The MLT is the honest entry point of the Manaras trolley range: a medium-duty operator for smaller and low-cycling industrial standard lift sectional doors. Where the OTH/OTBH class covers hard-working commercial doors and the MGT covers heavy industrial ones, the MLT is what a small shop, a low-traffic warehouse bay or a strata utility door actually needs, without paying for duty rating the door will never use.
What This Operator Suits
Smaller industrial standard lift sectional doors that cycle a handful of times a day. The intermittent-duty motor is the tell: this is not a unit for a busy loading dock, and specifying it onto one is how operators die young. Maximum door height for the limit system is 14 ft.
Specification
| Item | Detail |
|---|---|
| Motor | 1/2 HP, 115V single-phase intermittent-duty, instant reverse, internal auto-reset thermal overload; removable without disturbing limit settings |
| Reduction | 4L/A V-belt first step, #410 chain and sprockets after; 5/8″ input shaft and 1″ output shaft on ball bearings |
| Output speed | 112 rpm for a door travel of 11″/sec |
| Trolley | #48 (#410) full roller chain drive; dual 12-gauge pre-drilled galvanized tracks for doors to 12 ft standard (14 ft max); cast aluminum trolley with chain tension adjuster |
| Clutch | Friction type on input shaft, adjustable from outside |
| Manual operation | Quick-release disconnect arm for manual push-up operation |
| Limits | Rotary cam limits, bronze-bushed shaft; stays in time through manual operation |
| Enclosure | Nema 1, hinged cover |
| Control | BOARD 070, monitored entrapment protection, ANSI/CAN/UL 325 compliant |
Duty rating in plain terms. Medium-duty, low-cycle trolley, the right size for the right door, wrong for a busy one.
What Fails on This Unit
The intermittent-duty motor’s thermal overload is the classic call-out: on a door that cycles more than the unit was specified for, the motor heats, the overload trips, and the door “randomly stops working” until it cools. That is not a defect, it is the operator telling you it is undersized for the traffic. Otherwise the V-belt (tension and glazing), the friction clutch and trolley track alignment are the routine service points. If a door has grown in traffic since the MLT went in, a new tenant, a busier operation, upgrading to an OTH/OTBH is usually cheaper than replacing burned MLT motors on repeat.
Manufacturer Documents
The step up is the OTH / OTBH trolley; the worm gear heavy-duty trolley is the MGT.
Choosing Between Models
If you are unsure which unit you have, the model code is on the data plate on the operator housing. Note the voltage and phase while you are there, and roughly how many cycles a day the door runs, those three facts decide most of what we would bring to a call.
See the full Manaras model reference for the whole range, or Manaras operator repair for service.
Parts and Accessories
Pairs with the full accessory range: photo eyes, light curtains and sensing edges, radio controls, control stations. One point that causes repeated confusion: on a UL 325 monitored circuit, a failed safety device makes the operator refuse to close. That is correct behaviour, not a malfunction. A door that suddenly will not close, with no other symptom, is very often a photo eye or sensing edge that has failed or drifted out of alignment.