Rail and chain parts shared across LiftMaster chain drive garage door openers. If you know your opener model, the model page will show you the exact parts for it — this page covers the rail assembly itself.
Measure your door, not your rail. Chains and rails are sold by door height, and the two must match. A 7 ft door takes the 7 ft rail and the 7 ft chain. If you are replacing a stretched chain only, you need the chain assembly at ref 5 — not a whole rail.
Rail Assembly Parts
| Ref |
Part Number |
Description |
| 1 |
004A1008 |
Master link kit — the links and pins that join the chain |
| 2 |
041A4813 |
Chain pulley bracket, sprocket type. Fits most LiftMaster chain drive rails |
| 3 |
041A2780 |
Chain pulley bracket — ATS, 2595 and 3595 models |
| 4 |
041A3489 |
Complete trolley assembly. Includes threaded shaft, nuts, washer, clevis pin, ring, master link and chain extension |
| 5 |
041D3484 |
Full chain assembly — 7 ft (2.1 m) door |
| 5 |
041D3483 |
Full chain assembly — 8 ft (2.4 m) door |
| 5 |
041D3485 |
Full chain assembly — 10 ft (3 m) door |
| 5 |
041A4554 |
Full chain assembly — 12 ft door, ATS models only |
| 6 |
83A11-2 |
Rail grease |
| — |
K144C0056 |
Cable idler pulley (not shown) |
Complete Rail Assemblies
If the rail itself is bent or the trolley track is worn, replace the whole assembly. T-rail and I-beam are not interchangeable — match what your opener already has.
| Type |
Part Number |
Description |
| T-rail |
1707LM |
One-piece T-rail — 7 ft (2.1 m) door |
| T-rail |
1708LM |
Complete chain drive rail assembly — 8 ft (2.4 m) door |
| I-beam |
3707CH |
Chain I-beam rail system — 7 ft (2.1 m) door |
| I-beam |
3708CH |
Chain I-beam rail system — 8 ft (2.4 m) door |
| I-beam |
3710CH |
Chain I-beam rail system — 10 ft (3 m) door |
| I-beam |
G3712RV |
I-beam rail assembly — 12 ft door |
| ATS |
CD1008 |
Chain I-beam rail, ATS units — 8 ft door |
| ATS |
CD1010 |
Chain I-beam rail, ATS units — 10 ft door |
| ATS |
CD1012 |
Chain I-beam rail, ATS units — 12 ft door |
| ATS |
CD1014 |
Chain I-beam rail, ATS units — 14 ft door |
Door Arms & Hardware
| Part Number |
Description |
| 178B35 |
Curved door arm section |
| 178B34 |
Straight door arm section |
| 041A8094 |
Door arm kit — curved and straight sections together |
| 41A2770-6 |
Installation hardware kit |
| L6950 |
Multi-purpose spray lube, green |
| L6960 |
Multi-purpose spray lube, blue |
While You're In There
| Part Number |
Description |
| 041-0136 |
Safety sensor kit, sending and receiving eyes. Replaces the older 41A5034 |
| 041B0873 |
Sensor sunblocker bracket — for sensors in direct sunlight |
| 041A3504 |
Antenna extender kit |
| 041A3504-1 |
Antenna extender kit with adapter |
