The OTH is the heavy-duty low headroom trolley for industrial standard lift sectional doors. The OTBH is the same unit with a drum-band solenoid brake added. They share a specification, so they are covered together.
What This Operator Suits
Industrial standard lift sectional doors, particularly where headroom is tight, that is what the low headroom design is for.
The brake is the deciding factor between them. Without one, a heavy door can drift after the operator stops. The OTBH’s drum-band solenoid brake holds it. As door weight climbs, or where a drifting door would be a hazard, specify the OTBH.
Drive detail worth knowing when specifying or repairing: #48 (#410) full roller chain on the 1/2 HP build, #41 on the 3/4 and 1 HP builds. Dual 12-gauge pre-drilled galvanized tracks are provided for doors up to 12 ft, with longer tracks available.
Specification
| Item | Detail |
|---|---|
| Motor | 60Hz high starting torque, continuous-duty, single-phase capacitor start or 3-phase, open drip proof, protected against overload. 50Hz 220V 1-phase and 380V 3-phase available |
| Reduction | 5L/B V-belt first step, additional step by #41 chain and sprockets. 5/8″ input shaft in precision ball bearings |
| Drive and trolley | #48 (#410) full roller chain on 1/2 HP; #41 on 3/4 and 1 HP. Dual 12-gauge galvanized tracks up to 12 ft |
| Brake | OTH: none. OTBH: electrically activated drum-band solenoid brake |
| Manual operation | Quick release disconnect arm for manual push-up operation |
| Limit system | Rotary oil-impregnated steel cams, commercial grade switches, self-lubricating bronze bushings. Stays in time through manual operation and after motor removal |
Duty rating in plain terms. Heavy duty, continuous-duty motor, the step up from the OMT.
What Fails on This Unit
On the OTBH, brake wear: coil or pawl, showing as drift after stop. On both, the quick release disconnect arm is a frequent false alarm, left disengaged, the motor runs and the carriage does nothing.
The limit system is a genuine strength here and worth understanding. Because the limit shaft stays in time through manual operation and even after the motor is removed, a door that suddenly stops in the wrong place usually needs the cams reset rather than any part replaced. Repeat drift points back at the door: binding track, worn rollers, or springs out of balance.
Manufacturer Documents
Originals from Manaras-Opera, useful if the paperwork for a unit already in your building has gone missing:
- Specification sheet (OTH / OTH-A.00)
- Specification sheet (OTBH / OTBH-A.00)
- Sell sheet (OTH)
- Sell sheet (OTBH)
- Dimension drawing (OTH/OTBH/OSL)
- Mechanical drawing
Choosing Between Models
The A.00 apartment versions of both are built for high-cycle strata parkade duty. 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
Manaras publish a full accessory range that pairs with this operator: monitored and non-monitored photoelectric cells, light curtains, electric and pneumatic sensing edges, interface modules, push-button and key switch control stations, pull switches, keypads and card readers, radio receivers and transmitters, and traffic light kits.
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.
- Accessory catalogue (PDF)
- Accessories and replacement components list (PDF)
- Radio Series 900 dip-switch compatibility chart (PDF)
- Radio Series 100 rolling code compatibility chart (PDF)
- Operator codes explained (PDF)
We stock the common wear items for the Opera and MEGA series, control boards, clutches, solenoid coils, limit switch assemblies and safety edges. Anything we do not carry we source through our distributor, and you will hear about a lead time before we attend rather than after.
Frequently Asked Questions
How do I confirm I have a OTH?
The model code is on the data plate on the operator housing. If the plate is unreadable, which happens on older units in damp parkades, send us a photo of the operator and we can usually identify it from the frame and drive layout.
Do you stock parts for it?
We carry the common wear parts across the Opera and MEGA series. Model-specific components come through our distributor, typically within two business days.
Is it worth repairing or should we replace it?
Clutches, brakes, boards, limits, safety devices and wiring are repairs. A seized gear reducer or a burnt-out motor on a very old unit is usually a replacement. We tell you which one you are looking at and why, rather than leading with a new-operator quote.
Can you service a unit we did not buy from you?
Yes. Most Manaras units we attend were installed by someone else, often years ago.
The door will not close but opens fine. Is the operator dead?
Almost certainly not. That is the classic monitored safety circuit symptom, a photo eye, light curtain or sensing edge that has failed or moved. Check the lenses are clean, the alignment is good, and nothing is parked in the beam before assuming the worst.