man |
| 33 | K80-8001 | Lock and Key Kit |
| 34 | K11-8062 | Intermediate Shaft |
| 35 | K20-1050B-2P | Motor, 1/2 HP, 115/230V, 1PH, BM |
| 35 | K20-3050B-4P | Motor, 1/2 HP, 230/460V, 3PH, BM |
| 35 | K20-3050M-5 | Motor, 1/2 HP, 575V, 3PH, BM/CF |
| 36 | K25-2006 | Overload, 6A |
| 36 | K25-2008 | Overload, 8A |
| 36 | K25-2010 | Overload, 10A |
| 36 | 25-4001-5 | Relay, Overload, 1.0-1.6A — no longer available |
| 36 | 25-4002-5 | Relay, Overload, 1.6-2.5A — no longer available |
| 37 | K24-115-1 | Relay, 120V, 10A |
| 37 | K24-230-5 | Relay, 3PDT, 230V, 7A |
| 38 | K91-G0122 | Limit Collar |