The OMH is the medium-duty jackshaft with the Hoist-a-matic chain hoist built in. It is the unit we find most often on light-commercial and warehouse doors around Metro Vancouver where the ceiling has to stay clear and staff need to move the door by hand when the power drops.
What This Operator Suits
Standard, high and vertical lift sectional doors, small rolling doors and grilles, and rolling sheet doors. It wall, hood or shelf mounts on either side of the opening.
What sets the OMH apart from its sibling the OMJ is the Hoist-a-matic: a patented self-engaging chain hoist that needs no floor level engagement device to operate. On a door that staff genuinely have to open during an outage, a shipping bay that can’t wait for power, a strata garage with no other vehicle exit, that hoist is the whole reason to choose this model over the cheaper OMJ.
Specification
| Item | Detail |
|---|---|
| Motor | 1/2 HP, 120V single-phase, intermittent-duty, open type with instant reverse and internal automatic reset thermal overload protection (60Hz). Removable without affecting limit switch settings. |
| Output shaft speed | 36 rpm |
| Drive | #41 roller chain with 41B12 sprocket; door sprocket selected for 6″/s to 12″/s travel |
| Reduction | First step 5L/B V-belt, additional steps by chain and sprockets. 5/8″ input shaft, 1″ output shaft with 1/4″ keyway, precision ball bearings |
| Brake | Mechanical brake |
| Manual operation | Hoist-a-matic self-engaging chain hoist with automatic cut-off and electrical interlock. Hoist on right is standard, handing must be specified when ordering. |
Duty rating in plain terms. Medium duty. 1/2 HP on 120V single-phase means it runs off a standard circuit, which is part of why it is so common in older buildings that never had three-phase run to the door.
What Fails on This Unit
The friction clutch on the input shaft is the wear item, and it is adjustable from outside the housing without opening anything up. On a medium-duty door that means a slipping OMH is often an adjustment call rather than a parts call, worth knowing before anyone quotes you a replacement.
The second thing we see is hoist handing. The hoist is supplied on the right as standard, and if a unit was ordered without specifying handing for the opening it sits in, the chain ends up somewhere awkward. That is an ordering problem, not a fault, but it turns up as a complaint.
Manufacturer Documents
Originals from Manaras-Opera, useful if the paperwork for a unit already in your building has gone missing:
Choosing Between Models
The OMJ is the same operator with a floor level disconnect instead of the hoist. If nobody needs to hand-crank the door, the OMJ costs less. 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 OMH?
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.